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On the Great Filter, existential threats, and griefers

So IO9 ran a piece by George Dvorsky on ways we could wreck the solar system. And then Anders Sandberg responded in depth on the subject of existential risks, asking what conceivable threats have big enough spatial reach to threaten an interplanetary or star-faring civilization.

This, as you know, is basically catnip for a certain species of SF author. And while I've been trying to detox in recent years, the temptation to fall off the wagon is overwhelming.

The key issue here is the nature of the Great Filter, something we talk about when we discuss the Fermi Paradox.

The Fermi Paradox: loosely put, we live in a monstrously huge cosmos that is rather old. We only evolved relatively recently -- our planet is ~4.6GYa old, in a galaxy containing stars up to 10GYa old in a universe around 13.7GYa old. Loosely stated, the Fermin Paradox asks, if life has evolved elsewhere, then where is it? We would expect someone to have come calling by now: a five billion year head start is certainly time enough to explore and/or colonize a galaxy only 100K light years across, even using sluggish chemical rockets.

We don't see evidence of extraterrestrial life, so, as economist Robin Hanson pointed out, there must be some sort of cosmic filter function (The Great Filter) which stops life, if it develops, from leaving its star system of origin and going walkabout. Hanson described two possibilities for the filter. One is that it lies in our past (pGF): in this scenario, intelligent tool-using life is vanishingly rare because the pGF almost invariably exterminates planetary biospheres before they can develop it. (One example: gamma ray bursts may repeatedly wipe out life. If this case is true, then we can expect to not find evidence of active biospheres on other planets. A few bacteria or archaea living below the Martian surface aren't a problem, but if our telescopes start showing us lots of earthlike planets with chlorophyll absorption lines in their reflected light spectrum (and oxygen-rich atmospheres) that would be bad news because it would imply that the GF lies in our future (an fGF).

The implication of an fGF is that it doesn't specifically work against life, it works against interplanetary colonization. The fGF in this context might be an emergent property of space exploration, or it might be an external threat -- or some combination: something so trivial that it happens almost by default when the technology for interstellar travel emerges, and shuts it down for everyone thereafter, much as Kessler syndrome could effectively block all access to low Earth orbit as a side-effect of carelessly launching too much space junk. Here are some example scenarios:

Simplistic warfare: As Larry Niven pointed out, any space drive that obeys the law of conservation of energy is a weapon of efficiency proportional to its efficiency as a propulsion system. Today's boringly old-hat chemical rockets, even in the absence of nuclear warheads, are formidably destructive weapons: if you can boost a payload up to relativistic speed, well, the kinetic energy of a 1Kg projectile traveling at just under 90% of c (τ of 0.5) is on the order of 20 megatons. Slowing down doesn't help much: even at 1% of c that 1 kilogram bullet packs the energy of a kiloton-range nuke. War, or other resource conflicts, within a polity capable of rapid interplanetary or even slow interstellar flight, is a horrible prospect.

Irreducible complexity: I take issue with one of Anders' assumptions, which is that a multi-planet civilization is largely immune to the local risks. It will not just be distributed, but it will almost by necessity have fairly self-sufficient habitats that could act as seeds for a new civilization if they survive. I've rabbited on about this in previous years: briefly, I doubt that we could make a self-sufficient habitat that was capable of maintaining its infrastructure and perpetuating and refreshing its human culture with a population any smaller than high-single-digit millions; lest we forget, our current high-tech infrastructure is the climax product of on the order of 1-2 billion developed world citizens, and even if we reduce that by an order of magnitude (because who really needs telephone sanitizer salesmen, per Douglas Adams?) we're still going to need a huge population to raise, train, look after, feed, educate, and house the various specialists. Worse: we don't have any real idea how many commensal microbial species we depend on living in our own guts to help digest our food and prime our immune systems, never mind how many organisms a self-sustaining human-supporting biosphere needs (not just sheep to eat, but grass for the sheep to graze on, fungi to break down the sheep droppings, gut bacteria in the sheep to break down the lignin and cellulose, and so on).

I don't rule out the possibility of building robust self-sufficient off-world habitats. The problem I see is that it's vastly more expensive than building an off-world outpost and shipping rations there, as we do with Antarctica -- and our economic cost/benefit framework wouldn't show any obvious return on investment for self-sufficiency.

So our future-GF need not be a solar-system-wide disaster: it might simply be one that takes out our home world before the rest of the solar system is able to survive without it. For example, if the resource extraction and energy demands of establishing self-sufficient off-world habitats exceed some critical threshold that topples Earth's biosphere into a runaway Greenhouse effect or pancakes some low-level but essential chunk of the biosphere (a The Death of Grass scenario) that might explain the silence.

Griefers: suppose some first-mover in the interstellar travel stakes decides to take out the opposition before they become a threat. What is the cheapest, most cost-effective way to do this?

Both the IO9 think-piece and Anders' response get somewhat speculative, so I'm going to be speculative as well. I'm going to take as axiomatic the impossibility of FTL travel and the difficulty of transplanting sapient species to other worlds (the latter because terraforming is a lot harder than many SF fans seem to believe, and us squishy meatsacks simply aren't constructed with interplanetary travel in mind). I'm also going to tap-dance around the question of a singularity, or hostile AI. But suppose we can make self-replicating robots that can build a variety of sub-assemblies from a canned library of schematics, building them out of asteroidal debris? It's a tall order with a lot of path dependencies along the way, but suppose we can do that, and among the assemblies they can build are photovoltaic cells, lasers, photodetectors, mirrors, structural trusses, and their own brains.

What we have is a Von Neumann probe -- a self-replicating spacecraft that can migrate slowly between star systems, repair bits of itself that break, and where resources permit, clone itself. Call this the mobile stage of the life-cycle. Now, when it arrives in a suitable star system, have it go into a different life-cycle stage: the sessile stage. Here it starts to spawn copies of itself, and they go to work building a Matrioshka Brain. However, contra the usual purpose of a Matrioshka Brain (which is to turn an entire star system's mass into computronium plus energy supply, the better to think with) the purpose of this Matrioshka Brain is rather less brainy: its free-flying nodes act as a very long baseline interferometer, mapping nearby star systems for planets, and scanning each exoplanet for signs of life.

Then, once it detects a promising candidate -- within a couple of hundred light years, oxygen atmosphere, signs of complex molecules, begins shouting at radio wavelengths then falls suspiciously quiet -- it says "hello" with a Nicoll-Dyson Beam.

(It's not expecting a reply: to echo Auric Goldfinger: "no Mr Bond, I expect you to die.")

A Dyson sphere or Matrioshka Brain collects most or all of the radiated energy of a star using photovoltaic collectors on the free-flying elements of the Dyson swarm. Assuming they're equipped with lasers for direct line-of-sight communication with one another isn't much of a reach. Building bigger lasers, able to re-radiate all the usable power they're taking in, isn't much more of one. A Nicoll-Dyson beam is what you get when the entire emitted energy of a star is used to pump a myriad of high powered lasers, all pointing in the same direction. You could use it to boost a light sail with a large payload up to a very significant fraction of light-speed in a short time ... and you could use it to vapourize an Earth-mass planet in under an hour, at a range of hundreds of light years.

Here's the point: all it takes is one civilization of alien ass-hat griefers who send out just one Von Neumann Probe programmed to replicate, build N-D lasers, and zap any planet showing signs of technological civilization, and the result is a galaxy sterile of interplanetary civilizations until the end of the stelliferous era (at which point, stars able to power an N-D laser will presumably become rare).

We have plenty of griefers who like destroying things, even things they've never seen and can't see the point of. I think the N-D laser/Von Neumann Probe option is a worryingly plausible solution to the identity of a near-future Great Filter: it only has to happen once, and it fucks everybody.

What other fGF scenarios can you think of that don't require magical technology or unknown physics and that could effectively sterilize a galaxy, starting from a one-time trigger event?

678 Comments

1:

It seems like any civilization with that kind of goal in mind would be better served by ye olde fashioned VN probes. They can set up shop in every system they can reach and nuke anything that looks intelligent within a few hours of it poking its head over the barricades. Lasing single planets from lightyears away seems like an unreliable approach when it only takes a century or two for a civ to go from broadcasting their first radio transmission to hitting up other stars.

2:

Sorry for tempting you off the wagon, Charlie. But the catnip is lovely!

I think the griefer scenario is a subset of a bigger set of scenarios, where people launch von Neumann probes to impose some rule set on the universe. If you don't like it, you better launch counter-probes ("police probes", but one civ's police is another civ's griefers). One scenario I am turning into a paper is old civs aestivating until late cosmological eras where computation is very cheap, and leaving behind a infrastructure of robotic equipment to (1) protect them, (2) prevent anybody/anything from wasting "their" resources.

Overall, this whole bundle of scenarios have some fun properties: they only require a certain tech base, so if something prevents them it must prevent the minimal tech base. If it is hard to prevent (maybe the police probes cannot see your basement labs) it looks hard to keep stable from defectors and infiltrators unless all resources get locked up in probes, stockpiles and battling hardware. It also doesn't require strong cultural convergence to get uniform volumes of space: if the Zorgons set up a policed zoo in our quadrant, the griefer Yurkians (or rather, one of their teenagers) kill everybody in the next quadrant over, and the Virgo cluster is run by the ancient Xi waiting for year trillion, each of these regions will be quiet without any assumptions what advanced beings want or aim for.

3:

If we postulate griefing von Neumann machines, seed the system you want to grief with replicators. As long as they, on average out-replicate the local life, it'll be a long and horrible slog.

In "out-replicate" I do include attrition from the local life form.

From the griefer civilisation side, there is a possible advantage to doing it this way, because the local life form will spend quite a while knowing they're being griefed whereas the "simple" interstellar laser is relatively quick.

Of course, there is a distinct risk that prolonged exposure may show an informatics approach to stopping the replicators, so...

4:

Tangentially related, one of the author of an SF series that has such a great filter (computer life forms wipe out organic ones) seems to like the current griefers who are messing up the Hugos.

It would be somewhat entertaining if we were the griefers, landed by automatic probe 50k years ago. (Of course all the evidence is that we evolved here)
But that leads to the question, when is a griefer system that uses VN machines distinguishable from a local life form, especially if the VN have been evolving for the last two billion years?

5:

We extend the VN probe scenario and have the first tech civilization (The Elder Race) in each galaxy do the who H+ thing and turn it's entire galaxy into computronium. This happened billions of years ago in "our" galaxy, and what we are living in now is an evolutionary simulation running in a few tonnes of computronium where the primordial Earth used to be.
Consider it a question of both scientific interest and ethics to the Elder Race.
And because they know that this happens as a matter of inevitability in the real universe, they make sure that each burgeoning civilization does not encounter any others. Until the time is right when they newcomers are evaluated and judged. Then it's either deletion or an invitation to take a step in reality for tea and biscuits with our custodians/makers.

6:

@Charlie: Robin Hanson, not Henson.

7:

So this dials up the speculation a few notches but a possible fGF could be a scientific discovery that provides the same benefits of interstellar travel without requiring it. Important modifier: the edges of this discovery lie along multiple paths that would need to be taken in order to develop interstellar technology.

As an example; a new theory of high energy/exotic physics (useful if you want an interstellar rocket) that makes it possible to construct wormholes. But these wormholes don't travel within our universe but connect to other ones. Third and final point to put the last nail in the coffin for interstellar travel, it's possible to influence these wormholes to connect to a universe with desirable physical laws.

The consequence of this is that before any civilisation gets to the point of sending out rockets they find it much easier to colonise into much more hospitable universes.

8:

Or something simpler - an easy way of turning matter into energy. So easy that most individuals in a hitech society can do it.

9:

"What other fGF scenarios can you think of that don't require
magical technology or unknown physics and that could effectively
sterilize a galaxy, starting from a one-time trigger event?"

This is slightly invalid, because it assumes unknown physics, but
we don't actually have reliable (let alone direct) evidence that
physical constants or laws are constant over very long time or very
long distances. It wouldn't require much of a glitch or change to
eliminate the very complex systems needed for life, let alone
multicellular life. Most SF that uses that assumes that we could
survive such conditions, but my understanding of modern
biochemistry is that it would be implausible.

10:

Episode of the Outer Limits addressed this question. It was called "Final Exam"

https://www.youtube.com/watch?v=SsZsfXNPHec

11:

I suppose it depends on what level of thoroughness and at what level of interception you are looking for. "Kill off the dominant life form and 85% of life on the planet before they have opposable thumbs" is fairly simple, you just have your probes toss asteroids at the dinosaurs. If you are worried about handling a more technologically advanced species, then it gets more complicated - Charlie's scenario wouldn't do much if, say, they had an asteroid belt civilization sufficiently established that it could sustain itself. I'd say pointing the beam at the star and triggering a massive eruption and destabilization of the stellar cycle would be better. Though that wouldn't help with a europa style planet - the search criteria are wrong and it has shielding in the form of a gas giant.

Looking at things like the Open Source Ecology and their Global Village Construction Set, the takeaway is that it is possible to simplify advanced infrastructure down to where it can be built incredibly simply. The less acknowledged part is that advanced infrastructure tends to have some nasty second order effects - second order effects get you every time, we are learning that the hard way with Global Warming - we just don't mention that when talking some of this stuff because, having the advanced infrastructure elsewhere, we are aware of these and how to take steps.

But consider if you didn't know about all the bad things that result from some of advanced technologies. That's my suggestion - use VN probes to create a series of repeaters that hand out nifty "civilization boosters", but don't come with "Warning: Choking Hazard, keep away from children under 5" label. Easy to build, tempting to use, but with incredibly damaging secondary effects. As in, what if someone had given the plans of "how to build your own nuclear reactor" to Victorian England, with the notes "Free Energy!". Of course, the designs were for a supercritical reactor design, left off the need for shielding, forgot to mention the use of boron in stopping meltdowns, but did highlight that "oh yeah, the more fuel you toss in before you crank it up, the longer before you need to refill it, and that step is expensive". It isn't that hard to think of poorly implemented advances that have had disastrous consequences for civilization (eg first round of modern globalization giving the Spanish flu the scope it did), the issue would just be dialing that up to 11

Of course, if I'm going with this plan, I may as well go the full Peter Watts and have the secondary effect be that it spreads my civilization

12:

Step 1: Identify planets with atmosphere (we presume that 99% of life requires this).

Step 2: Target planet and mess with magnetic field / reconnection at distance.

Step 3: Watch their local star CME the planet.

Step 4: Planet is either sterile or severely crispy or even just had a bad case of the disruptive to DNA sunburn. You're only aiming to disrupt higher organisms anyhow.

Step 5: Identify your next planet.


Due to various factors, I'll let you examine the science involved, but it's all currently theoretically possible. Requires a lot less energy production than a gamma burst as well.


Note: this is known in the business as severely impolite and generally not how things are done.

13:

Oops, somehow I misread this requirement:

What other fGF scenarios can you think of that don't require magical technology or unknown physics and that could effectively sterilize a galaxy, starting from a one-time trigger event?

14:

The thing left out above seems to be civil war. As weapons get more destructive, civil war becomes more likely to destroy all participants. And it may be quite difficult to handle a high velocity mass targeted at your home sites. It would need to be target seeking, but I don't see that as a major problem, even if you get up to a respectible fraction of C, light will be faster, so you can use radar, perhaps UV radar, to do targeting. Break into multiple independently targeted missles on approaching the system which only need to be adjustable enough to refine the targeting. One missle should take out all be a tiny fraction (shielded by the sun) of the large inhabited structures.

I am assuming not FTL capability, and that star ships need to be quite large, and a few other (reasonable) things. But given the time lage between launch and arrival, the launching planetary civilization could well have been destroyed before the arrival of the destruction. (Yes, I swiped most of this from Iron Sunrise.)

So I think civil war would be quite likely to kill off all participants in a really high tech society. The question would be "How could such a civilization come to be in the first place?". It seems to me that communication lag would mean that there couldn't be any unitary civilization, but only an aggregation of independent civilizations with some original root. And that many of them would be living in mobile habitats between the stars, browsing on free planets and asteroids. That kind of thing could only be wiped out (and then not reliably) by some sort of von Neuman replicator, analogous to Saberhagen's Berserkers, but done a bit more carefully. (Well, he made the basic design what 20? 40? years ago.)

15:

The interstellar lasers would be pretty thorough, but there is also a risk of danger to the species that implements them. They would need to be pretty certain that such weapons wouldn't end up accidentally targeting them at some point, over the course of millions of years. There's also a time lag problem -- if these things are a couple hundred light years apart there could be several centuries of delay between detection and extermination. A fast developing species may escape...

A similar but less dangerous scenario would be seeding the asteroid belts or comet belts of various systems with sleeper machines, that could redirect small celestial bodies toward worlds if certain criteria are met. Though admittedly I would think our current level of civilization would be a good trigger, and we haven't seen anything like that.

Of course, there are some other scenarios too that don't require hostile filters. It could just be that there is some sort of "transcendence" that species work out before they move outside of their home system. And it would take a special species that was too dumb to transcend but smart enough to travel between stars in order for the galaxy to be colonized.

Or we may be making some wrong assumptions about alien civilizations and their habitats. Perhaps our sort of star is actually very bad for civilization, and all the other intelligent life has developed around red or brown dwarves. They wouldn't consider colonizing our star any more than we would look toward planets around blue supergiants.

It's also possible that there was some sort of past filter that is now gone. And we are the first intelligent species since that...

16:

I've thought about some similar scenarios too.

One is that this is a simulation, one where the first species to colonize everything is now examining what would have happened on various worlds if they were left alone. The real Earth was colonized a billion years ago...

The other is that there is an infinite number of universes, and we just happen to be in the universe where by pure chance no other species evolved close enough for us to detect. And in universes where they did evolve, humans don't exist because our planet was colonized long ago.

17:

Paul McAuley, Little Lost Robot.
Although in that story "Griefer" culture sent the material destroyer itself, not the seed-egg-recipe, but it was somewhat self-sustaining and self-repairing, in some degree.

18:

Well, if you take the multiverse seriously then we are inevitable. It is also inevitable that we occupy a section of it where no potential competitors have arisen, or we would not be here. Anthropic Principle

19:

Yeah. I'll admit that it is also a sort of non-answer. Because in a sufficiently large multiverse all of the answers are correct. There's one where we're a simulation, one where we lucked out and are the first in our area, one were the filter wiped out those before us, and one where a high powered laser is on its way...

20:
But suppose we can make self-replicating robots that can build a variety of sub-assemblies from a canned library of schematics, building them out of asteroidal debris?

That might be the issue there - perhaps the "complexity" argument applies to interstellar robotic exploration as well, such that you need a decent industrial infrastructure to build interstellar spacecraft (or a fleet of them) that can actually survive a trip to even the nearest stars under slow speed. The devil could very well be in the engineering details of this, sort of like how fusion power turned out to be way, way harder than predicted, with particular problems in scaling it to a useful size.

You'd only need to couple that with a very small number of space-faring-capable civilizations in a galaxy to get the Fermi Paradox, especially since a smaller number makes it more likely that some of them could go down non-expansionary paths by pure chance (like wiring themselves for pleasure and becoming completely sedentary once they figure out how to do it, or manipulating their own brains/minds with technology to be more comfortable in a static civilization).

21:

I'm not so sure the ass-hat griefers have to be alien, given the Hugo awards situation and other recent geo-political situations with an aim to return to the dark ages. Is it perhaps inherent in civilization itself that it tends towards imbalance and then to get wobbly and crash most of the time? Equality and balance or what-have-you being extremely difficult to attain and then maintain.

22:

There's also Larry Niven's World of Tiers theory that everything beyond a few light years away is only a projected simulation of a large universe---if we're in a small one, there's no Fermi paradox.

23:

They would need to be pretty certain that such weapons wouldn't end up accidentally targeting them at some point, over the course of millions of years.

That's not really much of an argument against it, though, because it relies on the idea that sufficiently advanced technology is accompanied by sufficiently advanced and widespread wisdom. All it takes is one griefer civilization (or subset thereof) that thinks they can avoid the danger to get things going.

24:

Let's say the self-replicating robots are benign. They never attack a civilization. They just quietly spread through the galaxy building mines and factories and warehouses full of goods for their alien masters. Who of course are long gone, so the stuff keeps piling up. When we get to the outer planets we find that they have been converted into a vast array of alien hydrotherapy spas, dinette sets, recliners, golf clubs and wide-screen TVs. None of it works, the robots have not received any customer feedback for hundreds of millions of years, and the designs are strange. And we also find that we are stranded in our solar system because the robots have already used up all the readily accessible volatiles and metals. The galaxy is a wasteland of crummy malls and empty gas stations.

25:

Not Larry Niven though ...


" The World of Tiers is a series of science fiction novels by American writer Philip José Farmer. "

http://en.wikipedia.org/wiki/World_of_Tiers


Starts out as a really good series but then falls victim to the Philip José Farmers tendency for most of his male protaganists to morph into Tarzan.

http://www.depauw.edu/sfs/backissues/11/letson11.htm

26:

Or, worse than that ... we are caught up in an incomprehensibly vast Alien version of IKEA. We are meant to understand the instruction sheets and assemble STUFF and Bits and Pieces into all manner of useful things.

27:

DAMN! DAMN! DAMN" I've lost the little metal thingy gum which, when combined with the wot not, would have not only countered every Alien Artefact argument thus far advanced but also anticipated all future arguments so that I could Declare, HA! Got You! To all comers!

28:

The thing about Griefers is that they almost always have their shit come back on them. I mean its almost impressive how you can watch in real time how assholes create their own enemies.

29:

"Civil War" requires a unified polity, which requires magical technology at the least - even on an intrastellar level, consider the problems in trying to govern mars from earth. Even the communication has a very long lag, and actually sending in anything to enforce it is a problem. On an interstellar level it is billions of times worse.

30:

Didn't Asimov, in the later Foundation/Robot novels, have probes sent out to wipe out life on other worlds to make room for humans as an explanation for the lack of aliens? Or was that in the "Killer Bs" prequels?

31:

Maybe by the time a species is capable of expanding beyond one star system it's also been winnowed of exponential growth and hoarding tendencies. Yes, I know, "all it takes is one" to spam the galaxy with copies of itself. But that's a bit like saying that in a world where most social groupings have reached sub-replacement fertility that "it only takes one" super-fertile family to fill the Earth with its own descendants. Not all things that are theoretically possible will actually happen in a large-but-finite span of years.

For all we know, there are thousands of star faring species currently in our galaxy. And they no longer care about hoarding planets or stars. Most star-faring groups see megastructures as pointless tics, like filling your whole house with a collection of rubber bands. Every 10 million years or so some group in the galaxy will build a Dyson swarm or other megastructure that could be visible to human telescopes, but it's symptomatic of underlying instabilities and all the Dyson-builders to date have fallen into destructive internal conflict within another million years or so. The most recent one built in the Milky Way collapsed 6 million years ago.

Interstellar species left boom-bust reproductive dynamics behind ages ago. They have been space-faring for a long time, can't be threatened with extinction merely by destroying naturally occurring celestial bodies, and in any case if there are griefers out there then building megastructures is exactly the sort of thing that would draw attention. Better to be patient, cool, and quiet even if you've never witnessed evidence of galactic griefers. They can last nearly forever that way. The galaxy will look empty of space dwellers at interstellar distances unless you watch and record long enough to spot the rare, transient algal bloom of megastructures. And if a would-be galaxy spammer shows up in another stellar neighborhood, there's almost always a few quiet types already waiting and able to stop runaway expansion. Once the galaxy was seeded with a couple of early quiet watcher types there was no longer a chance of later species monopolizing the galaxy.

Humans haven't had telescopes long enough to see a megastructure within the Milky Way come into being. We might eventually spot them in distant, older galaxies where one of the first interstellar species really did go runaway, took over the entire galaxy, and kept the megastructures for a long time. Without closer examples to examine in detail it might be really difficult to distinguish distant galactic scale engineering from Yet Another Unsolved Mystery of Cosmology, though. It could be that our own solar system already has watchers from a half dozen interstellar species in it, they've been here for at least 30 million years, and we won't know for decades yet because our telescopes can't pick them out from the background of other cool 20 meter objects. Perhaps even longer than that if they really wanted to stay hidden. How long could modern electronic recording devices remain undetected (including looking right at it but not understanding what you see) if they were used to conduct field wildlife observations of 15th century London?

32:

You're talking about interstellar civil war, but I don't think we need to get anywhere near that far before internal conflict becomes an existential threat, even assuming we get over the threat of nuclear war. Technology keeps advancing, and people find all sorts of unexpected and alarming uses for it. (Who would have guessed, not so many years ago, how vulnerable the world's infrastructure would be to, of all things, a breakthrough in prime factorization?) We've all read and watched cheesy sci-fi and spy-fi yarns about a mad genius threatening to destroy the world if his demands aren't met. But how long will it be before technology advances (if that's the right word for it) to the point where a single pissed-off individual really could have the power to end civilization?

33:

So this dials up the speculation a few notches but a possible fGF could be a scientific discovery that provides the same benefits of interstellar travel without requiring it.

That's the gun on the Merchant Princes mantlepiece -- trigger is definitively pulled in book 9.

34:

Or shorter: the Fermi Paradox dates from 1950. That was still the (late) age of colonialism and before hormonal contraception, before human population growth had peaked. The assumption that population dynamics of space faring technological civilizations match those of e.g. yeast thrown into a big vat of sterile nutrient broth is a very big and now-dated assumption. Maybe the great filter that stops species from spamming the galaxy with themselves is already in our past and it's a blessing rather than a hazard: it's named the Sexual Revolution and Demographic Transition. Where is everyone else? Happily and invisibly touring the galactic wild life with their 0.7 children.

35:

Step 2: Target planet and mess with magnetic field / reconnection at distance.

Step 3: Watch their local star CME the planet.

That does require actually traveling to the system in question, which makes it more complicated than Charlie's scenario (you're not going to mess with planetary or stellar magnetic fields from several parsecs away).

(There might also be planets with very dense atmospheres which help protect against solar flares at some level, even without a magnetic field.)

36:

On a more optimistic note: As our host points out, a past GF would be good news. There are really two distinct kinds of past GF, which you might call extrinsic and intrinsic. An extrinsic PGF is the kind of astronomical disaster he mentioned - gamma ray burst, supernova, asteroid impact, Venus-style resurfacing event, etc. An intrinsic PGF would be some step along the road from prebiotic planet to technological civilization that turns out to be very difficult, so that only a tiny fraction of biospheres ever get past it. An intrinsic PGF would obviously be better news than an extrinsic one, since we would definitively be past the danger.

One suggestion I saw somewhere a few years ago: The first signs of life on Earth are about 4 billion years old, while the first multicellular life only dates back about 600 million years. The intervening period wasn't entirely uneventful, evolutionarily speaking, but does the fact that it took so long hint that the jump from single-celled to multicelled life may actually be the really difficult bit? If we find a lot of planets with thriving bacteria-level ecosystems, that might be further evidence in favour of this hypothesis. Granted, it's not clear why that particular step would be so hard - but then, everything looks easy after somebody already did it.

37:

Berserkers don't have to be large, obvious or resource-intensive, at least if some people's belief in replicating AI nanoassemblers is correct.

One possible scenario would be to drop a few grams of such devices into some remote part of an ocean, with instructions to first replicate like crazy and then create large numbers of microscale (bacteria-sized) factories producing CFCs. Said compounds are not only very toxic to the ozone layer but are also extremely efficient greenhouse gases, so they should mess up an ecosystem fairly thoroughly. (In Earthlike conditions, anyway.)

For added misery, add some grey goo to the mix and if you are really paranoid send the offending civilisation a few hundred comets as a goodbye present. (Doing the work way out in the Kuiper Belt or local equivalent, so they don't see you doing it.)

I submit that the fGF might well be essentially the same event as the Singularity.

38:

A nasty version of panspermia? A primitive but voracious and very hardy replicator evolves to live in Kuiper belt / Oort cloud conditions.

Every so often a displaced comet / meteor fragment brings the replicator into the more high energy high resource environments where intelligent life might evolve. (Sure, extremely unlikey, but we've got billions of years.) It promptly goes on a binge and eats everything.

39:

I think the problem is, people assume advanced civilizations engage in interstellar travel. But there's little reason to assume that, if you look at the progress of our own technology.

We've advanced far, far more rapidly technologically down on the small scale, the nano-scale, than we have up on the macro scale. Rockets aren't all that much better than they were when Wernher von Braun was blowing up chunks of London 75 years ago, but computers, computers are massively more advanced. It's not even close.

I see no reason why other civilizations wouldn't follow a similar course.

Unless there's some clever way around the speed of light, that means it's always going to require an incredible amount of energy and resources to move a substantial number of intelligent beings anywhere in the galaxy, and they're going to have to be willing to sit cooped up in a tin can for decades or centuries. Who has time for that?

Sure, you can send probes, but even that's ridiculously expensive, unless you're willing to wait centuries to get results back. Probably cheaper just to build big remote-sensing devices in your own system.

As technology advances, population growth appears to decline, or even go into reverse. Also, all these advances down at the nano scale lead to more advanced materials and more efficient machines, so at some point the civilization's energy and material needs are going to start decreasing, not increasing. They're exploring the atom and - eventually - the subatomic realm, not outer space. That's because it's ultimately cheaper and easier to do and returns more immediate rewards. You don't have to spend a bazillion dollars and wait 20 years to harvest an asteroid for iron - you invent some new material that takes the place of iron or improves upon the iron you've already got. It's the technological miracle of the loaves and fishes - technology starts turning a little into a lot.

Maybe you get so good at making things really small that you eventually send out microscopic probes to explore the entire galaxy, probes so tiny we wouldn't notice them or we'd take them for natural objects. You might keep a wary eye out for any civilizations that look prone to sending anything larger than a grain of dust your way, but you'd have plenty of warning - and right now we look like anything but a threat.

As for exploration, assuming their remote sensing and probes are advanced enough, they wouldn't bother. If they wanted to "visit" the Earth, they'd just fire up a simulation in their living rooms. With advanced enough technology you'd be able to create something like a Star Trek holodeck, and visit whatever worlds you like whenever you like without spending decades getting there. In the same way more and more humans telecommute these days, alien civilizations televacation. Doing so even allows them to "visit" environments that would otherwise be deadly.

So I think there's a "great filter", but that filter is just technology. If your technology is advanced enough you don't travel because you don't have to.

40:

Because I tend toward Evil at times, I'm going to suggest this one: psycho-cultural manipulation. Where this one starts is simple: small probes, insect-sized (possibly even insect-shaped) which are seeded onto any world which has the potential of spawning intelligent life. These probes are instructed to effectively act as an evolutionary filter, and kick in at the point where a species has reached the stage of generating culture, but to cease activity when this culture starts being literate.

The purpose of these probes is simple: it is to impart a very basic memeplex of ideas. Small ideas, building blocks. Things like "the strongest one gets rewarded". Or "the weakest one deserves nothing". Not to mention "you are the only ones who matter".

The idea behind them? You're implanting these potential civilisations with a set of inbuilt minefields and ticking time bombs, because from these building blocks, they'll create all their own potential problems. If you're really lucky, they'll keep carrying on from those basic principles and fighting amongst themselves in a manner which effectively limits technological innovation (and thus prevents space flight from developing). If the cultures fight back, and create antibodies (it's feasible this is what a lot of major religions started out as - memetic antidotes to the problem of evil) technology may have an opportunity to progress, but even so, these particular thought forms are very persistent... as organising principles and contaminants, if nothing else.

The aim is to ensure whichever species reaches the point of sentience and cultural creation is implanted with these little psychological time bombs which will ensure they self-destruct before they can reach the stars - just leave them there, forever trapped on their own little mudballs.

Seems to be working so far here...

(Okay, so there's a certain amount of "magic tech" in there in that I'm not specifying how the probes work; there's also a certain amount of non-compliance because the galaxy isn't sterilised by these things per se - instead, everyone's just locked in their rooms in permanent time-out. I still think it might be a feasible possibility, and if anyone else wants to run with it, feel free!)

41:

We've been viewing this as a two-party problem: nascent civilisation versus griefers. I think it's a three-party problem: nascents, griefers, and any other nascent civilisation within sight range.

For griefers to be sure they've caused a hard extinction of a nascent civilisation, they've got to aim for copious overkill. Such overkill has a substantial and obvious signature to all of the neighbours - if a planet suddenly gets hit with 10^26 Watts and evaporates in an hour, that exploding cloud of plasma makes the existance of the griefers very obvious.

So here's the key point: are nascent civilisations going to spot griefers before the griefers spot nascents? By definition, the griefers are waving a huge flashlight around. If they are using a Nicoll-Dyson beam to deliver the energy of an entire star to a target, that that's equivalent to a star turning on and then off. That's visible across the galaxy.

That's a major incentive to nascents to shut the hell up, harden, and disperse off-planet.

And then the follow-on question: which scenarios can plausibly zap any planet showing signs of technological civilization without being bleedingly obvious at huge range to any other technological civilization?

(A complete aside here - I've worked on laser-driven metal plasmas in the 10^3 Watt range. They're pretty, stunningly monochromatic, but bright enough to require eye protection.)

42:

The problem with the idea of griefers is, what stops them from being confined to a single galaxy? And what happens when one intergalactic griefer detects another griefer? Methinks really nasty civilizations like that have a short shelf life, which might involve mutual intergalactic annihilation.

Also, assuming you're the first, how do you know for certain you're the first? It's always possible there's someone out there older and more advanced than you, that you simply can't detect. If you go around vaporizing planets, they're likely to notice, and they might griefer your ass.

43:

Might I suggest the wonderful--if soul-crushingly depressing at times--series by Baxter?

Manifold: Time
Manifold: Space
Manifold: Origin
plus
Phase Space

44:

I never understand why the people who like to poo-poo speculation about exotic topics like space travel and the Singularity don't simply answer the Fermi Paradox by saying, ''Space travel is impossible, or as near to impossible as makes no difference, and that is all the answer you really need.'' I hate to admit it, but it seems the most likely actual ''Filter''.

45:

@43 Manifold: Time is probably the best ''big idea'' sort of science fiction story I have ever read.

46:

Ian, cf "The Death of Grass". You really don't need much to totally screw up a civilisation, provided you are on the spot, small enough to hide, and intelligent enough to study and understand.

In part that's a good reason why Charlie's 'Death Star' is less likely - you can get a better effect for less effort. It would only make sense if it were a byproduct of other efforts - probably as a last ditch sterilisation weapon that's well away from your home star (surely you'd build it around the hottest, brightest, star - which was also useless for other purposes?)


In the end I think the great filter is quite simple. A species that looks outward, to colonise the galaxy is going to be competitive to some degree (even hives fight each other). Also star systems that give birth to new intelligences are likely to only have one planet that's particularly suited to that life form.

I think simply the pace with which planet screwing up technologies develop is well in advance of interstellar technologies - and effectively the species gets trapped in a cell with its own homicidal maniac twin cousin.

99% filter efficiency is probably enough to account for what we see.

47:

Given the energies involved in any plausible tech that would allow interstellar travel, pretty much any group that could make starships could also destroy planets. So colonizing planets could well be suicide, next time some minor fringe group pops up.

What intelligent species there are that have developed to that point may be hiding out in stealth fortified habitats drifting through interstellar space. Doing everything they can to avoid being noticed by each other.

There's no purposeful filter aimed at wiping everyone out, just enough one-off crazies that everyone sane is in hiding.

48:

Because I'm getting old and pessimistic, I think I have to agree, to a large extent.

The galaxy is a desert, and the oases are few and far between. I mean, really far. One might think it's a long walk to the pharmacy, but that's kissing distance compared to the gaps between stars... and so on in a similar vein.

I won't say it's impossible to reach the stars — Voyager is making a good fist of it, considering — but it's going to be difficult and uncertain. Designing a replicating probe is going to be difficult, not to mention field-testing it — especially if it's meant to be lethal to civilizations and lifeforms unknown. Launching it into space is going to be difficult. And it surviving until it reaches the next star is going to be difficult. All of which means not just slow to spread, as though the interstellar medium was a form of agar that's particularly thick, but fundamentally uncertain.

There are typically bare patches even in a friendly medium for lifeforms. In a desert, it's all bare patches, and any patch friendly to life has a precarious existence. An extra-dry year, an earthquake draining an aquifer; conversely, a wet year leading to too much fecundity, the locals using up all the easy resources and the population of everything crashing when things get back to normal.

A given patch of the galaxy might have a fair number of oases close together in a certain time, leading to some form of interstellar civilisation filling the available niches for a while. But after a while, as the galaxy turns the nice stellar systems will begin to move away from each other. The faster moving stars get too far away to sustain contact first, then the whole volume gets spread out, and fewer friendly stars come into the volume. Civilisation breaks up into single systems, they withdraw into themselves; some collapse into extinction, some into sub-sapience, some find stability and stay there.

Other areas are probably just too thinly spread in living worlds to ever sustain an interstellar polity. The local lifeforms either never learn to bang the rocks together, or just never get the hang of multicellularity. Or if they do, and manage to keep it together enough to launch probes at the nearest stars, the probes either don't make it, or they just don't find anything interesting or useful. The lifeforms stay at home, and play with the local planets a bit, and eventually give up on the whole thing. Maybe, at some point, they exchange a few signals with something very far away, but the signals are difficult to decipher and seem vaguely threatening, so they quietly hang up the phone and pretend they've gone away for the eon.

49:

My fGF isn’t a one-time trigger, but a distributed natural filter: civilizations run out of energy before they get out of their own solar system, or generally even off-planet.

Imagine our planet is rare in that it possessed a huge amount of easily-liberated energy in the form of hydrocarbons. (Second-order effects notwithstanding.) If so, the Universe might well be full of planetbound civilisations, subsisting at the farmer level, having used up all their local energy stores other than food sources (e.g., plants) before they got much of anywhere technologically. We’re already at risk of falling into this trap if we can’t bootstrap ourselves into a solar-based energy infrastructure.

Although I really like voidampersand’s scenario. That should absolutely be turned into a short SF story, if it hasn’t been already.

50:

I submit that the people who consider memes as actual contagions are correct, and that we have already been sown with the virus that will kill us: Greed.

If you can infect a culture with a destructive ideology, you can just let them kill themselves... Greed fits the bill nicely.

51:

I would think that any sufficiently advanced VN machines would be subject to evolutionary effects. Building super-giant space lasers is a pretty big waste of effort without providing any survival benefit to the machines themselves. Over millions or billions of years I would expect they would drift from whatever their original design was for to survival and reproduction, perhaps diverging into different groups and competing to produce a galaxy spanning ecosystem. For all we know that might be what the Oort cloud is made of. Silent machines eating comets, starlight and each other; waiting for the next lot of naive VNs (or generational ship) to be cast off from the inner system into their open mouths.

52:

Well, I remember (plot but not name) one SF story in which each class M star was surrounded by a bubble that could be easily broken by an out-going spaceship but was utterly impermeable to incomers. The result was that you couldn't harm (or even contact) a pre-interstellar civilisation.

53:

David Brin. Don't recall the name of the story.

54:

I don't think VN Berserkers are a sufficiently good explanation for the Great Filter.

Suppose a griefer exists and can implement the plan Charlie suggested. Within a cube of 100 ly on side, there are only approximately 1000 stars, and so maybe the max of about 10000 planets. If the griefer wanted to grief, why not *shoot all of them*? Indiscriminate griefers would have the advantage of not having to anticipate what other civilisations might look like, and also would choke off the supply of planetary materials for other griefers and their VNs, thus defending themselves. To win, the discriminatory VN berserker has to have a substantial headstart. In a galaxy with multiple griefers, it's the KILL-EVERYTHING VN that triumphs.

Except that we look out at the sky and a lot of planets still exist!

55:

I think the point people miss with Great Filter arguments quite often is that the Filter needs to be *subtle*. And a lot of proposals aren't intrinsically subtle, so that just shifts the mystery to the question of why we haven't seen the Filter working.

I don't really buy the technological impossibility argument either. Interstellar travel is hard, but it's not hard enough to stop even us from right now sending a probe at Alpha Centauri if we wanted to - and could bother to wait a few tens of thousand years for it to arrive.

Personally I favour the galactic police force explanation. If the threat of VN is very real, then at least some of the galactic civilisations would try and cooperate to deal with the issue. Sending out their own VN would probably be too late, the chances are the griefers have a head start. So instead, send out schematics for defences, to try and immunize the galaxy as a whole. Of course you wouldn't want to hand out nukes to cavemen, so a period of quiet monitoring would be wise, to see whether the civilisation in question is one of the more enlightened types, or rather paranoid and murderous....

56:

I think the problem is, people assume advanced civilizations engage in interstellar travel. But there's little reason to assume that, if you look at the progress of our own technology.

I think you fundamentally misunderstand the Fermi paradox. It's not necessary for all advanced civilizations to engage in interstellar travel; it's only necessary that not all of them abstain from it. Because all it takes is one, and exponentiation does the rest.

Also, it doesn't have to be people who do the travelling; self-replicating probes will do the job just as well. Again, just one probe of a sufficiently good design that it creates >1 child per star system visited will succeed in a cosmologically short period of time in saturating the galaxy, even at chemical rocket speeds.

Finally, there's the diminishing cost curve. We're talking about "alien spacefaring civilizations" as if they're monolithic individual entities. In reality, I'd expect any successful spacefaring species to be at least as diverse as we are, and prone to rapid memetic evolution. You may not want to go and live in an aluminium tent in a poisonous desert for the rest of your life, but Mars One wasn't short of volunteers. And you're wrong about our rocketry. It may not be orders of magnitude more efficient since 1945, but it's vastly more reliable and accurate and, in real terms, getting a lot cheaper.

57:

It's possible we wouldn't know an interstellar civilization if we saw it.

Absolutely every bit of what we know about things beyond our solar system comes from our interpretation of electromagnetic radiation. (plus cosmic rays. and -- heh -- neutrinos.) Our understanding of EM radiation dates back no more than 150 years. Before Maxwell we didn't have a clue. Well, but throw in relativity and quantum theory about 100 years ago. QED about 65 years ago, with quantum chromodynamics about 50 years ago. I expect the pace of progress in physics to slow down now, because it takes a lifetime to understand what's already been done. (You can sort of understand a tiny specialized part of it after 4 years of undergrad physics and 6 years grad school.) It will take a long time to simplify the ideas enough to improve on them.

Alien civilizations that understand physics better than we do, might have an entirely different set of problems to solve. There's no reason to think we would understand them.

They might be working with forces we have not noticed. EM radiation might be something they try to tune away as a waste leakage.

We mostly think they aren't out there because we think they haven't come here. After all, humans have spread everywhere on the surface of the earth, no matter how undesirable, into deserts and swamps, humans live in polluted rivers and polluted nuclear contamination sites, in oil fields and coal mines, on the polar ice and in sewage treatment plants. The only places on the surface we don't live are pieces of the ocean that aren't on the way to anywhere. Aliens who are like us would come here despite our low reserves of yterbium, despite our infestation of humans. There's nothing particularly good here but we do have sunlight they could take.

The reasoning is that if they're like us, they will take everything they can get and use it up, and go looking for more, no matter how marginal. Why haven't they used us up?

Here's one possibility -- maybe two big galactic empires had a war around 200 million years ago, and as part of their truce afterward they declared a demilitarized zone where nobody was supposed to go. Mostly nobody sneaks around inside the DMZ because there's nothing here that's worth the risk. But any day now the truce might end....

58:

Such overkill has a substantial and obvious signature to all of the neighbours - if a planet suddenly gets hit with 10^26 Watts and evaporates in an hour, that exploding cloud of plasma makes the existance of the griefers very obvious.

Good point. But yes, it's overkill: the energy landing on the planet is roughly equivalent to what it'd receive if its star went supernova. You don't need to go that far -- you could easily fuck things up irreparably by hitting it with six orders of magnitude less power (merely igniting all biomass on one hemisphere and heating the atmosphere on one side to several thousand degrees, creating supersonic shock waves that would mess up all surface structures on the far side and turning a good chunk of the oceans to superheated steam, which would replace the current breathable atmosphere -- now mostly on its way out into space).

That's a much harder thing to spot; unless you're studying the illuminated-by-laser side of the planet you'd probably mistake it for just a bigger-than-usual supervolcano kicking off, and at any range over a handful of light years it'd probably be un-noticeable unless directly observed.

And anything that turns the atmosphere of $HOME_WORLD into a moist facsimile of Venus (with added 2000mph tornadoes) is probably going to spell doom for a space-capable civilization that hasn't yet fully migrated all its supply chains off-world. It just depends on whether the griefers spot the target and zap it early enough during the development of space travel, or wait too long and have to go to full power.

(As we've been launching spacecraft for over 50 years, and might send a manned expedition to Mars within the first century of spaceflight, I think the hypothetical griefers may have some margin for error here ...)

59:

My answer to the Fermi paradox is, rather boringly, the moon. Specifically, terrestrial planets without a fully functioning magnetic field have had the water stripped from their atmosphere by the solar wind. The only terrestrial planet to retain a planet-wide magnetic field capable of stopping this also has a sister dwarf planet. (Reminder: the moon is about 1.2% the mass of the Earth and the pair co-orbit around a barycentre that's ~0.7R_earth from the centre of the Earth.) So my guess is the moon is tidally heating the Earth's core, keeping the dynamo running. So the filter is several GY in the past.

I did some more research on interstellar laser communication: lasers suffer from beam spread (I'm not a laser person!) which at parsec distances amounts to spreading hemispherically. I don't know if an array can solve that. But if not, any beam will cover steradians at interstellar distances and will need large powers (which you solve this time). Like I said, just modulate the star's output in the direction of interest.

60:

I don't think stealth is a concern. A species technologically advanced enough to make beserkers would find it reasonable to assume that large proportions of galactic civilisation already knows that beserkers can exist - Especially the most threatening ones. Indeed, they would most likely assume, as they launch their beserker, that they are not the first to do so. So what's the advantage in hiding what you are doing?

61:

So my guess is the moon is tidally heating the Earth's core, keeping the dynamo running.

No, the Earth's (outer) core is molten due to the combination of: a) leftover heat from the formation of the Earth (various planetesimals smashing into each other and the proto-Earth; b) friction from heavy elements sinking to the core and lighter elements rising; c) latent heat from solidification of the inner core; and (most of all) d) radioactivity.
http://phys.org/news62952904.html

Over very long periods of time the Moon is slowing the Earth's rotation, which might arguably weaken the dynamo effect, though probably not by a lot.

62:

Agreed.

What the Moon does do is stabilise our axial tilt (in contrast to Mars) - but as our axial tilt might well have been caused by the Moon-forming impact in the first place, it's unclear what to conclude from that. (Venus' (lack of) axial inclination is apparently stable, and slow retrograde rotation is what you would expect in the absence of large impacts.)

One thing worth considering is that a pGF need not be a single highly improbable event: it can be a series of moderately improbable events (if there are 10^10 suitable planets in our Galaxy, then a series of 4 events in our history with a probability <10^-2.5, or 1 in 300 or so, would be enough to make us the only civilisation in the Galaxy). The evolution of the eukaryotic cell is a candidate; so is the development of language.

63:

Hmm, for some reason the last line of my post has vanished - I should preview these things.

That should continue:

...with a probability of 10^-2.5 (about 1 in 300) or less would be enough to make us the only civilisation in our Galaxy).

[[ The reason being that you'd started an HTML tag with the < character and never closed it. If you want the less-than character, use &lt; - mod ]]

64:

The Moon probably suppressed the development of multicellular life, and the colonization of land, for some billions of years.

When it formed, in much closer proximity to Earth (but just outside the Roche limit) Luna orbited the still-molten Earth much more frequently and raised vastly higher tides: I'm looking for a source, but the figure I heard was around a 36 hour lunar "month" and tides over 70 metres high every 18 hours. Tidal drag has caused the Moon to migrate outwards -- in the absence of external effects (like Sol leaving the main sequence of the Hertzsprung-Russell diagram) it would continue to move outwards.

Thing is, multicellular life forms really don't like being smashed onto coastal rocks by 70 metre tides on a daily basis. So they couldn't have formed until the Moon receded far enough to permit them.

Another possible pGF is the Great Oxygen Catastrophe. It took 1-2GYa for the proto-algae to oxidize the lithosphere enough for O2 to begin building up in the atmosphere and hydrosphere -- at which point the toxic waste product killed off about 98% of life on Earth. Luckily some survivors then worked out how to use a powerful oxidizing agent to drive their metabolism -- and once the oxygen level in the atmosphere rose high enough, the new multicellular organisms (which in turn had to have developed a rudimentary circulation system because gas diffusion really doesn't scale well if you're more than a few cells thick) were in a position to begin colonizing the land.

But the whole land colonization thing just isn't viable unless you have a high energy environment close to hand (the atmosphere), multicellularity, a circulatory system, and a giant moon which isn't trying to kill you once every day or so.

65:

David Brin - The Crystal Spheres.

Where every solar system is surrounded by a protective barrier, only breakable from the inside. Once they break it (and the survivors recover from the billions of comets now incoming) they go on to find the five worlds left behind by the last to evolve, who possessed the four worlds of the previous etc etc.


The idea is elegant, I guess in a few hundred more years when Voyager hits the edge we'll know if it was true.

66:

Thing is, multicellular life forms really don't like being smashed onto coastal rocks by 70 metre tides on a daily basis.

Although we have fossils of stromatolites suggesting stable, multicellular aggregations of bacteria dating back to at least 3.5 billion years ago, so monster tides didn't delay things that long. (Plus, they wouldn't matter very much in the ocean away from the coast.)

67:

My main thought would be timescales.
The dinosaurs were around for ~180MY. That's about the most stable time period we really know of, and a shedload of species evolved in that time.
As far as we know there was very little technological development, but it is possible a spacefaring race came by, saw what was happening and threw a few rocks at it in passing.

Humanity has been around for a fraction of that - effectively only 0.5MY if we count tool use.

There is a strong chance that if there is a "griefing" race out there ... they haven't actually noticed us yet.

A nice and relatively cheap way of disposing of potential races would be to throw a rock or three every few million years at suitable targets. If they get hit ... no more problem till the atmosphere rebalances and the fires go out. If they miss ... time to go take a closer look.


In honesty though, assuming interstellar travel is feasible, I think the Uplift/Fallow World idea is probably closest to reality - assuming lifebearing worlds are less common than non, then any civ that evolves either takes over all of them, or has an intrinsic motivation not to with a corresponding motivation to prevent anyone else taking over all of them and out competing.

In that idea, Earth is simply in a no-go zone, and we haven't been listening long enough to hear anything interesting.

I mean, SETI has only been going on for 70yrs, by the scales of solar systems, that's no time at all.

68:

Thanks; that can now stop bugging the H*11 out of me for a while.

Now, how many more times to we have to mention David Brin before he appears again? ;-)

69:

In addition to the effects of the Earth's rotation, the outer core is acted upon by tidal components and components arising from the Earth orbiting the barycentre. I don't know the magnitude of those effects, but dynamo's are non-linear and not well modelled so it's possible (give me a big grant and a bigger computer!) that the moon plays a *cough* pivotal role.

Or maybe I'm wrong about the mechanism. The Waltham paper that argues the moon doesn't produce chaotic obliquity does speculate that it allows a lower rotation rate. Waltham suggests that reduces the frequency of ice ages. But it could prolong the dynamo.

And if the moon needs to be exactly the right size---big but not too big---then that really is a filter.

70:

I mean, SETI has only been going on for 70yrs, by the scales of solar systems, that's no time at all.

Well, further than that SETI focuses on the 21 cm Hydrogen line because ~*~reasons~*~, basically 56 years ago we decided that was a sensible place to look for a directed signal, and we haven't bothered to reconsider at all since.

The reasoning for why that is optimal for interstellar communication may still hold up, but that doesn't make it the optimal way to look for an interstellar civilization. For that you would want to look in the IR spectrum - look for the waste heat from their activities. But that would require a very large number of satellite telescopes searching, and would be much more expensive.

And of course, both approaches are limited by the coherence of any indication of activity falling off in accordance with inverse square. Past a certain point the ability to read it distinctly drops below your mechanical abilities

71:

The Laskar paper is here. But Waltham thinks the moon acting as a stabilizer is a "misinterpretation".

72:

"...and a giant moon which isn't trying to kill you once every day or so."

Twice every day or so, surely? One of those with somewhat less vigour?

73:

... SETI focuses on the 21 cm Hydrogen line because ~*~reasons~*~, basically 56 years ago we decided that was a sensible place to look for a directed signal, and we haven't bothered to reconsider at all since.

One of the main reasons is that that part of the radio spectrum is fairly quiet in galactic terms, making it easier to detect faint signals. That hasn't changed at all, and won't for several billion years at least.

For that you would want to look in the IR spectrum - look for the waste heat from their activities.

That would generally be a bad idea, since the sky is pretty bright in the IR, with stars, planets, interstellar dust clouds, and distant galaxies all putting out IR radiation, most of it thermal. You'd certainly never detect our civilization that way, though you could detect our radio emissions if you were close enough.

74:

Haven't we already done this one before? And in the last couple of years? But very well:

I submit that there is only one habitable planet in all the galaxy, Earth itself. Yes, there are uncounted planets where what we would recognize as life exists.

We just can't live there ourselves. No, not even on worlds that have water/carbon-based life. You might be able to breathe the atmosphere, and even drink the water. But -- at best -- all life there is inedible. At worst . . . some sort of super-allergenic reaction maybe? Trying to live on one those planets would be just like trying to set up a long-term habitat on an asteroid, with the added disadvantage the of atmosphere and gravity making it hard to travel anywhere else.

So basically you're limited to travel from one asteroid belt to another. Acceptable for von Neumann's, perhaps. But not for life as we know it.

75:

True.

What I was trying to say is that we're effectively observing a 70yr wide slice of the universe - the actual ages within are wildly different, naturally.

But our monitoring is effectively looking for differences - places where stuff has changed since we started looking.

The window we have to look at those differences is extremely narrow.

Humanity for example has put out a blast of RF and modified the albedo of earth significantly, but that has only really been over the last 300yrs. In another 300yrs, there is a reasonable assumption that our emissions will be more focussed, and in 1000yrs they will probably be extremely different. (the move from copper to fibre has reduced our global RF leakage substantially, while Satellite signals are getting tighter.)

I think now we have the ability to start looking at a scale of planets within solar systems, then we have a higher chance of detecting ... stuff ... but most of the SETI work is on a scale of suns, and I think we barely send out enough emissions to be detectable above our own at distance.

There is also the likelyhood that if another race evolved and went through the same shouty phase, that the signals passed us 1000yrs ago, and we weren't listening. What we would see now would be their evolved baseline, and we probably can't recognise it as unusual.

76:

SETI focuses on the 21 cm Hydrogen line because ~*~reasons~*~,

I imagine a group of swiss mountain people cut off from humanity for hundreds of years by glaciers etc. They start to wonder wether anybody else is still out there. They communicate across the hillsides by yodeling, so they build a big listening post that can detect faint yodeling from far in the distance....

basically 56 years ago we decided that was a sensible place to look for a directed signal, and we haven't bothered to reconsider at all since.

We look for the keys under the lamppost. We can't look everywhere, and they might be there....

77:

At worst . . . some sort of super-allergenic reaction maybe?

Yes. See "Bios" by Robert Charles Wilson, among others.

(It's one of the things I'm thinking about wrt. the third Freyaverse novel -- working title, "Waxing Uranus" -- which is on my to-do list about 2-4 books down the pile I need to write, now that I know what it's going to be about. It might surface some time after 2018 ...)

78:

On the 17th April (BST) the moon will only "transit" once. So I *guess* you'll only get one tide.

(By "transit" I mean cross your meridian OR antimeridian .)

79:

One of the main reasons is that that part of the radio spectrum is fairly quiet in galactic terms, making it easier to detect faint signals. That hasn't changed at all, and won't for several billion years at least.

Yes, but that is based on the assumption there will be signals there in the first place, that because it is quiet it is great for talking if you want to talk. But that's not how it works. When you go into the forest looking for deer, you don't listen to try and hear their calls. You look for tracks, spoor, game trails, bedding sites, and grazing marks. Then, once you have established where they are, and set up your blind you *might* use your call.

It is the same thing here, if we want to find them, we should be looking for the signs of their presence then trying to talk, rather than assuming they will find us and decide to talk.

That would generally be a bad idea, since the sky is pretty bright in the IR, with stars, planets, interstellar dust clouds, and distant galaxies all putting out IR radiation, most of it thermal. You'd certainly never detect our civilization that way, though you could detect our radio emissions if you were close enough.

Our civilization also doesn't have an extensive series of orbital habitats consuming as much power as a city here on earth, spacecraft sitting on GW output engines, or any extensive space infrastructure. Our civilization is sitting at the bottom of the gravity well, with a layer of atmosphere blanketing anything distinct. Our radio emissions have already sharply dropped off from where they were at their peak - for one we now use tighter, better signaling that doesn't dump so much into space, for another so much is over cables these days. Anyone looking to detect us had better be in a few dozen light years, and needed to be listening at a very specific time, because it is much quieter now. Meanwhile the IR output of an advanced civilization will only increase with growth, and once you get off the home planet and start doing more it gets much easier to see.

As I recall, it was back in 2010-2011 there was a very interesting post here about this, and the raw energy of sending a detectable signal out and the various spectrum. I think that fed some of the stuff in Neptune's Brood.

80:

I think the missing factor in the Drake equation might just be apathy.

If the aliens are anything like humans, the griefers are lazy. Sure if there's an existing mega-laser device that was built for some other reason (propulsion) and has bad security, maybe the griefers can hack it on a whim and take a few pot-shots at nearby stars. But most wouldn't have the knowledge or resources to build something themselves (see script-kiddies).

Apathy also comes in other flavors. For example, there are millions of ant colonies scattered across our planet. Say one of them develops unusual mental skills and starts spelling out advanced mathematical equations in their chemical trails in an attempt to communicate with higher beings. Would we notice? Would we care? Unless the ants directly attacked us, or unless they build their colony in some space that we wanted to use, the answer is we just wouldn't notice. Now if they developed some sort of "advanced technology" (say gunpowder) and started setting it off, then maybe that would grab some attention.

There's also the possibility that most sentient life lives in gas giants, and the group living in Jupiter have been flooding our solar system with massive EM radiation while communicating with nearby stars and we just think it's noise, because of course heavily compressed and encrypted communications are more or less indistinguishable from noise...

81:

The Laskar paper is here. But Waltham thinks the moon acting as a stabilizer is a "misinterpretation".

I'm more impressed by this 2012 paper from Lissauer et al. (partly since it's an actual refereed paper with detailed calculations rather than a 2-page conference paper) which argues that a moonless Earth wouldn't have dramatic obliquity variations. From the Abstract:

We calculate the obliquity evolution for moonless Earths with various initial conditions for up to 4 Gyr. We find that while obliquity varies significantly more than that of the actual Earth over 100,000 year timescales, the obliquity remains within a constrained range, typically 20-25° in extent, for timescales of hundreds of millions of years.... A large moon thus does not seem to be needed to stabilize the obliquity of an Earth-like planet on timescales relevant to the development of advanced life.

http://barnesos.net/publications/papers/2012.01.Icarus.Barnes.Moonless.Earth.pdf

82:

Very small probes sent to every single star system to monitor developments, able to interact with electronic communications.

Once a civilization approaches starflight, the probe starts to subtly interfere with spacecraft development: test vehicles explode or crash. Precisely-aimed tiny particles take out vehicles in flight. Conversion errors from one unit type to another appear, causing mission failures.

New civilization gives up space exploration as too expensive and failure-prone and commences terrestrial navel-gazing.

That gives the probing civilization enough time to reach the star system and [do whatever].

83:

Also, the ants in my scenario could be postulating that an advanced civilization full of griefers could construct amazing devices. Giant glass lenses that could focus the power of the sun to a fine point which would destroy our workers from a distance, or they could harness the chemical output of just *one* hydrocarbon well and make enough napalm to completely destroy all ant civilizations in a multi-square-mile area. So why haven't they yet?

Again, apathy. Maybe it's just really not the trouble and we aren't important enough to be worth the bother, especially if we happen to be far away in an unfashionable arm of the galaxy.

84:

The Milky Way is about 100K light years across. Assume the species that wants to exterminate us is centrally located. Therefore it takes around 50K years for them to see signs of intelligent life on Earth and 50K years for their laser beam to arrive. It seems that we could dodge that -- getting off the planet should take less than 100K years.

Unfortunately it would make sense for them to set up multiple Nicoll-Dyson lasers to reduce the latency. Sucks to be us.

I wonder what an occupied star would look like? I suppose they'd avoid capturing almost all of the starlight until it's time to zap somebody, so maybe all we'd see is stars that blink off and then back on, very rarely. If they don't need to use the whole power source, then perhaps the segment they use is not between us and the power source, so we might not even see that. Of course, we see something else entirely if we're the target, but that's not useful.

I can't see a way to even predict the possible pending doom, much less anything to do about it. I therefore don't see how it should affect our plans beyond adding a little bit of urgency to getting off the planet. Any ideas?

85:

Well-known effect, normally called "precession of tides".

86:

Megpie71,

Your scenario is awfully primate-specific. It would only work on species where competition between related individuals exists to begin with, and the concepts of "strong" and "weak" make sense. It would fail utterly when applied to a hive species, or to a species where reproduction does not depend on social hierarchy.

87:

I would contend that occasionally (as in every few tens of millions of years) dropping by oxygen-atmosphered worlds and chucking a few rock at them doesn't actually count as griefing, so much as doing them a favour.

It may be that intelligent life isn't as common as we would like to think. It took billions of years for hydrogen sulphide reducing bacteria to mutate into water reducing bacteria, and a long time thereafter for the oxygen levels to reach useful levels. Once oxygen levels did get to higher levels, it took one or more "snowball earth" events for the Ediacaran fauna to be replaced by the Cambrian Explosion groups. Even then, most animals had external skeletons, which limits ultimate body mass.

Vertebrates had the potential to become brainy, but the Permian amphibian and reptile fauna did not do so. Nor did the Jurassic-Cretaceous dinosaur and avian fauna; animals as smart as modern crows were about as good as it got.

My point is that ecosystems seem to hit stable points where big-brained animals simply do not evolve. Repeatedly hitting the reset switch every fifty or sixty million years by chunking some big rocks or comets into the inner solar system may not in fact count as griefing so much as giving something else a chance. As soon as something brainy does turn up, it may well look at the fossil record, realise that every so often high velocity rocks happen, get scared then start looking out for extra-planetary trouble with increasing levels of skill.

If this is the case, then the periodic griefer system isn't actually a griefer at all, but instead a benevolent elder civilisation that wants to foster smart beings, and goes about things the brutally simple way, knowing that anything capable of surviving this is definitely intelligent. For all we know there may be a great big "Do Not Bombard" notice parked out around Jupiter, just waiting for us to turn up and switch it on.

88:

I think "super-allergic reaction to alien life" is a red herring. I am fairly sure that a civilization capable of keeping its members alive between stars will be able to control their immune systems -- and that's all allergies really are, human immune system attacking an inappropriate target.

But you don't need allergic reaction to make a planet with incompatible biosphere effectively off-limits. Any Terran plant or animal you try to grow there would be a terrible resource disadvantage.

89:

That does require actually traveling to the system in question, which makes it more complicated than Charlie's scenario (you're not going to mess with planetary or stellar magnetic fields from several parsecs away).

You sure about that?

A mystery of first order Fermi processes is the injection problem. In the environment of a shock, only particles with energies that exceed the thermal energy by much (a factor of a few at least) can cross the shock and 'enter the game' of acceleration. It is presently unclear what mechanism causes the particles to initially have energies sufficiently high to do so.

https://en.wikipedia.org/wiki/Fermi_acceleration

The main mechanism by which the magnetized solar wind powers the magnetosphere was first proposed by J. W. Dungey [4, 5] as sketched in Figure 8. In the top panel the interplanetary magnetic field is southward and becomes connected to the terrestrial magnetic field at the subsolar point in a process known as reconnection. Reconnection produces open field lines with one end connected to the Earth, by combining interplanetary field lines, not connected to the Earth, with closed field lines, connected to the Earth on both ends.

p13

http://www-ssc.igpp.ucla.edu/ssc/tutorial/solwind_interact_magsphere_tutorial.pdf


In a surprising twist, astronomers at the Max Planck Institute for Radio Astronomy (MPIfR) and Lawrence Berkeley National Laboratory (LBNL) have found that in fact magnetic forces can be as strong as gravity near supermassive black holes.

http://www.astronomy.com/news/2014/06/powerful-magnetic-fields-challenge-black-holes-pull


The ability to transmit magnetic fields over relatively long distances could have important applications. In particular, Navau and pals point out the potential in quantum information devices, where magnetic fields are crucial for manipulating quantum bits. “This could be particularly relevant in the context of nitrogen-vacancy color defect centers in a diamond nanocrystal, which have recently been identified as promising systems for the implementation of quantum information processors, or quantum repeaters,” they say.

http://www.technologyreview.com/view/514201/physicists-build-worlds-first-magnetic-hose-for-transmitting-magnetic-fields/

Note: there may be some rather unsubtle physics jokes in this response.

90:

Deater wrote about the Drake Equation.
Recent planet discoveries have shown that we inhabit a very unusual solar system with no hot Jupiters and small rocky planets in the inner orbits. So we may well inhabit one of the few systems in the galaxy capable of producing planetary life. If this is true there is no need of another filter but interstellar travel would not lead to colonising any habitable planets because similar systems to our own would be too far away reach.
Similarly most jovian planets we have found so far are all probably too close to their sun for life.

91:

Recent planet discoveries have shown that we inhabit a very unusual solar system with no hot Jupiters and small rocky planets in the inner orbits.

Not true: you have forgotten to correct for the fact that hot Jupiters are far and away the easiest class of planets to discover. Quantitative estimates, e.g. Wang 2014, show that hot Jupiters are quite rare (about 1% of planetary systems); Earth-sized planets are considerably more common, see for example Petigura et al 2013, who conclude that 22±8% of Sun-like stars have an Earth-sized planet in the habitable zone.

92:

Recent planet discoveries have shown that we inhabit a very unusual solar system with no hot Jupiters and small rocky planets in the inner orbits
It's still far too early to make statements about how common various types of systems are. We've found a lot of Hot Jupiters around low mass stars so far because they are easy and quick to spot with current methods.

In general you need to observe for at least two orbital periods to detect a planet, for a large close in planet orbiting its star once a fortnight that's a months observation, for the Solar System you need at least 24 years to detect Jupiter and nearly sixty for Saturn. The inner planets are probably below the limit of detectability for the current state of either radial velocity or transit photometry.

93:

The thing that impresses me about these griefers is the timescales they think on! We can barely manage beyond the term/life expectancy of the current government/dictator, let alone tens of millions or billions years. I wonder why they want to exterminate all other technological life.

Perhaps cosmology informs their foreign policy, and they feel that long term, the universe can only support one civilization into the indefinite future.

94:

I have difficulty with sterilizing an entire galaxy, short of colliding galaxies, or a nearby one turning into a quasar.

Now, for defending against incoming threats... that's a lot of lasers for Nicoll-Dyson Beam. I'd rather just move a bunch of asteroids to the right orbit, and use solar power to turn the solar system into a giant power vacuum tube.... (And why can't I remember the name of the Galactic Patrol's chief scientist?)

mark "when *I* grow up, I want to be Dick Seaton...."

95:

Instead of "Griefers" how about "Mourners" - those who make sure technology never advances again AFTER a technological disaster (nuclear war, grey goo, hostile AI, etc.) wrecks a civilization. They come to believe that technological progress is evil and and make sure the species stays primitive (like the Simpletons in "Cantcile of Leibowitz").

Instead of killing a civilization like the Griefers, Mourners make sure it stays dead.

96:

Goddamnit Charlie, you are such a buzzkill. We space opera types just want to play with our rockets and space stations and whatnot without being told they're impossible--do you go around raining on the fantasy types telling them "come now, there's no such thing as werewolves and dragons and elves"? Do I come by here and ruin your nice Lovecraftian fun by sternly lecturing about the improbability of these things?

97:

The inner planets are probably below the limit of detectability for the current state of either radial velocity or transit photometry.

True for radial velocity; not true for transit photometry. Kepler could do Venus and Earth (not sure about Mercury and Mars) – that's the basis of the Petigura et al paper I linked previously.

98:

A. It only takes one spacefaring intelligent species to spread across the galaxy.

B. There are no signs anywhere of such a species.

Conclusion: There are no other intelligent speecies in the galaxy (every other argument is special pleading).

See Dvorsky's recent column "Is it Time to Accept that We Are All Alone in the Unverse?

http://io9.com/is-it-time-to-accept-that-were-alone-in-the-universe-1654960619

99:

As a matter of interest has NASA, or anyone taken an in-transit probe and pointed it at earth? Was life detected?

100:

From the MIT Technology Review article:

Their conclusion is that a “magnetic hose” consisting of concentric tubes of superconducting and ferromagnetic materials ought to do the trick. They say that a tube consisting of 20 concentric rings that is about ten times longer than it is wide, should transmit about 90 per cent of a magnetic field at one end to the other. ... These guys have tested this idea with a single superconducting tube 7 cm long

I think trying to build a tube of superconducting material with a length/width ratio of 10 from one solar system to another just so you can manipulate magnetic fields at the far end is a bit more difficult than just sitting in the first solar system and firing lasers at the second, per Charlie's original suggestion.

As for some of the other things you quoted:
If you have the technology to manipulate supernova shock waves to order, why are you messing about with trying to tweak coronal mass ejections?
Yes, supermassive black holes and their accretion disks and jets can have really strong magnetic fields. Not very useful if you're not in the immediate vicinity of an SMBH or its jet, though, which leaves > 99% of the galaxy out of reach.

101:

A bunch of comments ...

Seed planet with detectors that monitor specific signals (radiation, chemistry, mechanical). Once a threshold is reached, these either send a signal or just do a gigantic ‘reset’ on the whole planet. Comets could be seeded with detectors that monitor for unusual changes – greater/sooner than some specific limits because such changes could be either produced by a rapidly evolving (intelligent) species or some sort of ‘natural’ catastrophe. Detectors could also be placed on any planetoid anywhere in the local solar system, or could be one of millions in the extrasolar system.

I’m of the opinion that the more advanced a civilization is, the more cooperative its members must be. ‘Must’ because each member would be needed in order to maintain a great collaboration or ‘the great interdependency/synergy’. If this is so, civil war doesn’t make sense because it wastes critical resources. ‘Must’ does not mean coerced just strongly predisposed or hard-wired. (This civilization is not the Borg.) Newness might be an attractive, potentially valuable end/commodity in itself. An advanced/established civilization confronting something truly novel would first try to study it. This is sensible either to see what could be adapted/incorporated from the new resource/civilization, or actively quarantine it.

How much interaction does the advanced civilization need to have with humanity before it makes up its mind about our future? What would its likeliest sources of information be?

Self-sterilization/annihilation … self-limiting problem. Just a few more tweaks to the atmosphere, crops and life style preferences and we’ll stop reproducing all on our own within a few generations. There are a number of environmental and medical conditions that reduce fertility, including addiction. Followed by the ‘right’ sort of socio-economic policy to kill off a sizeable proportion of those who are born, this further reduces the number of individuals able to reproduce in the next generational round. (Would an alien race choose to help the species along by targeting the types of humans they prefer, and in so doing weed out any they find troublesome? What/how would they choose?)

Irreducible complexity … I’ve been thinking about how to make this work .. and the only thing I can come up with is modelled on ‘transplant plugs’. How it works: Excavate plugs of about one kilometer diameter from various parts of the Earth, store plugs in their entirety for transport, then replant allowing some distance between. Note: The one kilometer diameter size is a figure pulled out of the air as I don’t know the minimum/maximum sizes. The sizes may in fact vary depending on which ecosystem you needed to transplant. The plugs might be further broken down into pluglets for easier removal/hauling/replanting. The key is to reassemble it as one unit at the destination because you already know that this is in fact a stable/viable system. To kill a civilization, all you’d have to do is the same but using something toxic to the existing biome … distributed more or less evenly throughout the planet/system. Would uranium, radon or methane gas do the trick?)

Accidents also kill … So an advanced species/civilization that accidentally sends a probe into Earth atmosphere that contains a microbe that can outbreed everything else on the planet would be a planet-killer. If something like this ever happened, this would be sufficient reason for implementing a two-way safety envelope: restrict the travel off planet of any already space-faring races, and impose a quarantine on any emerging civilizations pro tem.


Re: 24 voidampersand : “And we also find that we are stranded in our solar system because the robots have already used up all the readily accessible volatiles and metals.”

Robot factories continually producing (no longer) needed goods … if a civilization can build robots that can function this long, I’m assuming they’re equally capable of building in some sort of in-put mechanism/algorithm to manage production, therefore avoid total annihilation of a planet/galaxy.

Re: 30 James PadraicR – “Didn't Asimov, in the later Foundation/Robot novels” - Yes, it was Asimov, as per R. Daneel Olivaw

Re: 31 Matt – “The galaxy will look empty of space dwellers at interstellar distances unless you watch and record long enough to spot the rare, transient algal bloom of megastructures.” Therefore smart/prudent civilizations might be more likely to build ‘into’ their ecologies, the less smart/therefore on the watch-list for potentially to-be-offed civilizations will be shouting their presence by building ‘atop’ their ecologies.

Re: 39 Sunspot42 – enjoyed your analysis.

Re: 48: NelC – Like this … ”The local lifeforms either never learn to bang the rocks together, or just never get the hang of multicellularity.” Think this would also fit in describing civilization, i.e., society is a multicellular organism comprised of individual humans.


Light signature – it would probably be easy to detect the beginnings of any technological civilization just by measuring changes in its light signature/frequencies. Consider how bright certain regions are in the photos here. If you wanted to off a civilization, these lights are your targets. (Secondly, this photo/analysis would also tell you which energy source would have the highest pay-off if you disrupted it.) Related to this is looking for complex molecular signatures.

http://www.thecoolist.com/earth-from-space-2012-nasa-black-marble/

Re: 60 – Fangz – “So what's the advantage in hiding what you are doing?” – It buys you time; in interstellar terms, this means opportunity to develop countermeasures.

102:

''I think "super-allergic reaction to alien life" is a red
herring.''

I don't. There are lots of fairly simple molecules that aren't
used by earthly organisms as toxins because they are so lethal
to the host. It only needs one of those to be used in a major
biochemical pathway for the whole ecosystem to be toxic to earthly
life. The simplest solution would be to build a quasi-human from
scratch, using the local biochemistry and the earthly structure.
Yes, really.

However, that doesn't stop terraforming, nor does it stop the
building of space habitats. So, at best, it's no more than a
fragment of the answer.

103:

The inner planets are probably below the limit of detectability for the current state of either radial velocity or transit photometry.

True for radial velocity; not true for transit photometry.

Ta, I'll have a read of the paper tomorrow. I knew the limit was somewhere around Earth/Venus size but thought it was still a bit above.

104:

I have difficulty with sterilizing an entire galaxy, short of colliding galaxies, or a nearby one turning into a quasar.

Actually, colliding galaxies are most unlikely to do planet-based life any harm at all: stars are a long way apart, and the probability of a star from the other galaxy coming close enough to disturb the planetary system is minute (perturbing the orbits of stars around the Galaxy, sure, but that doesn't do us any damage).

A nearby galaxy turning into a quasar would only be alarming if the outflow was pointing in our direction: they're quite strongly collimated. Our own Galaxy had a temper tantrum a few million years ago that blew a couple of large bubbles in the gas around the Galaxy, but did Earth no harm. I'm not sure how much damage a blazar pointed in our direction would do: the Galactic magnetic field would deal with the charged particle flux, but they are rather luminous in X-rays and hard γ radiation.

105:

do you go around raining on the fantasy types telling them "come now, there's no such thing as werewolves and dragons and elves"? Do I come by here and ruin your nice Lovecraftian fun by sternly lecturing about the improbability of these things?

...

"Don't be silly, Bob," said Mo: "everyone knows vampires don't exist." (The Rhesus Chart)

...

" Watch my lips: Cthulhu does not exist! And there is no tooth fairy." (Equoid)

Nope, no guns on mantlepieces there, nothing to see here, move along now.

106:

Studies of this were done in connection with the proposals for space-based aperture synthesis telescopes for imaging extrasolar terrestrial planets (ESA's Darwin and NASA's TPF). Infra-red spectroscopy shows you an absorption line from ozone, which is detectable from tens of light-years away. Our current knowledge indicates that a terrestrial planet with an ozone layer has photosynthesis – we don't know any way to maintain a high enough oxygen level without plants. OTOH, as far as I know nobody has yet worked out what's causing Mars' methane plumes (on Earth methane is either biogenic or outgassed by volcanoes, and Mars isn't supposed to have either widespread life or active volcanism), so I'm not sure how model dependent this argument is. Plus, of course, for nearly the first half of life's history on Earth it wasn't making much oxygen, so absence of ozone layer is not proof of absence of life.

107:

As a matter of interest has NASA, or anyone taken an in-transit probe and pointed it at earth? Was life detected?

Yes. The earliest example of this is probably Carl Sagan and collaborators using data from Galileo's fly-by:

In its December 1990 fly-by of Earth, the Galileo spacecraft found evidence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium; together, these are strongly suggestive of life on Earth. Moreover, the presence of narrow-band, pulsed, amplitude-modulated radio transmission seems uniquely attributable to intelligence. These observations constitute a control experiment for the search for extraterrestrial life by modern interplanetary spacecraft.
http://adsabs.harvard.edu/abs/1993Natur.365..715S


A more recent example: the Deep Impact mission looked at Earth in 2008:
http://online.liebertpub.com/doi/abs/10.1089/ast.2011.0614

108:

"Finally, there's the diminishing cost curve. We're talking about "alien spacefaring civilizations" as if they're monolithic individual entities. In reality, I'd expect any successful spacefaring species to be at least as diverse as we are, and prone to rapid memetic evolution."

So all it takes is one small memetic group of one civilization to populate the galaxy?

Why not rival groups from the same civilization (provided the competition does not lead to total destruction of the civilzation)?

Suppose space flight arrived in the Victorian era. Instead of a "Scramble for Africa" there would be a "Scramble for the Solar System".

Or suppose the Outer Space Treaty did not ban nukes in space. You just can't fully automated nuclear weapons systems, you have to have humans in the loop making the final launch decisions (and stop launch decisions, like Col. Petrov during operation Abel Archer). Nukes would require astronaut, cosmonaut and taikonaut launch officers which would in turn require orbiting infrastructure and support bases with associated personnel and support for these personnel, etc. - until superpower rivalry drives human expansion throughout the solar system.

P.S. If an American is an astronaut, and a Russian is a cosmonaut, and a Chinese is a taikonaut - what would a European be?

109:

I think trying to build a tube of superconducting material with a length/width ratio of 10 from one solar system to another just so you can manipulate magnetic fields at the far end is a bit more difficult...

Hmm, not what I was suggesting: that study was just to show that it's possible using conventional science to direct and transfer magnetic fields, which you initially poo-poo'd. It was also a joke about the internet.

Stop being an engineer for a second.

"It's called a flux transfer event or 'FTE,'" says space physicist David Sibeck of the Goddard Space Flight Center. "Ten years ago I was pretty sure they didn't exist, but now the evidence is incontrovertible."...

Sibeck believes this is happening twice as often as previously thought. "I think there are two varieties of FTEs: active and passive." Active FTEs are magnetic cylinders that allow particles to flow through rather easily; they are important conduits of energy for Earth's magnetosphere. Passive FTEs are magnetic cylinders that offer more resistance; their internal structure does not admit such an easy flow of particles and fields. (For experts: Active FTEs form at equatorial latitudes when the IMF tips south; passive FTEs form at higher latitudes when the IMF tips north.) Sibeck has calculated the properties of passive FTEs and he is encouraging his colleagues to hunt for signs of them in data from THEMIS and Cluster. "Passive FTEs may not be very important, but until we know more about them we can't be sure."

There are many unanswered questions: Why do the portals form every 8 minutes? How do magnetic fields inside the cylinder twist and coil? "We're doing some heavy thinking about this at the Workshop," says Sibeck.

http://science.nasa.gov/science-news/science-at-nasa/2008/30oct_ftes/

http://phys.org/news/2012-11-high-frequency-flux-events-mercury.html

http://www.igpp.ucla.edu/public/THEMIS/SCI/Pubs/Nuggets/FTE_nugget/themis%20nugget.html


The quaint idea would be as described: you're invoking a FTE event that results in a CME. How you do that is probably the magical bit.

http://paperity.org/p/35377050/charged-particles-tunneling-in-a-modified-reissner-nordstrom-black-hole


This is very much a 'butterfly's wing' model, but I'm suggesting it to break out of the (constraining) idea that physical matter has to be part of the "solution".

110:

I seem to recall a whole bunch of literature relatively recently on bacteria based on arsenic chemistry. Single celled organisms can live on an extraordinary range of conditions. Multicelled ... not so much, but that may be to do with the starting conditions here on Earth.

It wouldn't take much for a planet to be essentially inimical to us while still meeting every requirement of being an "earth like world".

111:

Agree, but that's not [i]allergies[/i]. Which, by definition, are an immune reaction gone haywire.

112:

You just failed elementary logic, on several counts:

(1) The word "spacefaring" in your premise A is essential, so you cannot omit it from your conclusion.

(2) There are several implicit assumptions in the argument:

(a) All intelligent (defined for these purposes as high-tech) civilisations become spacefaring (not obviously true: we haven't, so far – the Moon doesn't count).

(b) Any species technologically capable of colonising the galaxy would do so. (Charlie has written several earlier posts pointing out that interstellar colonisation is economically a mug's game.)

(c) We would notice if they had done so. (Again, Charlie has pointed out several times that canned apes are sub-optimal as a means of interstellar exploration: a hypothetical AI civilisation could have set up home in the Kuiper belt and I don't think we'd necessarily know.)

If the logic were corrected, this would be a straightforward statement of the Fermi paradox. There's an enormous literature on this: sweeping generalisations that "any contrary argument is special pleading" don't cut it. (The post linked to is a standard discussion, containing nothing new.)

Personally, I suspect that life is common, multicellular life much less so (on Earth, multicellularity evolved at least three times independently, but always from eukaryotic cells, and it is not at all obvious that the development of the eukaryotic cell is "easy"), and technological civilisations still rarer (I worry about the fact that true language would clearly be useful for many social species, but only hominids seem to have evolved it). But I'm not daft enough to think that the lack of obvious evidence for Galaxy-spanning civilisations proves this (and I'd love to see it disproven).

113:

So, how 'bout another "limiting" effect: just because, in the Skylark series, Doc had them look for the oldest cluster they could find, to try to find the most advanced civilization for help.

Unless I'm papering it over, our stellar neighborhood is comprised of the young kids on the block, mostly. How 'bout if life, and civilizations, started in the old neighborhoods, reached beyond their solar systems, and if they didn't collapse, or reach either a steady state, or a continuing ongoing cycle of expansion and collapse, then perhaps they either ran into others in the old neighborhood, with a resultant explosion of science, engineering and culture that singularity or not, the moved *beyond*, and aren't especially interested in the little kids playing out in the 'burbs?

mark

114:

All it takes is one.

115:

@Charlie Stross

I think you fundamentally misunderstand the Fermi paradox. It's not necessary for all advanced civilizations to engage in interstellar travel; it's only necessary that not all of them abstain from it. Because all it takes is one, and exponentiation does the rest.

That really depends on how many civilizations you have in the first place. If you have a 1000 civilizations in your galaxy, then it gets harder to believe that not one of them aggressively spreads as long as the technology is available for them to do so. But 10 civilizations? It's much more believable that they might go down a Non-Berserker path just out of chance.

Sure, no civilization is homogenous and there may be pro-expansionist factions within that civilization, but look at your own example of Mars One. How likely are they to get to Mars? Not very, because they don't have enough support to marshal the necessary resources.

116:

I also think people might be over-estimating the effectiveness of self-replicating machines.

Earth has been over-run with a form of grey goo running genetic algorithms for billions of years and it only very recently seems to have figured out how to escape our gravity well, and not very effectively at that (apathy again! a poor result to have your access to space depend on bureaucratic budget whims)

While intelligently designed devices might fare better, there are still limits that seem will be tough to overcome. How exactly do you power your grey goo living out in the Kuiper belt and beyond?

I feel like self-replicating machines are yet another of those technologies that has been 20 years in the future for the past 75 years.

117:

1. Baxter posits the influence of moons in various parts of the Manifold series. The one which seems most critical that has yet to be mentioned is that a large moon tends to soak up a lot of impacts from the parent body, I don't see how that couldn't have some effect on the development of life.

2. Manifold: Space covers a much simpler way to sterilize a galaxy than trying to do something silly like zap stars one at a time. If you have the ability to collimate the output of one star and zap another you have the ability to move stars and can bash white dwarfs and neutron stars and such together which will be far more effecive at wiping out large chunks of habitable real estate. I'm not sure how readily detectable a Shkadov Thrust around a dwarf star would be though sadly.

3. There is a lot of talk about us finding intelligent life and intelligent life finding us which seems to presuppose the idea that we qualify as intelligent ourselves. Setting aside our own tendencies for self-destructive behavior one could easily say that a civilization which hasn't yet converted an inner planet to solar collectors and begun producing anti-matter doesn't count as intelligent, or one which hasn't converted their planetary system into computronium and uploaded themselves into a substrate housing a benevolent A.I. god doesn't count as intelligent, or insert your own yardstick here.

4. In a scenario with previous berserker activity a simple definition of "intelligent life" precludes "announcing your presence to the galaxy" doesn't it?


The galaxy is big and dark and scary, there are no police, and we don't hear anyone screaming around other lightposts... but I'd still keep quiet or shoot the darkness (because it's funny!) rather than start screaming myself.

118:

Crap, forgot to add: Waking Uranus, I'm totally cool with this.

119:

(on Earth, multicellularity evolved at least three times independently, but always from eukaryotic cells, and it is not at all obvious that the development of the eukaryotic cell is "easy")

For what it's worth, I found this review article which mentions independent evolution of multicellularity having occurred either at least thirteen or at least twenty-five times (depending on your criteria):
http://www.amjbot.org/content/101/1/6.full.pdf+html

When described simply as a cellular aggregation, multicellular organisms are estimated conservatively to have evolved in at least 25 lineages (Grosberg and Strathmann, 2007), making it a “minor major” evolutionary transformation. When more stringent criteria are applied, as for example a requirement for sustained cell-to-cell interconnection, communication, and cooperation, multicellularity has evolved multiple times in bacteria (e.g., Actinobacteria, Myxobacteria, and Cyanobacteria; see Bonner, 2000), but only once in the Animalia, three times in the Fungi (chytrids, ascomycetes, and basidiomycetes), and six times among the algae ...

Brief discussion of some multicellular bacteria:
http://sandwalk.blogspot.de/2008/03/multicellular-bacteria.html

120:

Crap, forgot to add: Waking Uranus, I'm totally cool with this.

I believe you misread that.
Sounds potentially very painful, if you happen to have hirsute nether regions.

121:

I suspect the reasons are a great deal simpler.

Organisms that have evolved in a gravity environment are not adapted to travel in micro gravity. This makes long slow travel through space unfeasible, not impossible, but very, very difficult.

Secondly I suspect that "intelligence" or at least as exhibited by humans is not something that evolution selects for. (I suspect that a more stable outcome is environments like the age of dinosaurs with apex predators and no particular dominant species, certainly not on the global scale we currently have.)

We have managed to get to the edge of making our planet uninhabitable by us and I don't really think that we will successfully pull back from the current brink. That won't effect the biosphere much but it will eliminate or reduce our likelihood of survival.

Thirdly, assuming we survive, our population is peaking and will start to decline after 2050 or 2100. At that point we may stabilize at a level capable of maintaining a high technology culture, say between one and two billion which is fully sustainable and very comfortable for all those alive. If that happens there may very well be remote mining of asteroids and some interest in interstellar exploration but insufficient to reach, much less colonize other planets.

It would not surprise me if this is the normal curve of life. It would not surprise me if there were interstellar civilizations close in the the galactic core where star systems are packed much more closely and travel between them is a more feasible prospect.

Regards,
Chris

122:

... that study was just to show that it's possible using conventional science to direct and transfer magnetic fields, which you initially poo-poo'd.

No, I poo-poo'd the idea that this would be simpler and easier than Charlie's (LASERS!) approach. Your scenario implied doing this from another star system, which means carrying out magnetic manipulation across interstellar distances. Which, I suspect, isn't quite as easy as doing it in a laboratory (which we've obviously been able to do since the 19th Century).

It's a bit like saying, "Look, I can ride a bicycle down the street, or even across town -- how difficult can interstellar travel be?"

123:

See also "The Forge of God" and sequel "The Anvil of Stars" by Greg Bear. Not his happy fun mode by a long shot.

124:

Although humans are bags of mostly water, we need our bones to house the production facility for much of our immune and nutrient delivery/waste-disposal system (blood), etc. However, our bones need gravity - astronauts have shown us this. So, if we could figure out how to re-organize some of our bodily functions, we might be better able to live off planet. (Or, figure out how to build gravity-generating machines.) Following along this thought train ...

Given their distribution and very different way of doing pretty much everything, sea sponges could be biologic alien VN machines. (See Syringammina fragilissima - remarkably weird. Mere coincidence that this creature was first found off the coast of Scotland just after the Scottish Enlightenment.)

http://www.newscientist.com/article/dn18468#.VSwOmZMsDmY


125:

http://en.wikipedia.org/wiki/The_Killing_Star

Plot summary[edit]
The late 21st century seems like a good time to be alive. Earth is at peace. Humans now command self-replicating machines that create engineering marvels on enormous scales. Artificial habitats dot the solar system. Anti-matter driven Valkyrie rockets carry explorers to the stars at nearly the speed of light. All seems well.

Then, from the uncaring black of space come swarms of relativistic missiles. Though they are merely boulder-sized hunks of metal, they move fast enough to hit with the force of many nuclear arsenals. They are impossible to track and impossible to stop. Humanity is all but wiped out by the horrific bombardment. (To read a discussion of relativistic weapons and an excerpt of the attack, look here.)

A handful of survivors desperately struggle to escape the alien mop-up fleet. They hide close to the sun, inside asteroids, beneath the crusts of moons, within ice rings, and in the fathomless depths of interstellar space. But most are hunted down and slaughtered.

126:

Older, Male and hairstute in body - if not on scalp - Persons would Suffer.

Mind you I did read of a " Beauty " treatment that was said to be especialy popular with some sexual / gender populations and it is called is called ... " The Back, Sack and Crack Wax "


http://www.cleverdodo.co.uk/back-sack-crack-wax/11

Try doing a search in Google Images?

127:

" The late 21st century seems like a good time to be alive. Earth is at peace. Humans now command self-replicating machines that create engineering marvels on enormous scales. Artificial habitats dot the solar system. Anti-matter driven Valkyrie rockets carry explorers to the stars at nearly the speed of light. All seems well. "

Try reversing the perspective, with Humans taking pre-emptive action against the Aliens...especially if these Aliens threatened to become Illegal Immigrants.

I wonder how such a novel would be received by the Human Literary Community.

128:

I think that was actually the paper I was looking for. There are points I don't understand. There's more I'd want to read up on. And I'd love to hear from a geologist about the effects of a 20 degree variation in obliquity over 100kYr. But Lissauer and Waltham both conclude that an Earth without a moon should be stable enough for life to evolve; differing lines of argument only strengthen that conclusion.

Fun take outs from Lissauer:
- retrograde rotations are much more stable.
- 0° obliquity leaves the planet a snow ball.

129:

Have you got a source? Google came up with thirteen results (when in quotes). And my google-fu didn't turn up anything else.

130:

H+ - If it does not yet exist, it will because we will make it

131:

I think Susan is on to something.
Also, I seem to remeber something about the heavy element inventory (metalicity) of the milky way beeing relativly young. So it's not that unlikely that we are among the first generation. But his is not my forte, so maybe someone else can help out.

I tend to think that organizing enough production capacity in a coherent way to build one vN and send it wayward is actually quite involved. What is anybodeis guess how big and heavy such a thing will be, and how complicated?
Everyone keeps saying 'we could be a spacefaring species if only we tried', when we have no idea how to really try and how to behave as a 'we'. Serious, how society organizes itself is as relevant as the rocket science.

Also, any discussion of the Fermi-paradox smells of theleology to me: History marches on, so do we, everything gets better and/or faster all the time and out destiny amongst the stars is manifest - ad astra!

132:

Exactly. You can argue the fermi paradox suggests that the universe is not set up in a manner that makes self-replicating machines capable of extra-solar propagation viable (because otherwise we'd be seeing them - as already stated you only need to succeed once)

Possibly space exploration is always "loss making"; i.e. complex life* can only thrive in a biosphere it has evolved in. You can use some of the "surplus" of that biosphere to explore space - even, as someone said above, get to neighbouring stars with enough resource and a long-enough planning threshold. But non of your efforts are self sustaining and all need a "subsidy" from the home biosphere.

*I'm including machines capable of replicating as "life"

133:

Ok, btw - anyone who has living offspring, apologize to them since you just made the Basilisk angry and have proved yourself a future threat with all this genocide planning...

No, I poo-poo'd the idea that this would be simpler and easier than Charlie's (LASERS!) approach. Your scenario implied doing this from another star system, which means carrying out magnetic manipulation across interstellar distances. Which, I suspect, isn't quite as easy as doing it in a laboratory (which we've obviously been able to do since the 19th Century).

Ok, ok. I understand now; however, what I was attempting to suggest breaks the fundamental issue with all of this: Time. Even lasers are constrained by non-trivial Time constraints.

Fire now, hit in 500 years, but Space has moved and you have to calculate Xn objects that might intercept the path in that period at all plots along the course, calculate all possible interfering events (in 4D) and so on... It's actually a harder problem than just cheating and using Quantum hijinks to squish the neighbors.

As noted, no-one understands why every 8 minutes a FTE comes to life (8 minutes, weirdly... the time it takes light from the Sun Earth to travel is 8 mins 20, so consider it one of those quantum tick-tocks).


Fun fact that I've not seen SF note:

Cognitive and neuroplasticity mechanisms by which congenital or early blindness may confer a protective effect against schizophrenia

http://journal.frontiersin.org/article/10.3389/fpsyg.2012.00624/abstract

Or, you just admit you live on a 5D brane and the way it works is that light is put through a dimensional kink and... that's enough of that, thank you very much.

Editor's note: this is not done in public little one, desist now, or else.

134:

Watch my lips: Cthulhu does not exist!

It seems to me that you're going to have to decide, pretty soon, whether or not Cthulhu exists in the Laundryverse. If the stars come right and the world doesn't become an all-you-can-eat brain buffet, nothing deserving of the name exists.

I'm kind of hoping that, when Alex is the protagonist, the villain is Bob, who has come to the rational conclusion that the secret to saving London was to eat everybody's souls.

135:

Does this qualify as a bit of crowd-sourced research for the next novel?

136:

"A nasty version of panspermia? A primitive but voracious and very hardy replicator evolves to live in Kuiper belt / Oort cloud conditions.

Every so often a displaced comet / meteor fragment brings the replicator into the more high energy high resource environments where intelligent life might evolve. (Sure, extremely unlikey, but we've got billions of years.) It promptly goes on a binge and eats everything."


I'm pretty sure that scenario can be combatted by genetically engineering up some dragons...

137:

>Editor's note: this is not done in public little one, desist now, or else.

Once again, CatinaDiamond befuddles me. I cannot tell if the above is a real Editor's note or part of the performance art.

Editor's note: An unknown fraction of Editor's notes are forgeries.

Editor's note: Yellow card. Don't forge Editor's notes.

Okay, fine, I won't do it again.

138:

I think the big filter might be an internal one: we have no idea what extraterrestrial intelligent life might look like. We think all life needs water and ozone, because that's all we can imagine. We also assume that the time scale of life is similar to ours - what if there are life forms that live 1000 times as fast as we or 1000 times slower? We also think that intelligent life would behave like humans (i.e. not very intelligent...): expand, fight for resources, be curious about outer space, use similar categories to describe our ecosystem. Why couldn't they experience our ecosystem as a single lifeform ("Look at Gaia, isn't she a beautiful lifeform? Unfortunately she has some kind of disease, see these billions of bipedal cell sacks that pollute the atmosphere and mess everything up? Let's help her out...") or focus on single cells and view all organisms as social associations like our tribes and nations? ("Let's help those plucky cancer movements overcome the hierarchical and freedom-denying chains of their enclosing organism"). And even that is just projecting human ideas on aliens.

139:

The time those aliums butt-probed Mary causing her to miraculously deliver the highly nano-augmented nigh-android Jebus (whose mortal, well, mechanoid remains had to thoroughly self-destruct after mission completion) was reasonably effective at slowing humanity down and hamstringing our technology - never mind the Dark Ages, even today there are billions who think that the Bearded Cloud-Dweller will look after the faithful even if we wreck this planet, and that technology is evil and 'playing God'.

It nearly worked outright and certainly bought them an extra millennium in which to deliver the Grey Goo of Unlimited Appetite or adjust the velocity of a 100km asteroid.

Why the former? Because it was funnier! Just because you're a genocidal race of (justifiably) paranoid megalomaniacal Aliums, doesn't mean you can't have a GSOH. The look on Joseph's face was so priceless that it has been a popular Arcturan Imgur meme for over 2000 years!

140:

How about a probe that goes around seeding the universe with aggressive cyanobacteria or similar organisms. When the probe comes to a planet, it merely selects a bug from the catalog to significantly and rapidly change the atmospheric chemistry. It could even phone home with current and future prospects for colonization.

This may not sterilize a world, but it is definitely a massive setback unless you are catching the world at the presumably narrow band between a technological civilization developing and it being able to move off world and/or deal with the problem. Perhaps this soft approach would be good enough to take care of the vast majority of problems while being safer than some horrible griefer probe building dyson-scale weaponry or processing everyone it finds into paperclips, you may even get some terraforming prospects out of the mix.

Bonus points if the aliens ran the math and figured that aerobic life is a dead end.

141:

part of the performance art.

Well, being honest, that's really close to the mark. My own personal experience is a little bit more immediate to Surface Detail than the average Catholic Priest who diddles little boys. I do get spanked for these posts, quite actively and not in the nice way. But, meh, Greedo shot first.

“If you want to tell people the truth, make them laugh, otherwise they'll kill you.”

Ok, some hints:

Time perception is based on internal mechanisms. There's a great SF story I can't remember the name of that touches this (set on a ship over many eons, turns out they're tiny)...

http://www.scientificamerican.com/article/small-animals-live-in-a-slow-motion-world/

Hint: this isn't limited to small mammals, but largely it requires you peeps to be pumped full of adrenaline. Note: this isn't an absolute, and you can Edit, again little one, no.

https://en.wikipedia.org/wiki/Miles_Teg

Your internal biome is really important, as is your "secondary brain" aka your gut fauna.

Hint: there's a reason why your diet is what it is, and why certain parts are being removed. Gaia isn't a theory, it's part of your weltanschauung. Be very careful of those who take it from you. Not even being funny, part of being Human is having that link. The Fungi say HI (and they kinda love you).

https://www.youtube.com/watch?v=WANNqr-vcx0


And so on, and so forth.


I can say, without doubt, that at this very moment, a filter is being enacted. 6th extinction event and all that.


8 minutes. 8 minutes 20 seconds. Find someone to explain it. Your lives do really rest on it.

https://www.youtube.com/watch?v=RxabLA7UQ9k

142:

Thinking about it, there is an added bonus. Much easier to sell internally if the locals have some manner of ethical opinion about this sort of thing. This would probably open up the option to many more civilizations.

Also, much easier to explain if the neighbors start asking about it....so much easier to explain than laser-building kill -bots.

143:

Yeah, those led me to go check out The Killing Star but I've never been able to find a copy outside of an audio-book.

In a similar vein is Starfall, one of Baxter's shorts though technically it is in the Xeelee Sequence, not the Manifold series... though you could just as easily argue that we could canonically be in the Manifold series post-Time... but down that rabbit hole lies madness... I do want my own Nightfighter though.

Also, yeah, I think I read "Waxing" as "Waking" due to having hair on my ass and finding the whole idea of applying hot wax to it and ripping it out to be frankly horrifying.

144:

8 minutes. 8 minutes 20 seconds. Find someone to explain it. Your lives do really rest on it.

No they don't. It's coincidence.

145:

No they don't. It's coincidence.

Ahh, I get to use my card:

[Citation Needed]

If you understood the science and the weird way in which portals are being formed between the Sun and the Earth's magnetosphere then you wouldn't even type that.

Since I have another card left over:

[Citation Needed]

Please explain the temporal gap between these FTE events between solar entities - Earth and Mercury will do.


Thanks for playing though.

146:

I like it. In a world of perfectly beautiful android sexbots (built on current prevailing tastes), the only time there'll ever be Waxing Uranus is if someone had inadvertently reinstalled a human infestation.

147:

Hint to the prior post:

No-one knows currently why. So anyone claiming: "No they don't. It's coincidence." is blowing smoke.

And why would they do that?

Game. Set. Match.

148:

I have to admit I have no idea why somebody would build self-replicating Von Neumann machines. I do think I know why colonies wouldn't fill a galaxy, or at least do so extremely slowly.

Species colonize for economic reasons, and in two modes - the "organic" mode exemplified by the pre-Colombian colonization of the Americas ("Indians") and the race mode of the "race to Africa" fame. Both are self-limiting.

In organic mode, once you dump a few colonists ("few" could be "millions") on an Earth-sized planet, it will be a very long time before they run out of room sufficient to be interested in colonizing another planet.

In race mode, the whole point of colonization is to extract / redistribute wealth from the homeworld into the pockets of those running the colonies. Get too far from home, and this economic redistribution doesn't happen.

So, what I suspect is that there's a rapid expansion phase out from the homeworld to some transport-imposed limit, then a very long stasis period while the species absorbs the colonized worlds. Expansion out from this bubble would be slow - driven by individual colonized worlds - and uneven - some worlds would be "ready" to expand before others.

149:

but .. surely it'd be 'waxing venus' and 'bleaching uranus'

150:

> I have to admit I have no idea why somebody would build self-replicating Von Neumann machines.

well obviously to protect and serve our mighty freedom-loving holy empire's essential hypernational security, so Siptoc Sitizens can freely roam forever more and never be a slave

151:

All civilizations with interstellar capability will eventually run into the problem of AI. If they lose, there's now a hostile AI conquering the galaxy and converting it into the local equivalent of paperclips. If they win, they have a strong incentive to prevent any alien civilization from creating unfriendly AI. The most effective way to prevent AI development is to destroy the civilization creating it. This has the further benefit of ensuring that their unique values don't get threatened by aliens.
In both of these situations, there's a strong incentive to kill everything else that looks like a civilization. Therefore, any civilization which is advanced enough to think about the Fermi Paradox is one which has not come into contact with alien civilizations.

152:

Haven’t you heard? The world is actually flat and all those stars and galaxies are projections on a dome by a malevolent projectionist. The Fermi Paradox is an artifact of our mistaken worldview, UFOs are glitches in the demiurge’s control matrix, and our cosmology and space program are all a hoax. Occasionally the demiurge amuses himself by transmitting glimpses of the truth to one of the inmates of his prison, and they become prophets and/or madmen (Lovecraft's Mythos and Dick’s VALIS being recent examples).

153:

Thinking about it, there are two questions inherent in the original supposition:

1) If galaxy spanning civilisations exist, why can't we see them, or at least the evidence of them.

2) Since "we ain't dead" yet, have we bypassed the filter, or is it in our future?

What about if the answer to the first one is "because they don't want to be seen"? That makes sense in that doing something noticeable gets you noticed, and you never know if there is a bigger fish out their, waiting to swallow you.

So let's assume any galaxy spanning civilisation worth the name hides, well.

Second, so why aren't we dead yet?

Well, if you take the Star Trek viewpoint, it's because we aren't developed enough to welcome into the galactic community. However a moment's cynical thought highlights that any 'not us' civilisation is a competitor for galactic resources. We might play with studying apes for research, but we don't want any "damn dirty apes" actually competing with us for dominance.

So what if we are items for study, with the galaxy spanning civilisation seeing what can be learnt from us, or by us (fresh set of eyes) with sterilisation/extermination only following when we are on the verge of becoming a problem. A quiet, unnoticeable, extermination from an agency close at hand and able to take swift action. All the while keeping on the look out for other similar civilisations doing the same thing. A silent galactic war.

Doesn't that maximise the value to be gained from the enterprise? Study everything, get all the value, then euthenise the study subjects when it becomes more trouble than it's worth - all whilst keeping as quiet as possible.

154:

It is interstimg to think about great filters that we may have already passed through. To do that, just look at events in the past that are incredibly unlikely

- the Giant Impact Hypothosis says earth had a collision with a Mars sized world about 4.5bya which rather then destroying boy planets. resulted in both the creation of the moon and earth acquiring a significantly larger iron core then before. Perhaps leading to a more powerful magnetic field?

- mitochondria seem pretty weird and unlikely and also get a lot of credit for allowing complex multicellular organisms to exist

- homo sapien also very nearly went extinct about 70k years ago after a super volcano eruption. The genetic funnel this near extinction created might in some ways have resulted in changing the human genome enough to trigger civilization ?

Really fun stuff to noodle on...

155:

Thinking more about the self-propagating probes, it's worth asking why any AI operating them would choose to hang around scattered across solar systems when they could transmit copies of themselves over interstellar distances back "home" to hang out with their "friends and family". They might choose to only have permanent facilities in "hub" systems with lots of resources (say, every 20-30 light years or so), and periodically send out waves of one-way probes that send their AI and information back home after surveys. Those facilities, in turn, would be operated at a lower level between surveys since the controlling AIs make the trip back home between them.

It's not inconsistent with a handful of civilizations doing the Von Neumann thing. We just wouldn't have seen it yet because the last explorer came 3 million years ago, survey the system and noted the continued drop in temperatures on Earth, and then sent its digital copies back before crashing the probe on to a moon or planet. You'd only run into problems if lots of civilizations were doing the Von Neumann thing, since their hubs would fill up any stars with resources.

156:

I think you fundamentally misunderstand the Fermi paradox. It's not necessary for all advanced civilizations to engage in interstellar travel; it's only necessary that not all of them abstain from it. Because all it takes is one, and exponentiation does the rest.

Right, but what I'm arguing is just that - they all abstain from it. Asking why they all abstain from it is like asking why we haven't slaughtered all the whales in order to make oil for our lamps. They abstain from it because they have other technologies which make actually traveling the galaxy utterly useless. They simply simulate it from the comfort of their living rooms. Cheaper, easier, more convenient.

If technological civilizations capable of spaceflight are fairly rare - which seems likely, given that it took 4.5 billion years for Earth to generate one - there might only be a couple dozen (or less) that have cropped up in the entire history of the Milky Way. Given the way our own technology has advanced, we're going to have the ability to remote-observe and simulate most of the galaxy long before we have the ability to travel to most of the galaxy. If there aren't many civilizations to begin with, the odds of their being some oddball civ that goes out and colonizes in spite of having that technology are pretty much zilch.

Also, it doesn't have to be people who do the travelling; self-replicating probes will do the job just as well.

I'm not holding my breath waiting for self-replicating probes. Again, that kind of technology might never get developed, simply because there's no need for it. Their technology gives them all the resources they need, and they can "travel" wherever they want in an instant. So, no probes - or at least, nothing big enough to detect. Maybe they send out dust-grain sized craft to feed back data for their simulations, but that's about it.

If anything, I think most smart civilizations would consider such devices a potential threat to themselves. Consider the scenario where you send out self-replicating probes, and a slightly less advanced civilization manages to get its claws on one and steals your technology. Or a slightly more advanced civilization hijacks one, amps it up, and sends it back to your homeworld to cause havoc. Or, the devices go haywire on their own and become a threat to homeworld. Self-replicators seem like more trouble than they're worth, if you don't have any need to colonize interstellar space in the first place.

If you were really paranoid and very advanced, maybe you'd go underground in your own system, and erase all traces a technological civilization ever existed there.

You may not want to go and live in an aluminium tent in a poisonous desert for the rest of your life, but Mars One wasn't short of volunteers.

Perhaps, but they're catastrophically short on money and resources. And what happens when I can perfectly simulate a trip to Mars in my living room, essentially for nothing? I think that's pretty much the death of actual space colonization.

Thing is, multicellular life forms really don't like being smashed onto coastal rocks by 70 metre tides on a daily basis. So they couldn't have formed until the Moon receded far enough to permit them.

Because of those high tides though - I think they used to sweep clear over the early continents - the moon receded really quickly away from the earth. I think by a billion years in - if not less - they weren't really an issue.

I feel like self-replicating machines are yet another of those technologies that has been 20 years in the future for the past 75 years.

That and AI.

If they don't hurry up with AI, we might find a way to clone the human brain, interface it with a computer and stick that in a tin can first.

One other point - we assume that as technology advances it opens up the possibility of space exploration. Well, maybe. But it could also open up the ability to explore some other nifty sheet we aren't even aware of at this point. Stuff civilizations more advanced than us find a lot more interesting than sailing thru space bored out of their minds for 75 years, or sending self-replicating machines out to do who-knows-what.

Beyond that, if there are other civilizations out there, the odds are they're millions of years more advanced than ours, and could probably care less about us one way or the other. They're no more concerned with us than we are with some colony of ants in the middle of the Amazon rainforest. Just don't invade their pantry and we'll be fine...

Now, if there happens to be a civilization nearby that's only a few thousand years more advanced than ours, that civilization could possibly be a threat. Even if they don't currently travel, I suppose it's conceivable they could decide to make a trip to the Sol system, if they perceived us as some kind of a threat - like a bunch of raccoons setting up shop in their garden shed.

Finally, we're assuming all technological civilizations engage in space travel, but that might not be a valid assumption to begin with. If most intelligent life lives on a high-gravity world, the cost of building chemical rockets to get into space could be so high they never even try. Ditto if most intelligent life is much larger than us - elephant or whale sized. Maybe we're the runts of intelligent civilizations. Or if most intelligent civs are parked on the habitable moons of gas giants, bathed in radiation. It might simply cost too much in terms of shielding and fuel for them to get away from their home system, so they stay put. If intelligent life is reasonably rare, circumstances like this might account for much of the Fermi paradox, shaving down the number who actually ever would travel in space.

157:

Worth mentioning that the "portals" being discussed are just open regions of the magnetic sheath dividing the magnetic field of the earth and the interplanetary field (which is mostly that of the sun this far in) and that these events involve a tube opening up which allows charged particles to pass in through the magnetosheath freely from the sun before the tube slides away towards the magnetotail.

There is no direct link between the sun and earth being formed, there are no "quantum shenanigans" taking place, it is a connection between the magnetic fields around these two bodies.

It is interesting that the period of these events is so similar to the light transit time but until a consistent relationship between the FTE periods of other planets and the distance from the sun is found it is either a coincidence or a banal feature of interplanetary magnetodynamics.

There is a lot of noise about these being new (and the use of "portals" was what kept me from realizing you were discussing a recent discovery related to the magnetic field reconnection problems identified back in the 70's as I recall) and there is a lot of noise about these being somehow bad or dangerous or proof of [insert whackadoo theory here] which is a pain to sift through.

These sort of events are by definition local in the frame of a given magnetic field and sheath, there are most likely FTE events taking place around the heliosheath allowing periodic injections of charged particles from interstellar space and vice versa.

The utility of a reconnecting flux rope in a discussion about intestellar exterminatus methods is... let's be generous and say negligible. It might be convenient if you could align them to allow free passage of some sort of directed energy attack or perhaps a charged particle beam, though getting it to survive through the interstellar medium is another problem entirely, and a rather more insurmountable one than the presence of a stellar magnetosheath would be.

158:

No-one knows currently why. So anyone claiming: "No they don't. It's coincidence." is blowing smoke.

No. One is a (pseudo) period of an event happening somewhere between Earth and Sun. The other is the time laps between a photon leaving sun and arriving at earth (or vice versa). One is 480 seconds and the other is 500 seconds, a difference of 4%.Why should they be related?

And why would they do that?

xkcd

159:

*spins keyboard around and holsters it somehow*

160:

As for exploration, assuming their remote sensing and probes are advanced enough, they wouldn't bother. If they wanted to "visit" the Earth, they'd just fire up a simulation in their living rooms. With advanced enough technology you'd be able to create something like a Star Trek holodeck, and visit whatever worlds you like whenever you like without spending decades getting there.

Yeah, this seems likely to me, assuming we aren't in a simulation and/or there isn't a demiurge in control of this region of space already. If you can generate simulated "infinite diversity in infinite combinations" using insanely powerful computers, who needs spaceflight?

Hell, a lot of people already find psychedelic drugs more interesting than flying to Mars, and we've probably only just begun to explore inner space. So a more likely future than Star Trek is "Mind Trek", via drugs, technology, yoga, etc. Ultimately, the material world may become strictly the province of Earth-side mundanes and minder-bots, and most of us will live full time in inner space. John Lilly tried this decades ago, and came back with a possible creed for future Mind Trekkers:

“In the province of the mind, what one believes to be true is true or becomes true, within certain limits to be found experientially and experimentally. These limits are further beliefs to be transcended. In the mind, there are no limits... In the province of connected minds, what the network believes to be true, either is true or becomes true within certain limits to be found experientially and experimentally. These limits are further beliefs to be transcended. In the network's mind there are no limits.”

161:

In organic mode, once you dump a few colonists ("few" could be "millions") on an Earth-sized planet, it will be a very long time before they run out of room sufficient to be interested in colonizing another planet.

It took early "primitive" humanity approximately 2000yrs to spread from the first landfall in Alaska to colonise patagonia.

If you give a rate of 1.1% growth from a start of 100 people, you'd cover the same ground in less than 1000yrs. With modern agricultural techniques and a similar lowballed growth rate, you would cover the same ground in probably 300-400 years with orders of magnitude higher population density.

Colonisation is a surprisingly rapid process, and when we talk about space travel we're talking LONG timescales.

Assuming current technology, we could get to Alpha Centauri in under a century. If there was a compatible earth like planet there, a colony established on the first trip could cover up to half the world by the time the third trip arrived. We breed fast, and rates get exponential with enough food. Look at India - it went from 250k in 1915 to 1250K today.

162:

And why can't I remember the name of the Galactic Patrol's chief scientist?)

mark "when *I* grow up, I want to be Dick Seaton...."

I think you're confusing 2 Doc Smith series?

Dick Seaton was the Skylark series.

The closest I can come to the Galactic Patrol's (Lensmen series) "chief scientist" is "Thorny" Thorndyke, who is explicitly described as their "master of mechanism", which sounds more like an engineer IMO.

163:

Dammit. The problem about getting old is that one's mind becomes
like the attic of a large house lived in for generations - you
know that something is there, but not exactly what it was, what
state itis in, or where in all that junk it is.

There was a science fiction story of the 1950s or 1960s that
described a personal, mentally-invoked 'bobble' (vide Vinge) and
someone who took a trip through the ages. Called the walking/
striding shadow/statue or something like that. Anyway, the point
is that it referred to an academic paper (which I did not look
up) that claimed there were three classes of life, and evolution
necessarily would lead to the third kind taking over. And the
third kind was a sort of super grey goo.

Can anyone remember what that was called? I am pretty sure that I
still have a copy in my attic, somewhere .... But, anyway, that
book (incidentally?) gave an answer to the Fermi paradox.

164:

But, meh, Greedo shot first.

That there's fight'n' talk stranger!! ;-)

165:

It's hard to disprove Fermi Paradox - as usual, you're thinking about pros and cons, and it's something like every pro adds to the probability they should have been here from long ago, and every con just disproves some specific case...

First, it is not hard at all hard to knock out a high-tech overpopulated society - every serious global natural disaster and every runaway social wobbling can do that. But it's a lot more harder to wipe out the species - I doubt that even a Chicxulub-scale impact could kill off all the survivalist omnivores, and there would be enough carrion and insects to feed the breeding minimum through all the impact winter. :-J. And it's even harder to wipe out all the knowledge. They may be thrown back to stone age, but when the dust settles, they would rediscover and rebuild in mere thousands of years. Already knowing that burning the remaining oil is not good and we should try solar energy instead, first with great reflectors and Stirling generators, then with solar cells. Then, certainly if the competition-between-tribes-and-individuals line isn't completely removed from species source code, they would go high-tech, and then complicated, imbalanced and wobbly again and again, but after millions of years and thousand crashes they'll eventually become steady and immune and stil willing to advance. Another dimension to Fermi Paradox, if it's so hard to wipe out the intelligent species completely, and if there is an effectively infinite number of attempts, where are any transcendents? So, the fGF about inherent instability doesn't work, by these arguments :-)

But then there is slowness of colonization. Once someone gets interstellar and able to replicate, it's the matter of time, but also of willing and effort. The difficulties mean everything. A human tribe can of course live in the forest and replicate, and it could walk around Earth by foot in a dozen years. (even this raises concerns, what are interstellar analogs for crossing Bering Strait if you started out in Africa?) And really, some conquests in our history were made almost as quickly. But the real expansion into the wilderness is much slower even if that is the wilderness we are suited for. It took some 10^4 years just to spread around and then again ten millenia to become quite noticeable from everywhere on Earth - three orders of magnitude slower than characteristic time. If we apply that to thermonuclear rockets and Galaxy colonization, this gives us billions of years. There are tribes and primitive states here and there...

And for the griefers with Dyson-Nicoll blasters, AFAIK, there are no Dyson swarms in a good part of our galaxy, by WISE survey - if there was a thermal IR source with the luminosity of the whole star within 1 kpc AND far away from any star formation regions, that would blaze in the data like a sodium lamp against the nightsky. So the roundtrip would be more than 10 thousand years, and we have some time even if someone saw the Great Pyramids and Sphynxes and now is taking aim :-)

166:

This is the perfect time to reintroduce my hypothesis: there is no 1 great filter. There are thousands of them. Some in our past, and some in our future.

An assumption hidden in discussions about the Fermi Paradox is that humanity and life on Earth have escaped the great filters. Perhaps several great filters were in our past, and life on Earth has failed some?

Perhaps multiple habitable worlds in the same solar system are necessary to provide enough motivation to sustain investment for the centuries needed to refine interplanetary technology enough to make interstellar travel possible? If Mars was as habitable as Jamaica, space exploration would probably not have atrophied as such?

Another possibility is that concern for individuals within the species is a filter? Let's say we wanted to build a Mars outpost that is NOT self sufficient. In other words, we know that it will NEVER survive without periodic resupply missions from Earth. We have built a > 10-year space outpost that would not be able to survive without resupplies every 3 months: the ISS. However, such an outpost at Mars or an interplanetary spacecraft still face a problem: radiation. One solar storm would kill the crew. If we were willing to have losses of 30% of interplanetary spacecraft, outposts, and their crew, we may have an outpost on Mars already that can't survive without 3-month resupplies and is praying to whatever god that they don't get hit with a solar storm.

167:

Correct. And the provisional elevator pitch for "Waxing Uranus" is, "to do for First Contact stories what the Marriage of Figaro did for hereditary nobility". (Comedy of misunderstanding meets political farce meets deconstruction of [interstellar] colonialism ...)

168:

If we apply that to thermonuclear rockets and Galaxy colonization, this gives us billions of years.

Well, probably not. Wright et al. (see URL below) adopt an extremely conservative approach: assume interstellar travel speeds of 0.0001 c (barely faster than Voyager 2 or New Horizons), a launch rate of 1 colonizing expedition per 10,000 years, and a maximum travel distance of 10 parsecs (and no further technological development to speed any of this up). Even with this, you can still get effective colonization of a large fraction of the galaxy within 1 billion years, and probably within a few hundred million years. (One of the neat things about their analysis is that if the travel speeds and launch rates are low -- as in their example -- then the relative motions of stars will speed up the diffusion rate of colonies.)

http://fr.arxiv.org/abs/1408.1133


And for the griefers with Dyson-Nicoll blasters, AFAIK, there are no Dyson swarms in a good part of our galaxy, by WISE survey - if there was a thermal IR source with the luminosity of the whole star within 1 kpc

I'm not sure anyone has actually put a limit like that using WISE data, though people have talked about doing that; the Wright et al. group is apparently focusing first on looking for waste-heat signatures in other galaxies:
http://sites.psu.edu/astrowright/2015/04/13/g-paper-iii-part-i-searching-the-wise-catalogs-for-type-iii-kardashev-civilizations/

Anyway, there's some freedom to "hide" the "blasters" because you don't necessarily need to capture the entire output of the star -- even if your Dyson swarm is only capturing 1% of its output, that's still an enormous amount of energy that could be put into a Nicoll-Dyson laser, and the waste-heat signature is only 1% of the stellar luminosity, and thus much harder to identify. (Plus, you could operate in a 1% or less basis during spy-on-the-neighbors mode, and spool up to, say, 10% (unfold the solar collectors) only when you need to fire the laser at a target.

169:

Galactic Patrol Scientist:
Sir Austin Cardynge

170:

I'm pretty sure the book you're thinking of is "The Walking Shadow" by Brian Stableford, published in 1979 -- and available here.

171:

That would be The Walking Shadow by Brian Stableford, I believe, actually a late 70s novel.

172:

Cheers; It's been a while, and my Mum binned most of my books that were at her house.

173:

I'm having trouble thinking of a scenario for building a civilization-destroying Dyson-Nicoll beam that wouldn't imply intelligent life being so common that a single beam wouldn't be able to make a dent in it, except locally.

You either build one because there's a civ close enough to be a threat to your own burgeoning civilisation, and you've got the resources to do it, in which case civs must be pretty common; or you build one because there might be one at some point in the future, in which case, your civilisation will be all through the galaxy anyway. (What's the theoretical range on those things, anyway?)

174:

[Eyes Charlie suspiciously.] Are you reading over my shoulder? :)

175:

What's the theoretical range on those things, anyway?

How long would you like it to be? Planets don't dodge!

It's been noted that laser beams spread into much over a range on the order of single-digit light years. The interstellar medium isn't a perfect vacuum, after all, and a density of one atom of gas per litre adds up when you're talking in terms of columns of vacuum on the order of 10^15 metres long. But I suspect you could clear a path through the interstellar vacuum by pulsing the laser, and initially starting at very short wavelengths -- to kick the atoms (or rather, stripped nuclei and electrons) up to relativistic speed until they clear the "tunnel" -- then dropping down after a few minutes to something more easily absorbed by the atmosphere of the target planet.

So if you see a distant, dusty star system suddenly light up like a supernova in the X-ray spectrum then begin to drop down towards UV while intensifying rapidly, prepare to kiss your ass goodbye ...

176:

1.1% is a high-ish growth rate. Modern humans don't seem to like having that many babies.

177:

Wrong.
1.1% is the current global growth rate, dropping from a high of around 2.2% back in the 60s.
The US is presently around 0.7%, but it only really dropped a few years ago. Go back to 1990 and it was close to 1.5%.
Nigeria currently sits at 2.8%. Libya and Kenya were both around 4% during the 80s following the food boom of the Green revolution.

A virgin planet with a new colony? Growth rates would substantially exceed ours, and that is with standard biological reproduction. Given the reproductive engineering required for us to send viable colonies across interstellar distances, and you could be talking exponential rates with uterine replicators raising prefertilised embryos (initially anyway).

178:

Thoughts on the OP:

The curious thing is that this model would only explain some versions of the Fermi Paradox -- e.g., "why aren't they in our solar system right now?", or "why don't we detect radio beacons all over the place?" If, however, you make a thorough search for K2 civilizations (K2 = Kardashev Type 2, using, say, 10--100% of a star's energy output) -- as we're starting to do -- and don't find any, then it doesn't really work...

The reason is fairly simple: A galaxy populated by griefer sites will, to a moderately sophisticated survey, be indistinguishable from a galaxy populated by non-griefer K2 civilizations, because each site is a technological artifact producing lots of mid-IR waste heat.

Given our limited current observations, the "lots of K2 sites" scenario could still be true for our galaxy and other galaxies; but we will probably be able to either confirm it or rule it out within the next fifty to one hundred years. Either we do find lots of K2 sites in our galaxy (or in other galaxies) -- in which case they could be griefer sites... or they could be standard "benign" K2 civilizations -- or we don't find them, in which case the griefer model can't explain their absence.

Of course, you can argue that the waste-heat signatures of griefer sites should be low, if the original builders decide to go for a "stealthy except when shooting" mode, as I suggested above (limited Dyson swarm carrying out the observations, cranking things up to higher power consumption when firing the N-D laser) -- but then you're having to specify rather particular motivations for the original builders, as well as assuming the original programming remains intact over multiple generations. (And that makes it much harder to explain how this would work in many different galaxies.)

179:

I'm not sure if griefers work as an explanation for a fGF. If you look at griefers within human societies you see a pattern that their success is limited by the number of their targets: Griefers who kill their own family are frequent and usually don't leave survivors, griefers running amok at their school or work place only manage to kill a percentage of people in attendance. Terror attacks rarely get into the thousands of fatalities and even genocide usually isn't as complete as its name suggests.

This indicates that galactic griefers will have a hard time to finish off 100% of all other civilizations. Having more time doesn't really help since it increases chance of detection and fighting back. Space is also really huge [citation needed] so it's difficult to organize an exhaustive search.

In conclusion: it's probably much easier to detect a griefer than being a successful one.

180:

Re: 177 Mayhem

"A virgin planet with a new colony? Growth rates would substantially exceed ours, and that is with standard biological reproduction. Given the reproductive engineering required for us to send viable colonies across interstellar distances, and you could be talking exponential rates with uterine replicators raising prefertilised embryos (initially anyway)."

While a good seeding scenario I wonder whether what you describe would be workable in terms of raising a society.

People under 25 years of age have a very large energy requirement on a per pound basis. Even worse, this is also when/for how long they require the greatest supervision and one-on-one care/education. To a colony, this means time away from exploration, tending machinery, doing experiments, etc. So although it would be nice to grow your own colonists, I think it would be more economical and perhaps even safer - for the first 100 years or so - to only import fully grown, functional adults. So, I think we're likelier to see zero 'natural' population growth for the first off-earth colonies.

181:

My main problem with your griefer scenario is that, if we assume the VN probes never move faster than light, it's perfectly reasonable to believe that civilizations will develop far enough to counteract them (maybe with their own VN probes, or maybe by detecting and destroying them as they come), even if the griefer civilization starts first, so long as the distances between technologically advanced planets are long enough.

Let's say, for instance, that a civilization capable of making these VN probes is also capable of counteracting them, that the VN probes never attempt to destroy other probes of the same type or the brains thereof (i.e., you avoid accidentally doubling the effort of previous attempts), that the probes move at exactly 100% of light speed, and the amount of time from life first appearing to the development of VN probes of this type takes 4 billion years on average. Then, civilizations outside a 4.7E22 kilometer radius of the griefer civilization will develop VN probes before the griefer civilization's probes reach them, even if life developed there just as the first griefer probes were launched. In reality, you could expect life development to overlap (if we assume it isn't rare) and probes to move slower than light.

In other words, we could expect such a thing to wipe out life in a big area surrounding a griefer civilization, but we could expect it to eventually be shut down out of self-preservation (and for other civilizations to survive, sometimes).

182:

I'm going to explicitly disallow colony planets seeded using uterine replications as a magic wand technology. Not because uterine replicators are impossible (they're probably not, although they're very difficult: the placenta is a pretty complex organ!), but because raising and socializing the resultant offspring is an AI-complete problem. At a minimum, just teaching an infant how to speak requires someone who can provide speech stimulus and meaningful, valid linguistic feedback -- in other words, something that passes a Turing test.

183:

I was thinking there would be a colony of fully grown adults, but given the nature of interstellar radiation, they'll probably be accidentally sterile by the time they arrive.
Still very capable of raising young, but not so good at making their own :)

Also removes the inherent bias that a biological imperative gives in terms of raising the next generation vs making your own. They'd be perfect communal caregivers as they wouldn't have a vested interest in individuals.


The key argument anyway is that population growth on a new world would greatly exceed the round trip flight time to send more colonists and/or supplies, unless we have handwavium speed engines or deliberately self-limiting populations (like space stations, or worlds where we can only live on mountaintops etc.).

184:

I was thinking there would be a colony of fully grown adults, but given the nature of interstellar radiation, they'll probably be accidentally sterile by the time they arrive.

More like crispy critters -- or dead of old age. Once you get above 1% of c you can approximate a stationary helium atom in the interstellar medium to an alpha particle, and each square metre of frontal area of your starship is getting hit by on the order of 30,000 of them per second. But that's nothing compared to the neutral hydrogen and free electrons. I would guesstimate that at 1% of c the incoming radiation will be measured in MBq, and at any relativistic speed high enough to get humans to the nearer stars in less than five decades' subjective time it's going to resemble the interior of the sarcophagus at Chernobyl. Or worse.

(As I've been saying for some time, without "magic wands" -- tech that is nowhere near the drawing board and may violate the laws of physics as we know them -- interstellar flight at >>1% of c is pretty much a non-starter for us. And at 1% of c Alpha Centauri is five centuries away. So it's generation ships, cryonic suspension, or some combination of the two -- or bust.)

185:

The lightspeed limit is a problem because our lifespans are so short and we don't pass consciousness across bodies.

We're not a type of life that's suited for space travel.

A shared consciousness or hive mind would have a huge advantage, being effectively immortal and able to plan across ages instead of merely years.

If we ran up against a hive, something like John Barnes' "One True" (a distributed AI running on linked human brains) might be the only way to be competitive...

186:

they would rediscover and rebuild in mere thousands of years

Perhaps not. Going beyond (roughly) 18th century technology requires fossil fuels (as far as we know), and the easily extracted fossil fuels are long gone.

It's a bootstrapping problem: survivors of a civilizational collapse would not have enough technology to reach the fuels that could power their technological revolution.

187:

I believe OGH has written along those lines though the aggressive hive can't be the whole story...

188:

1.1% is a high-ish growth rate. Modern humans don't seem to like having that many babies.

In the moderate term, that's debatable. In the long run, spamming the planet with your offspring is a proven evolutionary strategy. Whatever traits cause people to outbreed their competition will be progressively enhanced in future generations. They may not be happy, but that's not the point.

Consider the case of hunter-gatherers versus subsistence farmers. Subsistence farming is miserable drudgery with little variety in diet, but billions of people do it. Hunter-gatherers are happier, work less, eat better, and are all but extinct.

189:

Re: "Once you get above 1% of c you can approximate a stationary helium atom in the interstellar medium to an alpha particle, and each square metre of frontal area of your starship is getting hit by on the order of 30,000 of them per second. But that's nothing compared to the neutral hydrogen and free electrons. "

Not to derail the discussion, but I've been wondering whether any SF writer has ever used a '(helium/hydrogen) sweeper beam ship' in advance of the actual passenger ship to clear the space lanes. Conceptually, this isn't much of a stretch from ice-breakers on the seas/in ports, or snow-clearing the highways in winter. (And, might not such space lane-clearing be a sign of interstellar commuting? Look for empty spaces when looking for life?)

190:

How long would you like it to be? Planets don't dodge!

Actually, planets do dodge on the relevant timescales (the years it takes the Griefers' killing beam to arrive), which is to say, they orbit. Suppose that you've collimated your laser sufficiently well that even with spreading and interstellar scattering, it just fills the solid angle occupied by your target, which is an Earth-like planet 5 parsecs away (just over 16 l-y, for the non-astronomers). You have to know where your target is to a positional accuracy of about 18 microarcseconds, while it's moving back and forth across the sky by 0.4 arcseconds on a timescale of 1 year. How many astronomical objects do you think we know the orbits of that precisely?

Also, on a more general point, something flaring up as a source of radio noise and then fading away is a signpost of improving technology: as Randall Munroe points out in his hilarious What If? (I highly recommend it), having a substantial fraction of your broadcast power leaking into space is very wasteful, and the Earth is much quieter now (from an interstellar perspective) than it was 50 years ago. (He also points out that, ironically, the USA's Early Warning radar system was by far the most powerful announcement we made to the rest of the universe that We are here!) People also have wildly exaggerated impressions as to how far our leaked radio/TV signals would actually be detectable.

191:

The downside is you need it to be pretty large and close to the following ship to avoid too many particles reinvading the passage before the ship arrives.

The classic solution is to put as much mass as you can get right in front of you. A few gigatonnes of ice might be a decent shield, and I'm sure you could think of other uses for it.

(Drives being what they are, you might want another couple of gigatonnes of ice between you and the back too.)

As for seeing cleared lanes ... space is large. You're looking for where the vacuum drops from say 1 particle per cubic metre to 0 for the period before the gas laws close the tunnel up again. I'd expect that period to be quite short. I'd look for the ship instead, especially since it's going to be radiating quite interestingly.

192:

I should add that I also assumed that the Earth-like planet has an Earth-like orbit (1 AU from its sun), which is where the 0.4 arcseconds per year number comes from.

193:

An alternative to the OP:

Dysonize Everything: if you have the technology to generate von Neumann probes which can convert a star system into a Dyson swarm and also generate new von Neumann probes to repeat the process -- why not just do it to every star in the galaxy? Rather than having the individual griefer sites study other star systems in detail and have to worry about when to zap them, you just make sure you "colonize" every star in the galaxy. In each system, you convert any potentially life-bearing planets (or just all the planets) into part of your local Dyson swarm, and you're set -- no planet-based intelligent life is going to arise there at any time in the future.

The main thing to worry about is the formation of new stars, but that's not really a problem. Each Dyson swarm can monitor the local volume for stars that don't already have a Dyson swarm, and if they find one, they send a von Neumann probe to convert it. (This is, for what it's worth, simpler than looking for signs of planetary life. This also takes care of any halo stars on highly radial orbits when they wander in to the denser parts of the galaxy.) Presumably you build in some protocols so that the second and subsequent von Neumann probe that arrive at a young, pristine star yield to the first one...

Of course, we can be sure this didn't happen to our galaxy, since we seeing lots of stars (including our own!) with planets and without Dyson swarms (and even more that aren't Dysonized, even if we can't tell yet whether they have planets).

Still, it's perhaps a weak argument against the OP, since you can ask why a primordial griefer civilization (or, more plausibly, griefer faction within a primordial civilization) would necessarily choose the isolated N-D laser solution over the Dysonize Everything approach.

194:
exaggerated impressions as to how far our leaked radio/TV signals would actually be detectable.

Quite so...

I can't get radio 4 fm, 50 km from London, so how do they enjoy the Archers in Tau-Ceti?

195:

You have to know where your target is to a positional accuracy of about 18 microarcseconds, while it's moving back and forth across the sky by 0.4 arcseconds on a timescale of 1 year. How many astronomical objects do you think we know the orbits of that precisely?

Well, you are firing this hypothetical laser from a Dyson swarm that also functions as a solar-system-scale interferometric telescope, so that's not really a problem. (We can do microarcsecond resolution at radio waves from the Earth right now...)

196:

Then, civilizations outside a 4.7E22 kilometer radius of the griefer civilization will develop VN probes before the griefer civilization's probes reach them

You haven't accounted for the expansion of the universe, which will carry civilizations in other galaxies further away from you while the probe travels. But even ignoring that, 4.7E22 kilometers is about about 1.5 gigaparsecs (5 billion light years).

The OP is, I take it, suggesting a way of suppressing the emergence of intelligent life within a single galaxy (radius roughly 30 kiloparsecs or 100,000 light years), not within the entire observable universe...

197:

Going beyond (roughly) 18th century technology requires fossil fuels (as far as we know), and the easily extracted fossil fuels are long gone.

It's a bootstrapping problem: survivors of a civilizational collapse would not have enough technology to reach the fuels that could power their technological revolution.

People started building hydroelectric dams in the 19th century and as far as I can tell the materials could be prepared with charcoal: steel, concrete, copper. The best natural ores are gone now but pick through the right parts of our trash and you will find copper more highly refined than nature ever gifted. I think that you need fossil fuel depletion plus a societal breakdown that lasts enough for all the libraries to rot, or literacy to be lost, to get a prolonged reversion to the pre-electrical age.

198:

The good news is that alpha-like bombardments don't go all that deep, just a few microns (depending on energy). The bad news is that the collision process liberates electrons and produces x-rays, both of which can be much more penetrating (depending on energy, of course).

The worse news is that anything larger, like a grain of dust, could really ruin the astronaut's day.

199:

Another possible pGF is the Great Oxygen Catastrophe. It took 1-2GYa for the proto-algae to oxidize the lithosphere enough for O2 to begin building up in the atmosphere and hydrosphere -- at which point the toxic waste product killed off about 98% of life on Earth. Luckily some survivors then worked out how to use a powerful oxidizing agent to drive their metabolism...

By itself I'm not sure how well this counts as a pGF, since as you point out it has the effect of providing a useful metabolic boost once you figure out how to use it -- and I would imagine that cyanobacteria themselves had a head start on being able to survive oxygen...

Moreover, increasing atmospheric oxygen is a prerequisite to forming an ozone layer, which certainly enabled land colonization. So one could argue that not developing oxygen-producers might be a pGF.

On the other hand, it's been argued that increased levels of oxygen removing methane from the atmosphere helped trigger the Huronian glaciation and a near-snowball-Earth situation, so there's an alternate way to get a pGF from oxygenation...

200:

True, but you can't scan the sky with one (angular resolution is spectacular --> field of view is miniscule).

201:

Charcoal production involves a lot of wood and a fair amount of work. For small scale production (e.g. a medieval smith) it works, but metal produced that way is incredibly expensive by modern standards. For something like a major hydroelectric dam, it's probably impractical.

A barrel of oil has about as much energy as a decade of manual labor (roughly), and the average American uses two barrels a month. If a society didn't have access to fossil fuels, it's not likely they would ever reach a standard of living anywhere comparable to ours.

202:

Also, astronomers generally avoid looking in the vicinity of the Galactic Plane (the midpoint of the Galactic disk), which is where all of the planets are (because that's where the cold, dense gas that star formation occurs in is found) precisely because that's where all the gas and dust is, and ionized gas wreaks havoc on radio wavelengths. I don't recall the numbers off the top of my head (I'm, erm, supposed to be at work), but for example, we only have an upper limit to the size of the radio source associated with the Galactic Center black hole (known as Sgr A*), because the source size we observe is entirely set by interstellar scattering - we know this because the wavelength dependence of the observed source size obeys precisely the scaling expected from interstellar scattering.

203:

"I would guesstimate that at 1% of c the incoming radiation will be measured in MBq, and at any relativistic speed high enough to get humans to the nearer stars in less than five decades' subjective time it's going to resemble the interior of the sarcophagus at Chernobyl. Or worse"

The confinement shell at Chernobyl is a 13 M thick layer of concrete and reinforceing steel. A difficult and fascinating engineering problem (the rail mechansim they will use to slide it into place is an engineering feat of its own) - but far from impossible.

A starship just needs sufficient forward mass to protect it from impact radiation. Again, since future starships will probably be built from hollowed out metal asteroids - this will be challengineg but far from impossbile.

"So it's generation ships, cryonic suspension, or some combination of the two"

Why not cryonic suspension of a crew of adult humans AND millions of frozen embryos?

It is also possible that a suficeintly advanced android AI could mimic human parents enough to raise them adequetly. It does not have to be perfect - very few parents are perfect anyways.

204:

But you're really only interested in the habitable zones (radius of a few AU) around the nearest few hundred or few thousand stars, so small field of view isn't a problem.

205:

If you can build an artificial intelligence good enough to raise and socialise a human you've probably just build a full on sentient AGI. If so colonise the universe with them, machines can be far more durable and adaptable.

206:

The classic solution is to put as much mass as you can get right in front of you. A few gigatonnes of ice might be a decent shield, and I'm sure you could think of other uses for it.

This and a few previous comments have reminded me of Clarke's "The Songs of Distant Earth". Has ice shields, cryogenic colonists, people grown 'from seed', and probably plenty I'm not remembering. That is, if I'm remembering correctly, haven't read it since it came out in (runs to bookcase to check) 1986. Looks like I'm adding to my re-read (someday) list.

207:

Also also (sorry for all the addenda, but perhaps I didn't make this clear in my original post) it isn't a question of how accurately you can determine where your target was 16.3 years ago (which is when the radio waves you are now detecting were emitted) but of knowing, to the same precision, where it will be 16.3 years after you fire.

208:

I'm leaning towards three different possibilities, myself:

First, a pGf way back at the beginning of life on Earth, before multicellularity even: that life based on the central dogma of biochemistry (DNA->RNA-Proteins, essentially each living cell being a universal nanofactory and a set of bluepritns for itself) managed to evolve before highly efficient specialist self-replicators did seems like it was highly unlikely to me.

Second, a fGf on the planetary/civilizational scale: that as technology increases the amount of damage that a single rogue individual can cause also increases, and eventually that reaches a point where civilization and technological progress cannot be maintained, well before it's possible to get any interplanetary engineering going.

And finally, there's the possibility that there are a lot of very strong Great Filters going on pretty much all the time everywhere, and we happen to be the first technological civilization at least within our light-cone, either by pure happenstance or a strong Anthropic principle argument. (Strong as in pretty near to Quantum Immortality, on a species-level rather than an individual one necessarily...)

209:

Some really great Troll / griefer slayers here, very fun (Max / Andreas particularly, love the comments). I might skirt a little close to the edge, but it's never fun without a guillotine.

(and the use of "portals" was what kept me from realizing you were discussing a recent discovery related to the magnetic field reconnection problems identified back in the 70's as I recall) and there is a lot of noise about these being somehow bad or dangerous or proof of [insert whackadoo theory here] which is a pain to sift through.

To ditch the meta for a moment, there's a real case to be made that Data Smog (in informational terms) is the real great filter both on the human scale and on the binary scale. Pollution preventing insight, action that has at least some decent effect and all that[1]. You could probably argue that it arises naturally out of complexity technology, the problem being that it's inherent to the medium.

So - heuristic search is a hot topic for current technology companies (e.g. Bing / Google), computer modelling with supercomputers is a big one (climate / nuclear simulations) and given what we know about human cognition (and how easy it is to fool / "hack" either accidentally or deliberately by bad faith actors) do we take seriously the idea that intelligence itself needs to build its own prevention to prevent the paradox?

Throw that into 8,000 years of history, where's the gardeners? (Genocide need not apply - not even building mini-Inhibitors, although spiders all over the web are effectively having an unseen war as we speak).

~

Precise: what if the Paradox doesn't require O.C.P or hostile Others, but is merely a by-product of intelligence itself?

[1] Insert your government gridlock of choice or global spanning crisis of choice.

210:

Oh, and on the topic of N-D lasers and their range: isn't there a distance beyond which the chaotic nature of solar systems makes it impossible to accurately predict where the planet is going to be when the front of the laser beam arrives?

211:

Well, it depends on how small: for the numbers we were quoting above, that would amount to billions of pointings per star. But of course, that would be an insane way to do it; you'd build something with a much bigger FOV to locate possible targets.

Also, really need to return to work now.

212:

I mentioned radio wavelengths only in the context of what we can do now with our technology. The Dyson swarm/Matrioshka brain would of course observe nearby star systems in the optical and IR, since that's how you'd detect the planets (OK, it'd monitor in the radio, too, to pick up possible transmissions). The resolution will naturally be much better than in the radio, because the wavelengths are shorter; the resolution of a 1-AU-diameter optical array at a wavelength of 1 micron would be about 10^-12 arcsec, which is about 5 kilometers in a system at a distance of 100 ly. And you can do parallax with subarrays on opposite sides of your Dyson swarm to get really accurate distance measurements to the individual planets

And of course in the vast majority of cases you'll observe the system for millions of years before something interesting happens, so you'll have the orbits of all the planets (and most of the smaller stuff) mapped out to a fare-thee-well.

213:

> Assuming current technology, we could get to Alpha Centauri in under a century.

Er, which current technology do you have in mind?

Getting to Alpha Centauri in a century means an average speed of c/25, aka 12,000 km/sec. Voyager 1, the fastest probe now heading into interstellar space, has a heliocentric speed of 17 km/sec, c/17,650.

214:

How about a more mundane explanation. The evolution of a planetary species results in life so dependent on a specific physical environments (light spectrum, atmosphere, chemistry) that advanced civilizations all do the cost-benefit analysis and quit for a golf game. A planet hospitable enough to generate discretionary resources to push out into space is probably one worth staying put upon. One so crappy to deserve a farewell likely hampers the evolution of the very beings that would make that judgment.

215:

There is a huge space between "consuming energy like a present day American" and "limited to 18th century technology." I sometimes think that people forget or never learned how much industrial development preceded oil's expansion to the largest world energy source.

216:

> The confinement shell at Chernobyl is a 13 M thick layer of concrete and reinforceing steel.

Why that thick? Concrete confinement shells around running reactors seem to be about a tenth that. The decay products at Chernobyl should, if I understand correctly, be producing mostly alpha and beta radiation and relatively little penetrating stuff.


http://www.fukuleaks.org/web/wp-content/uploads/2011/09/ASME_Ch14_p001-026_Oct-7-08.pdf

217:

Sorry, did not make myself clear. The 13 M is the overall structural thickness including the support struts for the arched shell which actually contains the radiation.

The point remains, if you are worried about hte effects of radiaiton during space flight or star flight, all you need is mass.

218:

Which has its own problems in and of itself - you have to move it. You can partially get around it by hiding in your fuel tanks, but as you move along, there's less shielding.

219:

Relevant #1:

The Knowledge - Amazon.com
www.amazon.com › ... › Disaster Relief
Amazon.com, Inc.
The Knowledge: How to Rebuild Civilization in the Aftermath of a Cataclysm [Lewis Dartnell]....

www.the-knowledge.org/
The official website that accompanies The Knowledge, the best-selling book by Dr Lewis Dartnell.

220:

Relevant #2

Alan Weisman speaks about his groundbreaking book, The World Without Us

1. Your new book, THE WORLD WITHOUT US, poses a fascinating, extraordinary thought experiment: if you take every living human off the Earth, what traces of us would linger and what would disappear? It asks what might happen to our world if humans vanished? What was the inspiration for your book?

I recommend both books.

221:

The point remains, if you are worried about hte effects of radiaiton during space flight or star flight, all you need is mass.

Yes, but that doesn't help any. In fact, it compounds the problem, because the problem with space or star flight is the energy required to move the mass. So "oh, you can just make the problem worse to solve the problem" isn't a very good response

222:

My wild idea for the day: what if most advanced intelligences are Jovian? Not only is the gravity well more formidable for starting off on space exploration, but they might need very particular layers of their gas giant in order to survive; so even the other Jovians in their system might not have the exact right layers to be worth moving to. On the other hand, if they do go interstellar, each world they colonize has way more living space to fill than a terrestrial species equivalent. So maybe they go very slowly and deliberately, never swarming over large patches of the galaxy.

I would say they would have difficulty developing technology to support them on interstellar trips, but then we're not suitable for those voyages either. (I have read The Algebraist, but there you are entering Clark Magic Land.)

223:

Make that warm (not hot!) Jovian dwellers.

The problem with gas giant life -- and gas giant moons as places to look for life -- in our solar system is that they're cold. Life as we know it relies on chemical processes: chemical processes run much more slowly if you do them in a cryogenic refrigerator! (I'm guessing that there might be life on Titan or Europa .... but it'll look at lot like life on Earth some billions of years ago, because it simply hasn't been around long enough to evolve any great complexity, because it's running in a very low energy environment.)

Hot Jupiters look very inhospitable indeed -- insane winds and molten-metal temperatures -- but a hypothetical "warm" Jupiter in the triple-point water region of its star might be another matter. Especially if it had accumulated rather more heavy elements than our gas giants (which appear to be mostly gaseous).

224:

At a minimum, just teaching an infant how to speak requires someone who can provide speech stimulus and meaningful, valid linguistic feedback -- in other words, something that passes a Turing test.

Don't some twins and others create their own languages? We don't necessarily need to talk to them if they talk to each other. However, we might not want to create an alien human culture that has essentially nothing to do with ours. It might turn out as alien as a real alien griefer culture.

About magic wands, there's stuff we know how to do.

Then there's stuff we don't know how to do. Some of that might turn out to be easy. We don't know how to do it yet so we don't know how easy it will be. Once we can do it we might look back and see it was simple once you figured out to bang the right rocks together. Or maybe not.

Then there's stuff that violates current theory. We might someday find circumstances where total entropy decreases. Theory says no, but it's only theory. However, if we're guessing about the future of humanity and somebody wants to base his guesses on the idea that we will find out that entropy doesn't always increase, I'd understand if nobody took him seriously.

There's a big difference between magic wands that do things we don't know how to do yet, versus magic wands that do things we think can't be done.

225:

That's true, but much of the difference is coal, which would also be unavailable after a collapse. If not for the spreading use of coal for heating in Europe, fuel-related deforestation may have done for Europe what it did to the Maya before the Renaissance ever got rolling.

http://www.smithsonianmag.com/science-nature/why-did-the-mayan-civilization-collapse-a-new-study-points-to-deforestation-and-climate-change-30863026/?no-ist

P.S. Yes, I know, Mayan history was more complicated than that.

226:

This current technology - Project Longshot

Ok, that is for an unmanned probe, but the basic concept would scale up with extra mass for a manned mission taking a century.

The only problems then are our limited effective lifespans, the dangers of acceleration, and the sad fact that there isn't anything in Alpha Centauri B worth visiting.

227:

That wikipedia article appears to be from a parallel universe.

Apparently "Longshot was designed solely using existing technology although some development would have been required."

and then it goes on to talk about laser powered inertial confinement fusion, which we certainly had in the late 80s. Somewhere in the universes configuration space. Maybe.

Sadly where I live Some development = several major breakthroughs which still haven't quite managed to arrive 25 years later.

228:

Don't some twins and others create their own languages? We don't necessarily need to talk to them if they talk to each other.

They don't do it in a vacuum, they've already learned how to speak from their parents.

229:

On the subject of griefing. If you have access to a nicoll-dyson beam or several then why would you stop at planets with obvious signs of life?

If you are paranoid enough to do this sort of thing in the first place then the assumptions that:

1. Life is diverse, and liable to come in forms that are difficult to recognise.

combined with

2. There is probably a minimum amount of matter required to support a population of evolved intelligent beings, but it's probably somewhere between "large asteroid" and "small moon".

leads to the conclusion that you should probably beam spam anything larger than an asteroid just to be on the safe side. You can make arguments about energy supplies in the outer solar system being too low, but what the hell. You are tapping the entire output of a star so why not?

I wouldn't expect to see any planets anywhere.

Maybe that's why there are no griefers - they tend to start with the big targets and make the mistake of hitting a Dweller world.

230:

... laser powered inertial confinement fusion, which we certainly had in the late 80s.

I get the impression that the mid-80s was still a time of (unrealistic) confidence in the process; the Nova laser at LLNL was built in 1984 with the expectation that it would actually achieve ignition (it didn't).

231:

I think Hannu Rajaniemi kind of tops this kind of speculation in "The Causal Angel".

232:

What's the theoretical range on those things, anyway?

How long would you like it to be? Planets don't dodge!

It's been noted that laser beams spread into much over a range on the order of single-digit light years. The interstellar medium isn't a perfect vacuum, after all, and a density of one atom of gas per litre adds up when you're talking in terms of columns of vacuum on the order of 10^15 metres long. But I suspect you could clear a path through the interstellar vacuum by pulsing the laser, and initially starting at very short wavelengths -- to kick the atoms (or rather, stripped nuclei and electrons) up to relativistic speed until they clear the "tunnel" -- then dropping down after a few minutes to something more easily absorbed by the atmosphere of the target planet.

So if you see a distant, dusty star system suddenly light up like a supernova in the X-ray spectrum then begin to drop down towards UV while intensifying rapidly, prepare to kiss your ass goodbye ...

=====

Actually, it's not so limited as one might expect. I can't swear that the following is entirely correct (in particular, I have ignored absorption of light and gravitational lensing effects), but neither of the two effects you might expect to factor in are that limiting.

Firstly, diffraction - how well you can collimate a laser beam over long distances.

This is characterised by (in a Gaussian beam, at least) the rayleigh range - the distance it takes a laser beam area to double relative to its focal spot (the source star). Stars are, not to put too fine a point on it, big. UY Scuti has a radius of 1700 solar radii, or around 1.2e9km - assume your cloud is orbiting at the solar surface (i.e an underestimate), and this allows a near infra-red beam to travel 4.7e14 light years before it doubles in area, not accounting for diffraction around/through galaxies that get in the way. Consider that the Milky Way is a mere 1e5 light years across, and... well, you get the picture.

Scattering is the larger factor (and is the reason I'd opt for an infra-red, or even radio frequency laser). The dominant scattering process would be Raleigh scattering - the same process that turns th sky blue (bluer, i.e. shorter, wavelengths are scattered much, much more strongly).

Setting aside large bodies such as asteroids, planets and stars for a moment, the interstellar medium has a density of about 1 atom per cubic centimetre. To a first approximation, all those atoms are Hydrogen atoms. This would give an 1/e attenuation (intensity drops to 36.7%) distance of around 160 million light years. Using a mid UV laser instead would drop this to just 160 light years, hence why it's a bad idea (and why we don't see much in the UV X-ray or gamma part of the spectrum, except ludicrously bright sources like active galactic nuclei)

Now, that's a significant overestimate, I haven't attempted to look at absorption by the dust - but then, I also haven't factored in the tendency of this beam to get rid of everything in its path either. It would have an effect something like using the exhaust plume of a Saturn V rocket as a leaf-blower. (i.e. there would be nothing left).

You might have to sacrifice a few (a lot) of other systems that happen to be in line of sight of the one you had in mind, but you could use a laser like this to take out anything not only in your own galaxy, but also in the next few hundred nearest, as well.

233:

I think solar energy going steampunk is entirely feasible if you know from the beginning that oil is bad. Build some kind of closed-cycle Stirling generator, fill it with alcohol, build towers with black-painted heat exchanger tubes at the top, surround it with some foil-plated solar concentrators, aim them roughly in the direction of heat exchanger. It's all 19th century at most, robust, quite easy to repair, no need for fine adjusting. Build a windmill below the tower, and a cookery and a sauna at the top, if you don't want to make the electric generator with all these complicated windings and wirings :-) And there is wonderful thing about heat balance, the concentrators reflect more radiation than the soil under them, and what misses the tower, goes back to space - no global warming side effects.

The arXiv article about colonization still uses a highly idealistic model - every colony is a seed, and the cycle lasts 10000 years on average. But the human expansion here on Earth was still much slower than it could be imagined on a simple assumptions, and it is patchy. Even now human infestation isn't so obvious from a substantial percentage of Earth's surface. Why would they go here in the wilderness, where there are three times less metals in the comets and asteroids than in the metal-rich Center, where you have to waste so much time to travel even between nearest stars, and where the next OB-class giant for massive projects requiring solar energy is hundreds of parsecs away? And it is more likely that we still could be in the Middle Ages, or even in the Dawn Ages of galactic history if the development/travel_speed rate is close to 10^3 like here on Earth. The first explores set out from Africa tens of thousands of years ago, but on the site of St.Petersburg there were only swamps and woods even 30000 years ago, and 3000 years ago too. (and glaciers 12 kya.) We don't need to live in the Galactic Outback to be sufficiently far from the folks - there could be next village behind the hills in one direction, half thousand miles of forest in another (and a big city behind it), there could be ancient ruins just "there by the river", and we still would think we are alone. Or... we could be unhappy enough to live next in time and space to some kind of Roman Empire :-)

234:

Don't some twins and others create their own languages? We don't necessarily need to talk to them if they talk to each other. However, we might not want to create an alien human culture that has essentially nothing to do with ours.

And that is going to be functionally illiterate and can't be educated or trained.

Space colonization isn't just about bodies: it's about culture. Ahem. (I've only written two books in a space opera series about this subject so far ... both Hugo-shortlisted, in better years.)

235:

That article had me right up until "... 264 tonnes of Helium-3/Deuterium pellet fuel/propellant."

Riiiight.

Deuterium is cheap as water compared to 3He. Per wikipedia, "Current US industrial consumption of helium-3 is approximately 60,000 liters (approximately 8 kg) per year; cost at auction has typically been approximately $100/liter although increasing demand has raised prices to as much as $2,000/liter in recent years."

So, assuming the fuel requires 1 mole of He3 per 2 of De (hydrogen being a dimer), this plan calls for 113,000Kg of 3He or about 14,140 years of production, at a current peak market value (because this is an insane demand) of ... jeez, is that $15M per kilogram? Let's just call it a round $1.7Tn.

But of course, we can't scale 3He production up by four or five orders of magnitude just by snapping our fingers. This idiocy comes from the "Lunar regolith 3He mining will fuel our third-generation magic moonshine fusion reactors!" department, doesn't it? Although we could probably get there with fission if we just build a fuckton of reactors fine-tuned for generating Tritium from Lithium-6.

Upshot: suuuuure we could possibly build a starship running on this technology ... we'd just have to scale up our global 3He production by several orders of magnitude, demonstrate that the new propulsion system works, and overcome all the other engineering challenges. Easy! Give me a $20Bn/year budget and I'll get it ready for launch by this time next century ...

236:

I think the first line says it all - "This page has some issues".

That'll teach me for writing posts from a phone.

That being said, I know I read a number of articles in the past year following a lengthy discussion somewhere else, all of which mention an expected duration of a mission to Alpha Centauri being in the region of a century or so. It's possible they are all based from a single flawed assumption, my memory is hazy. I'm pretty sure they all came back to exploration of nuclear pulse propulsion - Project Orion is a favourite as it really is the best engine we've ever thought of so far. Tested or practical? Maybe not, but lots of fun for thought experiments.

Here is one from the 1990s - Project ICAN which seems to be using nukes AND antimatter.

The larger issue of there being nothing there that we know of worth sending a manned trip for needs reiterating.

237:

I think Hannu Rajaniemi kind of tops this kind of speculation in "The Causal Angel".

Tee-hee. Yeah, so do I. Might have even... bleh, I am the main character, ffs.

Space colonization isn't just about bodies: it's about culture. Ahem. (I've only written two books in a space opera series about this subject so far ... both Hugo-shortlisted, in better years.)

Yeah, ignore them: grammatical hard-wired structures in the brain are done and dusted by age 7-9 (pre-puberty stage) and it's vitally important you do this hard-wiring early on, otherwise you end up with humans who can't do meta/higher order thinking.

Not. Even. Fucking. With. You.

Hint: bait for that element? sure! True: absolutely. Roundhouse kick: not your skin colour that determines it. It's the 100% confirmed way of breaking a human mind and preventing it from ever progressing.

You might want to check the levels of grammatical "indoctrination" within coal mining towns in the British Empire circa 1903 to get a fucking clue.

Yep. Men who worked 14 hr shifts, walked home and so on and their wives had this education. It's why... and after a lot of heavy messing with Google:

You would not believe how hard it is to get this via searches

Only the most important feminist writer of her age on social issues, and unlike Dickins, you know, actually went and did some research.

Our kind don't go mad. But don't be surprised when we rip you to shreds, little ones.

238:

I remember Carl Sagan in an episode of his series "Cosmos" talking about potential starship designs, comparing their current stage of conceptual development with Leonardo DaVinci's designs for flying machines.

He also commented that a starship design represents engineering on the scale of a small planet.

When you are talking about a behemoth craft hewn out of a nickel-iron asteroid and propelled by energies that exceed the world's nuclear weapons stockpiles by many orders of magnitude, a few dozen meters of extra shielding in the front ain't no big thing. It's already pretty massive. Some more shielding won't add that much to relativistic energy requirements.

239:

If you need a translation:

Gaskell, Dickins and so on actively fought to educate everyone. Did it work? Meh... not sure, look at the progression of culture, technology, philosophy (hello Scotland! loving the coal engines!) and so on. (Hint: yes, it did - however, of course, there were major failings in areas they didn't address).

Current USA policy is to raise animals and keep them being animals and prevent higher order thinking ever existing and then treat it as a "racial" issue. White, black, hispanic, native: doesn't matter as long as they can make sure you're an animal, be it via denying health care, flooding the area with drugs, minimal education and so and so forth.


Yeah.
Not sure at your endgame there.

We know what you're doing. And we're really pissed off about it.

241:

Warm Jovians or even Brown Dwarfs (can't we come up with a cooler name, like Dark Stars?) that give off infra red so that an orbiting moon can have liquid water - even around Brown Dwarf's located between the stars.

It's easy to imagine life based on infrared photosynthesis on moons orbiting brown dwarfs which give off heat but not light. Not just imagine it, we already know of such life here on Earth, green sulfur bacteria. And if Brown Dwarfs floating between the stars greatly outnumber suns, then visible light spectrum based life may be the exception instead of the rule.

Recent computer modeling shows that methane based life (instead of water based life) is possible on cold worlds like Saturn's moon Titan. Methane based life forms are a fascinating subject (Would they be slower due to the colder temperatures? Would intelligent methane life take years to form a single thought due to slow chemical reactions?). Ironically the potential "Goldilocks" zone for such life is far greater (extending across the range of Jovian worlds out to the Kuiper belt) than our much more narrow zone for water based life forms.

So "life as we know it" based on water and the visible light spectrum for photosynthesis may be the rare exception in a universe dominated by methane based life and life that utilizes infrared photosynthesis.

242:

Im going to explicitly disallow colony planets seeded using uterine replications as a magic wand technology.

Hang on. You are creating Dyson Sphere Death Stars and you want to disallow replicators as 'magic wand'? I think of the ladder of 'magic happens here', dismantling the entire mass of a solar system and converting it into a controllable phased array laser weapon is several rungs above capturing and encapsulating a human mind in data form (you don't actually need, or want, your conventional hard AI).

And in talking on this subject, it's worth considering the basics of anti-air missile design. You want the control and smarts up with the thing that's getting closer to the target, and thus errors/timelag getting smaller. Bulk power from base is just about OK (even there, inverse square law hurts), but there's a reason command guidance only happens on short range missiles.

243:

Project Orion makes star flight simple, easy and fun!

Just find a good sized nickel-iron asteroid. Hollow it out and shape it to look like a pencil. The sharp end is pure mass shielding at an acute deflective angle (like sloped armor on a tank). The rear is a reactive plate where the nuclear charges go off accelerating the craft. The entire ship is spun on its longitudinal axis to provide artificial gravity on the inside walls of the hollowed out interior.

Viola! A starship via the brute fore method.

244:

...then dropping down after a few minutes to something more easily absorbed by the atmosphere of the target planet.

Actually, you wouldn't care about this at all; the column through an Earth-like atmosphere is so large that it's opaque to just about any photon energy. I think you'd probably just want to use hard X-rays (~ 10 keV or so), which pretty much don't care what state matter is in (an electron is an electron is an electron...) and for which interstellar absorption is negligible in almost all cases (Compton scattering has a very small cross-section) and blaze away.

245:

How tough does a Turing Test have to be when the listener is a toddler? The colonizing kids don't have to perfect specimens, just sufficiently well adjusted enough to allow them to work together while building the colony will be fine.

Or you could have frozen adults thawn out for the purpose of raising the kids (who would come to term in artificial wombs). Once the colony is established these adults can go back into hyper-sleep and travel to the next star to plant another colony with the millions of remaining frozen embryos. They keep doing this as long as medical science can keep them alive (or even effectively immortal) -living thousands of years, spending most of their time in frozen sleep but devoting their lives to raising families and colonies on hundreds of worlds.

246:

Ulver laughed. 'It looks,' she snorted, 'like a dildo!'

'That's appropriate,' Churt Lyne said. 'Armed, it can fuck solar systems.'

No, really. Sort your own system out before imagining that you can reach others.

247:

Catina @237/239,

One thing I don't often see stressed is how cut throat the Scottish system used to be, and how hard they "taught to the test" to use modern US parlance. I personally remember a WEEKLY test in my last half-year of Primary school in the mid-1960's, with similar questions to those found in the 11-plus, and your seat in the classroom for the following week being determined by your result.

Then where we lived your 11-plus result determined which high school you could go to, and for those going to the Grammar School which class you were in. My family emigrated to Australia at the end of my first high school year so I don't know how much reshuffling occurred between years, but basically if you weren't in the top Grammar School class then you weren't going to university.

248:

how do they enjoy the Archers in Tau-Ceti?

We're not sure, but we have decoded part of a message. It reads "PS. Please tell us who killed JFK? It's driving our conspiracy theorists nuts!" ;-)

249:

Also carina #237 and also refers to #247.

I was fortunate enough to miss the end of the 11-plus, but my Mum was a teacher during that period. I don't normally defend "teaching to the test", but in this case you had to do so. Sample question:-
"Name something good to eat."
Correct answer (yes singular) - Sweets.
Wrong answers would include Chocolate, Ice-cream, Bon-bons, Cake, biscuits...

Everything else Alex says in #247 is actually or potentially correct, with the note that at that time only the top 10% of school students were even likely to be seriously considered for undergraduate places by the universities.

250:

Ah,
ART CRITICS in other words ...

As in "Johnathan Hoag"

251:
We're not sure, but we have decoded part of a message. It reads "PS. Please tell us who killed JFK? It's driving our conspiracy theorists nuts!" ;-)

It was C.G.B. Spender, known for his nicotine habit and probably in the pay of big tobacco.

252:

Now, that's a significant overestimate, I haven't attempted to look at absorption by the dust ...

Well, "significant" is putting it a bit mildly; dust is overwhelmingly the main source of attenuation for UV, optical, and IR light in the interstellar medium.

http://apod.nasa.gov/apod/ap050605.html

In the general vicinity of the our Sun, optical light is attenuated by roughly a factor of 2 for every kiloparsec (3300 light years) in distance. But it can get a lot worse: if you tried shining an optical laser from our location at the Galactic Center -- about 26,000 light years away -- it would be attenuated by a factor of about 10^12. (A near-IR laser with a wavelength of 2 microns would be attenuated by only a factor of 20 or so.)

253:

I wonder what the first message we intercept from aliens will say? If we ever intercept one. If there are aliens (Which like Fermi, I doubt). Will it be Spam as OGH suggested in Nature! Or some variant of "Convert or Die!!!!". Or something else. How about a message that destabilizes any society no matter the evolutionary history or nature of the recipient. Perhaps a cross species joke that's so funny you die laughing.

That would be cheaper than a BFG powered by a star.

254:

>> ... laser powered inertial confinement fusion, which we certainly had in the late 80s.

> I get the impression that the mid-80s was still a time of (unrealistic) confidence in the process; the Nova laser at LLNL was built in 1984 with the expectation that it would actually achieve ignition (it didn't).

For some reason I was recently reading up on what might be going on in military black projects, trying to figure out capabilities and tech research priorities and applications by working back from announced capabilities and the threat-model that they implied they were countering.

WRT they new fad for 'conventional strategic strike', for instance, or 'bunker buster' conventional bombs that claim to penetrate dozens of meters of rock, etc.

Led me to this fascinating overview (2008) of fourth=generation nuclear weapons, superlasers, antimatter, pocket fusion devices.

From 'conclusion':
------------------
7.1 Military aspects
1. FGNWS can have yields in the 1 to 100 tons gap which today separates
conventional form nuclear weapons.
2. Compared to previous generations, FGNWs have enhanced direct coupling
to dense targets and reduced collateral effects, as well as the capability to
drive powerful “jets” and “forged fragments.”
3. FGNWs are in line with the “increased precision” and “reduced collateral
damage” trends of modern warfare.
4. Proponents will claim that FGNWs have a high-potential to destroy “biological
and chemical” weapons, as well as future “nanorobots...”
5. The military “sweetness” of FGNWs is such that they will eventually be built
by all technologically-advanced countries, including non-nuclear weapons
States such as Japan, Germany, Brazil, etc.
------------------

Fourth Generation Nuclear Weapons:
Military effectiveness and collateral effects
Andre Gsponer
Independent Scientific Research Institute
Box 30, CH-1211 Geneva-12, Switzerland

http://arxiv.org/pdf/physics/0510071.pdf

255:

Worth noting that there are layers air in Jupiter and Saturn which shouldn't be too uncomfortable with an air supply, much like Venus has the cloud decks, if you want a particular pressure/temperature range a Jovian is a good spot to check, they're big and get hotter towards the center, something for everyone!

256:

Hang on. You are creating Dyson Sphere Death Stars and you want to disallow [uterine] replicators as 'magic wand'?

Yes.

I'm not optimistic about the prospects for -- or desirability of -- achieving "true AI". And socializing new human beings is one of the hardest intelligence-intensive problems our species tackles -- consider all the failure modes! But Von Neumann machines are basically bacteria made from Meccano. They don't need intrinsic smarts -- the intellectual input is all front-loaded, on the shoulders of the people who design them. Nor is what they do inherently terribly complex. Energy intensive, yes, and time-consuming, but once you've strip-mined the crust of the first medium-sized asteroid for photovoltaic cells you can strip-mine the next one a whole lot faster ...

There's a qualitative difference between infesting a solar system with bacteria and doing so with a self-extending and evolving culture (human culture -- which is the real payload you want to transmit, not just human bodies) which, as a prerequisite, requires a human-compatible biosphere (with umpty-how-many tens of thousands of other interacting species to keep each other alive).

257:

Plus kids are truly horrific, if I was forced to pick between being attacked by a swarm of replicating killbots or a swarm of kids other people raised, I'm leaning towards the killbots.

At least with them I could be assured a swift clean death.

258:

While I agree that there is a qualitative difference, I don't
think that it quite what as Carl Sagan was quoted above as
saying. If you look at current population densities (in
living space, agricultural and oxygen regeneration terms), it
isn't out of the question (just high).

What we don't know is how to keep either an ecology or culture
viable over the millennia needed for any starship using
anything like existing technology. We know that relatively
small groups can remain culturally viable for millennia, but
they were all very low tech, and we are only beginning to
look at the stability of smallish ecosystems. But we don't
have any reason to believe that we couldn't do it with, say,
100,000 people. Nor do we have any reason to believe that we
can.

This would need some ruthless social engineering to ensure
that almost all remained effective. We have seen what can
happen in the UK over the past 50 years. And that's a mere
eyeblink. And that science is being strangled in its
infancy. That's where I think the problem is.

259:

I guess that ties back to the original post - the most likely failure mode for us then will be something going wrong with our own colonising machines which we sent out to economically strip mine the solar system - in order to gather the resources to go looking interstellar.

I imagine having something designed to disassemble asteroids into an efficient collection of valuable minerals would play merry hell with Earth if it should accidentally (or deliberately) be released on the Moon. The effects of having the mass of the moon spread out all along its orbit in convenient shipping sized lumps of Si02/iron/feldspar etc would probably be best described as catastrophic.

260:

Headlines today:
http://phys.org/news/2015-04-advanced-civilizations-earth-obvious-galaxies.html

"Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies"

So it looks like that are no H+ aliens rampaging across any galaxies we can see converting them into computronium.

A good indication of the near term possibility of interstellar flight would be the Dense Plasma Focus fusion effort achieving breakeven. It is ideal for a propulsion system:
http://lawrencevilleplasmaphysics.com/

261:

In summary - we are the only intelligent species in the universe for some reason, and there is no "conventional" plausible explanation.

262:

Please delete this if you feel that it is a red herring.

It is a mind-boggling comment on modern science that a science
fiction author is restricting himself to known physics, whereas
research scientists are quite happy to assume unknown physics
to explain their results!

http://mnras.oxfordjournals.org/content/449/4/3393

Now, what if we assumed that dark / light matter interactions
subtly disrupted the quantum physics of the latter enough to
destroy at least multicellular life and comparable electronics?
And that a pure light matter system could not control dark
matter enough to protect against it? All compatible with, er,
modern scientific hypothesising.

That could make space travel infeasible, and could isolate
populations as effectively as Brin's method :-)

263:

Not exactly:
"The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization's technologies would be detectable in mid-infrared wavelengths."

It only proves that colonizing entire galaxies is not the intelligent thing to do - otherwise it would have already happened in some other galaxy.

264:

Er, that only proves that it did not happen at such a time that we would be able to detect the IR footprint of that civilisation.

265:

You're ignoring the enormous information-processing efforts that would have to go into both constructing and maintaining a Dyson swarm and operating the whole spy-and-lase system it's supposed to support.

Each solar system is going to be unique in some way, so part of the first stage of "infection" has to be a thorough scientific survey: what are the resources, and where are they? E.g., is there an asteroid belt? A Kuiper Belt? Where are they? What kinds of resources do they have, and what kinds do they not have? Do you need to disassemble any planets? Will you have to fetch resources from the Oort Cloud? (Is there an Oort Cloud?). Et multiple cetera.

Then there are going to have to be decisions made about how to construct things -- what do you need to stockpile, and where should that be done? How do you route different types of resources efficiently to where they need to go? Should you chart out the existing planetary resonances so you can avoid or take advantage of chaotic orbits? And so forth.

Once you've built the whole thing, there's maintenance to worry about. The traffic-control problem by itself is probably a superhuman task, even ignoring the necessity of repairing things under ordinary wear and tear, or rebuilding things when there's a solar flare, or when comets come wandering in from the Oort Cloud, or you're close to a nova when it goes off, or any of a hundred other possible problems. Some of these problems may be unique to a given system, or only appear over long timescales, which means the Dyson swarm has to be able to learn.

But on top of that, you're trying to run a colossal, multi-target, broad-spectrum interferometric observatory, with the (insane amounts of) image processing that's necessary to extract basic images and spectra[1], and the higher-level processing necessary to identify meaningful features and signals -- and then decide when to fire up the N-D laser...

Your hypothetical griefer Dyson swarm will require not simply the AI equivalent of a human, but rather that of a small advanced civilization.


[1] Here are the computing requirements for the Square Kilometer Array, which will be at best a hopelessly simplistic version of a single pixel in a Dyson swarm array:

https://www.skatelescope.org/software-and-computing/

266:

Now, what if we assumed that dark / light matter interactions subtly disrupted the quantum physics of the latter enough to destroy at least multicellular life and comparable electronics?

Then we wouldn't be here having this discussion ;-)

Dark matter is pretty thoroughly intermixed with normal matter -- this paper estimates billions of DM particles passing through an average human body each second...
http://arxiv.org/abs/1204.1339

267:

Yes

But you will admit that copying an existing human brain into a non-biological form isn't massively 'way out' SF idea (you don't need the hard AI actually) or indeed that a bunch of evolutionary processes has empirically kicked up at least some intelligence at least once - but never a non-biological Von Neumann machine?

Empirically we know intelligence, as we define it, can be done. Via a variety of potential avenues. Not many dismantled planets creating Dyson spheres around...

I'll bet you we see AI of some description before we see a bunch of machines capable of taking planets apart. In fact 'going virtual' is one of the proposed answers to the "where are they" question - as you are well aware. Plenty of room at the bottom.

268:

I considered that, but I imagine they also need a particular chemistry suite as well. I imagine, but don't know, that "terraforming" would be harder for a gas giant level than for a small rock. On the other hand, terraforming small rocks is hard. I've often wondered how such projects would look to the long term: what stops your New Mars or New Venus from going back to Old Mars or Old Venus? What duration of habitability is acceptable for the effort expended? Etc.

I would guess that combining bio-engineering with terraforming is the way to go. You tweek a planet part of the way and you design organisms to meet the new planet the rest of the way. (Assuming you don't just settle for machine life as the logical successor species.)

269:

Actually, if you wanted to postulate some bizarre effect of DM on ordinary matter, you might have the basis for something a little like the Zone of Thought in Vernor Vinge's A Fire Upon the Deep, since the local dark matter density does get higher as you move towards the Galactic center... (The DM density a few hundred parsecs away from the Galactic center is probably about a hundred times higher than it is out here by the Sun.)

270:

Oh, that sounds like it'll be fun. Though of your upcoming projects, the two I'm looking forward to most are Merchant Princes: Next Generation and the novel treatment of Palimpsest. I'm curious as to how you plan to round that yarn out.

271:

Assuming that the current hypothesising bears any relationship
to reality, a question about which there is some doubt ....

To your first point, the same is true of neutrinos, but a
sufficient flux would be lethal. One would have to get the
interaction rate such that homebodies would survive to
reproduce (physically and culturally) but that starfarers
would not. Frankly, my reaction always has been to use the
old saying "There are fairies at the bottom of my garden"
with fairies replaced by Higgs bosons, dark matter objects
or whatever spooks the current speculative physicists are
conjuring up for our entertainment.

272:

But you will admit that copying an existing human brain into a non-biological form isn't massively 'way out' SF idea

Do we have to admit that?

I guess because I am in the electrical/computer field I sort of more clearly see issues in that area ( evil AI? uploading brains? computers capable of raising a toddler? self-replicating nanobots?) and know how far we are from the required breakthroughs that would even remotely accomplish that kind of stuff. Whereas things like propulsion systems and stellar evolution models, etc, are all outside of my expertise so I am more willing to accept the handwaving about the issues.

Modeling something as complex as a human brain is many orders of magnitude more complicated than I think most people would realize, and that assumes we even remotely understood how the wetware worked in the first place. And after that, you'd have to set up the initial conditions by some sort of scan. Even if you destructively scan (not just use a fancy MRI of some sort) it's unclear how and what you should be scanning for.

Then you'd need the hardware. Probably something massively parallel. Humans are *really* bad at writing parallel algorithms.

So at best you end up with something like current weather models. You can have massive petaflop machines but even they are limited in the detail they can model, and then once you run the model the results are very very sensitive to the initial conditions and go off the rails easily (hence why weather forecasts are usually wrong). Now imagine uploading your brain image to that.

In the end you might be better off just figuring out how to take your brain scan and uploading it into something similar to a human brain, like a monkey brain.

273:

Re: 191 Bellingham

Thanks for your reply!

A question: Is there direction in space comparable to direction on the seas - as in sailing into vs. against the wind? If there is a direction, then some directions would be easier/faster to explore than others. Exploring 'against the galactic wind' would happen only after this.


Also, related I guess - in what direction is space expanding? One might assume that an advanced, stable civilization knowing about how space expands would opt to stay out of the way of on-coming galactic traffic. This would mean they're sitting parked outside the wildly swinging galactic arms. The alternative is to park right next to a mega black hole - which could be their self-renewing source of mega energy.


Then there's the matter of style --- how one gets to a destination matters at least as much as where one gets to. So, if there is a galactic cop/babysitter, they'd be looking for signs of 'least harm' in any culture worthy of being uplifted/brought into the club. Inefficiency is its own penalty ... if you're so stupid you destroy your own planet just to step into space, you do not deserve membership.


Going back to my previous post ... (and using that Google science contest winner's small-temp-difference flashlight idea) ... how about using a scoop ramjet in combination with a laser-like feedback loop to increase/change/redirect energy from space motes to spaceship velocity/push. You're not stealing or hand-waving energy into being, you're just transforming/moving it about.

274:

...with fairies replaced by Higgs bosons, dark matter objects
or whatever spooks the current speculative physicists...

Uh, anyone besides me find it amusing that something which came out of CERN (the world wide web) can enable whoever feels like it to disparage the science done at CERN?

The LHC team found a particle which possesses the properties required to be a Higgs Boson and tested this to find that it agrees with predictions at greater than 99% confidence rates about 2 years ago, if there were some finding which invalidated this between then and now I'm sure we would all have heard of it.

They're just about to start 13 TeV runs and I'm sure they'll let us know if it turns out that it was in fact a fairy and not a scalar boson, as it first appeared to be.

Dark Matter is another matter entirely(ha ha!), as it is a label for an observed phenomenon wherein you can measure the deflection of photons from distant objects as they pass closer more massive objects and notice the discrepancy between how much said photons are deflected and how much "stuff" appears to be present in the regions they are deflected across.

Further examination shows various other observations which point towards an inescapable conclusion: there is something massive which does not interact strongly with baryons, leptons, or photons except through gravity.

That is not a theory or speculation, it is an observation, a starting point, it is that upon which one may speculate, as is the original topic of discussion: there do not seem to be any of the expected signs of intelligent life in the sky around us.

Speculation would be what you do after you ask "why don't we see these signs?" or "what could be causing these clusters of galaxies to behave as though there is a significant amount of massive yet non-visible matter present?" and so forth.

Speculating is what was done when the standard model was being developed, questions were asked and explanations were proposed, one of these explanations included predictions of certain particle families with certain members with certain properties which have since been found. Calling the Higgs speculative is like calling electrons or neutrons or quarks speculative at this point, it's silly.

275:

I guess the logical solution to the hard-AI problem goes back to Generation Ships.

You take your large spinning Asteroid Ship™ and fill it with a bank of a million or so prefertilised embryos, and a crew of sufficient size and diversity, probably several thousand.

You have a bank of several hundred uterine replicators, that can raise an embryo to term, and every 40yrs or so you bring up a new batch. The existing crew can teach them what they need to know to be human, and the knowledge in the computers can teach them what they need to know to do their roles. You would probably need some form of guild structure to preserve the knowledge of how to settle and explore a new solar system/world for the duration of the trip. Once they reach the destination, they can then raise the proper settlers.

That way assuming an average lifespan of 80yrs for humans without disease and/or wars interfering and you have roughly 10yrs of development, 10yrs of training, and 20yrs of overlap with skilled employees.

Unknowns : lifespan of humans born in space, effect of reduced gravity on human lifespan and conditioning, likelyhood of crew descending into Lord of the Flies territory, ethics of essentially raising people to be living cogs in a machine etc...

I'm still fairly confident in the development of reproductive technology in the near future - there is almost certainly *someone* who will have the combination of interest, funding, and suitable lack of ethical guidelines to kick things off in animals at least. Whether it can then be applied to humans is a totally different story, but there is one hell of a demand for IVF these days, which is getting increasingly sophosticated, and complete external development is a logical extension of that line of thought.

276:

You take your large spinning Asteroid Ship™ and fill it with a bank of a million or so prefertilised embryos, and a crew of sufficient size and diversity, probably several thousand....

...Unknowns : lifespan of humans born in space, effect of reduced gravity on human lifespan and conditioning, likelyhood of crew descending into Lord of the Flies territory, ethics of essentially raising people to be living cogs in a machine etc...

You forgot a few unknowns relevant to your population:

1) How many people are needed at minimum to maintain the economy necessary to maintain the generation ship. That's not just the high tech industry for the spare parts, or even the surrounding industries for consumer goods and services, but also the ecosystem maintenance industry. The answer to this question strongly depends on your level of automation. (our host took a whack at this several years ago)

2) What long lasting social institutions could be created that keep the society on mission and alive. It's obviously no good if the economy, culture and government are so poor that eventually there's a violent revolution that destroys the hab. Beyond this it's equally not good for colonisation if the society elects not to bother and just drifts through space instead.

277:

Or at some point society decides that raising and training all these uterine batches is just too much work, and instead they just enjoy life and each other's company until they die of old age.

278:

"'...with fairies replaced by Higgs bosons, dark matter objects
or whatever spooks the current speculative physicists...'

Uh, anyone besides me find it amusing that something which came out
of CERN (the world wide web) can enable whoever feels like it to
disparage the science done at CERN?"

Unless Sir Tim has changed out of all recognition since I discussed
his proposal with him, I am not sure he would agree with your
assertion. HTML certainly did, that's true, but his prototype was
one among many. But let that pass - he deserves credit for judging
the approach that would be most successful. The rest of us backed
the wrong horses :-)

You have completely misunderstood my point. While I am no kind of
particle physicist, I know quite a few of them, and do know
something about that area. I have no intent of arguing the
point, except to point out that the terms "99% confidence",
"observations" (of Higgs bosons, that is), "inescapable" and even
"quarks" all make sense only when one has already assumed the
standard model. And the identification of the signature that
matches the Higgs boson was the last part of the 'proof' of the
standard model. Self-referential proofs are not highly regarded
among mathematical logicians - there are too many opportunity for
loopholes!

What we have no idea is whether there is another theory that fits
the actual observations we have (e.g. of cloud chamber tracks) as
well as the standard model. That's true of several other aspects
of modern physics, too.

279:

I think it was shortly after that topic that OGH said this was a fractal problem ... tending towards infinity.

280:

Are you a Michio Kaku fan?

281:

You have completely misunderstood my point. While I am no kind ofparticle physicist, I know quite a few of them, and do know something about that area.

Actually, judging from your comments, no, you don't seem to know a whole lot about the subject, nor indeed how science is done in general. In particular, it's on you to prove you're right, not on anyone else to prove you wrong. IOW, you aren't allowed to say 'What if there's some strange new physics that completely supersedes anything we know?' Or rather, you can. But no one is going to take you seriously.

282:

The traffic-control problem by itself is probably a superhuman task... Yeah, just the thought of the logistics involved simply in repositioning and focusing the system is enough to give me a headache. (Especially when you toss in self-gravity...)

This reminds me of a funny story. Back in the 1990s, the then-administrator of NASA gave a speech before the American Astronomical Society in which he showed a ground-based photo of Mars and announced that he wanted to see an image like that of an extrasolar planet, taken with a telescope with an aperture of ~ 8". No one was able to make him understand that you couldn't do that if the planet was further from the telescope than, oh, Mars is from Earth.

One of my colleagues had the graduate students in his instrumentation class work up a system that could produce an image like that (I don't recall exactly, but I think they were trying to get something like 100 pixels across the disk). Not surprisingly, the system wound up being a many-element near-IR interferometer that was so huge you would have to build it somewhere out around the orbit of Uranus, and would have cost something like a trillion dollars to build.

283:

There is nothing new under the sun; check out Hoyle's The Black Cloud for another take on where most of the intelligent life (naturally) resides. Notably, Hoyle's eponymous Cloud was also limited to speeds of ~1% of c. Not a problem for the timescales the Cloud operated on.

For another take on just what these hypothetical von Neumann replicators would look like, there's Wilson's Spin series. Again, very slow moving by our own perceptions. But by their own lights they got around pretty good :-)

TL;DR life of our sort is just too energetic and too fast to be suited for reasonable interstellar travel, i.e., travel at around 1% of c. The problem is simply one of different energy, time, and distance scales.

284:

Heh, I like that description.

To be fair, it's all a thought experiment anyway until we start properly exploring our solar system.
Half the physical requirements to send a craft interstellar will be solved in simply trying to live in the relatively energy rich and hospitable asteroid belt, and we aren't doing that any time soon.

285:

One would have to get the interaction rate such that homebodies would survive to reproduce (physically and culturally) but that starfarers would not.

That's a potentially interesting problem... After all, a ship traveling at 0.1 c will encounter dark-matter particles more often, and with significantly higher kinetic energies, than is the case for people just sitting on planets orbiting within the Galaxy. On the other hand, my limited understanding of hypothetical DM particles is that the probability of actually interacting with a nucleus of ordinary matter (say, in your body, or in your ship) goes down as the relative velocity goes up.

So you'd have to do the proper calculations to see if collisions with dark-matter particles would actually matter for a starship and anyone on board (and even then you're relying on purely hypothetical particles...). My completely wild-ass guess is that they won't matter as much as collisions with ordinary hydrogen atoms, dust grains, etc.

286:

"Are you a Michio Kaku fan?"

No, but he looks worth a trial. Generally, I don't like scientific
popularisers, because modern ones are usually dumbed down far too
far, promote a hobby-horse as if it were The Whole Truth, or are
none too literate. But I am always happy to try a new hope.

287:

Yet another model for successful interstellar colonization: Bruce Sterling's Swarm. Again, once the planet-bound get off-planet and into the asteroids, they never really go back down again. And if once you've seen one asteroid belt you've seen them all . . .

288:

On dark matter and what is between the stars, surely we could send out a properly built probe out of the solar system. Give it a small reactor and an ion drive and a couple of loops round the sun should see it going at a good speed. Then once it's out beyond the heliopause start the radar and other sensory equipment searching for anything at all.

289:

The trouble is that dark matter is currently little more than a
finagle factor, and its properties are simply those necessary to
make the universe fit the current cosmological hypotheses. That
means that I am more than just cynical about using those to model
anything.

Indeed, at the risk of starting some of the posters off, that is
true of both the Hubble red shift (being due to recession) and
the whole black hole circus. I have seen serious academic papers
that described alternative explanations of both that cannot be
excluded on the basis of current direct observations. Those
papers were specifically and purely speculative, and their
consequences were NOT explored in detail, so don't read too much
into that.

But, if Hubble's hypothesis of the red shift being due to
recession were flawed, most of modern speculative cosmology would
collapse.

290:

Retread warning. I wrote a blog post about three solutions to the Fermi Paradox on March 27. This is a retooling of what I wrote there.

The first Great Filter is our own blindness.

Seriously. If there's a planet with water and an oxygen atmosphere around one of the Alpha Centuari stars, we can't see either the planet or its atmosphere. With a few exceptions, we can't see the atmosphere of extrasolar planets yet.

Nor, as XKCD What-if explained so well are we likely to hear alien radio broadcasts.

So basically, right now, asking where everyone is right now is pointless. We couldn't see them if they were there.

The second great filter is peak fossil fuel. Given the way the carbon cycle works on Earth, I think it's pretty normal for a planet with an oxygen atmosphere and water to sequester a lot of carbon (the tl;dr version is that it's hard to break down complex carbon molecules in an anoxic environment, which is how the stuff that becomes fossil fuels accumulates).

Any civilization on its way up the technological progress ladder so beloved of 20th Century civilization will find those fossil fuels and exploit them. Why not? They're an incredibly good, cheap source of energy. Of course, they take hundreds of millions of years to accumulate. As we're discovering right now, it's hard to find good replacements for fossil fuels. It's also hard to go into space to get at all that good sunshine directly. It's harder still to even colonize other planets in our local solar system. Unless we get to fusion power really, really soon, what's likely to happen is that we'll run out of fossil fuels and be stuck running on directly collected sunlight (everything from firewood to solar panels and wind) and gravity (hydropower) for millions of years, until the fossil fuels build up enough surplus that we can try the energy intensive indrustrial push into space thing again.

That's answer 2: there are alien civilizations everywhere. Alien civilizations only have the possibility of jumping into space in a very small window, when they're fully exploiting their fossil fuel resources to make the huge industrial ecosystem needed to support space exploration. By the time they've figured out how to explore space, they no longer have the fossil fuels, and fusion plants may not work as adequate substitutes. As a result, alien civilizations remain bound to one planet. They may live on that planet for millions or even billions of years, but they can't escape it.

Note that if aliens are stuck in a low energy environment, spending large amounts of energy blasting signals at other stars probably isn't considered a useful option. They may even be scared to do so, considering that anyone who tracks them down will have access to more energy than they do.

Answer 3? Interstellar space is even harder to travel in than we thought. The photons left over from the Big Bang, when hitting a ship traveling at relativistic velocities, exert millions of joules of pressure on the front of the ship (Io9 pop-sci link). As I understand it, this light pressure will slow any ship down, which means that a ship traveling between the stars has to leave the motor running as long as constant forward velocity is desired. Coasting at high speed between the stars may not be an option.

So there's three options for a great filter:
--we can't see them if they are there.
--If they are there, they're likely to be planet bound and not able to receive radio calls from random strangers, let alone respond to them.
--Interstellar travel is at best difficult and likely impossible. The whole idea of any life form traveling between stars is based on an unverified linear model of technological progress.

291:

Actually, you only have to get out to about 550 - 1000 AU to take advantage of gravitational lensing by the Sun. I've heard of resolutions of less than a kilometer for Alpha Centauri.

292:

That's answer 2: there are alien civilizations everywhere. Alien civilizations only have the possibility of jumping into space in a very small window, when they're fully exploiting their fossil fuel resources to make the huge industrial ecosystem needed to support space exploration. By the time they've figured out how to explore space, they no longer have the fossil fuels, and fusion plants may not work as adequate substitutes. As a result, alien civilizations remain bound to one planet. They may live on that planet for millions or even billions of years, but they can't escape it.

Surprise! Hoyle also did this one . . . back in 1974. I wouldn't be surprised if the resource-constraint window predated him by several decades, it's so obvious.

293:

Interstellar space is even harder to travel in than we thought. The photons left over from the Big Bang, when hitting a ship traveling at relativistic velocities, exert millions of joules of pressure on the front of the ship (Io9 pop-sci link). As I understand it, this light pressure will slow any ship down, which means that a ship traveling between the stars has to leave the motor running ...

Not really. I've read the original paper, and the threshold for effective drag is only valid for ridiculously hyper-relativistic ships, travelling at about 1 – 3 x 10^-(17) time the speed of light. That's basically 0.99999999999999997 c; if instead you want to travel at, say, 0.999999999999999 c, you're fine.

294:

The whole idea of any life form traveling between stars is based on an unverified linear model of technological progress.

The fourth option is that there's no there, there. The idea of colonization I think rests on the implicit assumption that there will be green Orion girls and Sirian brandy -- the sailing the seven seas model of commerce IOW.

So not only is interstellar travel very difficult for life like us, the payoff for anything other than pure exploration is very, very small.

295:

Not really. There are also (large) space habitats, which give
access to the local resources. There are no known road-blocks,
though there is a lot of unknown engineering (mainly ecological
and social, but some resource extraction).

There is also terraforming of worlds with no life (like Venus),
which again has no known road-blocks, but is dependent on close
to Von Neumann machine space mining technology and would have an
unknown timescale and probability of success.

296:

Thanks for the reference. I'll make sure that gets updated in the blog. I'm not surprised at all, because you're right, it is so obvious.

What IS surprising is how many people appear to dislike the idea of intelligent species lasting for millions or billions of years on their home planet. On the basis of pure logic, it should make no sense. On the ideological basis, of course, it does make sense. Still, it's very tiresome and kind of scary that many people prefer the imminent extinction of our species to the idea that we'll be stuck here living a fairly good approximation of sustainably for a very long time to come. I guess many of us urbanites, toiling away at our computers, prefer the dream that we can homestead Mars to the idea that we'll have descendants here tens of thousands of years from now.

297:

Thanks for the clarification. Now all they have to worry about is everything else...

298:

Uh-huh. Get back to me when you've got some sort of cost benefit calculation for this sort of terraforming.

Again, you're not allowed to just say, 'what if?'

299:

Your answer (2) doesn't hold water, though it may do for other
resources (like rare earths). Uranium and thorium are common
in extractable concentrations, even in the UK, so there is no
chance of running out of fission power in the next 30,000 years
or so, perhaps the next 3,000,000. The ecosystem can take only
so much heating, after all Pollution from the residue is another
matter, but is probably soluble (given the will).

And, given power and the raw materials (mainly water and carbon
dioxide), it isn't hard to produce the fossil fuel materials.

300:

It's worth reading about asteroids. The basic problem is that, with the possible exception of Ceres, they're largely unsorted conglomerates of elements.

On our planet, our biogeochemistry acts to concentrate elements at high enough densities that they're worth the work to mine and extract. This goes to everything from fossil fuels to all metals. It's also the reason we don't extract gold from seawater. There's a huge amount of gold there, but it's in such minute concentrations that it's not worth the trouble filtering it out. Rare earths are rare (AFAIK) not because they're particularly uncommon, but because their chemistry means they rarely tend to concentrate anywhere enough to be worth mining.

Since there's not geology, core melting, or life to cause the elements in an asteroid to concentrate in some vein in an asteroid, basically asteroid mining is equivalent to filtering gold from seawater. A rather better metaphor is mining landfills. We can do it, but generally it's not terribly cost-effective. Shipping the equivalent of a landfill mining rig to rendezvous with an asteroid probably is even less cost-effective.

Worse, if this model is wrong and someone does find, say, an iridium asteroid, that trick works precisely once. Then the market for iridium on this planet is saturated for the next 1,000 years, and you've got to find something else where it's profitable to spend billions to lug a few tonnes back to Earth.

As for terraforming Venus? The heat gets radiated off into the vacuum by (process X) which takes, um, how many thousands of years? Just cooling the place down to make it worth terraforming (and honestly, it isn't), is a non-trivial challenge.

301:

The idea that intelligent civilizations are going to run out of energy is ludicrous. We already kinda ran out of easily extractable oil, didn't seem to slow things down much. Or friendly neighborhood star dumps a ridiculous amount of energy on us every day

I always feel like the people that go down this route are starting with some kind of desirable "return to the hippy earth" end state and performing whatever logic machinations are required to get the there.

A civilization killing itaelf off through some kind of envirohmental collapse is much more likely. However it's hard to imagine it is inevitable so it doesn't really hold as a fG

302:

Mining asteroids. Go after smaller ones, Spin, then melt

303:

What IS surprising is how many people appear to dislike the idea of intelligent species lasting for millions or billions of years on their home planet.

Wright et al. (http://arxiv.org/abs/1408.1133) note that a number of attempts to explain the Fermi Paradox using sociological/cultural arguments -- they all decide not to do the interstellar expansion thing for noble or transcendant/inscrutable reasons, apathy always wins, everyone gets too excited by VR, etc. -- are guilty of what they call the "monocultural fallacy": such explanations only work if you assume that all alien cultures behave the same way, that all subcultural units within a given civilization behave the same way, and that they continue to behave the same way as long as they exist.

It seems to me that you're demonstrating how the monocultural fallacy is indeed a fallacy even within our very specific subculture: you see nothing wrong with everyone staying put on the same planet, while you recognize that other people disagree...

And in any case the general idea of the Fermi Paradox isn't that everyone, or even most people, leave the home planet, only that some small subset with the resources and numbers to make a go of it elsewhere decide to do so. (This is true for most historical colonization efforts, from the ancient Mediterranean to the Pacific to the Atlantic. Most Norwegians stayed put and had descendants in the same place a thousand years later, rather than traveling to Iceland, for example.)

304:

The idea that intelligent civilizations are going to run out of energy is ludicrous.

No, that's not the idea. The idea is that they are going to run out of the sort of energy that makes space travel possible.

Rots 'o ruck with that launch loop or space elevator or whatever -- that first step is a doozy.

305:

And in any case the general idea of the Fermi Paradox isn't that everyone, or even most people, leave the home planet, only that some small subset with the resources and numbers to make a go of it elsewhere decide to do so.

That phrase 'only some small subset' sure takes a beating here. If 'some small subset' is an entire planet devoting all it's surplus gross planetary product to the cause for several thousand consecutive years, then, well, your argument kinda loses a lot of its force, doesn't it?

306:

Technically, we have colonized space for decades, and it's providing critical resources for our global civilization.

The way we did it, of course, was to use what space has a lot of: space. We used that space to hang all sorts of critical infrastructural satellites that even now play a key role in weather prediction communications, even solar weather prediction (critical in power grid maintenance), as well as land monitoring, spying, ad nauseum.

You're right otherwise: resource extraction is a cost ineffective reason to colonize any other body in space. However, getting the right angle on a particular situation is well worth the cost.

307:

You're right otherwise: resource extraction is a cost ineffective reason to colonize any other body in space. However, getting the right angle on a particular situation is well worth the cost.

Let's assume that the asteroid belt is colonized the way so many fanboys suppose, the thin gruel of resource extraction being what it is and all. And let us suppose that eventually there's a technical base that makes an interstellar voyage by ark lasting hundreds or thousands of years technically feasible. Would it be 'worth' it to make the trip?

No! There will come a tipping point on Earth where recycling, say, copper, is more economic than mining it. This will hold doubly and triply so in the belt. Yeah, you might argue for more 'living room'. Maybe. On a timescale of the lifetime of Motie civilization. Not sooner.

Exponentiation is a bitch coming and going.

308:

Unless we get to fusion power really, really soon, what's likely to happen is that we'll run out of fossil fuels and be stuck running on directly collected sunlight (everything from firewood to solar panels and wind) and gravity (hydropower) for millions of years ...

Surviving the loss of fossil fuels is perfectly feasible from a technological point of view: even with solar efficiencies of only 20%, you can supply the estimated world energy budget of 2030 with a solar collecting area roughly the size of Spain:
http://landartgenerator.org/blagi/archives/127
(And there's something like several hundred years' worth of energy potentially available from thorium fission and more if you run uranium through breeder reactors...)

I don't really see how having the energy production of the early 21st Century is somehow supposed to prevent us from making workable fusion power over millions of years, or having a space program.

And of course there are example of local societies on Earth being able to approach sustainable non-fossil-fuel, high-energy use: Denmark already produces about 40% of its electricity from wind (and has reached 60% for some months), and plan on boosting that to about 85% by 2035.

The problem for us is fundamentally history-dependent and sociological -- can we pull it off given current opposition from vested interests, corruption, short-term profit motives, etc., etc.? For this to work as a Great Filter you have to assume all alien civilizations will be at least as bad as we have been and are: at least as afraid of nuclear energy (or at least as focused on using it for nuclear-weapons programs), at least as unwilling to invest in alternate-energy research, at least as corrupted by short-term capitalism, at least as dumb/unlucky in fusion research, etc. And of course that they all follow the same historical trajectory in terms of energy use. So I'd argue it's another example of the monocultural fallacy.

309:

We don't have a good source of energy for space travel TODAY and if we do end up with something it is not likely to be based on fossil fuel

310:

Well, there is a much nastier possibility that I've mentioned before: starfaring civilization is possible, but sustainable civilization is not. Octavia Butler's Xenogenesis sort of looks at this idea.

Basically, when a starfaring culture lands on a planet, they need to do truly massive resource extraction to make their civilization work. This isn't sustainable of course, but if they're good at what they do, they can go from first landing to launching starships fast enough that they can go onto the next planet before civilization collapses in the colony. This leaves behind a planet stripped of all fossil fuels, minable mineral deposits in the top two kilometers of the planet's crust, a lot of clean water, and so forth, but hey, who cares about what's left behind? This could take probably no more than 500-1,000 years, especially with fancy exponentially expanding technology.

However, assuming that a starship can either safely fall between the stars in stasis, or that there's some sort of hyperspace/NAFAL jump drive that obviates the problems of interstellar space travel, it's quite possible that such a civilization could persist indefinitely in the galaxy, moving from star to star. It's not sustainable (except when in stasis traveling between stars), but it always manages to outrun resource collapse.

The reason this could work is that planets with plate tectonics regenerate. Over the course of hundreds of millions of years, erosion, vulcanism, plate tectonics, and all the elemental cycles will restock the planet, expose new veins of minerals, sequester some more fossil fuels, and so forth. If your hypothetical starfaring civilization only revisits its old colony planets every 100-200 million years or more, it's visiting something approaching a virgin planet each time--assuming, of course, that the starship launch didn't leave behind survivors to keep mining the planet. I'm not sure how many trips around the galaxy would be needed before this culture started to run the whole galaxy down and stop doing this trick, but I suspect it would take a very long time.

Of course, a galaxy where a civilization like this is running around would be a very quiet place indeed. Hmmm.

311:

Interesting tidbit from the expert astronomer side ...

http://www.sciencedaily.com/releases/2015/04/150414101000.htm

Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies

Date: April 14, 2015
Source: Penn State

Summary: After searching 100,000 galaxies for signs of highly advanced life, a team of scientists has found no evidence of advanced civilizations there. The idea behind the research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization's technologies would be detectable in mid-infrared wavelengths

Bit (excerpt) I like most ...

"When you're looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it's not what you were looking for," said Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State's Center for Exoplanets and Habitable Worlds and a co-investigator on the research team. "Sure enough, Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what's going on."

Among the discoveries within our own Milky Way galaxy are a bright nebula around the nearby star 48 Librae, and a cluster of objects easily detected by WISE in a patch of sky that appears totally black when viewed with telescopes that detect only visible light. "This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study," Povich said.


"As we look more carefully at the light from these galaxies," said Wright, "we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning."

312:

"It's worth reading about asteroids. The basic problem is that,
with the possible exception of Ceres, they're largely unsorted
conglomerates of elements."

Oh, dealing with THAT is well-understood! Basically, the key is
to use one of the several forms of extraction and purification
that use heat alone. E.g. you turn one into ions, accelerate
them, separate them sideways, and spatter the result onto another
asteroid. Or zone refining, or .... The point is that, once
you have got solar collectors operational, energy is free and
pollution not a big deal. The engineering would be a challenge,
even so, but doesn't need any technology we don't already have.

"As for terraforming Venus? The heat gets radiated off into the
vacuum by (process X) which takes, um, how many thousands of
years? Just cooling the place down to make it worth terraforming
(and honestly, it isn't), is a non-trivial challenge."

I never said it wasn't, nor that it would be quick! When I
read stories that terraformed Venus in an (extended) human
lifetime, I was dubious. So I did some very crude calculations.
No way, Jose! Thousands of years, at least, probably a lot
more.

313:

Considering how much trouble the local large solar farms are causing (frying birds in flight? Why yes, solar thermal does that rather nicely. Sucking up all the groundwater in a desert to wash the panels? Why yes, PV has that issue, as does solar thermal. Twenty-year power plant lifecycle? Yep.) I think large scale solar farms out of sight of cities aren't going to be a cure-all. Rooftop solar sort of works, but the politics and legal issues around it are still being worked out. Dispersed generation isn't nearly as easy as you might want to believe, and yes, the human problems are far more difficult than the engineering problems are.

That, incidentally, probably goes for non-human aliens as well. Coordination among multiple individuals is often much more difficult than solving a few engineering equations and cranking out a blueprint. Go look up Dunbar's Number if you don't understand the physical basis for why this might be true. Also read Scott's Seeing Like a State if you don't understand how scaling up from a pilot program to running a civilization can be difficult to impossible. It's a truly serious problem.

As for fusion, there are basic physical problems with most of them. Magnetic confinement means you've got to go from a super-cold superconducting magnet a few meters to a super-hot plasma. Maintaining that titanic temperature gradient without putting in huge amounts of energy is quite difficult. For laser fusion, getting it to work more than a few times per hour turns out to be very hard, and it needs to cycle multiple times per minute to break even. And so it goes. Daniel Clery's A Piece of the Sun goes into the problems. Even though Clery's bullish on fusion, he says that it's still 30 years in the future, and that a fusion power generator won't look like anything we're doing now. That's pretty much what they've said since the 1960s.

I'd also point out that the power industry, after their experience running hugely complicated power plants, isn't interested in running a plant that's any more complicated than a nuclear reactor. This is a matter of both politics and logistics. No fusion power plant even in the design stage meets this criterion, but I suspect it's a real problem that few have considered in depth.

As for nuclear, if we tried to meet the Earth's current power capacity with uranium, we've got about a 10 year's supply available (reference from world nuclear.org). At present use rates, we've got perhaps 100 year's supply of uranium. As for thorium, no one seems to know how much usable thorium we've actually got (this from a thorium proponent I talked to back in January) so no one knows how long we could power the world on still-hypothetical thorium reactors. With uranium and possibly thorium, we may well be off in the nightmare of ultra-low EROEI (energy returned on energy invested), where there's plenty of the element on the planet, but it takes more energy to get the elements out of low-quality ores than we'd make back by refining them for a reactor.

The reason this topic is a strange attractor on Antipope is that we go through this as an educational process several times per year. Yes, sustainability should be easy from a technological point of view. Unfortunately, the standard nerds catechism of "the technological hurdles are always the biggest problem, and once we solve those, the politics are trivial, and only stupid people prolong their solution," has very little to do with reality. The reality is that the political problems are generally much more difficult to even partially solve, while the technological issues tend to be easy to trivial. I keep reiterating this simply because, as a nerd turned environmental activist, I'm in the trenches dealing with these issues on a routine basis.

314:

The reason this topic is a strange attractor on Antipope is that we go through this as an educational process several times per year.

Unfortunately yes. But if you want something truly horrendous, go to the sci.space.tech archives and see where this was all hammered out in endless dreary detail. Back in the 90's. Fortunately, all the old space nuts seem to be dying off one oppo at a time, and in another twenty years what is merely well-known should become universal knowledge.

315:

"As for nuclear, if we tried to meet the Earth's current power
capacity with uranium, we've got about a 10 year's supply
available ... As for thorium, no one seems to know how much
usable thorium we've actually got (this from a thorium
proponent I talked to back in January) ..."

Those figures are from existing mines and for high-grade ore.
Some 3-4 decades back, Canada stopped even registering most
uranium/thorium claims, because of the surplus. The point is
that we have a good idea how much there is in total, and there
is masses, but most of it is in low concentrations. For
example, granite is about 10 ppm. I can believe that we have
a limited supply at present prices, but the price is low
($40/pound for the oxide!) because the stuff is so plentiful.

There was another analysis I saw (more recently) that found
that using granite as a source for fast-breeder reactors
produced about ten times the energy needed for the whole
process - construction, operation and decommissioning. And
there are a great many sources of low-grade ore, that is still
better than granite.

The problems with fission are NOT the uranium/thorium, but
the pollution/risk issues and overheating of the earth.

317:

Fortunately, all the old space nuts seem to be dying off one oppo at a time, and in another twenty years what is merely well-known should become universal knowledge.

Or they all died in the Mars One colony.

318:

Dunbars number and humanities problems coordinating itself are real. For humans. Whether they apply to extraterrestrials probably has a lot to do with how much those extraterrestrials resemble humans

There are sort of two intertwined concepts

1: whether a long term technical civilzation is even possible. The two things that have been mentioned that could break it are energy depletion and suicide. Energy deplition is a fantasy of the "back to nature" crowd and is in no way a real thing. Racial suicide on the other hand, either through war or stupidly wrecking the ecosystem is a real fG however it's hard to believe it's going to be universal across all species

2: can a long term sustainable planet based civilization actually get out of the gravity well and off to another star reliably? Jury seems to be out here, but I don't really see fossil fuel availabilry playing Into this hugely. If you assume a civ passes thru the gate 1: above they have millions of years to build whatever they need to build to get to the next star. If it's possible, and they have the will and the patientnce it could happen after fossil fuels are depleted

319:

"Rooftop solar sort of works, but the politics and legal issues around it are still being worked out. Dispersed generation isn't nearly as easy as you might want to believe, and yes, the human problems are far more difficult than the engineering problems are."

I don't understand this statement. Rooftop solar more then sorta works, it woks just fine thank you and is becoming pretty heavily deployed, I live in Calofornia, it's becoming so common here that it's not even dinner party conversation anymore. There are multiple companies that will come and install it at no money down

its not a panacea for sure but most of the issues I am seeing are engineering issues not political and legal ones. What are you referring to?

320:

Well Here's a theory for a pGF

http://www.newsweek.com/aliens-are-enormous-science-suggests-319448

University of Barcelona makes some leaps and figures that other intelligent species are going to be 300+ kgs

Accuracy of that aside *cough cough* if we take it that they are, then it imposes some much greater technological challenges for getting into space - mass of the individual is about triple for a human, and associated biosphere requirements to keep these bigguns alive will be correspondingly greater, and thus the problems previously articulated here with space colonization will be greater.

"They were, in fact, people. They might even have been humans, or at least had humans in their ancestry before someone, hundreds of years ago, had said, 'Let's see how big and fat we can breed people. Let's try for really big bastards.'"

321:

Yes, sustainability should be easy from a technological point of view. Unfortunately, the standard nerds catechism of "the technological hurdles are always the biggest problem, and once we solve those, the politics are trivial, and only stupid people prolong their solution," has very little to do with reality. The reality is that the political problems are generally much more difficult to even partially solve

I'm not actually disputing that; I'm only disputing your implication that these particular political problems must necessarily apply to all potential alien civilizations across all of time, in pretty much exactly the same way, regardless of differences in mentality, social structure, and history (not to mention differences in geology and planetary history). Alien civilizations may well have political problems, but they probably won't always be the same ones, or about the same issues. (Our difficulties with nuclear power, for example, are partly to do with the particular history of nuclear technology and its ties to nuclear weaponry, and also with specific historical accidents.)

As it happens, I agree that none of the possible options for us will work all by itself; what's more plausible is a combination of things, based partly on what works better in different areas and partly on what the local and regional politics and history make easier. I was just pointing that your "Well, there's nothing other than oil that will ever power civilization, and we'll never in a million years figure out fusion!" argument wasn't entirely correct, especially from a "will this be true across all possible alien worlds" perspective.

(Must all alien civilizations have birds that they object to being hurt by wind farms or thermal solar installations?)

322:

That was cryptic, wasn't it?

The basic issue is replacing power plants with distributed power from a lot of rooftops. I'm another California bombarded by solar ads too, but that's not quite what I'm talking about.

Here's my problem: I can't put solar on my rooftop, because I don't own the roof where I live. This is a problem for everyone from apartment and condo dwellers to the denizens of malls. Walmart may want to go solar, but they often don't own their buildings. If they want solar powered stores, they have to convince all the building owners they lease from to install solar and sell them the power. That's one level.

In Marin County and elsewhere, they're working on the legal issues of distributed solar, working out out you wire a bunch of homes together to power the entire city. There are multiple issues here:

The big one is that power companies only know how to buy large amounts of energy from a few sellers and sell that energy to many customers. They want a predictable energy supply, because it makes it easier to sell it to everyone, and they know how to do this pretty well. Part of this is called load balancing, matching up inputs of power with outputs, so that the system doesn't crash.

With distributed power, you've got a bunch of inconstant tiny suppliers, many of whom are also buyers, all hooked up together. If they're all running solar, there's a surplus of energy in the day and a dearth at night. Who owns and runs the batteries to balance that power load across the entire day? It's easy when it's one house, but across hundreds of houses, do you build a battery substation, require everyone to put a battery bank in their garage, or what? If it's the latter, who pays for those batteries, especially if they're hooked up to the grid and not under the homeowner's control? If a grid battery explodes in someone's garage, who pays for the damage? What if the homeowner's young child broke the battery? Similarly, if someone's rooftop panels are part of the distributed grid and they're not being maintained properly, who maintains them? Is it the power company's job to go up on the roof? The panel owner's job? If they get injured up there, whose insurance pays?

They're still working all this out, because inevitably there will be freeloaders, deadbeats and cheats if power is crowd-sourced, and there need to be effective ways to keep these people from crashing the power grid.

It can get even more complicated. For instance, if every home is part of a distributed solar system, what happens if, as in my city, there's a proposal to plant an urban forest to sequester carbon? If the trees start putting the panels into the shade, who pays to trim the trees? What if there's a regulation saying the trees must be maintained, and homeowners will be fined for cutting them down?

None of these are showstoppers. What is slowing the roll-out is that only a couple of communities are trying to solve these problems head on, Marin County in California being one of them. Everyone else is waiting for them to have solutions in hand so they can copy them, rather than trying to figure it out on their own.

For-profit utilities are also trying to derail distributed solar, because they fear it would put them out of business (they'd have to own and maintain a grid that most people only used on dark and stormy days). I think they've contemplated instituting the fairly strict rules they use with their big power suppliers, but unsurprisingly, most homeowners don't seem to be cool with having their roofs taken over by the power companies. If this continues long enough, people will learn to live off their rooftop solar, and the power companies will have crashed themselves. Of course, if people go to using backup diesel generators with solar power, then air pollution will soar, because backup diesel generators put out a lot more pollution than do heavily regulated power plants. And so it goes.

There's also the issue of fire departments not knowing how to work around energized solar panels when battling house fires. Hopefully that one will solve itself in the next few years.

Does it make any more sense now? As I was pointing out to Peter above, the political and legal problems with distributed solar are a lot more complex than simply wiring a bunch of homes into a common power grid.

Still, I don't think fossil fuels will go away anytime soon, and the reason is heavy equipment. No one's developing on a solar-powered bulldozer, let alone a solar-powered passenger jet or naval cruiser. So long as we need to build and rebuild cities, engage mass shipments to deal with emergencies, fly planes, and to fight wars, we're probably going to be using a lot of fossil fuels, simply because batteries don't yet have the energy capacity to replace a tank full of petroleum. Every time there's an emergency of some kind, whether it's dealing with the aftermath of fighting a war over water, food, or petroleum, we're probably going to be blowing a lot of petroleum on it.

This is both a technological and political problem. On the technological side, we simply don't have a sustainable substitute for petroleum-fueled heavy equipment (nuclear power? You want to drive a nuclear-powered bulldozer or fly a nuclear-powered fighter jet?). On the political side, do you think any leader is going to be able to sit there with a reserve of petroleum and tell people that it's not going to be tapped into to deal with the latest emergency?

If we could get away from emergencies or build better batteries we'd be fine, but unfortunately, climate change and resource over-exploitation promises more and more crises, not fewer. As for super batteries, I'll believe them when I see them. Better batteries are harder to build than better circuits or engines. Hopefully I'll be wrong about this.

323:

"I don't understand this statement. Rooftop solar more then sorta
works, it woks just fine thank you and is becoming pretty heavily
deployed, I live in Calofornia, it's becoming so common here that
it's not even dinner party conversation anymore."

We don't all live so close to the equator!

Solar water heating works very well, even as far north as the UK,
though it is not adequate on its own in winter. Its main
components are aluminium, copper, glass, etc., all of which are
recyclable, and it can be 95% efficient.

Solar electricity generation is more marginal, and is nothing but
greenwash in the UK (50-58 degrees north, with a lot of cloud
cover). I heard from an expert that it delivers less energy in
its lifetime than is needed to make it, let alone recycle it, and
it contains lots of scarce and toxic elements. Also, the total
insolation is 0.8-2.2 MJ/day in winter, when there is most power
draw - at cost-effective, it has to be subsidised to the order of 75%.
But it makes perfect sense to drive air-conditioners in the USA!

324:

If you assume a civ passes thru the gate 1: above they have millions of years to build whatever they need to build to get to the next star

Over the long term, a culture that invests heavily in space travel must compete against cultures that invest in more immediately useful things. On our planet, the biggest investor in space travel, as a fraction of available resources, was probably the USSR.

325:

The old kneejerk dismissal of solar. Would it surprise you to know that solar PV is now cheaper than domestic mains in half the world, without subsidy? And solar, year on year, gets cheaper and cheaper and cheaper...

And now for a report from those tree hugging yoghurt knitters Bloomberg:
http://www.bloomberg.com/news/articles/2015-04-14/fossil-fuels-just-lost-the-race-against-renewables

326:

http://www.businessgreen.com/bg/news/2360377/citigroup-solar-set-to-shine-as-costs-plummet

"It adds that grid parity is likely in the UK as early as 2018, is on track to be reached in Japan between 2014 and 2016, and in South Korea between 2016 and 2020."

327:

Yes, sustainability should be easy from a technological point of view.

Although I agree with the thrust of your post, I feel the need to remind you that many things which seem like they should be easy from a technological point of view actually turn out to be difficult or impossible, for reasons that only become clear in hindsight. Scaling solar power to fossil-fuel-replacing levels may well be one of these, for technical reasons as well as political reasons.

328:

fGF scenario's:

Other than the forementioned smart weapon that departs from it's home system and spreads copies of itself across the galaxy I find it difficult to come up with anything.

Just another version:
Something selfreplicating that can recognize ANY sort of DNA and starts chopping it up in short strands whenever it encounters DNA.
Process a few Pluto sized KBO's into a couple of trillion objects. Launch and let them float until they hit something and start cranking out the first selfreplicating choppers and more copies of itself. Like Autofac. (story by Philip K. Dick)

A few other GF's, probably all mentioned in some of the previous 300+ posts, might be:


They're all playing Kerbal Space Program on the couch with a beer nearby. Why bother with with all those annoying details of interstellar travel, not to mention the fact that it takes a really long time to go anywhere.

Hit the bong. The populations of the richest countries on our planet spend huge amounts of money on any chemical that influences state of mind. We don't want no stinkin' reality!

Nobody who becomes rich enough to do it wants to.
They're very well off in their societies and the people that want to don't have the cash to go. Interstellar space is an even better barrier than the mediterranean sea. A few days on a boat and hundreds die. Now you want to cross a void that takes 1000's of years? Nothing crosses it and lives. The people that have the money and the means have their nicely polished ship in orbit around the planet where they can show it off and invite guests on board. Think Monaco.

Another possible filter option:
Gravity. Most intelligent species develop on planets that have gravity high enough to make it impossible to get into orbit.

Idiocracy, the environment people/creatures live in becomes just smart enough to keep itself going and support anything that has the capability to breathe and breed, superwelfare state. Saw a doc. a few days ago about an english guy, 49 year old alcoholic, on welfare for his entire life, 20 children with 3 women. Receives 35000 a year to keep things going. Imagine a planet full of that.

329:

Still not large enough to be seen from our system, according to ScentOfViolets @291:

Actually, you only have to get out to about 550 - 1000 AU to take advantage of gravitational lensing by the Sun. I've heard of resolutions of less than a kilometer for Alpha Centauri.

330:

Thanks Dirk, I hadn't seen that episode.

331:

of your upcoming projects, the two I'm looking forward to most are Merchant Princes: Next Generation and the novel treatment of Palimpsest.

The former won't be sold/marketed as "Merchant Princes" (sales figures were too low), so look for (probably) the "Empire Games" trilogy, book 1 of which, "Dark State", is theoretically due out next April.

Palimpsest ... no set deadline, I still don't know where the final third part of the three-act structure goes (although I've got a good idea about act two, and act one you've already read).

332:

Mining asteroids. Go after smaller ones, Spin, then melt

That assumes they're tightly bound solid objects -- not jumbles of dust and small boulders that barely hold together due to gravity alone. This appears to be the case for comet 67P/Churyumov–Gerasimenko; admittedly not an asteroid, but it's suggestive of what we'll find on the smaller ones.

Asteroids big enough to be properly gravitationally bound, like Ceres or Vesta, are more properly dwarf planets -- and the energy cost of melting them would be insane (short of having a Kardashev Type II civilization's resources available).

333:

Let's assume that the asteroid belt is colonized the way so many fanboys suppose, the thin gruel of resource extraction being what it is and all. And let us suppose that eventually there's a technical base that makes an interstellar voyage by ark lasting hundreds or thousands of years technically feasible. Would it be 'worth' it to make the trip?

Yes, but if and only if the colonization/mining/resource extraction is carried out by a self-sufficient indigenous asteroid civilization, i.e. one that can take on all the necessary economic and social roles required to maintain itself in being -- including breeding up and educating and entertaining a new generation every so often, replacing all essential and most non-essential hardware that runs out, and so on.

Once you've got that sort of asteroid colony, you just strap a rocket on the back and head on out to the Kuiper belt. And then the Oort cloud. And then the Oort cloud of the next star system over.

All of which will work, but is likely to take thousands of years -- or longer -- and will result in a civilization that is virtually unrecognizable to us and is almost certainly uninterested in colonizing earthlike planets.

334:

how many thousands of years? Just cooling the place down to make it worth terraforming (and honestly, it isn't), is a non-trivial challenge.

Actually, Venus isn't entirely useless for our colonial purposes -- without terraforming!

We might want to dump some cometary nuclei into Venus' atmosphere to add hydrogen (currently very scarce) but there's a layer in the stratosphere where the atmospheric pressure is ~1 bar, the temperature is in the range 20-40 celsius, and the composition is such that 80% N2/20% O2 (breathing gas) is a lifting gas about as effective as helium would be in Earth's atmosphere (a mostly CO2 atmosphere with bits of H2SO4 is rather dense). So we could in principle live reasonably comfortably in pressurized airships/balloons in the upper atmosphere. Drop tubes to the surface and run heat exchangers for power to drive surface-level resource extraction -- we'd need to develop high temperature tolerant robotics -- and you've got a possible reason for going there ...

335:

Kneejerk dismissal? Not really. I'm looking forward to powering my home with solar, and hopefully at least half a car, too.

What I'm also seeing are some real messes made in the pursuit of big solar plants out in deserts, plus the complexity of installing rooftop solar on homes in sunny spots. Personally, I think these will be partially solved in ten years (hopefully by moving distributed solar into cities), even as a pessimist. Still, it's going to be messy, even in places where we could go 100% solar on normal daily energy use.

Where we're in deep trouble is with everything that uses heavy equipment, with the possible exception of freight trains. I'm still looking for good examples of using nothing but solar and wind power to do the following:
--build a modern new city
--fight a modern war
--run an emergency relief operation after a major hurricane, earthquake, or other humanitarian disaster where moving large amounts of goods and people quickly is critical.

This is where we need concentrated energy sources in huge volumes. Right now, petroleum products seem to be the only thing available.

336:

I'd point out that, given what seems to be in a lot of asteroids and comets, you can get equal mileage out of the idea of freezing a landfill solid, strapping a rocket to it and heading to the Kuiper belt with it. It's a pretty similar challenge. And you're right, that would be a fairly alien culture to what we have now.

337:

Still, I don't think fossil fuels will go away anytime soon, and the reason is heavy equipment. No one's developing on a solar-powered bulldozer, let alone a solar-powered passenger jet or naval cruiser.

Might not biofuels provide an alternative to fossil fuels in cases such as these? (Biofuels being, of course, an indirect way of using solar power.) The US Navy seems to be fairly confident about using them in the future:

http://www.military.com/daily-news/2013/08/07/lowering-prices-on-biofuels-offers-navy-hope.html
("... an entire USS Nimitz Carrier Group, including both ships and air assets, were successfully powered by a 50-50 blend of biofuels and traditional fuel during last-year's Rim of the Pacific ... exercise")

338:

Actually, I do agree with you on that, although I was trying not to be too pessimistic. It is that whole solar-powered bulldozer thing, really. Hopefully the prototype is out there, and I've just somehow missed it.

339:

Yes, the thought of building a society around Zeppelins that recycle all their materials internally does strongly appeal. On my 20 minute downtimes between shifts, I could even read Girl Genius comics.

340:

It's protected against reading. Anyway, as far as its UK statement
goes, I have this bridge for sale ....

341:

Something like this may be what Dirk was linking to:

http://www.treehugger.com/renewable-energy/striking-chart-showing-solar-power-will-take-over-world.html

Still, I agree that solar in Britain needs some rather more efficient panels.

342:

The LHC team found a particle which possesses the properties required to be a Higgs Boson and tested this to find that it agrees with predictions at greater than 99% confidence rates about 2 years ago, if there were some finding which invalidated this between then and now I'm sure we would all have heard of it.

Is there anyone here who actually works on that? Not just has a degree in high energy physics, maybe theoretical high energy physics, but actually familiar with the details?

See, the things they decided are Higgs bosons are pretty rare, and a combination of other events can simulate them some, so they ran the experiment for a long time until it happened enough more than they predicted by random chance if there were no Higgs bosons. And then they decided it had been found.

So my question for someone who knows, is what did they use for a control group? Ideally they should have chosen particle properties at random (not completely random though, they shouldn't pick particles that look theoretically impossible). They should put just as much effort into discovering the randomly-selected particles as they put into the Higgs boson, and if too many of them are found, then announce that the Higgs boson was not discovered after all.

How many times did they actually do that?

343:

I recall reading about a solar powered steam engine, years ago. It was (IIRC) 20 feet on a side and half a horsepower.

344:

No reason you couldn't have electric bulldozers or ethanol ones. Just that no one has bothered. For armies, some electric makes sense and the rest of the use cases will likely stick to petroleum in the near future

You don't have replace fossil fuels entirely all a once you have to gnaw away at them. Each 50% decrease makes your supply last twice as long

As far as the social and conomic resistance to solar, it's well past the tipping point at this stage. The energy utilitis only really have two options. They eithe don't buy the excess power at a lower price then it costs them to produce it, or they try not to sell power to solar producers,

One of those options is directly against their own profit motive, the second is usually illegal.

The utilitis are are in a rough spot for sure and likely to go bankrupt and get nationilized in the areas where they are not already nationalizied of course.

345:

All of which will work, but is likely to take thousands of years -- or longer -- and will result in a civilization that is virtually unrecognizable to us and is almost certainly uninterested in colonizing earthlike planets.

Assuming those Earthlike planets exist (for various values of 'Earthlike'). But yes, that was the point I was trying to make above: The intelligences who would want to colonize Earth don't have the capability for interstellar travel and those that do simply aren't interested. I think this explains the filter rather neatly.

Another thought: the griefers are only interested in those that can do interstellar travel; but by our very nature we're not and never will be because we're the filter. We were in fact designed to keep other species in our solar system from ever being able to pull that one off.

346:

I suspect Higgs Bosons are not rare at all, just sightings of them?

347:

"Yes, but if and only if the colonization/mining/resource extraction is carried out by a self-sufficient indigenous asteroid civilization"

That is a giant Catch-22. The asteroids won't be colonized unless they can be made self sustaining. But there is not much point in creating a self sustaining asteroid civilization.

There has to be some economic reason for starting up such an enterprise. We won't do it just because we can. But what do the initial investors get even if the endeavor can grow on its own after its first establishment? As someone else pointed out, even if you could lasso an asteroid made of a valuable/rare material and bring it back to earth for processing, the subsequent oversupply would flood the market and depress prices, eliminating the incentive for further asteroid resource extraction.

So the example of Jamestown and the Virginia colony (which sustained itself via the sale of tobacco back to England) doesn't apply. The more asteroids you mine, the less demand for asteroid mining.

How about the Botany Bay model and send condemned convicts to a life of mining and colonizing the asteroids? It helped establish Australia. But do we want convicts or any other unwilling colonists put in control of large chunks of rock which can be diverted back to impact with Earth?

How about good old fashioned Soviet-style central planning, like the Soviet attempt to colonize Siberia? If there is no profit to be made for investors back on Earth, why not try socialism? But like the Soviets in Siberia any centrally planned colonization of the asteroids will result in mismanagement, waste and failure.

(For an interesting comparison of Soviet colonization of Siberia vs. Canadian colonization of the Arctic see: http://www.brookings.edu/research/articles/2003/09/fall-russia-hill)

How about emulating the Puritans? If there is no rational reason for establishing an asteroid civilization, perhaps an irrational religious motivation to build a "shining city on a hill" will suffice and establish the asteroid version of the Plymouth Colony. The Puritans of their day were actually very high tech. Under Cromwell they had the most advanced army with the best weapons in the world, built a navy from scratch that easily defeated the Dutch, started the worlds first trade and industry economy, and readily adopted any scientific or industrial advance that gave them and advantage in business or war. But the religiously motivated of today are decidedly anti-science, a serious handicap when living and working in deep space.

So there is the profitable colony, the penal colony, the planned colony and the religious colony. None of these models seem sufficient reason to establish an asteroid civilization.

How then should an asteroid civilization get kick started?

348:

The LHC had two primary experiments, ATLAS and CMS, whose teams were sequestered, whose experimental methodologies were completely different from each other, and whose only real point of contact was CERN leadership.

In both teams, their many, many experimental runs essentially eliminated the possibility of the Higgs Boson existing outside a narrow range of specific energies, and their experiments gradually reduced these potentials.

Neither team were looking for the Higgs directly (it doesn't last long enough) but for its decay products. In both experiments, they identified candidate decay cascades, with the energy spectra as predicted by Peter Higgs, et al many years before. These candidates agreed across experiments (so demonstrating that the spectra were not the result of a particular glitch or tuning effect in a single device). The corroborated results agreed with theory, and with each other, at better than 99% confidence.

That's why the Physics community are pretty much in agreement that they found the Higgs (and re-confirmed the Standard Model).

Next step: super-symmetry?

FYI: There is a pretty good 'high level' documentary from Nova/Horizon "The Big Bang Machine" that discusses all this. You can also go directly to CERN - they publish a lot of "lay-person accessible" material suitable for education.

349:

and do know
something about that area. I have no intent of arguing the
point, except to point out that the terms "99% confidence",
"observations" (of Higgs bosons, that is), "inescapable" and even
"quarks" all make sense only when one has already assumed the
standard model. And the identification of the signature that
matches the Higgs boson was the last part of the 'proof' of the
standard model. Self-referential proofs are not highly regarded
among mathematical logicians - there are too many opportunity for
loopholes!

_____________________________________
Ah, true, I suppose there is plenty of room for a hierarchy of magical tinkle fairies with a mathematically definable set of interactions and relationships, as well as properties that fall within certain very tightly constrained experimental bounds.

We know that every single time you run [PARTICLE_PHYSICS_EXPERIMENT:A] you will find [EXPERIMENTAL_RESULTS:1], and you will find [EXPERIMENTAL_PARAMETERS:1a:1b:1c:1d:1etc], and that there is a known model which has correctly predicted [EXPERIMENTAL_PARAMETERS:foobar] for an entire set of [PARTICLE_PHYSICS_EXPERIMENT:foo] and [EXPERIMENTAL_RESULTS:bar], again to very tightly constrained parameters.

Therefore your magical pixie fairy model needs to exceed the predictive power and accuracy of the standard model before there is reason to take it as anything remotely approaching a serious alternative.

What we have no idea is whether there is another theory that fits
the actual observations we have (e.g. of cloud chamber tracks) as
well as the standard model. That's true of several other aspects
of modern physics, too.

Well, yeah, we do know that there are entire classes of possible theories which will map to the results, but those theories are then mappable directly to the standard model itself.

You can feel free to add something deeper or add something which expands the model, but we have a verifiable and testable framework with an absolutely stupid number of confirmed predictions, if you don't see how important that is scientifically then positing alternatives to a valid theoretical framework is not a useful way to spend your time.
__________________________________
@J Thomas: the control group would have been that no signatures matching the properties for a standard model Higgs will be found. If it is not related to a symmetry breaking process responsible for particles acquiring mass then there is no reason for a signal with the specific details (massive, particularly within the 110 ~ 150 GeV range favored by certain assumptions within the Standard Model, 0 color charge, 0 electric charge, 0 spin) to emerge.

Those specific properties imply that when the more massive particle decays it will do so in a manner that favors certain products over others, with predictable ratios, and predictable timespans over which these decays take place.

Finding decay products which should not be produced by other types of particle decay is one step, narrowing down which products are produced exactly is another, collecting a large enough set of data to be certain that you are actually observing a specific type of decay event is one more, and eliminating possible alternative explanations for the observed properties of the apparent signal rounds out a rough outline of what the detectors and computers in something like the LHC do.

Stating a given confidence level simply means that there is an x in y chance that these findings are (random background noise/computer glitch/detector bugginess/unlikely interaction not predicted fully/etc) or "noise" rather than an actual "signal", with an ever larger value for y. Once you start talking about there being 4 or 5 sigma results we're looking at something like this event showing up randomly 1 time in something like 1,000,000 or 3,000,000 runs as I recall.

350:

The other colonial possibility is the "bug-out and leave me alone colony" where people who don't want to be part of some dominant culture leavet. In this case, finding the most useless and non-threatening settlement area is ideal, because you want to be left alone. You want to be not worth taxing or capturing (the cost of conquest and rule isn't made back by whatever income can be extracted from you). You also want to be on an asteroid that would be really, really hard to turn into a weapon of mass destruction. A combination of orbital dynamics, size (larger might conceivably be better) and material composition would suit these criteria.

Note that living in such a place is not going to be all that prosperous. To really make this work, you need to be down there near survival level, and possibly you'll need to move fairly frequently. On the other hand, you'll be free. Depending on what the big powers are doing around you, freedom may be worth trading prosperity for and more.

Incidentally, people have used this particular tactic all over the world for many centuries. In fact, anthropologists of South East Asia and South America are pretty sure that the so-called "primitive tribes" that ethnographers described a century ago as timeless, unevolved primitives had actually been much more advanced generations to centuries before. They'd adopted their "primitive" lifestyles in response to encroachment by slavers and encroachment by authoritarian civilization.

So perhaps asteroids will be the ultimate boonies, places civilization hates, but which no one particularly bothers to go after because they're no threat, it's too much of a nuisance to conquer them and not worth the cost. With every technological change, what's useful and useless will change, of course, but this could be a way to realize the old libertarian dream of the free belters.

That they'll be following in the footsteps of maroons and barbarians will, of course, be lost on most. Still.

351:

I suspect Higgs Bosons are not rare at all, just sightings of them?

But sightings of them are quite rare.

If we look for random particles and find them just as often, that would say something. Maybe the random particles that nobody predicted also exist, and we can think about what they mean.

Or maybe they and the Higgs boson are stastical artifacts because we misunderstood just how often the various things happen which cause false positives.

The experimental group has been tested and the Higgs boson has been observed.

Which of the control groups have been tested?

352:

This is probably silly, but given a choice between:

1) The Nazis (or Khan and the Augments, or Commies, if you prefer) conquering the world (we’re already in one attractor, why not add another?) and going on to conquer space (hey, NASA was built largely by ex-Nazis, so why not?) (“Triumph of the Will IN SPAAACE”)

and

2) Failing to colonize space and being stuck on this planet forever, squabbling and screwing like monkeys, though not under the boot of any giant, oppressive empire (“Olduvai Regression”)

Which do you choose?

I’ve long thought that more aggressive, totalitarian civilizations are better suited for space colonization, and that the libertarian “gold rush on the High Frontier” scenarios are fantasies. Hell, Victorian England probably would have done more impressive things in space with late 20th century technology than the U.S. has. For example, my understanding is that the Orion Project was shelved because calculations indicated that it would on average kill a few people on earth every launch from fallout. Now, even Stalin would agree that this is a tragedy, but it’s also a value judgment that would’ve been made differently under a different regime, and which in the longer term might’ve paid off enormously. So which will it be? Space Nazis or Earth Hippies?

353:

the control group would have been that no signatures matching the properties for a standard model Higgs will be found. If it is not related to a symmetry breaking process responsible for particles acquiring mass then there is no reason for a signal with the specific details (massive, particularly within the 110 ~ 150 GeV range favored by certain assumptions within the Standard Model, 0 color charge, 0 electric charge, 0 spin) to emerge.

No, that is not a control group.

But you're in a lot of company, lots of people have trouble with scientific method.

In this case we started with a theory that made some predictions. Those predictions were observed to very, very rarely come true. After a tremendous number of iterations, the very, very rare events happened often enough to say it was not random accidents.

Let me give an analogy. I knew a woman who took up electron microscopy because she wanted to *see* things and not be stuck with elaborate hypotheticals about what was going on. she wound up working on some questions of how some specific proteins bound to DNA. They could bind to two strands of DNA, and she was supposed to observe just how they did that. So she looked at hundreds of thousands of them bound to DNA that had been broken open so the interaction could be seen. And she found that she could find any pattern of DNA/protein that she looked for. Among hundreds of thousands of examples, she could find anything. She wound up counting the different variations and doing elaborate statistics to guess which were real.

In general, when somebody says "My theory predicts that X will happen" and then they observe that X happens and they say "My theory has been proven true", they are not doing science. They need to at least do some controls.

Like, there might be some false-positives that happen for other reasons. So find circumstances where you would expect to find no Higgs bosons but everything else is as similar as you can make it, and see how many Higgs bosons you discover under those conditions. There are various things that can go wrong, but at least you get a lower bound on false positives.

And pick random signals that you inspect and confirm that you do not expect to see, and look for them too. Notice how often those show up.

Do it all double-blind. Lots of people say that they are too good to do self-deception. Lots of MDs say that, and engineers, and astrologers. Most of them are wrong. The scientific approach is to do it double-blind and do not depend on your special magic skills that leave you not requiring it double-blind.

This stuff is not all that hard to understand, but it's surprising how many otherwise-reasonable people do it wrong.

354:

The control in this case is just the null hypothesis: "given a set of events at this energy the only data in this range should be due to the background" which is competing with "given a set of events at this energy the data in this range should comprise a signal with these properties (...) and that due to the background" during the experiments.

Also: http://www.ge.infn.it/~osculati/LezioniStatisticaCern/StatisticsLecture2_CERN.pdf

355:

A favor for me, if you would, don't be condescending and wrong. I am not having a problem with the scientific method, I was the kid who was disappointed to learn "science fair" meant "put some pictures on a poster board with some general information about it and you'll probably get by" rather than "ask testable questions about observations and propose explanations which you seek to falsify experimentally, then share your results for others to examine and replicate when you are no longer able to perform or conceive of novel ways to falsify your hypothesis" as I assumed.

If there is not a massive particle in the ~125 GeV range with 0 color/electric charge and 0 spin which decays in certain ways that make it compatible with certain aspects of the Standard Model then there should not be detections of certain types of events with a certain frequency when doing runs at a given energy.

We know this because there does not appear to be a 115 GeV Higgs or a 165 GeV Higgs and so forth because the type of decay products which would be detected after said particles were produced and decayed were not decayed, the null hypothesis was upheld, other areas of the phase space were explored.

Next they're going to make sure the results hold up at 13 TeV, again with the null hypothesis being that they will not.

There is no control group of generic particle events you can inject into the LHC or otherwise trigger outside of them actually resulting from the collisions, other than the background noise from various sources of rf/em interference, cosmic rays, solar effects I would imagine, uh... lightning could probably play a role in producing something that might look interesting at first glance, and detectors could be buggy or fail and give a false positive. That is by no means a comprehensive list, but when you see a particle physics experiment using the term "background" then that stuff falls under it.

Getting a good ways off topic, but the scientific method is a useful way to sift through candidates for a great filter, so ehhh.

356:

Another thought: the griefers are only interested in those that can do interstellar travel; but by our very nature we're not and never will be because we're the filter. We were in fact designed to keep other species in our solar system from ever being able to pull that one off.

Ouch!

That's a good one!

Hmmmm...

357:

Designed by whom?

358:

Maybe aliens all end up fantastically wealthy and technologically advanced, with all work done by robots. The endgame might look something like Asimov's Solarians - solitary aliens living on vast estates with robot servants. They have little to do with one another, distrust physical contact, and have no desire to visit other worlds.

The galaxy could host millions of worlds like this and we'd never know it.

359:

I've seen some cool scenario's so far. Imagine this one.
Those griefers exist and are trying to do their jobs. That's what they're paid for. Now what if there is this really powerful immortal being that can travel through space AND time to fight them so Earth is protected! Just imagine.
I bet no one has thought of that one. :)

360:

There are two solutions.
One is fuel synthesis from solar energy, where a lot is happening, not least from the US military.

The other is battery technology, and IMHO it will not be Lithium based but more likely Sodium or Aluminium. With regard to the latter...
http://www.palatinate.org.uk/?p=57663

361:

BTW, is there some reason that griefers don't just take over the galaxy, having eliminated all competition?

362:

The ole Ni-Fe battery is also being overhauled with modern insights and technology.

http://e-stonebatteries.com/web/

363:

Violent, xenophobic homesters?

364:

"In general, when somebody says "My theory predicts that X will
happen" and then they observe that X happens and they say "My
theory has been proven true", they are not doing science. They
need to at least do some controls."

Well, yes. It's often worse than that, because they create the
theory after observing the phenomenon. In the case of the Higgs
boson, its existence and some of its properties were predicted
in advance, but others were chosen to fit the observations.

People nowadays forget how well the epicyclic theory of the
planets worked, though we now know why it did (Fourier theory)
and its notation is still used to describe orbital constants.
And ANY theory that relies on choosing constants according to
the results is a more-or-less close relative of that one.

In mathematics, and the more solid forms of science, there are
only two forms of actual proof:

To start with a set of assumptions and a set of rules of logic,
and show that the result necessarily follows from those.

To show that the assumptions explain the result, and (equally
importantly) no other hypothesis does so. This can be used to
prove Newton's law of gravity from Kepler's laws.

Statistics takes the second form, and weakens it by allowing
confidence levels below 100%, but the confidence estimates are
CRITICALLY dependent on the model being tested. Any serious
statistician knows how easy it is to reverse a result by very
minor changes to the assumptions, and how much effort can be
needed to avoid that happening by accident.

365:

So my question for someone who knows, is what did they use for a control group? Ideally they should have chosen particle properties at random (not completely random though, they shouldn't pick particles that look theoretically impossible). They should put just as much effort into discovering the randomly-selected particles as they put into the Higgs boson ...

That's not really how exploratory/discovery science works; I think you're a bit confused about what "control" means in this context.

Unconstrained imaginary alternate hypotheses are not "control groups".

When biologists search some previously unexplored (or poorly explored) forest and find evidence for a new animal (possibly one that had been postulated on various grounds), they don't go back and re-explore the forest repeatedly looking for all the other animals (or non-animals) someone imagines might exist, and only announce the discovery of the one they actually found after not finding anything else.

The purpose of a control group or control sample or control observation is to ensure that whatever effects the experiment might detect are not plausibly explainable as side-effects from "stuff we already know about that's unrelated to the special nature of the study/treatment group". (For a cancer therapy trial, this would include things like spontaneous remission -- even though you can't fully explain it yet, you know it happens.)

If you look at the papers discussing the experiments that led to the Higgs discovery, you will find that they do in fact refer to "control samples".[1] I gather that these are subsets of the general run of data -- including particle interactions that aren't expected to produce Higgs-like signals, or interactions which don't produce Higgs-like signals in a particular channel -- used in order to estimate the "backgrounds". Statistical fluctuations from the backgrounds might produce false Higgs-like signatures, but if you know (from your control samples) what the scale of these fluctuations are, you can compare those to any special signal you do detect.

You will also find that the papers tend to be careful about what the experiment actually showed, e.g. (from the abstract of one of the discovery papers): "Clear evidence for the production of a neutral boson with a measured mass of 126.0±0.4 (stat)±0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10−9, is compatible with the production and decay of the Standard Model Higgs boson."

[1] E.g., from this 2011 conference paper (PDF): "Both searches make heavy use of control samples to extract estimates of the rate of backgrounds from WW, top, W+jets, and Z+jets. The W+jets background is normalized using events selected by loosening the lepton selection criteria...."

366:

the subsequent oversupply would flood the market and depress prices, eliminating the incentive for further asteroid resource extraction.

Because, as we all know, every time in history there's been a major glut of a particular commodity, no one ever good looking for more of it sometime later...

(And the availability of cheap rare materials would never spur the development of new products making use of them, thus increasing demand...)

The Puritans of their day were actually very high tech. Under Cromwell they had the most advanced army with the best weapons in the world, built a navy from scratch ...

Actually, the Plymouth and Massachusetts Bay colonies were founded decades prior to Cromwell's victory, partly by groups who were so disgusted by England that they moved to the Netherlands (and decided to try for the New World in part because they were worried about their kids becoming Dutch). All the stuff you refer to (building a navy from scratch, etc.) was done by those who weren't motivated to try for the New World.

I'd be slightly wary of assuming that we can confidently predict what technological attributes and attitudes religiously motivated people will have a hundred (or five hundred) years from now. (I mean, your argument seems to be "Sure religiously motivated people in the 1600s did that sort of thing, but the religiously motivated people I know of today couldn't, so it'll never happen in the future.")

367:

Like, there might be some false-positives that happen for other reasons. So find circumstances where you would expect to find no Higgs bosons but everything else is as similar as you can make it, and see how many Higgs bosons you discover under those conditions. There are various things that can go wrong, but at least you get a lower bound on false positives.

And pick random signals that you inspect and confirm that you do not expect to see, and look for them too. Notice how often those show up.

Do it all double-blind.

All of that is exactly what the LHC collaboration did.

Well, except that technically the analysis used a form of single-blinding, because "double-blind" makes no sense outside contexts where your experimental subjects are sentient beings.

368:

There has to be some economic reason for starting up such an enterprise.

It depends on whether functional AI is feasible.

If mining asteroids for rare earth elements and so on is desirable, there's a strong incentive to do it as cheaply as possible. Which means robots.

Controlling robots by remote control with a multi-minute lag time is hard, as generations of Mars rovers now demonstrate. Lags on the order of 0.1-5 seconds are just about okay. Small chunks of asteroid can be dragged into Earth orbit, but for obvious (political/military) reasons it's undesirable to do this on an industrial scale. So large scale asteroid mining requires either enough AI to drive the mining robots on site, or spam-in-a-can located on site to control the mining robots directly.

If we get the autonomous mining robots, then colonization looks to me like a non-starter unless it happens very late in the game for ideological reasons (Angry Religious People who want to move the hell away from everyone else and who have the already-existing infrastructure and resources on site to build colonies -- at least the mechanical engineering side of them).

But if we don't get sufficiently strong AI, and end up with mining robots that need human supervisors, then there's an incentive to also develop closed-circuit life support systems and recycle/reuse/replace as much stuff as possible on-site.

An additional wildcard in the mix is military tech. The Pentagon currently has a huge hard-on for 3D printers because they do revolutionary things to military supply chains. The US Navy is talking about the F-35 as the last manned fighter they ever procure for carriers; they currently see the future as one where they print out a disposable drone whenever they need to fly one, tailored for the mission in hand. (We're talking about the 2050 time frame here.) If it's the Navy doing this, they're going to have a requirement with DARPA to print out all the components of the drone -- including the electronics -- because they'll want to be able to guarantee availability without relying on external supply chains in time of war. And that is very close to the tech baseline you need to build asteroid mining robots: the real issue is the control software.

369:

The US Navy is talking about the F-35 as the last manned fighter they ever procure for carriers

Technically what's happened is the Secretary of the Navy has referred to the F-35 as "the last manned strike fighter" (emphasis added), meaning "fighter/bomber"; there's already a preliminary exploratory program for the next manned Navy fighter-qua-fighter (confusingly called "F/A-XX", which literally taken implies something that can also work as a strike aircraft) -- though this is sometimes talked about as possibly including an optionally unmanned option.

But, yes, it's impressive that they really do think they won't need a manned successor to the F-35.

370:

- Under Cromwell they had the most advanced army with the best weapons in the world, built a navy from scratch that easily defeated the Dutch, started the worlds first trade and industry economy,

They did not build the Navy from scratch - they took it over from Charles I (The Ship Money fleet which helped provoke the Civil War ...).

And the Dutch where well ahead of the British in founding trading empire - which was one reason the Anglo-Dutch wars started.

Not sure how this helps answer your question though :-)

371:

But, yes, it's impressive that they really do think they won't need a manned successor to the F-35.

My $0.02 says that they're over-optimistic on the "drones are the future" front, like the British defense review of 1957 which said "the future is guided missiles" and cancelled a shedload of aircraft projects ... then had to be walked back over the next decade, after causing immense damage to the RAF. (Turned out AAMs and SAMs were still only half-baked in the late 1950s.)

If drones get big, then the front-rank answer will be (a) ECM, and (b) if jamming/signal spoofing fails, some sort of AI method for producing a "theory of mind" for drones during autonomous/swarming flight, in order to be able to shoot where the drones are going to go. Turning it into a software predator/prey arms race.

(Assuming there are still any front-rank military players left by 2050, in current terms: my gut feeling is that the USN is still trying to play by the rules that worked for them in 1945, and the only reason China and Russia are doing so is because it forces them to continue haemorrhaging money on pointless shiny penis extensions: something new is going to come along sooner rather than later once the USA's current hegemony becomes unsustainable, as always happens to trade empires when they pass their peak.)

And we now return you to asteroid colonization because really, wittering on about the 30-100 year out plans of a current nautical hegemon is so not relevant to the Fermi paradox.

372:

But if we don't get sufficiently strong AI, and end up with mining robots that need human supervisors, then there's an incentive to also develop closed-circuit life support systems and recycle/reuse/replace as much stuff as possible on-site.

Interesting, I've always thought the opposite is true. If we have to rely on humans to get things done on space outposts it's going to stay so expensive for so long that it won't be worth doing (it will be the sort of grand engineering project that gets brought up every few decades but never attempted).

Conversely if your automation gets really good then there are wide reaching effects on the economy, things become a lot cheaper if we don't have to pay humans to do it (assuming we move on from capitalism and avoid more bullshit jobs or robotic welfare dorms designed to keep the unemployable alive and fed but out of the way). With sufficiently advanced automation a moderately funded group (perhaps major university level as opposed to space agency) might be able to develop sustainable space habitats with the help of robot labourers and really smart software.

In terms of the Fermi paradox though I don't think it complicates things too much, all this gets you is a relatively easy avenue for colonising your own system. Anywhere else is still a long way off in time and energy.

373:

All of which will work, but is likely to take thousands of years -- or longer -- and will result in a civilization that is virtually unrecognizable to us and is almost certainly uninterested in colonizing earthlike planets.

Except for the space flight versions of our fan boys. Who will keep telling everyone how great things would be if they'd just land on a good planet and live there. :)

374:

I'm thinking in terms of humans being needed in the vicinity to provide guidance, and to repair/replace equipment as it wears out. Repairing a damaged robot (rather than shipping a new one up from Earth) may well be an AI-complete task, even if drilling out a seam of ore and feeding the rubble into a smelter isn't.

Also: small rocks can be steered into Earth orbit, but anything more than 1AU away really doesn't work so well without realtime feedback and control. I'm guessing initial mining expeditions would be run like Antarctic bases -- everything flown in remotely -- but later ones, especially to the Kuiper belt, would be more like Siberian mining towns, inhabited all year round.

375:

"... something new is going to come along sooner rather than later..."

When it comes to navies, the "something" is arriving now - ballistic missile attacks on ships. High angle inbound at around 7000mph+, and mostly solid penetrator.

376:

This is the problem right now with automated shipping. ships can already steer themselves port to port with minimal human intervention (apart from the occasional dodging of other ships), but fixing the shit that breaks continually?
You need a team of experienced people to diagnose, prioritize, and complete repairs. Working out exactly which seal in an engine has blown by listening to it, and whether it needs to be stopped in the next five minutes, or can be left for the next time the engine is scheduled to stop in six weeks isn't trivial.

377:

In terms of the Fermi paradox though I don't think it complicates things too much, all this gets you is a relatively easy avenue for colonising your own system. Anywhere else is still a long way off in time and energy.

True. The relevance for the Fermi Paradox is, I think:
1. Once you have actually self-sustaining colonies within the system, it becomes a little bit harder for the entire civilization/species to be killed off by planet-damaging events. (Not impossible, but harder.)
2. You have potentially more access to energy for weird projects like interstellar probes.

That is, "relatively easy avenue[s] for colonising your own system" tend to make the Paradox a bit stronger, in the sense that you're weakening the "No one can ever get off their home planet" filter.

378:

> When it comes to navies, the "something" is arriving now - ballistic missile attacks on ships.

It would seem so. See "Appearance of Apparent Antiship Missile Targets in Gobi Test Areas during 2013"

http://fas.org/man/eprint/gobi.pdf

379:

You still have to know where to put your missile - terminal guidance will only take you so far.

Which is why the first move will be to take out the enemies recon sats and introduce a nice bit of kessler syndrome before your carrier rocks up.

I don't think anyone is going to completely give up flattops until aircraft stop being useful. They might downsize and get cheaper and more numerous though.

380:

All of which will work, but is likely to take thousands of years -- or longer -- and will result in a civilization that is virtually unrecognizable to us and is almost certainly uninterested in colonizing earthlike planets.

Though they might still be interested earthlike planets from a scientific or entertainment perspective.

And a really advanced asteroidal civilization in our own Solar System gets harder to hide as astronomical observations accumulate, even if we'd be baffled trying to figure out what it was doing and why...

381:

The purpose of a control group or control sample or control observation is to ensure that whatever effects the experiment might detect are not plausibly explainable as side-effects from "stuff we already know about that's unrelated to the special nature of the study/treatment group". (For a cancer therapy trial, this would include things like spontaneous remission -- even though you can't fully explain it yet, you know it happens.)

Not exactly, you want to also look at side-effects from stuff you don't know about that happens. So you run controls where you expect it not to happen, and confirm that it doesn't happen with them, and then you can assume that it happens because of the thing you're looking at and not from something different that for unknown reasons is correlated with it.

"Spontaneous remission" is a catch-all for stuff that happens that we don't understand. Kind of like "UFO".

They invented the term because of anecdotal evidence -- like UFO. Then they confirmed that it happens so it became "background".

If you look at the papers discussing the experiments that led to the Higgs discovery, you will find that they do in fact refer to "control samples".[1] I gather that these are subsets of the general run of data -- including particle interactions that aren't expected to produce Higgs-like signals, or interactions which don't produce Higgs-like signals in a particular channel -- used in order to estimate the "backgrounds". Statistical fluctuations from the backgrounds might produce false Higgs-like signatures, but if you know (from your control samples) what the scale of these fluctuations are, you can compare those to any special signal you do detect.

Good! That's part what I was asking for. When you look for something you can very rarely detect, and then you try long enough that you are sure you have in fact detected it, you need to be *very very* sure that it isn't something else that's very rare. I talked with some other people who seemed to think that it was enough to estimate the probability of false probabilities theoretically, compatible with experimental work done under very different conditions. I'm glad to see it was not actually done that way.

"Do it all double-blind."

All of that is exactly what the LHC collaboration did.

Well, except that technically the analysis used a form of single-blinding

Oops! ;)


382:

And in related news, we recently had this lovely bit of marketing guff by NASA.
Alien life to be discovered by 2025

The key part will likely be the James Webb Space Telescope, which is theoretically going to be able to identify the atmospheric composition of the exoplanets we've been able to discover so far.

383:

What IS surprising is how many people appear to dislike the idea of intelligent species lasting for millions or billions of years on their home planet. On the basis of pure logic, it should make no sense. On the ideological basis, of course, it does make sense. Still, it's very tiresome and kind of scary that many people prefer the imminent extinction of our species to the idea that we'll be stuck here living a fairly good approximation of sustainably for a very long time to come.

I cannot speak for others, but myself, I do not believe that sustainability on the timescale of generations is ever possible. At least not without major neurological changes to human species.

The kind of sustainability you describe requires adherence to, well, sustainable practices in agriculture, industry and energy production. And given human nature, some will be always tempted to shortcuts. Lessons learned in one generation tend to be forgotten 2-3 generations later -- compare Great Depression and 2008. Someone always thinks he is smarter than the old fuddy-duddies (especially if fuddy-duddies in question are already dead), and can do things faster and better.

Moreover, long term sustainability requires rock-steady population. Not just no population growth, but no decrease either, lest you lose institutional knowledge and skills. And how on Earth do you ensure THAT? As long as there is widespread agreement that "two children per couple and three in every tenth" (i.e. 2.1 average) is What God Decreed, couples who break with tradition can be shamed or punished, but what happens when enough teenagers decide it is superstitious nonsense? Does not really matter whether they decide children are beautiful and start overbreeding, or decide children are a pain and all get vasectomies. Either way sustainability is screwed.

Sustainability on the scale of centuries or longer requires at the very least removing reproduction from individual decisions. Artificial wombs only, new human hatched every time an old one dies. And even that only addresses my second point, not the first: How do you keep either selfish assholes or well-meaning fools from mucking with systems designed to last for millennia? Some serious modification of how human beings think is in order. We'll need to become less like apes and more like ants.

Oh, and having read what I just wrote, I can see that quite a few people would prefer extinction. A post-human society which more or less matches the above has appeared in science fiction, and AFAIK is always meant to be repellent.

384:

A favor for me, if you would, don't be condescending and wrong.

Sorry, it's hard to avoid seeming to be condescending when it's things people think they ought to know and think they do know. That tends to make any disagreement look condescending unless it's done humbly enough to be ignored.

The control in this case is just the null hypothesis: "given a set of events at this energy the only data in this range should be due to the background" which is competing with "given a set of events at this energy the data in this range should comprise a signal with these properties (...) and that due to the background" during the experiments.

Teaching this attitude is one of the sins that Ronald Fisher should be suffering in hell for.

They found evidence for a particle that fit within the parameters they considered to be a Higgs boson. If the parameters had come out a bit different, they would still call it a Higgs boson. If they came out rather different, the announcement would be that the Higgs boson wasn't quite as expected and what implications would that have? If the particle was enough different that they didn't detect it because they were only looking for a narrow range of possibilities, then the announcement would be that they hadn't found it yet, that the signal was not yet statistically separate from the noise.

But this is all data that nobody has ever had the chance to see before. The null hypothesis that there is no Higgs boson is not the only alternative. Theory predicts the Higgs boson and no other new particles. If we were to look for new particles, like Peter Erwin looking in a forest for animals, what would we find?

Like the biologist ideally would turn over every stone, ideally we would give every potential new particle enough observations to confirm that it probably was not there. That isn't practical because the detectors must be carefully tuned for a particular small range, and it takes a long time to run the experiments, and most of the data must be thrown away because we don't have sufficient computing power or storage.

But if we didn't have the blinder that the Higgs boson is the only particle worth detecting because it is the only undetected particle predicted, who knows what we'd find?

Well, it's predictable that if we tested to p=.01 we would find many millions of new particles, given the amount of data being sifted. As testing continued, most of them would quickly fall out. But how many would remain?

385:

"Teaching this attitude is one of the sins that Ronald Fisher
should be suffering in hell for."

To be fair, he would be utterly horrified at the way that it
is so badly abused nowadays. It is a perfectly reasonable
approach to a controlled experiment, when the samples are from
the same population and are treated identically, except for a
single factor. That is very clearly NOT the way this
experiment was (or could be) structured.

386:

A post-human society which more or less matches the above has appeared in science fiction, and AFAIK is always meant to be repellent.

When I wrote this, I had a specific book in mind, but could not recall the title. It is "Half Past Human" by T.J. Bass.

387:

"What other fGF scenarios can you think of that don't require magical technology or unknown physics and that could effectively sterilize a galaxy, starting from a one-time trigger event?"

Dust. Dust is easy to make. As a griefer, I'd direct my vN probes to make a shitload of dust out of everything they could eat. I'd be looking for old to middling stars with a young dust disk around them. Or clouds of structured dust. That knowledge would bring my pants-shitting instincts to the fore.

388:

Yeah, that's the problem.

See, we've lived as sort of modern humans on this planet for about 80,000 years. And you're saying that's not sustainable?

Think about it for a second.

Now as far as what controls population, it's the Biblical four horsemen: drought, famine, warfare, and disease. One useful thing about this metaphor is that they do tend to "ride together," because these calamities tend to cause each other. Once the dust has settled after a major catastrophe, it's generally impossible to figure out what the ultimate cause of death was for most of the deceased. Was it disease caused by famine? War caused by lack of water? Lack of food caused by war? All combinations are possible.

Populations don't have to be constant at all for sustainability, and neither do resource use nor culture. They haven't been in the past. In the 17th Century, historical demographers estimate that the world's human population shrank by around 30%. The ultimate cause is murky, although a recent paper fingers the 16th Century depopulation of the New World by virgin ground plagues brought by early explorers. This caused a massive growth of forests (our current old growth forests), which dropped atmospheric CO2 and global average temperatures by about 1-2oC. This in turn led to global crop failures, the fall of the Ming Dynasty and the Kongo Kingdom, civil wars in Russia, the Ottoman Empire, and the Mughal Empire, and that huge swathe of wars in Europe that came between the Renaissance and the Enlightenment. Some historians call this period "The General Crisis." Our modern conception of the Westphalian nation-state arose out of this mess. (REF: Geoffrey Parker, Global Crisis)

Note that the human population recovered and expanded in the 18th Century?

This is what sustainability means: it means living as if you're at the mercy of the biosphere, and living as though your actions are critical in making sure your offspring have what they need for their livelihoods. This is actually reality, and it always has been. But for some reason, a lot of people think this is too hard to do and that technology gives them a way to get around it. It makes about as much sense as astronauts thinking they don't need a spaceship to get anywhere or survive, but there you have it.

My prediction is that we'll get to more sustainable populations running on 100% renewable energy by the end of the 21st Century. We can do this the humane way, through radical societal transformation*, fewer births, and accepting a drastically lower standard of consumption in places like the US. Or we can get there through global societal collapse, the four horsemen running amok, and survivors burning wood in the ruins. Oddly enough, many people, even though they're willing to conserve, do without, have fewer kids, and so forth, think that the second option is the only viable path, apparently because they don't expect their neighbors to join them in sacrificing for the common good, because everyone else is evil or something. Even more bizarrely, this includes a number of SFF readers.

So yes, I think sustainability will happen, and I also hope that more people get their heads around it as the inevitability it is. Personally, I'd rather get there the humane way, but I can't do it alone.

*The odd part about this is that most people think that the radical societal transformation between 1900 and 2000 is perfectly normal, but think that a similarly radical transformation between 2000 and 2100 is only reasonable if we end up as transhuman gods or on Mars or something. Again, what's up with this?

389:

Hi amigo,

"My prediction is that we'll get to more sustainable populations running on 100% renewable energy by the end of the 21st Century."

Hope you're right, because the most likely alternative to your 2100 is another P-T extinction event, courtesy of Us Truly, which AFAIC neatly explains the Fermi Paradox.

390:

A vastly underrated author (who only published two books, dammit).

Also noteworthy, on topic: "Hellstrom's Hive" by Frank Herbert.

Hmm. One of these days I ought to think about writing a metastable deep time human civilization that isn't a festering hell-hole of dystopian despair?

391:

I am perfectly aware that return to pre-industrial society -- "sustainability through Four Horsemen", -- is entirely possible, and that such society can last a very long time. I also do not find it the least bit desirable -- I would not go so far as to say I prefer extinction, but two are just about indistinguishable as far as I am concerned.

My previous post was directed at what you call "humane way" sustainability, and why it would be very difficult to maintain in the long term. No, I do not hold my neighbors in contempt ("everyone else is evil or something"), and am fairly sure that the scenario you hope for will come into existence by 2100 or so. My concern is that by 2200 or by 2250 people will forget why things have been set up that way, and will start doing shortcuts -- either for personal advancement, or out of misplaced altruism. End result is liable to be Four Horsemen again -- unless certain ape-traits are permanently removed from human genome.

392:

Which author are you talking about? John Kurman's post to which you replied, does not seem to mention any.

393:

> I don't think anyone is going to completely give up flattops until aircraft stop being useful. They might downsize and get cheaper and more numerous though.

This is thoroughly non-Fermian, and I promise this is the last I'll post about it. However, for those interested in the future-of-the-navy topic, this has just appeared and is relevant:

Maritime Competition in a Mature Precision-Strike Regime
By Andrew F. Krepinevich
April 13, 2015

http://csbaonline.org/publications/2015/04/maritime-competition-in-a-mature-precision-strike-regime/

394:

I suspect he's actually replying to your comment #386, where you mention T J Bass, author of two known novels.

(I always remember Godwhale instead, for some reason. Perhaps because the cover was sensawunda without starships.)

395:

T. J. Bass. (I linked to the wrong comment by fat-fingering.)

396:

We'll agree to disagree. I don't think we can easily get to the P-T level, mostly because (arguing against Peter Ward here), I'm not so sure we can get to the massively anoxic deep ocean that probably preceded the P-T event. Our oceans are configured differently, and even with a warm ocean, it looks like surface water still reaches parts of the abyss off Greenland and Antarctica. In the P-T, the continents were in the Pangaea configuration, and thermohaline circulation seems to have worked (or not worked) very differently.

I'm hoping we manage to hold it at PETM levels, which would be pretty good. If we don't I'd suggest that the Ordovician-Silurian mass extinction might be a better model. IIRC, the O-S consisted of two extinction events. It looks like what happened was basically a monster ice age. Oceans fell massively, killing off a bunch of reef organisms. Then the ice melted, oceans flooded, and wiped out a bunch of shallow water species. The loss of marine species is our major record of the O-S.

If we do the full greenhouse gas release, we may up with a two-tap mass extinction ourselves. The first tap will be now, with global civilization and a 200 year-long heat up (if we go for the full 5000 Gt C release). The second tap will be about 500,000 years from now, when the atmosphere has returned to 20th Century normal, and the next ice age starts. The reason it will be a double extinction event is that all the species adapted to the cryosphere will be wiped out by the great melting, and then a bunch of temperate-zone hothouse species will get wiped out by the rapidly advancing ice. In the end, we'll end up with a reverse O-S with a backflip, or something.*

As I said, I'd be much happier if we can keep our extinction rates to PETM levels or (ideally!) even lower than that. Not that the PETM was an easy time to live in. Animals shrank by 1/4 to 1/3 during that particular event, which says something about the harshness of the PETM climate.

*Note, we may not be the first organism to cause a mass extinction. Some argue that the late Devonian extinction event(s) (it's another multi-peaked mess) were caused by the tree genus Archaeopteris taking over the world, screwing up nutrient cycling, sucking in a lot of CO2, and triggering an ice age. You could even argue that cyanobacteria triggered an extinction "event" by changing the atmosphere to oxygen dominated. The problem with that is that the "Great Oxygenation Event" lasted around 1,750,000,000 years, and in my book, that's not an event.

397:

This isn't on the current topic, but congrats to Charlie for another accurate Halting State prediction

http://www.wired.com/2015/04/app-hides-secret-messages-starcraft-style-games/?mbid=social_fb

398:

I suspect Higgs Bosons are not rare at all, just sightings of them?

Well, the Higgs boson has an energy of 125 GeV, roughly, and decays almost instantly. kT is about 1 eV per 11,000 degrees K. So Higgs bosons become common as the ambient temperature approaches 1.3 quadrillion degrees. The heart of our sun is roughly a factor of 100,000,000 too cold to form Higgs bosons. Basically, except for a period after the Big Bang and, possibly, during the most energetic events in the history of the universe, I would expect Higgs bosons to be essentially nonexistent in nature.

399:

Sigh. No Higgs bosons means elementary particles have no mass. Your conjecture has been falsified by observation.

400:

As far as I can tell, and I'm no expert in these matters, the Higgs boson is implied by the principle of gauge invariance and the observation that bosons have mass. The fact that it can exist is important to particle theory, but no actual quantity of existing Higgs bosons is required for matter to behave as it does.

Having said that, the theory of the Higgs boson involves things like non-zero vacuum expectation values, tachyonic fields with imaginary masses, and a whole bunch of stuff I doubt either of us understands.

If anyone with a background in particle physics understands this better than I do, please speak up.

401:

Oddly enough, many people, even though they're willing to conserve, do without, have fewer kids, and so forth, think that the second option is the only viable path, apparently because they don't expect their neighbors to join them in sacrificing for the common good, because everyone else is evil or something.

"or something"

Most of us trying to live differently are look on as "odd" by most of the population. Even those doing what I think of as doing "recycling lite". They tend to think that tossing cans into a bin will change the ecology of the planet. Nothing else needed. Well maybe recycling newspapers.

402:

The fact that it can exist is important to particle theory, but no actual quantity of existing Higgs bosons is required for matter to behave as it does.

Boggle. So, millions of words to the contrary -- many of them written by very educated, dedicated and competent people -- you don't believe the Higgs boson is what gives elementary particles their mass?

I'm astounded at the number of people posting here who don't know some rather basic stuff, indeed, people who don't seem to have a clue how the scientific method operates. And these are guys who consider themselves smart and well-informed :-(

403:

Two notes on the deep time as a festering hell-hole of dystopian despair.

One is that utopia actually has two antonyms, not one. We're used to the dichotomy of utopia and dystopia, where it's either a perfect heavenly utopia or a hellish dystopia. That's very, erm, Christian.

So let's play the etymological game. Utopia means "nowhere," and it's a pretty good way to describe our global capitalist society. The idea in our culture is that place doesn't matter: you can live in a gated community that looks like 1980s California all over the world, if you're rich enough and have the right connections. Every airport tries to look the same, as does every office complex, and it's all to keep capital moving. You could describe this as an empire of capitalism, because it does fit the definition of an empire (a state that contains multiple nations, that treats the citizens of different nations, classes, etc., differently under the law), although it has no ruler. You could even say that political pushes to break down local laws (say, the tea party in the US), or to over-ride local laws with international treaties (as in the bureaucracies of the US and the EU) are simply the empire of capitalism slowly subduing its client states.

One thing to remember about this hypothetical global empire of capitalism is that it's not much more than a century old, and it seriously broke between 1914 and 1945. The current incarnation is a result of the Bretton Woods conferences. The other thing to remember is that empires that expand fast historically didn't last very long (cf: Alexander, Genghis Khan, the British East India Company, the British Empire), so I wouldn't be surprised if global capitalism shatters at some point in the next few decades.

Now the opposite of this kind of utopian nowhere land isn't a dystopian pit of hellish despair: it's a topia: it's somewhere. It's every place being unique unto itself, local culture mattering more than global culture, every placing being different and celebrating those differences. Yes, it's isolationism and virulent nationalism, so it's far from perfect. On the other hand, cultures are much more sustainable when they're small, when they're about adapting to somewhere, rather than trying to be uniform in a nowhere fashion.

As to how to write about somewhere in deep time, I'd recommend riffing on the old masters, specifically Edgar Rice Burroughs' Barsoom and Robert E Howard's Hyborian Cycle. These days, it's easy to play with the orientalist and imperialist fantasies that imbued Barsoom and Hyboria, and it's also easy to set such stories on a deep future Earth, where the relics of the past are so plentiful that only the historians really care and most people just recycle the rubble into new town walls. Substitute science for magic, and you can have a lot of fun. You can have even more fun if you read up on the barbarians (Scott's The Art of Not Being Governed is great for this) and make the reasonable assumption that barbarians societies are much more sustainable than civilizations are, but that civilization is much sexier and addictive.

404:

Actually, since you can make Higgs bosons by smashing protons into each other inside at least one laboratory on Earth, Nature will be making them with cosmic ray collisions pretty often. I've seen a back-of-the-envelope calculation suggesting that (very, very roughly) about 10 per hour will get made by sufficiently energetic cosmic rays hitting atoms in our atmosphere.

(In general, if you can do in a particle accelerator, Nature's probably doing it all the time with cosmic rays.)

Of course, since they decay really, really fast, you can also make the case that on average the number of currently existing Higgs bosons is zero. Or maybe one, if you integrate across the entire observable universe.

405:

Higgs bosons last about a tenth of a sextillionth of a second. If there were many of them around, it wouldn't be hard to detect their decay products. Frankly, it would be hard not to.

406:

''My $0.02 says that they're over-optimistic on the "drones are
the future" front, like the British defense review of 1957 which
said "the future is guided missiles" and cancelled a shedload of
aircraft projects ...''

Now you're talking a blue streak :-)

I am horribly afraid that they won't, and they will go even
further down the path of killing and destroying if there is
any doubt, and then classifying all the victims as terrorists.
Well, they must have been, or else the drone wouldn't have
targetted them. What do you mean, "They were all under five?"
The terrorists must have been using them as shields.

407:

you don't believe the Higgs boson is what gives elementary particles their mass?

You're confusing the Higgs field -- which according to the theory exists everywhere and gives most particles their mass -- with the Higgs boson, which is the particle associated with excitations of the field, and something that can only appear temporarily if enough energy is concentrated in a small region, and is thus rather rare.

408:

You didn't answer my question. What do you think gives elementary particles their mass if not for the Higgs boson? It seems like you are have some sort of conceptual difficulties here.

409:

I was wondering about that relationship myself. Thanks for the clarification.

410:

ADMINISTRATIVE NOTE:

Unless you can find some way to tie the mass of the Higgs boson directly to the Fermi paradox (without invoking the Strong Anthropic principle or Frank Tipler, thanks) please drop the subject.

411:

Sorry, no, you're making a common mistake. Let me ask you how electric charges interact. Is it via an electromagnetic field, or is it by the exchange of photons? There's a reason why these types of particles are also known as force carriers.

I'm guessing that you're not familiar with the concept of so-called virtual particles.

412:

Here's a nice little explanation from Matt Strassler's blog of the relationship between virtual particles and fields. I urge people like Jay to read this one.

413:

Well, if the average alien contains exactly one Higgs boson on average, and the Higgs boson decays in 1.5E-22 seconds, with an energy of 1.25 GeV, then the average alien experiences about 130 TJ of boson decay per second.

The aliens exploded. Paradox solved.

414:

ballistic missile attacks on ships.

http://en.wikipedia.org/wiki/DF-21#DF-21D_.28CSS-5_Mod-4.29_Anti-ship_ballistic_missile

The DF-21D is certainly a threat, but no-one who knows is talking. As others have pointed out, first you have to find the ships (the USSR had RORSAT for this, and we had high-flying Vulcans in the MRR role).

The risk is that a ballistic missile launch is seen as a possible "strike" - as in, "instant sunshine" :( it's one of the disadvantages of mounting the UK's sub-strategic nuclear weapons on top of a Trident, after we binned WE.177 - one can only guess that any use against a non-nuclear power would be preceded by a lot of phone calls on the hot lines to everyone else with a detection array, for the avoidance of confusion.

Protecting the CVBG against a ballistic strike appears to be a by-product of the US theatre missile defence program (which is limited to protecting against an isolated set of launches, say by North Korea or similar).

I should think it's certainly easier to see a hypersonic target on a ballistic trajectory from a predictable launch site / bearing, than a threat that screams in over the horizon at Mach Lots (courtesy of some X-37 or X-51 development)

415:

I wouldn't expect the ISM to spread the beam (that would require non-isotropic scattering). But, as best I can fathom it, lasers don't produce perfect plane waves (due to diffraction and imperfections in collimation) so the beam will diverge, even in a perfect Minkowskian vacuum. Unfortunately, I can't get a handle on a reasonable value for the spread. The people doing Lunar Laser Range-finding (LLR) attribute their divergence to atmospheric turbulence and diffraction off the reflectors; and their divergences are better than those I'm seeing for off the shelf lasers (which may or may not include atmospheric effects). But they're doing it over, like, 12nPc. It's been done to Mercury, too.

Anyway, as people have pointed out, you want at least a solar system-sized beam to hit another solar system. But a big beam spreads your power and extinction comes into play. Maybe I could suspend my disbelief for communication. But you could put mirrors round the sun and direct all its output to one star (at better efficiency than lasers) and I wouldn't expect it to top up the inhabitant's tan. So I'm not going to worry about aliens wiping us out with lasers till I see the sharks sums.

416:

Per Charlie's request, this will be my last post on Higgs-related topics (since I can't alas, think of any way to relate it to the Fermi Paradox, and only because leaving incorrect statements about physics unanswered bugs me):

From one of Matt Strassler's pages on the Higgs field:

Notice, by the way, that the Higgs particle has nothing to do with this. A Higgs particle is a quantum of the Higgs field — a ripple of minimum energy in H(x,t), a little wave that depends on space and time. What gives mass to the other known particles of nature is the non-zero equilibrium constant value for the Higgs field, H(x,t) = H0, all across the universe; this timeless and universally present constant is very different from Higgs particles, which are ripples that vary over space and time, and are both localized and ephemeral.

I suggest you read the page by Strassler that you linked to, and pay attention to the distinction he makes between virtual particles ("not like a particle at all, and I wish we didn’t call it that") and real particles.

417:

This will be my last comment as well. I suggest that you read this. Again. Carefully.

418:

A minor problem for prospective griefer factions: what do you do about stars (and thus potential locations for alien civilizations) in other galaxies?

You'd think the answer would be "leave them alone because they can't bother you", but the problem is that smaller satellite galaxies will tend to merge with the Milky Way over time (some have already done so,[1] some are currently doing so, and some will do so within the next billion years or so). Plus, sometime in the next three or four billion years we're probably going to merge with the Andromeda galaxy.

If you're really paranoid, you'd worry about competing civilizations managing to develop to who-knows-what levels of sophistication during the billions of years they're on their own.

So they might want to think about trying to infect neighboring galaxies, even though this would seem to be a lot harder (instead of sending your von Neumann probes to a star a few parsecs away, they need to survive much longer journeys -- the Large Magellanic Cloud, for example, is 50,0000 parsecs away).


[1] The globular cluster Omega Centauri is often thought to be the remnant core of an accreted satellite galaxy.

Kapteyn's Star, a mere 13 light years away (and only 7 light years away 11,000 years ago), has motions suggesting it might have originally been part of Omega Centauri's parent galaxy. It also has evidence for two super-Earth planets, one plausibly in the habitable zone...
(Alastair Reynolds wrote a very short story, "Sad Kapteyn", inspired by the latter discovery.)

419:

A 200 year long heatup. 200 years ago it was 1815. The human race was just starting to harness steam. The British were invading New Orleans

200 years from now will be 2215. Civilization at that time will be far beyond our current abilities. In all that time we won't have figure out how to remove the co2 we put in the atmosphere or mitigate the effects of it? the whole human race just sits around doe eyed I imagine waiting for the end i guess. Technological progress immediately grinds to a halt....

its entirely possible we may wreck our ecosystem at some point but it's not going to come from some slow burn like Global Warming. The things that we need to be afraid of are things that move fast.

420:

To clarify, there's a lag between when we release green house gases and when we experience peak heat. Right now, IIRC we're experiencing the greenhouse effects of gases released in the 1970s.

If we go for a full 5,000 GtC release (which is basically blowing all our fossil fuels and a good chunk of methane from the permafrost), it takes 200 years after the release is over to experience the full warming of 8-12oC. In the IPCC 5 scenario, this release finishes around 2100 CE, so we're talking peak heat around 2300 CE.

The problem with this is that by the time we hit peak heat, we'll be 200 years past when we had any usable fossil fuels to do large projects like pulling the CO2 out of the air. Presumably we'll have also burned through our supply of radioactive fuels as well, since it's about 10% of our "legacy fuels" supply (legacy=petroleum, coal, and radioactives).

Absent a miraculous technology like, oh, fusion, we've got the problem that it takes a lot of energy and infrastructure to sequester CO2 back underground. Vaclav Smil estimates that we'd have to move about 70% more CO2 by weight than we do oil right now, just to keep atmospheric CO2 from rising above 450 ppm (reference). And, unlike oil, which has a positive market value, CO2 sequestered underground has a negative market value--someone's got to pay to sequester it. If his calculations are correct (and they're generally pretty good), we'd have to a) build an infrastructural system larger than the present-day oil infrastructure, and b) do it within 20 years, and c) pay for it all with tax dollars, if we wanted to keep CO2 levels below the 2oC increase that is the consensus tipping point for bad things happening.

Note again, there's a lag: according to some climate scientists, we could hit +2oC by 2036 (this is due to some weirdness with the Pacific Decadal Oscillation, which partially controls where the energy trapped by greenhouse gases ends up). If we hit +2oC in 2036, we're in for a wild ride (I think John Kerry called it the end of civilization, but you know how politicians exaggerate). The problem is, even if the oil and coal stop flowing in 2036 or before, the Earth will keep heating up for at least 50 years and probably more like 100 years before temperatures level out. If we just keep blowing greenhouse gases as we cope with the inevitable emergencies, and especially if methane clathrates in polar regions start outgassing on a large scale, we could keep adding greenhouse gases until around 2100, keep heating up the atmosphere for another 200 years after that, and then take up to 400,000 years for atmospheric carbon concentrations to return to normal.

Hope this helps explain the scale of the problem a bit better.

421:

200 years from now will be 2215. Civilization at that time will be far beyond our current abilities. In all that time we won't have figure out how to remove the co2 we put in the atmosphere or mitigate the effects of it? the whole human race just sits around doe eyed I imagine waiting for the end i guess. Technological progress immediately grinds to a halt....

Civilization may be far more advanced than what we enjoy today, but will it advance in those directions that make interstellar travel easier? Advanced medicine, sure, I'll give you that, possibly even a life span measured in thousands of years. But how about practical fusion? I can see the visionaries of the day saying it's only twenty years in the future . . .

For that matter on how many worlds across how many millennia have technophiles been saying fusion is coming Real Soon Now? As I've said many times before, you can use the lack of aliens here on Earth to argue for a rough technological plateau that's more or less a universal. And that plateau -- insofar as interstellar travel is concerned -- is rather low. In fact, we're very close to the top right now.

422:

BTW, interstellar travel being hard for folks who are put together like us is not necessarily a bad thing. Look at our history of brutal exploitation. Look at how our species behaves towards our technological inferiors in classic sf (Hint: Imperialism and Colonialism have traditionally been very positively portrayed.) Given our Johnny-come-lately status on the galactic stage, I have no doubt that we'd be suffering under the alien lash if they're anything close to like us.

423:

The problem of interstellar travel reduces to the problem of whether or not it's possible to have a long scale technological civilization inside the home solar system

If the above is possible then you either believe in a technological plateau or you don't

Currently there is zero evidence for a technological plateau, but it is still possible. The "where is my flying car / fusion reactor" is a good argument of humanities poor ability to predict the if and when of a particular technological advance but doesn't say anything about the general trends.

If you believe in the plateau then you are arguing for Hetromeles vision of a static , in harmony with the ecosystem world. Even under that scenrio it's still pretty likely that at some point in its relatively long lifespan something like robotic probes or even generation ships will happen

Without a plateau you are buying into my future view where the difficult problems of today (how to string transatlantic telegraph cables say) become trivial or irrelevant in 50 years. it's almost inevitable that something gets to the next star then

So really the main fG is if technological civilizations are sustainable or not

424:

What other fGF scenarios can you think of that don't require magical technology or unknown physics and that could effectively sterilize a galaxy, starting from a one-time trigger event?


TIME. YOU'RE NOT GOOD AT IT.


You can sing a Star to death.


http://www.matteocantiello.com/old/articles/liege1.pdf
http://arxiv.org/pdf/0903.2049.pdf
https://en.wikipedia.org/wiki/Electron-degenerate_matter
https://en.wikipedia.org/wiki/Pauli_exclusion_principle
https://en.wikipedia.org/wiki/Chandrasekhar_limit


You can introduce a fermion on an identical wave pattern: it causes the Star to move towards a state that's guaranteed to kill off all life in the system.

425:

Moving away from particle physics, if there were an outpost of a foreign civilisation; waiting and watching developments on Earth; how could you detect it?

We've already covered that having a sensor/effector pair close at hand is a good move (from an OODA loop perspective) and keeping on the down low is also a good idea. So where would you hide?

  • On Earth invites detection, though gives you easy access to information and the ability to act.
  • In orbit is if anything easier to spot, but gives a more global view and ability to act.
  • On the moon gives you a gravity well to climb out of, but some clutter to hide in.
  • Elsewhere in the solar system gives you better ability to avoid detection, you can still receive radio comms, and you can move if you need to act.

So assuming our interstellar capable civilisation can deliver passable AI, have devices lasting millennia, and can understand our technology and biology - how do you arrange your system to monitor humanity and retain the ability to act to sterilise a dangerous infection?

And how would we be able to scan and find them there ourselves, given them trying to hide?

426:

Currently there is zero evidence for a technological plateau

What do you think a technological plateau is, and what would you count as evidence for it? I'm curious. Seriously. Because you seem to think that, for example, there's such a thing as arenak.

427:

"a metastable deep time human civilization that isn't a festering hell-hole of dystopian despair?"

It's been done.

It's called "Brave New World".

Soma makes everything better.

428:

First, sorry bout the derail, though it amused me when you caught yourself derailing your own thread, and I'm totally down for a "upbeat deep time" story.

Second, you threw down a gaunlet! Confirmation of the mass of the Higgs leaves room for various expanded standard models like supersymmetry and such which are compatible with said findings. During the process of investigating the new physics in this regime a critical interstellar enabling discovery can be made (let's steal Baxter's MacGuffin from The Quagma Datum and propose that there is a higher dimension supersymmetric extension to the standard model which we'll end up discovering after following cues in the properties of the Higgs we found) and this Susy Drive is now A Thing We Can Work On.

The implications start out exciting and lead to a flurry of newer and larger accelerators, but of course fleshing out the final parts of this technology involves probing the higher energy regimes needed to get the critical data so you can do the particle-sparticle-particle_somewhere_else translation reliably. In many cases we're talking megaprojects extending across large chunks of interplanetary space for these accelerators, which would mean you would have a certain type of signature which could be detected by curious neighbors and a large "yes this is what you think it is" sign pointing at us.

Cue the Griefers.

For the record I had no idea who Fisher was, if anything I'd be of the "contrast alternative hypothetical models" school of thought, though the idea of searching an entire phase space in a particle physics experiment for every possible iteration of whatever is wild.

Back to our originally scheduled discussion.

429:

It's helpful to think of technology as having two dimensions, complexity and available energy. In terms of the complexity that we can achieve in our technology, there's no sign of a limit. In terms of the energy inputs available to us, there are strong signs that there are limits, and we're near them.

430:

Vance's Dying Earth comes to mind as well.

431:

Absent a miraculous technology like, oh, fusion
Err ... it can be done - we know it can be done, so not miraculous at all.
As for "affordable & readily controllable" &/or "net energy output" that's a n other story, but still not "miraculous.
Which reminds me.
Any news on Lockheed/Skunk-Works "Sunshine-in-a-box" project, or has it gorn 'orribly quiet?

432:

There is no technological plateau. We don't have fusion or flying cars because collectively we put our money into making things smaller and faster instead of bigger. If people ***REALLY*** wanted flying cars, we would have them. But the price is too high and they cannot deliver the illusory benefits over what currently exists.
As for energy, there is not going to be an energy impoverished future, if only because solar PV is heading towards zero cost on a very short timescale ie a couple of decades.

433:

As I've said many times before, you can use the lack of aliens here on Earth to argue for a rough technological plateau that's more or less a universal. And that plateau -- insofar as interstellar travel is concerned -- is rather low. In fact, we're very close to the top right now.

We don't know enough science yet to predict what's possible.

Consider -- in 1890 or so, we knew most of the physics there was to know. With Maxwell's equations etc we had a complete understanding of electromagnetic radiation. With Mendelayev's atomic tables we knew the elements, and people were coming around to the idea that matter was made of atoms. It looked like there was hardly anything else to learn, just polish up some details.

But it turned out they didn't in fact know it all.

What's the likelihood that we know it all this time around? No way to really tell, it's only the second time we thought we did. It's true that the Standard Model appears to explain everything in the entire universe, with no room for anything new, but it's possible there are unexplained details we haven't noticed yet.

Similarly with technology. It might turn out that it just is not practical to build a tiny star. Fusion on the scale of a power plant might be impractical for the next thousand years, and just forget one you can hold in your hand. Maybe even if the engineering works out, we might figure out that enterprises on that scale are counterproductive, that it's bad for us to have corporations or bureaucracies large enough to do it.

But fusion is only the idea we've been thinking about since the 1950's, because we *wanted* it to work. Something new might turn up.

Of course, it doesn't make sense to use the fact that we don't really know what the limits are, to depend on there not being any limits.

So like Unholyguy's #419 guess that 200 years will give us such knowledge that we can easily clean up our mess. It's possible. But....

"Believe in miracles? I *depend* on them!"

434:

So where would you hide?

Obviously, hide among the asteroids. Anywhere closer and we could detect them.

And if they ever decided to do something about us, they could just activate one of those thousands of giant meteor things whose orbits cross ours that are always about to hit us, and....

Oh, wait.

435:

There is one major area of theoretical and experimental work that might yield significant new physics, and that is quantum decoherence at macroscopic scales.

436:

Absent a miraculous technology like, oh, fusion, we've got the problem that it takes a lot of energy and infrastructure to sequester CO2 back underground. Vaclav Smil estimates that we'd have to move about 70% more CO2 by weight than we do oil right now, just to keep atmospheric CO2 from rising above 450 ppm (reference). And, unlike oil, which has a positive market value, CO2 sequestered underground has a negative market value--someone's got to pay to sequester it.

That's why it's such a stupid idea to sequester CO2.
CO2 has (12 + 2*16)/12 * 100 = 366% more weight than the equivalent of charcoal. Since generation of charcoal is exothermic it might even be possible to sequester charcoal without spending net energy.

437:

"Unless you can find some way to tie the mass of the Higgs boson
directly to the Fermi paradox (without invoking the Strong
Anthropic principle or Frank Tipler, thanks) please drop the
subject."

I didn't realise that he had gone the way of Penrose. That's sad.
This triggered my memory, and I can provide a common explanation
of the Fermi paradox, Higgs boson and Frank Tipler, but it falls
foul of the "unknown physics" rule, and would assuredly inflame
several of the already overheated posters. It was a thought
experiment of mine some 40 years back, but I was amused to see it
mentioned as an extreme speculation by a respectable scientist a
decade or so ago. Sorry - I can't remember who or where.

Please tell me if you would like me to post it or send it by
Email. Otherwise, I won't pour oil on burning waters ....

438:

Hello Charlie,

I loved this post, thank you, it was great reading. Also enjoyed reading all the contributions (took some time, but always worth it, thank you everyone, time well spent).

I note that the majority of GF hypotheses were either technological (soft landing singularity), or else sociological (cue Wayne and Garth 'We're not worthy! We're not worthy!').

May I propose another filter : The biological.

At the moment, we are a species of 2 Billion on a fairly gentle planet, admittedly a little dirty in geosphere habits, still animal in nature, and generally at an evolutionary standstill in terms of development - certainly I'm a heck of a lot taller than my great granfather, but maybe thats thanks to the monocult