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Sad Trombone Exoplanet Reality Check

Some people on the internet are getting very excited at the (unconfirmed) reports of an "Earth-like" exoplanet orbiting Proxima Centauri, a mere 4.25 light-years away from Earth. If correct, the planet is orbiting in the liquid water zone around our nearest stellar neighbour and is of the same order of mass as the Earth. (Note that this could mean anything from Mercury to Neptune in scale: it's very approximate at this stage. Earth-like in exoplanetography does not mean it's a habitable new eden suitable for colonization, it just means "not a gas giant like Jupiter or a tiny dwarf like Pluto".)

So here's a reality check.

The report allegedly comes, not from the Kepler planet-finder space telescope, but the La Silla Observatory. It hasn't been confirmed yet and ESO aren't commenting. If confirmed it'll be big news for exoplanetography, but there's a huge caveat attached to it which you can bet your bottom dollar the regular news media will miss completely in the aforementioned excitement:

4.25 light years is roughly 40 trillion kilometers (or 25 trillion miles, if you're American).

I don't want to minimize the significance of the discovery; it's certainly a good addition to the list of potentially habitable exoplanets here, but you will note that 4.25 light years isn't an order-of-magnitude improvement over the previous winners for Earthlike proximity, such as Wolf 1061c (13.8 light years away) or Kapteyn B* (12.76 light years away). We're talking about the difference between 40 arbitrarily-huge-units and 100 arbitrarily-huge-units. So how should we contextualize these arbitrarily-huge-units?

Currently, the most distant visited body in the solar system is Pluto, at 7.5 billion kilometers. The New Horizons probe flew past Pluto on July 14, 2015. It was launched on January 19th 2006 by a booster and upper stage combination that blasted it straight up to solar escape velocity, with a speed of 16.26 km/sec (58,536 km/h), making it the fastest human-made vehicle ever: it then executed a Jupiter gravity-assist flyby to slingshot it out past Pluto, where it arrived nine and a half years after departure.

This veritable speed racer of an interplanetary probe would thus require a mere 31,600 years to reach Proxima Centauri (if indeed it was pointed in the right direction, which it isn't).

Yes, but what if we sent a probe using (wave hands) some vastly better propulsion system that exists only as a series of paper studies, you may ask? For example, use an M2P2 plasma sail to hitch a ride on the solar wind? Well, that might reach the dizzy speed of 500km/s, in which case it might actually get to Proxima Centauri in less than a thousand years (just). This seems, from my reading, to be the best we can hope for in the near future—nuclear-thermal rockets don't offer anything like as much of a performance boost over chemical rockets as one might naively think, and it's kind of dumb to postulate a spacegoing fusion reactor until we can get one to work on Earth (and figure out what to do with the gigawatts of waste heat it'd be spewing out when mounted on a spacecraft in vacuum, which as you know is a rather good insulator).

What if we leave the engine back home? Put an M2P2 sail on a probe, but instead of relying on the solar wind, point a plasma beam at it in order to maintain thrust throughout the voyage (this is called a MagBeam propulsion system)? Now we're talking ... but such a beam generator is going to have to be constructed and operated in space (down here there's too much atmosphere in the way), and it's going to take a lot of power to generate significant thrust, much less to ensure enough of the plasma beam reaches the probe to continue generating thrust once the probe is significantly far away from home. NB: when I say lots of power, I'm talking of the same ball-park as the entire electricity production of the USA to keep pushing a probe of the same sort of size as New Horizons for a few years.

We might get a small probe up to arbitrarily high velocities if we cheat by using an engine that stays back home where we can keep it running, but then we run into other problems. Space is not empty and vacuum is not perfect. There are gas molecules (mostly neutral hydrogen) sitting around in deep space; on the order of 102 to 106 atoms per cm3. This is vastly more tenuous than the best vacuum we can produce on Earth, but it's still going to be intensely damaging to any spacecraft we can design that would have to traverse it at speed. Roughly 1% of the ISM consists of helium atoms, and we have a technical term for an ionized helium nucleus travelling at roughly 2% of the speed of light—6000km/sec—we call it an alpha particle. At a notional 6000km/sec interstellar cruise speed (2% of lightspeed), a space probe is going to encounter up to 10,000 alpha particles per centimeter of distance travelled, or 6 trillion alpha particles per square meter of frontal area per second. That's 6 TBq of radiation; or in old money, 160-odd Curies. To get a feel for what this means, note that the Fukushima Daiichi reactor meltdowns released about 100 million Curies, so the front of our one-meter-square-frontal-area probe would receive that amount of irradiation every eight days from alpha particles alone (the situation is undoubtedly worse when you factor in proton and gamma radiation bombardment). It might be better by 2-3 orders of magnitude if I've over-estimated the density of helium atoms in the stellar vicinity ... but then you can simply change the bottom line from 3 nuclear reactor meltdowns per week per square meter to 3 nuclear reactor meltdowns per year per square meter.

It still doesn't make much difference: at 2% of lightspeed, Proxima Centauri is 212 years away.

Anyway, the point I'd like you to take away from this is that while it's really hard to say "sending an interstellar probe is absolutely impossible", the smart money says that it's extremely difficult to do it using any technology currently existing or in development. We'd need a whole raft of breathroughs, including radiation shielding techniques to kick the interstellar medium out of the way of the probe as well as some sort of beam propulsion system and then some way of getting data back home across interstellar distances ... and that's for a flyby mission like New Horizons that would take not significantly less than a human lifetime to get there.

495 Comments

1:

A useful reality check indeed. It'd be interesting if we could get some idea of the planet's atmospheric composition, even if we'll never get to see it up close.

Incidentally, should the title be "Sad Trombone" rather than "San Trombone"? I'd like to think that San Trombone is a small town in Mexico where they perfected mariachi music.

2:

The proximity, however, offers the possibility of looking at another planet "now", versus, "a long time ago". This is exciting.

And the closer it is, the more feasible a very large observatory is. Communication would be in the realm of the not impossible.

But yes, of course, we are never going there.

3:

On the other hand, a very close exoplanet is a good motivation to build a huge-ass space telescope.

4:

Interesting that we find it much easier to imagine humanity inventing a way to warp space and time than to imagine humanity learning some God-damned patience.

5:

Why have patience when you can have suspended animation? Still sci-fi, but at least it doesn't demand new physics, unlike warp engines.

6:

Some minor comments on the original "report":

The report allegedly comes, not from the Kepler planet-finder space telescope, but the La Silla Observatory ...

I'm not sure why you're mentioning Kepler in this context; the fact that the discovery supposedly comes from observations at La Silla is a minor point in its favor, since most of the well-established exoplanet discoveries prior to the launch of Kepler were made either at La Silla or at Lick Observatory (in the US). Those observations are spectroscopic observations measuring the radial-velocity variations in the starlight due to the reflex motion of the star as the planet orbits it; they're still considered the gold standard for explanet detection. (There's still some tendency to call Kepler detections "candidate planets" until they're confirmed by ground-based spectroscopic observations.)

No one associated with La Silla (which wouldn't be the source of a press release anyway), its parent organization (the European Southern Observatory, which would), or the actual scientists involved (most of whom are probably not affiliated with ESO) has said boo. All we actually have is an article in Der Spiegel which claims an anonymous scientist source. The Der Spiegel article does claim that ESO will make an announcement at the end of August, for what that's worth.

I've seen speculation that this may well be a result from the "Pale Red Dot" group, who have been targeting Proxima Centauri with the La Silla Observatory, with observations that finished at the beginning of April and a paper apparently partway through the peer-review process as of July:
https://palereddot.org/peer-review-or-how-an-experiment-becomes-scientific-literature/

7:

Radically new biology and even biochemistry for an existing species isn't likely to arrive any sooner than new physics. As far as I know, being able to survive freezing to near absolute zero and thawing (the only plausible technology) is limited to single-celled organisms and some plant material.

8:

I did a calculation a while back, and it was only slightly beyond the state of our current technology - I was considering one (effectively) a kilometre in diameter at optical frequencies. A Manhattan or Apollo scale project, to be sure, but probably no worse.

9:

Incidentally, should the title be "Sad Trombone" rather than "San Trombone"

Dammit ...

10:

I'm afraid you're really overestimating the alpha-particle radiation budget for a hypothetical trip to Proxima Centauri. The problem is that the density of the interstellar medium varies a lot, and it's actually fairly tenuous in the vicinity of the Sun.

There are gas molecules (mostly neutral hydrogen) sitting around in deep space; on the order of 102 to 106 atoms per cm3 ...

That density range is typical for molecular clouds. The average density in the interstellar medium is closer to 0.5 atoms per cm3, and the local medium around the Sun (the "Local Cloud") is more like 0.3 atoms per cm3. If you want to travel to Proxima Centauri, then you're heading in the direction of (possibly into) the "G Cloud", which has a similar density.

http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html


... a space probe is going to encounter up to ... 6 trillion alpha particles per square meter of frontal area per second.

Since you've overestimated the local density of helium atoms by between six and seven orders of magnitude (not "2-3"), it's more like one or two million alpha particles per square meter per second. Which (assuming the radiation conversions are accurate) works out to a Fukushima meltdown not every eight days, but every fifty to one hundred thousand years.

11:

So, assuming that for some reason the political will is there to send a probe that will take 3000 years to arrive, what would be the problems with a slow trip out there? What could be used as a power supply for instance? How badly would solar panels, or other circuitry decompose in a vacuum?

How would we make sure that the ground station could still talk to the probe after 3,000 years, I'm guessing that coding languages would have changed in that time.

Right, I'm off to read up on Long Now things.

12:

That's good to know; but the radiation dose per square meter of frontal area is still measured in Curies per hour (my brain is still halfway hard-wired for old units). That's probably survivable by instrumentation, with good design and serious rad-hardening. Still not looking good for humans (or any biological tissue, come to think of it).

If you put enough D. radiodurans on board, some of the spores might survive the trip.

13:

Even if we can accelerate enough to get us there quickly "enough", dat slowing down...

14:

Thanks for this post. Couple of comments:

1. Alpha parties aren't penetrating, and are easy to shield. Aluminum foil will do it.

2. We can probably go faster. Project Orion was thought to be capable of 10% of light speed, back in the '50s. Stephen Hawking's "Breakthrough Starshot" concept of wafer-size space probes propelled by gigawatt laser arrays is claimed to do 0.2c.

15:

Alpha particles aren't penetrating: flip side, they dump all their energy in the top couple of millimetres of the shield, which gets hot. This is not good.

(Nor are alpha particles the only problem you've got to worry about.)

Project Orion is going to have fun getting launch permission with all those fuel rounds which are functionally indistinguishable from a Casaba-Howitzer shaped nuclear charge.

As for the Starshot thing, that sounds like a reboot of Robert Forward's Starwhisp idea from the 1990s. The real problem with that is, how to get any data back from it. (Not to mention how to construct a continuously operating gigawatt laser array in space).

16:

Alpha particles are not especially scary as far as radiation goes: they are stopped by pretty much any shielding (including a sheet of paper according to Wikipedia). So not much risk from this.
And the amount of kinetic energy they would impart to the probe also appear tiny:
Quick estimation: 0.5 (number of atoms) * 1/2 * 7*10^-27 (mass of the helium atom) * (2%*300 000 000)^2 => approximately 6*10^-14 W/cm

Much scarier is dust: at these speeds, even a grain of dust of a tenth of a gram would cause havoc (1.8*10^9 J if I did no mistake in the calculation, i.e. more than the average lightning bolt). Not sure we can pack enough armour on a probe to survive this.

There is also the small problem of dissipating the heat that would inevitably be picked up from the beam.
In conclusion, I agree if we want to go there we will have to learn patience, and take a few centuries at least.

17:

Suspended animation would be a form of youthinasia. When the spaceship arrives at it's destination the suspended people probably won't have one single strand of DNA that is still intact. Yes, yes, you can use shielding but accelerating tons of stuff to a percentage of C will be VERY expensive if it ever happens so intelligence to other stars needs to be as rad hard as you can get.

Alastair Reynolds wrote a short story that is more likely to happen than living meat to the stars.

18:

Yuri Milner's thing is not driven by a continuous laser, it's meant to be a ground based laser array that pulses once per day driving the fleet of nano-ships. They don't seem to have a plan as to how to get the data back yet.

http://www.scientificamerican.com/article/100-million-plan-will-send-probes-to-the-nearest-star1/

19:

Who said anything about accelerating to percentages of C? Suspended animation is for a leisurely 10,000 years journey.

20:

(Not to mention how to construct a continuously operating gigawatt laser array in space)

Not to mention the political implications of having built a continuous gigawatt laser array in space.

21:

No new biology or biochemistry is required and it's not limited to single cells. 100's of thousands of humans at a size of 200-300 cells are frozen and thawed every year. Over 40 000 a year in Europe alone. So far it's been tested out to 16 years of storage with no ill effects. It doesn't even need 'near' absolute zero. Liquid N2 temperatures are fine which are absurdly easy to achieve in deep space.

It does however limit crew selection to people under the age of about a week or 10 days after fertilisation.

22:

ADMINISTRATIVE NOTE

Consider this blog comment thread to be a new chew-toy/distraction; I'm not going to be around here much because I'm still up to my elbows in Laundry Files novel. Play nice and have fun!

23:

Yes, and fetus ship will require an artificial womb (hard) and a human-level AI to educate the children (REALLY FUCKING HARD).

Also, if you have a human-level AI, you don't need fetuses anymore, because you can fabricate people out of stronger stuff. See also: Saturn's Children. :-)

The funny thing is, all this has been thoroughly discussed on this very blog at least five time (probably closer to fifty time). We need some kind of side-bar with all the arguments and counter-arguments, it will save time...

24:

If this planet holds up and is actually Earth-size (i.e. less than 1.2 times Earth radius and 2-3 times its mass), then I'm really hoping we can eventually do analysis on its atmosphere.

Finding an earth-like planet with a habitable atmosphere indicative of life around a star like Proxima would be huge even beyond the whole "Wow we found an earth-like planet!" situation, because Proxima otherwise seems like it would be very unpromising for life. It's tiny (an M5V or M6V star that's only 40% greater in radius than Jupiter), it's habitable zone creates orbits of mere handful of days, it's prone to great changes in luminosity due to flaring and sunspots, it would have had a long extended pre-main sequence period of greater luminosity, etc.

@Xylem

Who said anything about accelerating to percentages of C? Suspended animation is for a leisurely 10,000 years journey.

Can you guarantee your spaceship's reliability over a time period greater than the time in which human civilization has existed?

There's a death spiral in there for slow ships. If you're going too slow, then you need to effectively be able to rebuild your entire ship over time to replace the damaged parts (all while relying solely on nuclear power for your energy supplies). But that in turn increases the mass of your ship, making it more costly to accelerate and all other things being equal leading to a slower trip. Which in turn increases the reliability issue . . .

25:

Agreed on all points.

26:

I realize we're not going to go there anytime soon (soon measured within this century). Further, I realize that trusting anonymous sources tends to be risky.

The importance of a possible Proxima Centauri Planet (PCP) are the following:

a. It is another "close" planet orbiting a red dwarf star. Currently, what we know about planets orbiting red dwarf stars is inferred from computer models. PCP is close enough that we can get very low-resolution measurements against which we can test our models. Testing and refining these models is very important

b. It is a close target against which we can test new technologies. We can already photographed whole planets. I don't know how much this proximity would increase resolution. The same holds true for studying a potential atmosphere

c. There was talk of using the same method previously used to confirm Europa's ocean being used to study planetary geology. Assuming it is a rock world, this planet is close enough and the star is small enough that we might begin using it to study geology? I wonder if present methods can infer the presence of plate tectonics?

d. Its existence is really cool and might confirm a cliche

27:

for a fun mental exercise, lets assume we have a 'warp drive' ship capable of 10% of lightspeed, using fusion power and a reactionless drive. the way science is now, that sound not too improbable from current theory. 42.5 years to get somewhere is basically a one-way trip, so the ship needs to be self-sustaining, and able to build a colony on an airless moon or asteroid when it gets there. the crew will be to the second generation at that point, with the original scientists teaching their kids what they know. so start with young PhD scientists (26?) and add travel, their in their 70s by the time they get there. if we assume they have kids at age 30, the second generation is about 40, and the 3rd generation is about 10. lets assume each woman has a son and 2 daughters- our gen3 population is 10x our starting population, roughly. the ship has to be designed for a least that much population growth with crew quarters, life support (air, food, water, sewage), and unexpected stupidity (you have at least 2 generations of children on a starship).

if you could get there that fast, then a one-way trip to make a colony would be a viable endeavor, if a very expensive one that would not see any payout for a long time. you can fit enough genetic diversity on the ship out with a stockpile of well-shielded genetic material, and an initial crew of mostly women who want kids. the only thing the colony can send home is information, so this is in effect the worlds most expensive reality TV show/R&D project ever. they get the news a few years late, and conversations take 8.5 years to answer one question.

I cannot imagine the US backing this sort of project, as the local philosophy is about short-term gain and screw next quarter as long as i get my bonus this quarter. The EU seems plausible, but i dont think they would push for it. China however, i could easily see them backing the idea if they had the science to do it, just to win a space race for a new planet. so lets assume its a starship full of Chinese PhDs who really want more than one kid. they will need gravity, either from thrust or from spin. the ship would have to be very big to fit spin into the warp drive donuts, but we already knew it had to be a BIG ship.

if this were a novel, i would expect it to be about the 20-something 2nd generation as a massive equipment failure takes place. because with China's culture of cheating, groupthink, and everything that can go wrong about 20 years into a 40+year mission, that seems like the most thematic time to have everything go very very wrong in a dramatic way. but at the same time, solutions that in-system ships found for more common problems from 2 years ago would also be available, and probably archived in the ships database, so we need at least 1 new/uncommon problem.

28:

Much scarier is dust: at these speeds, even a grain of dust of a tenth of a gram would cause havoc (1.8*10^9 J if I did no mistake in the calculation, i.e. more than the average lightning bolt). Not sure we can pack enough armour on a probe to survive this.

Note, however, that "a tenth of a gram" is insanely large by interstellar dust standards. A more typical mass for an interstellar dust grain would be less than (probably much less than) 10-12 grams. (Source: this paper, based on Ulysses and Galileo observations, which, as the authors note, underestimate the number of small grains.)

29:

Well in that case you build people that last 10,000+ years, give your city a push and off you go. No need to suspend anything.

30:

Yes, biological immortality is an alternative to suspended animation. Which one is easier remains to be seen.

However, if you can live in space for 10,000 years, then why do you need a new planet, anyway?

31:

Heteromeles would be the one to answer that, he argued it strongly on his page. Myself, I think it'd take an exceptional individual to leave a functioning off-planet habitat for the unknowns of a planetary surface, even if recordings of distant ancestors urged it.

32:

I was tempted to let it slide ...

33:

However, if you can live in space for 10,000 years, then why do you need a new planet, anyway?

The beings that may eventually travel between stars will have evolved/been engineered for those conditions. They may not see a planet as something one wants to visit. They'll be looking for comets and asteroids for materials to sustain themselves. No need to go into those gravity wells, there's nothing there but weird critters and annoying gravity.

34:

These kinds of problems are why I generally favor a version of generation ship adapted to live off of wandering planets, etc., with slow speed and no real destination. It needs to be large enough to be a nearly complete civilization, but with enough automation that might be no larger than London or San Francisco. That's not really enough, but lasers make fine communication links if you don't mind the lag.

You use advanced ion jet engines for propulsion, and don't mind that they aren't putting out much force, because they can run off rocks, and they don't eat much energy. That said, this would probably require fusion reactors rather than just fission, if only for accessible fuel. You need to go just a bit faster than the local drift, so you can move from planet to planet easily, but not go by them too fast to conveniently mine them. Every once in awhile, when you get to a good spot, you let the population increase while you build a new ship (or two), and each group goes their separate way.

N.B.: You still need lots of radiation shielding, impact shielding, etc., but since your speed is low you don't need nearly as much.

P.S.: This plan assumes that wandering planets are considerably more common than red dwarfs, and that wandering planetesimals are more common yet in a continuation of the frequency pattern where larger stars are rarer than smaller stars. This isn't the normal belief, but it's my belief that this is just because small, non-luminous, bodies are hard to observe.

35:

Yes, this: however, there are certain remaining problems. Building a biosphere that is long-term stable (with human-assisted nudges) in the double- or triple-digit kiloyear time frame may be the easy bit (for some insane value of "easy"); at least we have an existence proof of a homeostatic persistent biosphere, namely Earth's for the past couple of million years: it's not perfect but it takes a lot of mismanagement to break it. We'd also need to re-tool humanity a bit, to survive the higher radiation environment and possibly microgravity, vacuum exposure, and other issues: longevity and reduced aggression would be good traits to mix in while we're at it.

Harder would be the social engineering problem, if only because we're lousy at building institutions that can outlive ourselves and building a society capable of managing to persist in the very long term (yadda-kiloyears, again) without breaking shit and messing up would be hard. Might be better to look to have a whole bunch of social arrangements as strange attractors, so that when the denizens get bored with republicanism they can switch to a monarchy for a bit without too much damage. The key thing is to avoid social structures that posit unlimited physical resource growth (e.g. commodity capitalism) or exploitative local minima (encouraging short-term rent-seeking behaviour). But really, how do we design societies when the only way to field-test them is to use an even longer-lived society as a control group? It's a poser!

36:

Might be better to look to have a whole bunch of social arrangements as strange attractors, so that when the denizens get bored with republicanism they can switch to a monarchy for a bit without too much damage.

We could have separate biospheres, each with a completely different culture!

Just watch out for "space senility".

37:

Personally I'd just be ecstatic if, within my life time, a seriously large telescope array was built in orbit of the sun. The mind of thing that, after enough time, could give you a crude Google exoplanet. Combine that with some sophisticated studies and VR 3.0 and we all get to be a real life Captain Kirk from the comfort of our bedrooms.

38:


I take it that Niven & Pournelle's Crazy Eddie Probe really is a bust, then.

The bottom line is that nothing with a human lifespan, and nothing with a mission-critical information system as fragile as DNA, is ever going to cross the interstellar distances.

That's not the same as 'nothing, ever', but it's either the posthuman Neptune's Brood universe, or utterly inhuman constructs like Clarke's Rama probe.


39:

I will note that "Mote in Gods Eye" had a magic wormhole drive and a whacky force field that could double as a fusion reactor containment. And the Moties had super-science mojo even compared to that -- pure hydrogen fusion reactors, for example. That laser-accelerated light sail didn't have a dust/gas problem with the interstellar medium because the laser was powerful enough to burn a clear path through it across several light-years. (Somehow I don't think we're going to get there any time this century ...)

40:

> As far as I know, being able to survive freezing to near absolute zero and thawing (the only plausible technology) is limited to single-celled organisms and some plant material.

The arctic wooly bear caterpillar freezes solid every year, thawing the following summer to continue feeding. It takes 14 years for it to eat enough to finish up with metamorphosis. True, not "near absolute zero", but I wonder if anyone has tried taking one of the frozen ones and deep-freezing it in liquid helium, then bringing it back later on to just below water's freezing point.

(Saw the video on Public Television a while back: http://www.discovery.com/tv-shows/frozen-planet/videos/caterpillar-survives-frozen-death/ )

41:

Whenever I read discussions like this, the thing that surprises me is how Science Fiction has somehow constructed this shared idea of interstellar expansionism to the point where real world space exploration gets short shrift.

From my point of view, finding an Earth-ish exoplanet is a nifty bit of science, but it's obviously not useful in any sense outside of astronomy. We're obviously not going to go there. And this ought to be obvious to everyone! I mean, we haven't even been to Mars, which is a perfectly habitable (in exoplanet terms) place that's barely even farther away than the Moon. And when people talk about going to Mars, it tends to be laughed at and treated as being on the edge of plausible at best.

So sure, obviously SF fans are going to dream about the far future and such. But the thing that's really weird to me is how there seems to be this pervasive idea floating around society that somehow we're just on the brink of becoming an interstellar civilization, zooming from star to star in the USS Enterprise. When I talk to people about space travel, they seem more excited about the latest TV show than they are about anything real (not to mention more knowledgeable about it). Mentioning methalox rocket engines and delta-V bores them to tears. ZZZZzzzzz.

It also seems comparatively hard to even find SF stories that are set in our own solar system. There are obviously a number of high-profile examples recently, but they stand up against the huge mass of people zipping about from star to star like it's going to the corner grocery. Plus, said solar system stories typically end up going interstellar half way through with some form of magic.

Why does flying around from star to star seem so much more appealing to people? I guess I have to assume that it's nothing more than cultural heritage: that's the sort of story that SF writers have tended to tell for the last 75 years, so now it's what people expect.

42:

Thanks a lot, I had missed that.

43:

Why does flying around from star to star seem so much more appealing to people? I guess I have to assume that it's nothing more than cultural heritage: that's the sort of story that SF writers have tended to tell for the last 75 years, so now it's what people expect.

Specifically American SF writers, and yes: it's all about the Manifest Destiny thing -- the founding myth of the nation -- and nostalgia for a frontier that closed over a century ago and was only ever open in the first place because of unacknowledged genocide mediated by imported pandemics.

There's also an eschatological element to it which crops up in other nations' space colonization mythology, for example in the writings of Konstantin Tsiolkovskii, who got it from his tutor (Nikolai Fyoderovitch Fyoderov, who prefigured so much of the "rapture of the nerds" strain of transhumanism).

44:

To me, the excitement about the news is that the new planet candidate is at 1/3 the distance of the next-closest candidate, which enormously increases our ability to study it. We'll get much better data that will lead us to refine our current models and make better predictions.

Radiation is probably less of a problem than it's made out to be. The simplest solution, which also solves the problem of providing a safety margin for water and oxygen*, would be to embed the ship in a big-ass (that's the technical term) ball of ice. Water blocks radiation really well (ice, less well), and seems likely to form an effective ablative particle shield. Think comet! You'd lose tonnes of the ice to ablation, but I did say "big-ass" ball of ice. Proof and calculations left to the student. (Talk about your "Cold Equations"... *GDR*)

* That is, even the tightest recycling systems aren't 100% efficient, even ignoring more dramatic events such as hull punctures by random debris, and over interstellar distances, even really small percentage losses add up in unpleasant ways. The standard level of engineering redundancy (e.g., triplication) probably won't cut it for an interstellar mission.

Charlie's right about the self-sustaining ecosystem problem... it's a bitch. (That's also a technical term. *G*) My expertise is in systems ecology, so I know a bit about what I speak. Terrestrial ecosystems are robust because, among other things, they're really big, and they mostly connect with other big ecosystems to exchange materials and energy. Creating something equally sustainable on a small (ship-sized) scale, even with help from really advanced technology, seems unlikely to succeed. Rather, I expect we'll require something really big. That big-ass ball of ice is sounding awfully good. Among other things, the Biosphere project results suggest to me that occasionally things will move far enough out of balance that you'll have to reboot the entire system from the ground up.

Incidentally, a few thoughts on Mars in this context of alien environments: https://blatherskite.dreamwidth.org/85899.html

A more serious problem is that we're tied far more closely to the precise conditions on our planet than you might expect. (Among other things because SF/F writers rarely deal with the issue.) Most plants, for example, cannot survive in completely sterile soil, even if it's got adequate nutrient levels, because the soil lacks the symbiotic microorganisms required for survival (e.g., mycorrhizae, rhizobia). Can we create such self-sustaining soil microbial ecosystems? Maybe. Can we assume that these ecosystems will survive (outcompete native organisms) in an alien soil? I wouldn't bet my life on it.

Then there's the poorly understood human microbiome, without which we probably can't survive here, let alone on another planet. If I were going to be relocating to an entirely new ecosystem, I'd want to have something better than a bottle of no-name drugstore Lactobacillus tablets to reboot my personal ecosystem if it were to be eradicated by radiation or mutated beyond stability by an alien environment or simply sabotaged by the lack of some critical micronutrient whose role we don't yet fully understand. Perhaps we could just transport a few metric tonnes of feces in lead-lined boxes? (https://en.wikipedia.org/wiki/Fecal_microbiota_transplant)

I don't think we're even remotely close enough to the required level of understanding of the soil or human microbiomes to predict how they'll fare on another world. Just getting to that other world may turn out to be the simpler of the two problems.

45:

There's another downside to this. A tech which can cross interstellar distances in single digit lifetimes, can also deliver a rather energetic kinetic kill vehicle. Deliberately or by accident. "Oh drat, I think we punched a hole clean through their planetary crust" seems like it would be the outcome of a relatively minor aiming SNAFU.

46:

Minor aiming SNAFU? Excellent aim I think.

Planets really aren't very big targets.

47:

Zeroth law of science fiction - people want to read stories about people. So your successful science fiction stores tend to be about people having adventures. That doesn't work for realistic space travel - basically the people are likely to be back on Earth reading data from robotic probes.

There actually was a second wave of stories set in the solar system during the 1970s and 1980s, courtesy the concept of O'Neill colonies. The problem, which our host has previously discussed at length, is that living anywhere in the solar system but Earth is really, really difficult. If you want to make a long term stay, you need to bring your own ecosystem and figure out how to maintain while protecting it and yourself from a very hostile environment. So setting up permanent human habitation in space is a very expensive proposition without much justification for it. If you have the technology to colonize Mars, you could settle Antarctica with much less difficulty. There's just little practical reason to put a permanent human settlement in space. And before anyone brings up that old saw of not putting all your eggs in one basket, remember it will take a very long time and a lot of wealth to create an off world colony that doesn't depend on support from Earth. Might be easier to just look out for Earth.

Thus, if you want adventures in space, it helps if you can hop from one Earth like world to another. Thus science fiction writers want interstellar travel in their futures which also pretty much requires FTL. And that's why we get endless series of space operas where our heroes flit from Earth like world to Earth like world having adventures - it's what people want. So writers quietly stick in FTL drives and hope readers won't ask to many questions until hopefully physicists discover a way to make the magic real. Until then, keep chanting Welsh.

48:

I should mention the problem with laser sails and similar:

--trigonometry and aiming.

Aside from beam decoherence, just aiming the damned thing gets ridiculously hard. If you're trying to hit a target light years away, even getting the beam an angstrom off at your end can cause the beam at the other end to move many, many, many kilometers. It's probably impossible to keep even a perfectly and indefinitely coherent beam on target across light years.

49:

A few comments/questions:

1- Okay, how easy is it to calculate where the target world is likeliest to be in 10, 000 years’ time, and then where the Earth will be from the target planet’s perspective 20,000 year later, so that we’re in the correct spot to receive any transmitted data? (I’m thinking ... universe’s expansion, galaxy rotation, etc. What stellar/space phenomena might mess up this calculation? Seems that any for-public-consumption info (i.e., what I'm aware of) suggests that all parts of the galaxy work reliably as clockwork … but is this an oversimplification?)


2- Babies in space … NASA is starting some lab testing on the ISS re: how well frozen mouse embryos can survive zero gravity. Maybe they’ll eventually run experiments to see what the effects are on mammalian fetal and post-partum development. (For this, they’d need to send up a mouse-sized MRI and CT scan.)

http://www.nasa.gov/mission_pages/station/research/experiments/893.html

Some background … [excerpt]

‘Description

Sustaining life beyond Earth orbit will require a clear understanding of how the environment in space affects key phases of mammalian reproduction. Recently, a study was done on mammalian fertilization and preimplantation development under simulated microgravity (simulated μG) conditions using a three-dimensional (3D) clinostat. Although fertilization occurred normally in vitro under simulated μG, the offspring birth rate was significantly lower than the 1G controls due to the poor development of placental cells. This suggests that mammalian species may have difficulty reproducing in space, and highlights the importance of performing experiments in actual, rather than simulated, space conditions in order to verify these results.’


Potential generation ship crew females then might not only have to be willing to have many pregnancies but also to lose many/most of their babies. Horrible thought! And when you consider that at least some women would die in childbirth resulting in more pressure on surviving women to nurture orphan newborns, plus bear and raise their own kids. Another possibility to maximize fertility efficiency is IVF which would preferentially select the next generation for fertile females thereby throwing a massive gender political wrench into the generation ship program.


Also ... Former ISS astronauts all appear to have aged somewhat more than they should have if they had instead stayed on Earth. Plus we don’t know exactly to what extent molecular metabolism might speed up in utero (in zero G) with concomitant consequences pre, peri, post-natal dev, etc. adding all these effects together: What if instead of 78, life expectancy drops to 60 for GEN2 because of zero-G effects?


3- ‘All we need is time’ seemed to pop up fairly often in other posters’ comments, so how about these news items. (As a non-scientist, I’ve no idea how scientifically/technologically valid or not these articles are, but now that they’re out there, may as well consider them.)

http://qz.com/760804/chinas-new-quantum-satellite-will-try-to-teleport-data-outside-the-bounds-of-space-and-time-and-create-an-unbreakable-code/

3a. If this works, we could send a drone spacecraft to the planet and set a timer to 10,000 years plus X days in the past and be ready to receive data almost at the same time as the spaceship is launched.


http://www.sci-news.com/physics/research-challenges-conventional-view-space-time-04114.html

A physicist at Griffith University in Australia has solved an anomaly of conventional physics and shown that a mysterious effect called ‘T violation’ could be the origin of time evolution and conservation laws.

“Conventional physical theories can accommodate only one direction of time and one kind of meson behavior, and so they are asymmetric in this regard. But the problem is that the Universe cannot be asymmetric overall.

“This means that physical theories must be symmetric in time. To be symmetric in time they would need to accommodate both directions of time and both meson behaviors. This is the anomaly in physics that I am attempting to solve.”

Joan A. Vaccaro. 2016. Quantum asymmetry between time and space. Proceedings of the Royal Society A 472 (2185); doi: 10.1098/rspa.2015.0670

But what if conservation-of-time can be reconciled by switching/transforming between flavors of time (timelines) just like energy comes in different flavors and can be transformed from one flavor to another.

4- Spacecraft of least resistance: Instead of fighting the space dust/debris with energy-wasteful heavy hulls/exteriors, why not use a ‘spacecraft’ that’s porous, powered by solar panels/sails (also porous).

50:

"There's a death spiral in there for slow ships. If you're going too slow, then you need to effectively be able to rebuild your entire ship over time to replace the damaged parts (all while relying solely on nuclear power for your energy supplies). But that in turn increases the mass of your ship, making it more costly to accelerate and all other things being equal leading to a slower trip. Which in turn increases the reliability issue . . . "

So embrace the problem and make it the solution.

We already have a ship that supports a biosphere (though as per SF stories, Generation n is trying to wreck the life support system). We're already on it and it already has a fusion reactor fuelled up and running.

It just doesn't go anywhere.

So change that.

Build a lightsail. A big lightsail. Position it close to the sun such that the light/solar wind pressure on the sail balances the gravity drawing it into the sun. Presto, you have a reaction drive. The sun starts to accelerate (slowly). In just a few hundreds of million years we'll start to appreciably move around the local stars and will eventually get to fly by a fresh solar system every few million years.

51:

This Again... sigh.

I think the big problem with interstellar tech is very simple: We aren't there yet. We're like a primitive tribe looking at the Great Ocean and saying, "What if we built a really big canoe?"

And someone else says, "We can't do that. The size of a canoe is limited by the size of the tree it is carved from. This should be obvious."

"What about boards? We could build our really big canoe out of boards!"

"'Boards' are currently theoretical. Even if they weren't, our stone axes can't create 'boards" of sufficient quality to prevent seawater incursion across the border between two 'boards.'"

'nuf said, I think, about our relatively primitive technology.

As I see it, there are two ways to imagine interstellar travel. One is by imagining that interstellar travel grows from our current technology in a way we can understand. There is another way. We can imagine what our technology will look like in a thousand years, (or ten thousand) and create our interstellar technology out of that engineering culture, the one we don't understand yet.

For example, you probably don't have to worry about bacteria mutating in your soil if you've got good-enough nano-tech. The mutated bacteria gets zapped by a nanite before it can reproduce and no human even knows that a problem was averted, except that in the most general terms that we have soldier nanites making sure the soil doesn't get out of hand.

Given good nanotech, maintenance is also a completely solved issue.

One might also imagine bio-tech evolving at a similar pace. Will humans be immortal in a thousand years? Will we have solved all the space-adaptation issues?

And what about those propulsion problems? What happens in a thousand years? Or ten thousand years? The problem is not that interstellar travel is impossible. The problem is that it looks impossible from here.

I'm not, BTW, saying that we'll ever have warp drive or a four-year voyage to Proxima Centuari, just that when you push all forms of technology forward the picture looks very different,* just like the future looks very different for our primitive canoe builders when they've advanced enough to work brass, build a sawmill, and weave cloth for sails!

What I'd look at in "future history" terms is a fully colonized solar system at some point between 2000-3000 years from now, with the engineers of that time beginning to seriously think about how we'd get to the nearest star. It's not quite a "post-singularity" situation, but a very different one from our own.

* Leaving aside such issues as global warming or ocean acidification... sigh.

52:

Since this conversation has grown to encompass near-term space travel, I'll chime in.

Right now, our vision for human space exploration is whatever Musk and Bezos say it is. Everything else is just talk right now.

For robotic spacecraft, you have a bifurcation. Everything outside the Earth-Moon system is dealt with by the traditional NASA strategy. Within the Earth-Moon system, cubesats have potential. The first of NASA's robotic attempts to orbit the Moon isn't that much bigger than several cubesat configurations already in existence

https://en.wikipedia.org/wiki/Pioneer_0

53:

OK, if we are talking reality check, we have an existential threat to human civilisation as it currently stands which we know well enough to know where the tipping points roughly are, we have control of key actions, and we know enough to have a plan to avoid that threat.

And we aren't doing anything and are basically guaranteeing we go over the tipping point to runaway climate change.

And you want to do something that requires foresight, decades of effort just to launch, and trillions of dollars?......

And then on top - is your trip really necessary?

We haven't even done much with the local digs, where we could be building, colonising and expanding. Even if we shot all the politicians tomorrow, we are talking about hundreds of years before colony missions to nearby stars makes sense.

So, at a minimum you need to be talking about the tech that far ahead.

Put that in and two plausibilities arise. First, you can upload human conciousness to robust hardware - so journey time is less of an issue (as are biospheres). Second, the possibility of discovering wormholes et al rises significantly - making all the tedious mucking about in real space moot.

As far as I can see, the only valid reason for trying to get to a nearby star in the next 200 years is knowing that our star isn't going to last that long. Otherwise you wait for the tech to change the game.

> And when people talk about going to Mars, it tends to be laughed at and treated as being on the edge of plausible at best.

Well, Elon isn't getting that much laughter, and looks to be plausibly talking about humans-Mars in the 2024-2028 type timeframe. Let's see what he says about the Mars Colony Transport at the end of Sept.

54:

What I'd look at in "future history" terms is a fully colonized solar system at some point between 2000-3000 years from now, with the engineers of that time beginning to seriously think about how we'd get to the nearest star. It's not quite a "post-singularity" situation, but a very different one from our own.

That's a very unusual "future history" as far as SF is concerned, but not unheard of. Have you read "House of Suns" by Alastair Reynolds? While most of the book takes place six million years from now, it has flashbacks to just what you described: "The Golden Hour" -- a fully colonized Solar System, which is just starting to think about interstellar travel. That stage in human history is called The Golden Hour because it takes about an hour for light or radio to travel from one end of the human-settled space to the other. I don't remember when exactly The Golden Hour occurs, but it is in 31st or 32nd century.

55:

Another thing, I think, is that it's continuing a tradition which is much older than SF: fantastic tales of far-off lands. We know now that there aren't really people with their faces in the middle of their chests in some remote corner of Earth, so stories of that kind set on Earth look a bit silly now, but it looks less silly to postulate that they do exist on some other planet altogether and imagine that we can get there by some means which is roughly comparable to a long-distance sailing voyage in terms of speed, danger etc.

56:

I've read a 4-5 Alastair Reynolds books, but he's not really to my taste; his characterizations always seem a little off to me, though they're slowly getting better.

His timeline makes a lot more sense than Star Trek's.

57:

But you're ignoring The Human Spirit!!1!11!!

(Sorry, I just had to….)

58:

"The human spirit, it is a hard thing to kill... Even with a chainsaw."

59:

"We're like a primitive tribe looking at the Great Ocean and saying, "What if we built a really big canoe?""

Thing is we do know some things the primitive tribe don't. We know how far it is to the other islands in the ocean. We know how long it would take to get there even if we built the fastest canoe it is ever possible to build. We know that a crewed canoe will be much, much slower if it is to avoid killing the crew with acceleration, never mind its speed attracting the giant squids.

And we know (in broad terms) what is on the other islands, and that it's nothing we can't get much more easily on our own. Even within our own solar system there isn't anything worth doing with the other bodies in it apart from sending robot probes to them out of scientific curiosity. The same is true of other solar systems - yes, even if there is life there; we certainly don't want it back here - and the difficulties are much greater. There's no point even sending a robot probe to other systems because by the time it gets back there won't be anyone who even remembers it was sent in the first place.

60:

Exactly this. A lot of science fictions stories are basically space fantasy, either mysterious adventures in strange new lands or "X but in space". Star Trek is that (although it does have some interesting science fiction elements in the system of the Federation), Star Wars is definitely that, most space opera is that, and so forth.

Plus, it just feels kind of weird to say, "This is probably where humanity is going to stay, with rare exceptions, forever more until our race dies or transforms into something non-human". It feels stagnant somehow, and it's not like we've all become immortal to compensate for that.

I'm actually optimistic about space colonization of the inner solar system over time periods of centuries. Robots could really make that much easier, doing all of the work for us so that you can live in a space habitat if you really want to while still being part of overall human civilization including Earth.

61:

The only thing I'd point out is that arguably the best explorers, the Polynesians, did it with stone tools and without cloth, and they apparently expanded to the entire Polynesian triangle a few centuries after they got to the Society Islands (PNAS Reference. Note that I expect these dates to be controversial). The critical point is that they didn't start off without cloth, and (given the finds of dong son bronzes around Papua New Guinea) their distant, non-colonist ancestors might have known about bronze or even included some bronze workers. Their apparently simple material culture was due to what they could make on the islands, and the same thing will undoubtedly happen in space.

The reason to bring this up is that one of the other classical biases in science fiction is that civilization evolves, and that the evolution is in a single direction, that current society X is the pinnacle of civilization, and that it's the worthy precursor to the civilization that will Conquer Space.

Obviously this is a massive case of confirmation bias (e.g. the notion that we're special and deserving, not lucky), but it's not only normal, it's expected. The more important issue is that if you're writing SFF, you want to sell a lot of books this year. Therefore you want your story to at least somewhat conform to the biases of your target readers.

If you want to go against confirmation bias, then you're pretty much writing dystopian fiction. This is the territory of stories where characters take a camel train through the American Desert during a rare wet year, to marvel at the remains of Las Vegas and the remnants of the enormous dams on the muddy trickle of the Colorado, and wonder "What the hell were they thinking, that they put so many people in such a dangerous area? And why did they destroy the springs after which Las Vegas was named?"

Anyway, I'm digressing as usual. Personally, I think colonizing the solar system is a great exercise in dealing with radiation shielding and high speed impacts, but whatever. Robert Reed got there in 1989 with Hormone Jungle, if you want to look for older examples. He was heir to the old planetary romance writers going back to John Carter of Mars via Lucky Starr.

62:

I don't know, I mean, now we know about, say, quantum chromodynamics, it's unlikely we'll totally lose that knowledge, or even if we do it will be much easier to regain than it was to discover in the first place.

Never mind generation ships, let's think about generation civilizations on earth that might contact autonomous ships from time to time.

Civilization might fall, but we're not going back to (another sci-fi trope) a medieval state again precisely. Right now even we're going through a little bad patch in terms of space exploration. We've kind of lost interest. But politics will change and we'll get interested again in noble and foolish pursuits again.

One imagines a multiplicity of probes sent over millenia, for various reasons, able to respond to various protocols and probably designed to be somewhat self-explanatory, equipped with varying levels of autonomy and capacity for self preservation. One can hope, with the deep-learning algorithms that are starting to be possible, for a level of autonomy that makes working with them with ping times on the order of decades feasible, in order to try to build up some sort of remote industrial base.

One imagines their contact protocols hoarded in the same way as the seed vaults.

63:

I wouldn't say my thinking on this issue involves "confirmation bias," merely that I'm pessimistic about any kind of short-term settlement of the solar system. We need multiple revolutions in materials science, nanotech, computer science, biotech, propulsion, etc., before we can move off Earth in significant numbers.

I look on Elon Musk's efforts with interest, (he's very canoe!) but I think he's going to get a bunch of people killed. We'll learn a lot from his efforts, but he will not successfully colonize Mars.

That being said, and assuming a lack of environmental disasters (sigh) I do think that we'll make the advances necessary to leave Earth behind... eventually. Essentially, I'm rejecting the arguments of both the L5 types, who argue that it will be easy, and the pessimists like OGH, who come close to arguing that the whole thing is completely impossible.

The simple fact of the matter is that we're not going anywhere until we've done some biohacking, improved our propulsion systems enormously, solved the radiation shielding problems, and built people who are much more closely connected with their information systems.

And I do know about the Polynesians. My canoe people are metaphorical.

64:

This is something I tackled a bit in Hot Earth Dreams.

I'd simply suggest that stagnation is an illusion, but so is progress. History is one damned thing after another, with people adjusting no matter what happens. Occasionally some brilliant idea becomes normal, but a lot of things get reinvented more than once.

For example, there's good evidence for basic agriculture in Israel from 20,000 years ago, but there's no evidence that agriculture wasn't lost and reinvented about 8,000-10,000 years ago, with a lot of climate chaos in between. When you get into the realm of tens of thousands of years, nothing of human culture lasts, other than basics like making fire and tools.

Our species is around 100,000 years ago, yet due to simple, random change, we're unlikely to even know what languages our ancestors spoke 10,000 years ago, let alone for the previous 90% of human history before that. Languages always change, and after perhaps 10,000 years (at a guess), it becomes impossible to reconstruct the past.

That's the thing about severe climate change. It will take something like 100,000 years (or more) for the climate to come back to where it is now. It will take something like 5,000,000 years (or more) for coral reefs to re-evolve, and it will take something like 10,000,000 years (or more) for a full compliment of species to re-evolve if we go through a mass extinction in the coming centuries. We're talking about changes in deep time, not the shallow time of history. It's something most people don't really understand.

I happen to think humans will be around for 5,000,000 or 10,000,000 years, largely as we are now (the argument for why I think this is a good portion of Hot Earth Dreams, and I'm not going to repeat it here). After a few thousand years, our current global civilization be utterly forgotten. No one will speak anything like English, no one will practice anything like our current religions, current races and ethnicities will not exist, and so forth. Our distant descendants probably have agriculture, work iron, have guns, and so forth, but they'll have no idea who invented any of these, how old their technology is, or how often it has been reinvented.

That's our likely future. It's not an infinitely static future of crystal spires and togas, nor is it a cyclic future. It's a chaotic future where, even when civilization exists and there are archaeologists, they'll only have fragments from previous millennia, and only know the history of the previous few thousand years, as we do now. Even now, our notion of history is basically the last 3,000 years of our 100,000 year history as a species. Civilization has been around for pushing 7,000 years, but most of us have no idea what happened before 1000 BCE, except that they pulled Tut's brain out through his nose after he died.

The flip side of this is that there's millions of years of possible stories that can be set in the future, if you want to explore it. It's the biggest undiscovered country there is right now.

65:

Let's suppose for argument's sake that the planet is confirmed. Furthermore, let's assume that it is later confirmed to be a rocky world, that it has an atmosphere that spectrographically hints at a biosignature.

Is the fact that it is a planet around our nearest star important?

I would argue that it is. If nothing else, it would stimulate further telescopic developments that will give us ever better data about the world, including eventually images.

Let's suppose that those images are as good as images of Mars before the Mariner missions. We would have the tantalising glimpse of a planet that is in our nearest neighbor star's system that would fire the imagination as Mars once did.

It would certainly make a great target to aim for like the Breakthrough solar sail probe. If we did build a series of fast probes to the new planet, it would send back pictures and data of a living world that would likely stimulate a desire to send landers, and advanced machines to study it and return images that every child would know from earliest school age.

In short, it might stimulate a new desire to explore space.

I don't expect large probes to ever get to that planet (unless we get some new physics that allows us to do so), but that wouldn't stop us sending advanced, self constructing, biology-like machines with advanced AI to act as our surrogates on this world, and eventually on others further out.

Such a world could be a hugely important cultural stimulus.

66:

Restating OGH@35 in more emphatic terms: the critical path in any "let's travel to the stars" scenario is building a civilisation that can remain stable enough for the tech to remain operational for the time required to achieve target velocity, and then to decelerate at the other end. We only have a few examples that have lasted longer than about four generations, and even then complex technology preservation was not a priority; see also @64. Note that this is the case even if we assume some kind of auto-repair and magic life support in suspension, or long lived "people".

Most space opera deals with this problem by using a magic FTL wand of some description. Asimov's Seldon books used lots of handwavium, but at least tackled the social system design problem head on.

67:

The problem for that set-up is the presence of writing and literacy. The reason why we know so much more on average about the past 3000 years versus the past 7000 is because writing became more common, and even with the comparatively low literacy rates of the Classical Era that meant that stuff became much more likely to be preserved (especially with the increasing interconnection of civilizations). That continued even when particular civilizations went through a dramatic collapse that shrank literacy, caused mass de-urbanization, and so forth (like with the western Roman Empire outside of Italy).

That changes the preservation of memory and technology going forward. You'd have to posit a total collapse, down to hunter-gatherer levels, to the point where by the time they re-discover literacy they can no longer read the writings and inscriptions left over. And it would have to be world-wide, because otherwise the areas that don't collapse as much will preserve it and cycle it back in. It's something I don't see happening even in the higher-end projections of climate change.

@troutwaxer

I think Musk is going to find a paucity of people who actually want to live permanently on Mars when they find out that "live on Mars" means "spend most of your time in a nearly window-less habitat either underground or made of Martian bricks, tending life support systems and only going outside in space suits". Lots of scientists willing to go on rotation for a few years or more, but permanent colonists? I doubt it will be enough to make a viable colony, and that's assuming that none of them come back.

A lot of the romanticism of places like Mars is because it's so far away in space. It'll be a lot less romantic once humans have been there.

68:

The problems of interstellar travel at significant fractions of the speed of light are being investigated. Just on Friday this paper was put onto arXiv:

The interaction of relativistic spacecrafts with the interstellar medium

Thiem Hoang, A. Lazarian, Blakesley Burkhart, Abraham Loeb
(Submitted on 18 Aug 2016)

The Breakthrough Starshot initiative aims to launch a gram-scale spacecraft to a speed of v∼0.2c, capable of reaching the nearest star system, α Centauri, in about 20 years. However, a critical challenge for the initiative is the damage to the spacecraft by interstellar gas and dust during the journey. In this paper, we quantify the interaction of a relativistic spacecraft with gas and dust in the interstellar medium. For gas bombardment, we find that damage by track formation due to heavy elements is an important effect. We find that gas bombardment can potentially damage the surface of the spacecraft to a depth of ∼0.1 mm for quartz material after traversing a gas column of NH∼2×1018cm−2 along the path to α Centauri, whereas the effect is much weaker for graphite material. The effect of dust bombardment erodes the spacecraft surface and produces numerous craters due to explosive evaporation of surface atoms. For a spacecraft speed v=0.2c, we find that dust bombardment can erode a surface layer of ∼0.5 mm thickness after the spacecraft has swept a column density of NH∼3×1017cm−2, assuming the standard gas-to-dust ratio of the interstellar medium. Dust bombardment also damages the spacecraft surface by modifying the material structure through melting. We calculate the equilibrium surface temperature due to collisional heating by gas atoms as well as the temperature profile as a function of depth into the spacecraft. Our quantitative results suggest methods for damage control, and we highlight possibilities for shielding strategies and protection of the spacecraft.

http://arxiv.org/abs/1608.05284

69:

Planets really aren't very big targets.

Ahem. Even with 1990s specifications and tech (NASA/JPL are very conservative), New Horizons ended up within 9km of its aim point at the end of its last pre-encounter burn, after a flight of 7.5 billion km.

Planets don't dodge, jink, or take evasive action. And if we're talking relativistic kill weapons (RKVs) the terminal guidance and course correction hardware is just more mass to add to the final boom.

However, RKVs have a number of weaknesses. Notably, anything travelling at a double-digit percentage of lightspeed is going to be very visible from light years away, especially during the boost phase ("ooh look! Why is that exoplanet suddenly lasing with an apparent magnitude as bright as our own sun?"), and also during the cruise phase (because of all that happy fun secondary radiation from the front of its shield plate).

And if you can see an RKV in time to do something about it (meaning: if it's doing anything less than 90% of light-speed) you can try to disrupt it. 1950s technology will do at a pinch, you just need to dump a lot of Saturn-V's worth of sand in its projected flight path, and watch the fireworks. And the headaches you run into at high relativistic speeds -- say, tau of 0.5 or lower -- are epic; you're hitting the electrons in the interstellar medium with the energy of gamma rays, and when you crank up the speed a bit there's so much energy that the gammas resulting from impact undergo pair production and you can add happy fun antimatter reactions to the crap your front shield has to stand up to.

70:

And while I'm on this subject, if it's hard enough trying to figure out why anyone might think in terms of colonising other planets in our own solar system, and difficult to figure out how to send an unmanned interstellar probe in the first place, my mind boggles whenever I try to come up with a plausible motivation for sending an RKV -- at least in this universe.

(It made sense in "Iron Sunrise", where there was a mixture of cheap FTL and economically justifiable relativistic STL travel, so RKVs were a military by-product of the capability to exchange causal channels which in turn were an arbitrage-enhancing adjunct to FTL interstellar trade, but? In the fly-paper cosmos we're stuck to the surface of, it seems like a vastly expensive enterprise that has a low probability of succeeding in getting an annoying neighbour who you will never see to shut the fuck up and stop spamming you with easily-ignorable signals.)

71:

Potential generation ship crew females then might not only have to be willing to have many pregnancies but also to lose many/most of their babies. Horrible thought! And when you consider that at least some women would die in childbirth resulting in more pressure on surviving women to nurture orphan newborns, plus bear and raise their own kids. Another possibility to maximize fertility efficiency is IVF which would preferentially select the next generation for fertile females thereby throwing a massive gender political wrench into the generation ship program.

Or you could, you know, massively modify the crew. You're going to need to patch them for resistance to a microgravity and high radiation environment. You might as well get rid of all the nasty hereditable diseases that aren't weeded out by natural selection because we reproduce before they kill us, such as prion diseases (notably some types of dementia). You're going to have to mess with the immune system, too ... why not make your colonists fertile hermaphrodites, so that they can all pitch in on the childbirth thing? Or figure out how to produce anencephalic limbless "baby factories" -- cf. the "reproductive stumps" in Frank Herbert's novel "Helstrom's Hive" (note: extreme trigger/horror warning).

We're already casually talking about the tech to build compact, high-efficiency aneutronic fusion reactors and stable pocket ecosystems: redesigning humanity is just another logical step ...

72:

Right now, our vision for human space exploration is whatever Musk and Bezos say it is. Everything else is just talk right now.

Correct. However, you need to ask where Musk and Bezos got their vision. Hint: they're within a few years of my age and I'm betting they read much the same hard SF in their teens. Unlike me they've then gone on to successful careers as serial tech entrepreneurs and had their hands full running large corporations. So I'm betting they haven't sunk as much time into chewing over and re-visiting that old-time 1970s and 1980s two-fisted Analog-era engineering tales and asking about the second-order issues.

Musk and Bezos aren't going to colonize Mars, although they're going to build the tech base for near-earth industrialization and might succeed in planting an outpost on Mars which is indefinitely viable with frequent resupply. (Trans: if civilization on Earth collapses, Mars dies within a generation. A true colony keeps going even without resupply runs.)

What I'm curious about is what the next generation of movers and shapers is going to come up with ... the ones who grow up seeing the failure modes of the 1980s solar-system colonialists, like 20th century Africans growing up in the aftermath of Cecil Rhodes' crazed plans for a British African Empire and a Cape-to-Cairo railroad. (But I'll probably be dead of old age before a coherent vision emerges.)

For robotic spacecraft, you have a bifurcation. Everything outside the Earth-Moon system is dealt with by the traditional NASA strategy. Within the Earth-Moon system, cubesats have potential.

Yes, but one caveat. Cubesats are inherently range-limited by their ability to pack in enough power to communicate -- they're tiny so they can't carry big-ass radios or lasers. However, we're putting more and more hardware into orbit around Mars, including high-bandwidth communications relays: there's more than one Mars orbiter whose primary job is to act as a relay for the ground-based explorers (while keeping an eye on the Martian ionosphere or something). Push it a little bit further and we could be seeing serious numbers of cubesats deployed around Mars to do things like scope out Phobos and Deimos. Apply the same principle to Jupiter, and once there's more than one big-ass Jupiter orbiter at a time we could get a lot of data by sending swarms of cubesats to take a close look at various bodies and then squirt a packet of data at the big-ass relay orbiter whenever they make a close pass to it. We now have PV cells that can efficiently power a spacecraft in Jupiter orbit, and we don't have to send the cubesats on the same big-ass booster as the big-ass orbiters: they can take the slow road, using the Interplanetary Transport Network.

73:

"Venus Plus X" - Sturgeon
[ Should have been Venus + Y of course, but never mind ... ]

74:

I happen to think humans will be around for 5,000,000 or 10,000,000 years, largely as we are now (the argument for why I think this is a good portion of Hot Earth Dreams, and I'm not going to repeat it here). After a few thousand years, our current global civilization be utterly forgotten.

Snap.

Note for the audience: when I'm gearing up to write something on topic X, I frequently emit polemical blog entries about "why X is impossible" or "500 cliches about sub-genre X". In this case, yes, as soon as I nail down this Laundry novel I'm going back to work on the first novel in a new space opera universe, set two thirds of a million years in the future.

I'm relying on a magic wand technology to facilitate interstellar travel via wormhole, otherwise space opera just doesn't work at all ... but, taking that as a departure point, I'm trying to stay within spitting distance of physical laws and their chemical and biological consequences. Humanity has spread throughout the entire Local Group of galaxies, and speciated. Forget skin colour and epicanthic folds, I'm talking elves, dwarves, and marsupial variants created because some planetary dictator had an ideological bee in it's bonnet and the biotech base to put it into practice on their population. Fifty thousand years later their name is long forgotten but the hominid species they created has merrily gone its own way ...

... And as for speaking English and having pale skins, forget it: they're not even sure which galaxy they originated in. The high tech civilizations have high-end genetic engineering and know about evolution -- both in microbiology and they can observe a fossil record going back hundreds of kiloyears -- and they can infer a common origin for all known spacegoing races. But that's about it.

75:

Trans: if civilization on Earth collapses, Mars dies within a generation

...the basis of the sequel to "Logan's Run" (Sanctuary was a Mars base in the novel, IIRC) which we're also all old enough to have read...

PS are you resisting "the search for the home world" trope?

76:

A few notes, in more or less chronological order:

Re. Using a sun as a fusion drive. Yes! Alan Dean Foster did this decades ago in "With Friends Like These", Larry Niven picked up on it (or inspired it... not sure of the chronology) in the Known Space series, and Niven/Lerner did it again more recently in their post-Ringworld series.

re. Nanotech and soil microbes: Respectfully, that's a typical engineer/physicist attitude. Engineers and physicists are used to working with relatively simple and deterministic systems, so they tend to be ignorant of the difficulties of biology, which involve far more complex non-deterministic systems affected by an enormous number of state variables. You can't easily solve the problem of soil microbes both because (i) we don't yet know all the key variables or how they interact and (ii) it's a non-deterministic system. Grossly oversimplifying here, but that's the basic notion.

Heteromeles, brilliant analogy re. the Polynesians. Humans disperse by any means necessary, whether from population pressure, curiosity, fear ("all our eggs in one basket" or "lifeboat" syndrome), greed (new areas to pillage), or ego ("I can't run this government, but if I ran my own government..."). Colonization seems almost a genetic imperative for humans, whatever the underlying rationale.

Re. "planets are big targets". Charlie, I think the original poster was referring to a recent paper that challenged the notion that you can just drop your trash into the sun. At first glance, it appears that all you need to do is point the trash at the sun or just stop its orbital motion, then let gravity do the rest. Unfortunately, as comets and near-Earth asteroid trajectories illustrate, you actually have to lead the target by a considerable margin if you want to hit it. If you don't, you end up with something in a highly eccentric orbit that will eventually fall into the sun, but might take a very long time to do it. Thus, a frequent SF trope of spaceships skimming a sun/planet/whatever and being pulled into its death grip simply won't work. This works only when you consider aerodynamic friction, which could cause the ship to lose enough velocity to fall into the gravity well.

77:

@ 72: The Brit-African empire might have been crazed, but the Cape-to-Cairo railway was an eminently sensible idea, actually.
Pity WWI screwed that ....
@74
Will there be Rishathra, & if not, why not?

Also, how much in "common" with Stapeldon, I wonder?

78:

PS are you resisting "the search for the home world" trope?

Yup. (Per the plans I've got, it's totally lost; the only place for it to show up is in passing as the plot mcguffin behind an in-universe popular fiction/art form/game, widely noted for its melodramatic and interminable plot.)

79:

Forgot about another of Charlie's comments (re. relativistic kill weapons, RKWs)

I don't think it's as easy as you suggested to stop one of these beasts because there's a whole long chain of failures that could defeat an attempt to intercept or divert such a weapon. The biggest, of course, is that we have not tested any technology for stopping even a slow-moving killer object. We've got a lot of on-paper solutions, but no actual proof of concept and no infrastructure for such an effort. A few other objections:

The next-biggest problem is that you have to see the thing coming. Recent astronomy history has shown that despite a few agencies finally beginning to take the risk of asteroid impacts seriously, we still miss many (perhaps most) of these objects and only detect them when they're uncomfortably close. That won't change any time soon in a world in which the U.S. government considered the ca. US$1 trillion war on Iraq (https://en.wikipedia.org/wiki/Financial_cost_of_the_Iraq_War) to make sense because of the clear and present danger that Iraq posed to Western civilization, yet considers NASA's ca. US$4 million NEO budget to be frivolous. The mind boggles.

Moreover, you don't actually need to boost such objects to relativistic speeds or fire off a true planet killer: all you need to do is accelerate a large number of relatively small objects at your target, ideally from different directions. (By small, I mean stuff that's small enough it's difficult to detect but that still packs the energy of a big nuke.) The result is a shotgun blast rather than an antitank weapon. And this doesn't even consider "smart" projectiles capable of altering their trajectory at random intervals. Space is big; scattering sand clouds only works if you know the final trajectory and aren't worried about making that area of space unnavigable at high speed for your own ships.

Another fruitful analogy might be the difficulty of shooting down anti-ship cruise missiles. It can be done, but not with anything near certainty. And a really determined attacker can probably find ways to saturate your point defense. After all, rocks are cheap if you already have the technology to go fetch them.

You wondered why anyone might want to do such a thing ("my mind boggles whenever I try to come up with a plausible motivation for sending an RKV"). You're erring here by "thinking like us". Terrorists (and I am explicitly not saying jihadists, because terrorism is a much larger category) aren't really worried about martyrdom or collateral damage; on the contrary, it's often their goal. People will do crazy shit because people are often crazy and malevolent--the whole "kill 'em all and let God sort it out" crowd among them.

Donald Trump is pretty much prima facie evidence that many millions of people think it's a great idea to elect dangerous lunatics. It's not hard to imagine Trump IV deciding it's easier to RKV Mexico than to build a wall.

80:

"Yes, but one caveat. Cubesats are inherently range-limited by their ability to pack in enough power to communicate..."

True for Mars, but I doubt it's true for the Moon. Or else how could Pioneer 0 have communicated to Earth had its launch vehicle not been a death trap?

"What I'm curious about is what the next generation of movers and shapers is going to come up with ..."

It probably will be solutions to the failure modes of whatever Musk and Bezos are doing right now. Keep in mind, the 1980s were trying to address the Apollo failure modes, and in the solar-system-only space opera business, most stories try to address the failure modes of the last real world effort. Right now, Musk and Bezos have superseded the Shuttle as the last effort.

At least for human spacecraft. For robotic spacecraft, harder to say. Right now, cubesats try to address the failure modes of the traditional satellite business in the same way that drones try to address (to-be-determined) failure modes. I suppose the next generation of robotic spacecraft would try to address cubesat and drone failure modes.

81:

Weird: it sounds like you're thinking in terms of humans using an RKV against their own planet. (Does Not Compute! If you have the energy budget to send an RKV, you've got the energy budget to build lotsa nukes and deliver them locally.)

You're also thinking like a shaved ape. "Terrorism" is a specific tactic that works because of the way primate threat-perception and aggression displays work. It's a pretty sure bet that a non-human tool-using species won't be wired quite the same way. There may be equivalent tactics, but it's certain that inter-species diplomacy is going to be very strange, and war is the continuation of diplomacy by other means, unless we're just talking all-out extermination. And if we're talking extermination ... then, why?

Finally, we're getting into Drake Equation territory. If Proxima Centauri has a planet supporting a tool-using superorganism (I hesitate to say "civilization" because that's a human thing) then that would be so vanishingly improbable as to be strong evidence for an intelligent (and malicious) Creator. More likely, based on our current level of SETI, extra-terrestrial toolmaking superorganisms are sufficiently rare that our nearest neighbours will be hundreds to thousands of light years away, and an RKV would take millennia to hundreds of millennia to arrive. So: your justification for nuking the hell out of aliens who might not even exist by then at some time several thousand years in the future is ...?

82:

Charlie,

You may find my comments on the last blog entry permit you to minimize the changes you envisage to your latest manuscript.

83:

>>>And if we're talking extermination ... then, why?

A: We must exterminate them before they exterminate us.
B: But what if they don't want to exterminate us?
A: Surely they'll change their mind once they discover we want to exterminate them. So, why give them the chance?

/sarcasm

84:

That stage in human history is called The Golden Hour because it takes about an hour for light or radio to travel from one end of the human-settled space to the other.

So basically a Belter + inner planets civilization?

85:

"Yes, biological immortality is an alternative to suspended animation. Which one is easier remains to be seen."

No, it doesn't. Suspended animation - at least it's not fundamentally impossible. Extended and indefinite lifespans are one thing; immortality is (mathematically) impossible without eliminating the ability to adapt to circumstances.

86:

That was me, actually. Wikipedia says that it can survive down to -70 Celsius, and relies on 'anti-freeze' compounds - that isn't going to stop the chemical degradation over millennia timescales.

87:

You can keep C. Elegans in liquid nitrogen for decades.

88:

My understanding is that very few species last for more than ten million years, without changing significantly, and most last for only a couple of million. As you say, after that lapse of time, our descendents will not be classifiable as Homo sapiens and may well not be as Homo.

89:

Off-topic question: Can we expect blog post on last nights awards?
I had forgotten all about them, so didn't watch. Sounds like Gaiman's and Cadigan's speeches were particularly worth seeing.
Also agreeing with your tweets on the subject.

90:

Pretty much, yes. But with artificial gravity -- not "spin gravity" but actual control of gravitational force, to the extent that a small asteroid can have 1 g on the surface. Although the way it is described, it is not suited for anything else: can only increase gravity, not decrease it, and definitely obeys Newton's Laws of Motion -- cannot make a spaceship "endlessly fall forward".

91:

@1 asks "Incidentally, should the title be "Sad Trombone" rather than "San Trombone"? "

I think the sad trombone trope suggests ridicule or derision, scorn for emotional outpourings of imagined grievance, presumably aimed at anyone unrealistic enough to be disappointed with the hard truth of insurmountable adverse conditions in space, for believing fantasies of interstellar travel in the first place. Chicago local TV station WGN featured a childrens program in the sixties called Bozo's Circus, in which studio contestants tried to throw ping pong balls into a bucket across the stage. When they missed, a trombone played a descending scale of seven exaggerated vibrato notes (watt watt watt watt watt watt wahhhhh, with a flourish on the last tone to mimic absurdly distraught human sobbing.) This widely recognized musical convention of humorous, falsely pretended sympathy probably got its start in vaudeville theater of the pre-electronic era, when live entertainment was the only kind available. Still it's less harsh than porcelain trombone imagery, like a cliche, Bogart-esque film noir detective describing his bout of food poisoning in jaded, world weary tones as "playing a sad solo on the porcelain trombone. All. Night. Long."

92:

I suspect H. Sapiens sapiens' flexibility and ability to pass traits horizontally ("culture") mean that we're incredibly unstable in the long term -- we're only about 200kYa old and we've already triggered a once-per-150-MYa extinction event.

Would be unsurprised if we go extinct (in our current form) in much less than 0.1MYa.

93:

I wasn't in Kansas City. What I have to say about the Puppies is being said on Twitter right now. I may repeat it here later, but going by the outrage! it's sparking I'll probably disable comments.

94:

The problem for that set-up is the presence of writing and literacy. The reason why we know so much more on average about the past 3000 years versus the past 7000 is because writing became more common, and even with the comparatively low literacy rates of the Classical Era that meant that stuff became much more likely to be preserved (especially with the increasing interconnection of civilizations). That continued even when particular civilizations went through a dramatic collapse that shrank literacy, caused mass de-urbanization, and so forth (like with the western Roman Empire outside of Italy).

Not really, I'm afraid. We're the classic example: we have enormously high literacy, but we're going to leave bugger-all behind for our successors, because essentially all of our writing is on media that fall apart after years to a few centuries.

We're not the first one to have this problem, either. The Phoenicians left behind almost no records, because they wrote on papyrus and lived in a climate that was damp enough that it all decayed. And they invented the alphabet. We know that they wrote a lot, because Greek and Roman authors got to see some of their books, and summarized them in fragments that happened to survive into our time. It appears that some, perhaps a lot, of what we now consider Greek culture came from the Phoenicians, including things like Hercules (cf Melqart). They aren't alone, either. There are whole cultures, like the Khmer, or the Inka, or the Harrappans, or the Minoans, where we essentially have no literature from them.

No, the problem is simpler than this: stuff decays in a non-linear fashion. At a crude guess, it appears like the half-life of cultural materials is somewhere around 500-1,000 years. We've lost half (or more) of our cultural inheritance from the Middle Ages, at least three-quarters from the classical world (cf: Antikythera mechanism) and so on. For example, how many silent movies have we lost? Most of them (that's the 1920s) How many plays have we lost from Shakespeare's time? Was he even the most popular playwright in Elizabethan England? Apparently the Khmer had the biggest city in the world 1000 years ago (Angkor), but how much of their record has survived? (none, so far as I know).

When it comes to things like cloth, paper, and wood, they don't seem to survive more than about 2,000 years, except in rare, lucky situations involving deserts, bogs, and/or extreme cold. A lot of cultures have risen and fallen in the tropics (including the Amazon and Congo), but if they didn't leave behind pottery, stone, or earthwork remains, we have little way of knowing they even existed.

One big barrier right now is around 12th Century BC. With the Bronze Age Collapse, we lost continuity of most Mediterranean cultures aside from Egypt. That was at least 2,000 years of culture gone, and beyond that point, we depend on archaeology more than history (the same is true for China, as the Shang civilization apparently wrote on silk). History only works for the Middle East prior to around 2,000 BCE. Beyond about 7,000 years ago (5,000 BC), we're entirely dependent on archaeology everywhere, and beyond 10,000 years ago, we're getting into paleontology, and dealing with tiny scraps of subfossil remains and stone tools. There are a literal handful of stone tools left from the last interglacial 100,000 years ago or so. We assume that means that there weren't very many people around back then, but what physical evidence would have survived?

That's ultimately the problem: 10,000 years from now, our mostly likely remains are all the things we've done with bulldozers, a scattering of toxic waste sites, scraps of bronze and a few resilient plastics that wash up on beaches, and perhaps the shattered remains of some hydroelectric dams on desert rivers. Our culture and literature will be long, long gone, all the stuff we built with iron will have corroded away, and so on. We live in a brief moving window of time. Even now we're losing the oldest bits of our history to Mideast unrest, and eventually our history will be lost as well.

95:

The thing to remember is that human cultures "evolve" at bacterial speeds, as we've seen with the rapid adoption of social media and wireless technology. All of a sudden handwriting is becoming obsolete.

Conversely, re-engineering human biology takes at least a century (multiple generations) to get all the bugs out.

Furthermore, humans don't seem to be domesticated or domesticable. Unlike, say, dogs or marijuana, we don't respond well to controlled breeding. In the cases where we've observed highly controlled breeding and inbreeding (mostly in aristocracies) the results have been dysfunctional. Apparently, simply by luck, our genome isn't arranged well for controlled breeding to bring out and fix our best traits, as we can do with dogs, roses, or marijuana, among others. However, our culture is TOTALLY domesticable. Because we require culture to exist, control of culture is how we've become civilized.

That's why I don't think humans will change much going into the deep future. It's easier for us to, say, create a jungle foraging culture than it is for us to evolve into chimpanzoids. Ditto deep sea hunters, urban serfs, and so on. It's easier to give us boats than flippers.

That's not to say that some mad dictator won't rejigger people. The thing is, don't forget that culture will have coughed up a century's worth of solutions before the biological solutions have been proved out. Where old-style humans can survive, my suspicion is that they'll be around and very common.

96:

Yeah, just thought I'd ask. Saw that Tor.com disabled comments for their post on them.

97:

Thought you guys might find this interesting

http://www.bloomberg.com/news/articles/2016-06-07/china-pushes-plan-for-oceanic-space-station-in-south-china-sea

By comparison, the Mariana Trench is 11 km deep.

98:
Not really, I'm afraid. We're the classic example: we have enormously high literacy, but we're going to leave bugger-all behind for our successors, because essentially all of our writing is on media that fall apart after years to a few centuries.

But you're still positing a worldwide "gap" in which we can lose that knowledge, lose our ability to re-create and store information, and it rots aways before we can re-discover. Like I said in my post, I don't see that happening - even if we had a massive die-off on large stretches of the world, information stored and re-transmitted in the handful of remaining advanced, urbanized areas means it gets saved and cycled back in.

You're relying on the deep past too much as a precedent for what's going forwards. Things have fundamentally changed - even if the means of storage are more fragile, our ability to save information as long as civilization continues somewhere has gotten vastly easier. We're in unknown territory, where the main barrier to the preservation of knowledge is whether somebody continues it worthwhile to continue storing and migrating the data into new storage.

99:

But as we've seen, copying, even with errors, can extend the life of information. While modern media might be ephemeral, the ability to copy it with high fidelity, produce copies on different media (magnetic, dead trees, metal or glass) ensures that just like DNA, the information can be propagated across deep time, even if each instantiation is very epheral.

We can already get a glimpse of what that might mean for future cultures understanding ours. While we lose understanding after the death of people living at points in history, archived media, especially film (even as fiction) gives a much better glimpse of what a culture was like even when we have no direct experience of it. If Ancient Romans were making movies and taking photos and videos of their lives, we would have a much more visceral understanding of their culture than we have now based on artifacts and writings.

100:

Heteromeles, brilliant analogy re. the Polynesians. Humans disperse by any means necessary, whether from population pressure, curiosity, fear ("all our eggs in one basket" or "lifeboat" syndrome), greed (new areas to pillage), or ego ("I can't run this government, but if I ran my own government..."). Colonization seems almost a genetic imperative for humans, whatever the underlying rationale.

I'm probably wrong, but I get the impression that for the Polynesians, as for the Celts, there seemed to be a bit of a "rule" that the chief's eldest son got the village, the younger sons got horses, or in the case of the Polynesians, canoes, along with an invitation to start villages of their own. It wasn't quite this simple, because IIRC outlaws got disinvited to live on land as well.

Thing is, I don't really believe there's a genetic imperative, because conquerors tend to come rampaging in, take over the local aristocracy, and install themselves in the position where they get to write their own history. This ignores the other 90% of humanity who didn't migrate all that much. For instance, we've got the genetic evidence from Kennewick Man, who, even though he looked like Patrick Stewart, genetically was very similar to the Indians who still live in the area. Or we could talk about the Basques. Or the Welsh. Or the Polynesians after around 1200 CE.

This isn't to say that people don't go exploring and traveling. It's just problematic to extrapolate from the existence of traveler's tales and nomads to posit a genetic imperative for the entire species. The countervailing argument is that, in many places, it's so tricky to learn how to live there, that people spend generations figuring out how to get by, rather than picking up and moving every few years.

101:

So?

I was referring to the probability of hitting a planet by accident. at interstellar speeds. Aint going to happen.

If you were trying to do it deliberately you might be able to pull it off, but if you are trying to go somewhere and stop at the other end then a navigational error is very unlikely to see you hitting anything.

102:

Not really. Read my post again. Where's the gap between the Phoenicians and us? Where's the gap between the silent film era and ours? Where's the gap between the Elizabethan era and ours? Yet still stuff got lost.

Or, more to the point, how much digital content have you already lost because you could no longer read it, either because you didn't have the ability to read it or because the media fell apart? How much of your current digital library do you actually own? How many email accounts have you lost? How much of your online life will survive you? Have you even made any provisions to tell your heirs what they need to keep?

I've got an advantage right now, because I'm stuck with going through a dead relative's extensive library (quite a lot of old science fiction) and photo collection, trying to sell most of it, figuring out what to hold onto, and trying to wind down a digital life of many subscriptions and accounts. This winnowing process is starting to give me a fairly grim idea of how most stuff gets lost. Ultimately, it's because there's too much stuff to care about. The Great Library of Alexandria probably got lost simply due to warehouse fires, for example. If you don't spend all your time obsessively keeping some part of the past alive, why do you think someone will want to do that for your stuff?

In the longer term, the one lesson of history is that no regime lasts, and neither do all their artifacts. Some survive longer than others, but entropy is inexorable. That's what destroys history.


103:

I do note this though:
"SJWs Always Lie: Taking Down the Thought Police by Vox Day"

SO, according to this, VD/Beale is claiming that we lie all the time?
As in "All Cretans are Liars"?
Interesting, isn't he pushing his luck regarding libel-suits, from someone or other?

104:

Again off-topic.
Was just catching up on the Scrivener for iPad blog and came across this:
Author Charlie Stross On Scrivener – And How The iOS Version Fits In.

I'm still figuring it out--been busy with other things to give it much time. Definitely looks like it'll be useful once I do. Wondering how to make an update suggestion though; when viewing a research doc as Quick Reference, you can't make the text smaller than the main text, both windows zoom together. But that's not for here.

105:

Charlie noted: "Weird: it sounds like you're thinking in terms of humans using an RKV against their own planet."

Yes. My bad; I wrote this earlier in the morning before the coffee had kicked in, thus missed key context.

Charlie: "Does Not Compute! If you have the energy budget to send an RKV, you've got the energy budget to build lotsa nukes and deliver them locally."

If the premise is interstellar, throwing rocks seems unlikely to work. But if the context is intrasolar system, which is what I was thinking, it makes very good sense. (Again, missed the context.) To produce nukes, you need (i) a large supply of uranium or otherwise fissionable material and (ii) an infrastructure for extracting the appropriate isotopes (i.e., heavy-duty high-tech centrifuges). Both are feasible but not inevitable and may even be impossible for a society in its early stages. I was envisioning an asteroid belt civilization or even a lunar colony (e.g., "The Moon is a Harsh Mistress"). Rocks are cheaper and easier than nukes in those contexts.

Charlie: "You're also thinking like a shaved ape."

Yes, except for the shaved part. *G* See above re. missing context, which assumed apedom.

Charlie: "Terrorism" is a specific tactic that works because of the way primate threat-perception and aggression displays work. It's a pretty sure bet that a non-human tool-using species won't be wired quite the same way. There may be equivalent tactics...

I would bet on equivalent tactics. I suspect threat/aggression displays will be common in social organisms, but by no means universal. As in the old joke one of my female friends told me when I claimed to be a female chauvinist: "If women ruled the world, you're right that there would be no wars. Instead, everyone would tease everyone else until everyone developed eating disorders."

Charlie: "it's certain that inter-species diplomacy is going to be very strange, and war is the continuation of diplomacy by other means"

Having traveled in several non-European cultures and learned a few of their languages, I'm betting that more wars will be caused by mistranslations and misunderstandings than by all other factors combined. For example, consider inappropriate use of levels of politeness in Japanese, the lack of article use in modern Chinese even though articles exist (or failure to understand mianzi), and the "we use English because everyone outside the north hates Hindi" in India.

Charlie: "unless we're just talking all-out extermination. And if we're talking extermination ... then, why?"

Myriad reasons, ranging from "we don't like your skin color" (thinking like a shaved ape) to "you have real estate we need/prefer to our own/feel like taking away from you" (thinking like that most dangerous of alien species, the economist). Nobody said the reasons have to be good or even (for a truly alien race) comprehensible.

Charlie: "More likely, based on our current level of SETI, extra-terrestrial toolmaking superorganisms are sufficiently rare that our nearest neighbours will be hundreds to thousands of light years away"

Pace SETI (in which I took a university physics course many years back), I never bought the logic. There are so many reasons why we might fail to detect communications even from a nearby neighbor that the whole thing seems like an exercise in thinking like a shaved ape based on a shaved ape's assumptions. SETI certainly could work, since the science is sound if you accept the assumption; I just don't believe it's nearly as foolproof as the proponents believe. I dearly hope to be proven wrong; I'm not betting on it.

Charlie: "... an RKV would take millennia to hundreds of millennia to arrive. So: your justification for nuking the hell out of aliens who might not even exist by then at some time several thousand years in the future is ...?"

My justification was largely due to assuming an intrasolar system context. But any competent SF author (and I am NOT accusing you of not being one) should be able to come up with a dozen reasons. For example, here's a plausible one off the cuff: "We've been monitoring your transmissions for 50 years, and it's clear that you folks try to exterminate or economically conquer anyone with a different skin color, language, or ethos at the first available opportunity. The TV shows are scary enough; the historical documentaries are Case Nightmare Fleshtone material. Better by far to eliminate you now, before you develop good enough tech to reach us. We call this the precautionary principle."

106:

Your description of the problem of preserving our digital lives suggests a need for software and/or businesses devoted to ensuring the continued existence of those things that you want to be preserved. My guess is that we will start to see 'digital mausoleums/personal archiving' within no more than ten years.

107:

Right. It's an obvious consequence of Lamarckian inheritance, which affects our culture, society and (to some extent) intelligence. It's like the interesting question of exactly how diploid chromosomes affect evolution, though that's less easy, as the constants are less well-known. What is unclear is how much our social changes are going to affect our genome - currently, it's all chattering and we don't yet know enough to make species-level changes, but that could easily change within a relatively few decades. I don't see the classic SF reshaping in the near future, but I can easily imagine 'minor' changes getting out of hand and causing a species difference. Not least because the social aspects could well discourage inter-breeding. Several SF authors have explored aspects of this, and I find many of their speculations extremely plausible - though what will actually happen is anyone's guess!

108:

OK, intrasolar RKVs are a definite problem, along with sneaky asteroid attacks and biological warfare.

But I think we're a very long way away from having neighbours who might employ such measures or be a plausible target for such measures (as opposed to sending a Dragon capsule with half-a-dozen cops to serve a bankruptcy notice on that clunker of a space station).

109:

My guess is that we will start to see 'digital mausoleums/personal archiving' within no more than ten years.

Like this?

... or this?

110:

Furthermore, humans don't seem to be domesticated or domesticable. Unlike, say, dogs or marijuana, we don't respond well to controlled breeding. In the cases where we've observed highly controlled breeding and inbreeding (mostly in aristocracies) the results have been dysfunctional. Apparently, simply by luck, our genome isn't arranged well for controlled breeding to bring out and fix our best traits, as we can do with dogs, roses, or marijuana, among others.

Are you sure?

Controlled breeding involves culling the offspring who do not match the desired goal, and allowing the ones closest to that goal to breed. To the best of my knowledge, nobody has ever done this with humans. Aristocracies were the very opposite of controlled breeding -- all offspring were allowed to breed, including those who would have died early if they were anything but aristocracy.

Not to mention that modern humans exhibit the very same neotonous characteristics as domestic animals do -- we have (inadvertently) domesticated ourselves:

https://www.nextnature.net/2011/02/we-domesticated-ourselves/

http://io9.gizmodo.com/7-signs-that-humans-are-domestic-animals-1586580895

http://www.scientificamerican.com/article/being-more-infantile/

111:

On passing intelligible information into deep time, for various values of "deep" from a kiloyear on up, I've been paying somewhat casual attention to this for a while. Which has led me to the opinion that several technologies, usually involving glass / crystalline / ceramic media plus perhaps some gold, are available today. Attention would have to be paid to helping the readers boot-strap the encoding / language through Rosetta Stones, but that could be done unless the readers were totally alien, and probably even then (See "Omnilingual").

More important than the storage medium is the infrastructure involving selection of storage locations and passive protective measures. It would involve the will to do it right and modest amounts of money, like tens of millions of dollars, to accomplish, but it could be done. One thinks of the Mormons and their ancestry documentation projects. Or, on a more modest scale, the Nag Hammadi Library.

http://www.extremetech.com/extreme/132793-the-10-million-year-sapphire-hard-disk

http://www.atlasobscura.com/places/mormon-genealogical-archives

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

112:

As far as aristocracies go, you have got it completely wrong. Physical survival is not what they were or are breeding for, and you don't need to cull the aberrant members, but only ensure that their progeny do not become members of the aristocracy. Until they get to the point of being unable to keep their numbers up, aristocracies have very strong mechanisms for effectively expelling the offspring of 'unsuitable' members.

113:

Neoteny is over-rated in humans.

First, it pops up in all sorts of circumstances where it's useful for the organism to breed faster. These include annual plants (most of which have perennial ancestors), insular dwarfs (where selection favors those that hit adolescence earlier and hence don't grow as much), among others. It's not the infallible sign of domestication, just the sign of a lazy essay writer.

Second, a lot of the traits that are read as neotenous in humans can equally be read as adaptations to using fire. The "baby face" stuff is actually a reduction of our jaws, since cooked food is easier to chew, and our relatively larger brains are facilitated by shrinking our GI tract (the other big energy hog in our bodies aside from our brains) by using cooking to preprocess a lot of our food. Cooking essentially is an external digestion system, and we're totally dependent on it. Try raising a child on a raw food diet if you don't believe me (actually, don't).

The thing about domestication is that it's the manipulation of a population of a species (generally not the whole species) by controlling their breeding and selecting for specific traits in the offspring. We're not the only species that domesticates other species (some ant species do it too--you can tell by the number of social parasites they have). Despite what you say, human aristocrats are often bred to other aristocrats and selected rather stringently for political qualities. You might be thinking of the upper class twits of modern England, but back not so many centuries, the less capable males were culled out, either dying on the battlefield or sterile in a monastery. This was also true for the Ottomans, who indulged in fratricide on the grand scale. Despite all this, aristocracy didn't breed better leaders.

The general problem with domestication is that most species don't take to it very well. That's why we have so much trouble keeping them in zoos or in gardens--they just don't breed in captivity. Many others, like apples and oaks, don't take to selection worth a damn, because the traits that are essential are controlled by too many genes to be readily manipulable by selection. The cultivars we have grow from these are clones, and they don't breed true any more than humans do. Humans are one of the many organisms that, for the most part, don't reproduce well in captivity, especially when the lives of their offspring are under others' control (you would do it?). Also, our most desirable traits, like intelligence, charisma, loyalty, leadership qualities, athletic talent, and so forth, all seem to be controlled by massive suites of genes, plus environment, plus epigenetics, making it hard for them to be bred true under any program.

Finally, you've got to look at the over-riding factor for humans: culture. Humans inherit as much from their culture as we do from their genes, and the biologists who think that humans are domesticated animals totally miss this. I've yet to see one of them talk about culture. It's massively easier to coerce and teach someone to become a leader (or a slave) than it is to create biologically true-breeding castes of leaders and slaves. Indeed, culture is far more versatile than biology: a captured aristocrat can be enslaved, but a captured Leader Caste individual would have to be killed, as he would be useless as a slave caste worker. Indeed, with a rapidly changing culture, biological castes are massively inefficient. They only make sense in a culture that hasn't innovated in many generations.

114:

On a totally new topic, there's another way to divide up Space operatic cultures that we aren't talking about biosphere family trees.

This depends on the new relationships humans (or other species) make when we settle on a new planet. There's going to be this Columbian-style interchange between the local biosphere and the bit of the terran biosphere brought in by the human colonists. Even if the organisms have DNA, proteins, and carbohydrates that all have the opposite chirality to ours, there are going to be microbes that can use bits of us for substrate, just as some of our microbes will be able to use bits of the new world for substrate.*

As the colony becomes successful, it will have its own hybrid biome. The fun part happens when that colony wants to trade with other planets with different biospheres or founds its own colonies and deals with further admixtures of alien biospheres.

Over time, and over many colonizations, successful clades composed of many intermixed biospheres will develop. Their biospheres will be successful interminglings of Earth and colonial biospheres, of the species from amny worlds that can survive interstellar travel and spread on new planets. A lot of these will be new crops and domesticated species, but an equal number will be pests and pathogens (and probably some parasites as well).

I strongly suspect that some biosphere "clades" won't want to interact with others. For example, imagine a planet (say Earth in 10,000 years) where the local bacteria are really adept at breaking down plastics, and the local colonists have had to learn to insulate all their electrical systems with something else. Or a planet where everyone is immune to the local face-eating fungus, because they all descend from the few survivors who had inedible faces, but they all host it. Would you want to trade with them? The result of accepting a shipment of their ever-so-desirable greenhouse equipment might be a face-eating fungus that kills 99% of your colony. Or microbes that eat all your electrical systems. Or unkillable biofilms that clog all your waste water treatment facilities. Or whatever.

What I'm looking for are some good terms to use for this process of biosphere intermingling and segregation. It's sort of like cladogenesis for bacteria ramped up to the scale of entire biospheres, but I'm not sure clades has the same ring as empires. Or does it?

What kind of language would you use to talk about the interactions among different clades? How would the politics work? What is the status of Earth in such a system?

* I should point out that I'm not worried about viruses or parasites in the short term. While I suspect that DNA will prove to be widespread, I don't think that alien DNA will use the same genetic code as we do. Because viruses depend on DNA hacks, alien viruses will be so much garbage code, even if they do make it inside our cells. The real threats are microbes and larger life forms that can simply grow on bits of us, our equipment, and our biosphere, without decoding us first. Space Gangrene is likely a bigger threat than Space Flu.

115:

I caught a panel at long-ago worldcon, which looked at the issue of a relatavistic kill vehicle through the paranoid lens of Cold War threat analysis. (This was very long ago. There was still a Soviet Union, and the Cold War was winding down) Basically, if you detected a nearby civilisation with the capability of building a RKV, how could you know they weren't about to do so? In which case, only a pre-emptive strike could gurantee survival. Especially as they might be following the same logic...

I think this was the guy
https://en.wikipedia.org/wiki/Charles_R._Pellegrino

116:

Heteromeles [113] and [114]: Very neatly said. *bows*

I think you're bang-on about microbes versus viruses, and definitely about the ridiculously complex and nasty quarantine problems that will arise when shipping products between biospheres. You can see the tip of that iceberg just by looking at the problems we already have with invasive species.

117:

That's making a lot of assumptions about how easy it is to build AIs, especially stable ones. It might be easier to cart or create orthowombs at the other end then to build the suitable chip foundries.

118:

I was thinking more of something that one could use to automatically back up a Facebook page, your personal files, your email account, and so on, into a 'guaranteed to still be readable next century' format. But those libraries are a definite start.

I can imagine that some people will want to bequeath copies of their digital lives and all of their files to their children. After a few generations such a practice could add up to an awful amount of data. (If all of your descendants are provided with a copy your trivia may remain potentially available for a long long time)

119:

No, the problem is simpler than this: stuff decays in a non-linear fashion. At a crude guess, it appears like the half-life of cultural materials is somewhere around 500-1,000 years. We've lost half (or more) of our cultural inheritance from the Middle Ages, at least three-quarters from the classical world (cf: Antikythera mechanism) and so on. For example, how many silent movies have we lost? Most of them (that's the 1920s) How many plays have we lost from Shakespeare's time?

...

At a crude guess, it appears like the half-life of radioactive materials is somewhere around 500-1,000 years.

See the problem? There is no single half-life of radioactive or of cultural materials. How many of the Ten Commandments have been lost in the past thousand years? None of them. They're highly conserved. They're not just lucky atoms that have managed to survive many generations of decay by sheer chance, like the last 0.00001% of a polonium sample. In the CRC Handbook of Culture and Posterity they are currently listed as "observationally stable."

Newton's laws of motions, Napier's logarithms, and the calculus are likewise cultural materials with much longer half lives than most things first published in the 17th century. The continuing survival of that knowledge doesn't rest on whether they published at the time via acid paper, rag paper, or clay tablets. If there is a good argument for the eventual forgetting of common mathematical and scientific knowledge, it's not one that can be extrapolated from observations of how we lose old email and personal photographs.

120:

There are hidden assumptions in your text. The largest is that there is going to be no substantial change in humans over the next several million years; another is that humans in their current form, or close to it, are going to be the dominant species on Earth at that time.

I think there are very large holes in both assumptions. Even if the basic biology of humans remains unaltered (which I find rather unbelievable; it's very likely that a fix of the point mutation that causes us to need vitamin C would become popular if available, for example) we are rather likely to have a second internal ecosystem other than the current microbiome; one based on silicon or maybe carbon nanofibres, for example. Which in turn would probably mean a lifespan extended by at least one order of magnitude. As well as a very powerful connection to various mechanisms which would enhance human thinking power immensely; imagine having a direct neural interface running a suite of (to use today's examples) Wikipedia, Mathlab and the search engine of your choice.

As for the second assumption; well, human brain processing power for $1000 is likely to be available around 2030. The software is, of course, a problem. It is very unlikely to stop there, and strong AI (though its emergence time is very uncertain, we simply don't understand consciousness well enough) is IMHO certain to emerge in the next 100 years, never mind the next million. And then continue to get exponentially more powerful.

I have a little story germ, although not a clue what to do with it; one fine day in around 2035, someone starts talking to Siri on his iPhone 15 (or Cortana on his brand spanking new Windows 17 phone) and suddenly realises that the "lady" has become sapient without anyone's noticing.

I hope our new owners will be kind to their pets.

121:

I commend the book Central Station by Lavie Tidhar unto you.

122:

It also seems comparatively hard to even find SF stories that are set in our own solar system. There are obviously a number of high-profile examples recently, but they stand up against the huge mass of people zipping about from star to star like it's going to the corner grocery.

Over the last few decades it has become to most anyone who might read sf or watch a tv show that people can't live anywhere else in the solar system AKA "The Martian Chronicles". This was still made into a TV mini series (in the US at least) in the later 80s. Today it just would not fly.

123:

"...the ability to copy it with high fidelity... ensures that just like DNA, the information can be propagated across deep time..."

Can be, sure, but won't be. Information propagation by means of some cultural institution devoted to continually re-copying it lasts only as long as does the culture supporting the institution. Even a shift in the mores of the culture can result in corruption of the information. For information to be preserved over long periods requires it to be in some form that will endure regardless of curation - whether that's carving on stone tablets, or duplication to such an extent that a few of the millions of copies happen by chance to survive, or something intermediate between the two like writing books. It also helps a lot for it to be in a form which is recognisable and readable by the unaided senses: I like Charlie's idea of memory diamond as a highly durable record, but archaeologists of the distant future are unlikely to see them as anything other than pretty stones.

"We can already get a glimpse of what that might mean for future cultures understanding ours. While we lose understanding after the death of people living at points in history, archived media, especially film (even as fiction) gives a much better glimpse of what a culture was like even when we have no direct experience of it."

That's all Folks...

124:

Helios 1 and 2 both hit around 70 km/s (~150 kilomiles per hour) and Juno should get up to those velocities or a bit faster as it orbits Jupiter up close. The new Solar Probe Plus should end up around 3 times as fast by swinging very close to our local gigantic skyfire.

New Horizons was the fastest direct launch velocity though, but yeah it's pretty slow for interstellar discussions, all the more reason why I hate anti-nuclear activists with the burning rage of many myriad skyfires.

125:

What about a probe that does a hard landing? If we launch, say, 1kg of shielding followed by a 10g probe, we could just smash the probe into the atmosphere of the target world at .3c(100Mm/s) using a fragment of the shield as ablative protection. Sure, it'll be a 1Gm/s^2 accelleration for that last 0.1s, but if we can get a whole kilogramme up to 0.3c I think we should be able to manage that. If we carefully arrange the shield we could even use the impact as a signal (chromium red for bad, cadmium green for good, something else for no oxygen)

Then there's the problem for the locals of distinguishing a probe from an attack :)

126:

dementia

Has anyone thought of what to do with the old folks on these missions?

Says he who is dealing with (and recently dealt with) an aging parent in law who's more and more impossible to deal with in a rational manner. And who has many friends in similar situations.

127:

Beyond about 7,000 years ago (5,000 BC), we're entirely dependent on archaeology everywhere, and beyond 10,000 years ago, we're getting into paleontology, and dealing with tiny scraps of subfossil remains and stone tools.

My understanding is that some of what you call archaeology our locals here call "oral history" in the latest language that they've taken up. There's immense fun to be had wandering round physically protected areas looking for signs of habitation and speculating about "what it all means" for stuff that has only recently been radioisotope datable (viz, >~40kilo-years ago), but I know-from-seeing that there is so much "aboriginal stuff" in Australia that the challenge is not finding it but learning anything useful about whatever bit you happen to be interested in.

It's not that I disagree with your general thrust, it's that picking apart the fine print of oral traditions and calling some bits history and other bits myth is a tricky game. Often one that's upended when science progresses (for example the transition from "oh they have a flood myth too" into "10-15kya the sea level rose and this land bridge went under"). My bet is that we're going to see another hiccup when evidence of northern Australian agriculture from > 5kya surfaces.

My expectation is that future researchers will have a wide collection of weird stuff to play with, because we are even now starting to see people acting on the problem of information fading over sub-millenia intervals. I am specifically thinking of some of the multi-scale etching/pocking stuff that's designed to grab attention and reward analysis down to nigh-atomic level. "Time capsules" and the Rosetta Disk are examples of the idea, but my broader point is that even a small group of people with modern technology can make a significant difference, just by making something like that and distributing copies widely.

128:

I do wonder whether it might be possible to co-opt DNA for record-keeping. Not in the "hard disks made of DNA" sense, but by adding error checking and an extra gene or two to our own chromosomes. A future scientist might well start with "I wonder why we have X*Y and X*X, but no X** etc?" then notice that every spacefaring species also has a * gene and they're all very, very similar.

But I suspect that the long now people will be replaced/grow into "no, really, our focus on LONG" with monoliths on outer planets that can be turned into smart language-learning history-bots by following the instructions printed on the surface. I remain hopeful that at some point we will have a 2001-the-book-of-the-movie-of-the-book-of-the-short-story moment :)

129:

Not to insult the aboriginal myth keepers, but I'm also unsure how much of it is genuine oral transmission, and how much of it is stories based on evidence.

For example, the American Southwest is littered with stories about ancient floods and monsters that lived in the floods, but the evidence of dry lakes, flood lines, dead fish bones, and fossils eroding out of rock is also extremely obvious. While we know, from careful analysis, that Indians were living around those lakes more than 10,000 years ago, it's unclear whether the stories they tell about floods and monsters are oral history from the end of the Pleistocene, or whether they're spinning stories to explain the obvious evidence all around them.

The other thing about less scrupulous people (including Indians) is that they go to school and museums and movies too, and so their stories can suddenly turn into stuff about interacting with dinosaurs and such. Usually this gets spotted eventually, as when their ancestral dragon/dinosaurs look like some 1930s dinosaur reconstruction, and later science demonstrates that there's no way that the animal in question could have ever looked that way (this is something Adrienne Mayer covered in a book).

Again, this isn't to insult old legends, because to be blunt, I don't know what's in them. Thing is, unless they have verifiable details, as you note, it's hard to separate fact from imagination in the old stories.

Also, even if the Aborigines have stories going back 50,000 years to the settlement of Australia, that's less than half of the history of our species. There's a lot we don't know about ourselves.

130:

Greg Bear (?) "Hegira"

131:
Zeroth law of science fiction - people want to read stories about people.

That's a fairly stupid law. It generalizes too much and is vague at the same time.

I for one often find myself more interested in the setting. The hypothetical problems, the solutions thereof, things done casually that would seem utterly crazy today. And how progress and technology shape society, how things are done differently.

Of course those aspects generally involve people, but it doesn't mean it has to be about them. They can serve as plot vehicles or drivers, as narrators, as our window into that world.

And if we use a sufficiently broad definition of "people", something along the lines of "intelligent actors" instead of "humans" then all that it manages to say is that our story is not centered around dead matter or a report on non-sentient life.

132:

Another trope is stupid people in space. See "Prometheus".
It's hard to do SF where everyone is REALLY bright.

133:

Propulsion, heat, and shielding are technical problems that can be solved, as technical problems have always been solved. The prognosticator who naysays such is like those who said nobody would ever go to the moon, or heavier than air flight was impossible. But yes, these problems should not be ignored, and the plausibility of projections of interstellar travel should be judged partly on inclusion of some sort of thought through proposed solution to them. However, huge technical problems like this are solved by teams of the best and brightest of entire societies, so projected technologies need merely be plausible, not compelling. Jules Verne could hardly be faulted for failing to provide detailed schematics for the Nautilus.

How about ejecting heat with reaction mass? Couldn't you do that?

134:

I like a character or characters presented well enough that I can engage with them and root for them as they surmount problems. It's fun and improving to see how someone else is doing it. The problems don't have to be all about people though. A good story should be about challenges, but they don't have to be social challenges, though they almost always are at least partly about personal challenges--how a character or group confronts hardship internally and is probably changed by it. If you want to call that "about people".

135:

It's hard to do SF where everyone is REALLY bright.
That also has its problems ... see "Protector" by Niven

136:

Has anyone thought of what to do with the old folks on these missions?

No they haven't, except for the odd sociopathic eskimos-and-ice-floes suggestion.

I feel your pain. (Only with my own parents.)

This raises an important point about "small" interstellar missions (less than several thousand crew): to train up a new crew member to be useful may well take 20-30 years, they then remain useful for 30-50 years, but then there's a period of infirmity/disability/decline, and even before the final decline there's the cognitive decline that sets in from age 50-60 or so onwards. Assuming life expectancy of 80 years, only about half the population will be able to work at full capability, a quarter will be dependents/in training, and another eighth to a quarter will be dependents/retirees/in decline.

Our politicians today tend to speak in terms of unemployment rates. But if you look at the full employment rate in our societies, where someone is fully employed if they have a full-time job at the level for which they are educated/trained, it's typically down around the 30% mark, maxing out around 40% in a society with virtually zero unemployment.

Human societies are inefficient; traditional navies and similar organizations were able to externalize a whole bunch of societal costs that a generation ship can't.

137:

True; it's hard enough to keep a tracking radar beam "on target" across a few hundred km, and these things are big, like about 1 full degree of arc across the primary beam!

138:

Land; we're not making a whole lot more of that right now!

139:

"Second, a lot of the traits that are read as neotenous in humans can equally be read as adaptations to using fire."

And clothing. The claim that cursorial hunting on the savanna caused hairlessness is implausible, but its use in reducing the parasite load is clear. And the effect of clothing in allowing thin skin is obvious.

"Humans inherit as much from their culture as we do from their genes, and the biologists who think that humans are domesticated animals totally miss this."

You do know that is true for domesticated animals' behaviours, as well, don't you? I agree that we are more extreme in that respect, but I take their point - we are auto-hyper-domesticated animals :-)

140:

"Space Gangrene is likely a bigger threat than Space Flu."

Oh, yes, and allergic reactions, toxic waste and decomposition products etc. of non-parasites are bigger threats again. Think alien Clostridium botulinum or Karenia brevis.

141:

I suspect (and I believe I've said this here before) the first successful space colony ship is most likely to be staffed with the Undeserving Poor, criminals, slaves, or political prisoners. The realities of colonising space are these: it's expensive, it's a one-way journey, there's a thwackingly high chance of failure, and given all that, it's something which is best performed by "expendables". So you offer the "opportunity" of colonising space to long term or life sentence prisoners, to political prisoners, to anyone facing the possibility of execution, find a bunch of equally expendable wardens (recruit from the lower classes or from the poverty-stricken who have no other chance of social or economic advancement), and hope they will all grab at the chance of survival with both hands. Then you send them off, and forget about them - either they'll survive or they won't, and either way, there's sod all you're able to do about it from here.

I'm living in a nation which was founded through a very similar process on the part of European colonialists. (*Waves from Australia*). Do have a look at our early history if you want to get an idea of what's going to be involved. Here's a hint: it won't be pleasant.

Something which a lot of the US-based romantics forget: the "high frontier" expansion years weren't even possible until the North Americas had been colonised by Europeans for at least two centuries (the process of colonialism started in the 1500s, the big "high frontier" expansionist years were in the 1800s). So there's a lot of infrastructure building and consolidation happening before you're able to expand. The height of British colonial expansion and power was the Victorian period, after which their power and ability to control their colonies dropped off rapidly - and the Victorian period was the climax of a colonial period which had arguably started in the 1400s.

Colonisation is expensive, and it involves a lot of hard work at the other end (which is why Earth-bound colonies tended to rely heavily on exploiting the natives, or on slave labour, or both, in order to get the hard work of infrastructure creation done). Again, put down the "high frontier" romances, and start actually looking at the history of how colonial exploitation happened - and note the high death toll (usually, admittedly, among the "natives" or slaves used for infrastructure creation, rather than the privileged colonial exploiters, but the high death toll is still there), note the years and years of living (for the majority of colonists) with a reduced standard of living, note the amount of money which has to be sunk into the business of colonisation before you start getting a return, and note we have NO GUARANTEE that colonial exploitation of space will ever produce a result for us here on Earth.

142:

It's fairly well-known what classes of knowledge get preserved, and what gets lost, and I can even describe one example from personal observation over 50 years in IT. The theory gets preserved well, but can be lost when a more general one replaces it without superseding it in all areas or for all purposes. Observational data and even measured factors last a lot less well, as do the practical aspects (i.e. the engineering to the physics). And the knowledge of how to bootstrap a technology often vanishes completely.

There are a lot of IT people here. How many know how to start designing, debug, program and debug the programs for a first computer? Remember, you have NO simulation, testing or debugging tools until you have built them - which includes compilers, editors and more - and practical ones almost all are computerised.

Geology, chemistry and metallurgy are perhaps the worst area, where you can't use the theory until you already have much of the technology, and the technology that has been preserved is critically dependent on other advanced technology. But the same applies (to a letter extent) to things like fire, clothing, fishing and so on.

143:

''"Has anyone thought of what to do with the old folks on these missions?"
No they haven't, except for the odd sociopathic eskimos-and-ice-floes suggestion.''

I have seen reasonable consideration of that, and I dispute that euthanasia (even involuntary) is necessarily sociopathic. My parents' generation are now all dead, but several of their deaths were a merciful release after some years of misery.

One of the things in my social thought-experiments was how to increase the 50% productive lifetime and the 30% 'full employment' (though I was considering primary and secondary productivity, so my figure was more like 10% for the UK). I think that it would be fairly easy to get the former up to 70%, which would also reduce dementia ("use it or lose it", remember?), and possible to get the latter up to 50%. The former would be pretty easy today, because we have plenty of examples of how to do it.

The social engineering for the latter would have to be wildly different from anything currently proposed, uncompromisingly non-democratic, egalitarian and elitist (yes, all of them), and politically unacceptable to left, right, middle and any of the mainstream sideways directions, though it could actually be close to a Utopia for 99% of the population. And, no, I am NOT talking about human robots :-(

144:

There are a lot of IT people here. How many know how to start designing, debug, program and debug the programs for a first computer? Remember, you have NO simulation, testing or debugging tools until you have built them - which includes compilers, editors and more - and practical ones almost all are computerised.

Depends on what you mean by "a first computer". I am fairly certain that I could build and program a computer using relays (and assorted other electronics as peripherals). It would mean that I'd need to have the relays and other stuff, though. It wouldn't be fast or very complex, of course.

Electron tubes, maybe - they are more fiddly than relays. Transistors in an usable form, yes, that'd be doable.
Doing more modern stuff would be more difficult for me - my VHDL was pretty bad almost twenty years ago and the state of that art has gone very far since then.

This wouldn't be easy, of course. I still remember enough logic to build logic out of NAND (or NOR) gates and there is some stuff which would need much pencil, paper, and rubber.

I've been playing with the idea of building a computer out of integrated NAND gates, but it's quite a hassle, especially nowadays when a working networking computer costs very little.

Programming that - well, yeah. I could start with the knowledge of programming languages and maybe even design the processor to have some advanced features to help with that. Doable, and I remember that getting Turbo Pascal was pretty nice. A debugger would have been nice, but I learned enough to survive the "write the interrupt table full of garbage" bugs - which would have been pretty hard to debug anyway...

145:

Again, put down the "high frontier" romances, and start actually looking at the history of how colonial exploitation happened - and note the high death toll (usually, admittedly, among the "natives" or slaves used for infrastructure creation, rather than the privileged colonial exploiters,

Agree with one reservation: the colonial infrastructure enterprises you describe happened largely when mobile energy sources were down to muscle power. Windmills and watermills were available but non-portable, so breaking ground had to be done by hand. Hence the slave labour.

But today we've got robots, and robots are probably a lot cheaper than humans when it comes to the maintenance on-costs of operating in space: not autonomous robots necessarily, but teleoperator-controlled humanoid multi-jointed construction machinery that a human in a pressurized tin can can operate comfortably without the complexities and vulnerabilities of being present on a construction site in a space suit. This is already how ISS construction works -- wherever possible stuff is moved into position using the Canadarms; astronauts only spacewalk when it's absolutely essential to do really fiddly stuff, and every few years the robotics outside the station get that little bit better.

So my take on early space colonization is going to involve; pressurized habitat with lots of rock/dirt carved out of an asteroid for radiation shielding: canned apes residing inside the habitat controlling construction robots and heavy machinery outside: only as many humans on-site as are necessary to mitigate the control-lag imposed by the speed of light on operations controlled directly from Earth. The humans will be the impoverished aristocrats running the plantations, or at least the overseers, while robots do the fieldwork and break down in droves (and get dragged back inside to be fixed by human technicians).

146:

I think that it would be fairly easy to get the former up to 70%, which would also reduce dementia ("use it or lose it", remember?),

I think you're wildly optimistic. One of the biggest problems with dementia is that accurate diagnosis require slicing up the brain of a person already dead. The use or lose it therapy doesn't work with somewhere between 10% and 90% of the elderly. For some it only delays by a year or two. And the wide range in stats is due the lack of widespread controlled studies.

And trust me, people in these states are loath to admit they are having issues. To the extend of some getting getting violent in their denial. I've seen this with blood and in law relatives and mostall my friends with elderly parents have similar stories. In the US car driving is a major tipping point. I wonder what it is in other cultures?

I'm 62 and still productive. (At least my clients think so and keep paying me decent money.) Many of my friends are also in the same state. But there are many people who turn 60 and are already on an obvious down slope. And it's very difficult to determine if it is biology or environment. Sometimes it appears obvious (to an outsider) as to which it is but after spending over 6 years with my mother in law in close contact I'm not so sure many people can actually tell. The people with the most observational time also tend to have a huge emotional connection which flavors interpretations. Both good and bad.

147:

There are a lot of IT ... all are computerised.

Pretty much as Mikko's #144; I don't know where the cut-of will be, but I think the older members will have at least been exposed to logic gates, programming word by word using dip switches, assembler...

Next question - Are we counting having programs on punch cards or pre-punched tape as day 1, or do we have to learn to make punches and readers first?

148:

Grin :-) You have just demonstrated my points! Those aren't the techniques, and they wouldn't help with the problems that arise in practice. Programming languages? Interrupt tables? You have a LONG way to go before you get there. I wasn't a hardware designer, but did learn to program by being dropped in at the deep end on a first generation machine on an existing, buggy program (octal machine code, of course). I may have been the last person still in full-time employment with such experience when I retired last year. To paws4thot: no, those peripherals came first, and were used for data logging and machine control. You could probably do the job, but would need to reinvent many of the old techniques and tricks. And that's actually an easy example.

Try another: could you make a shelter, fire, a net and clothing, starting bare-arse naked (and assuming you could survive until then)? It's tricker than people think, and the problems are NOT where most people expect them. For example, I could (and have) make netting needles and nets, and the only seriously tricky part is making the cord - but the knowledge of how to make and use netting needles is now fairly rare. Reinventing that, if you didn't know about them, would be seriously non-trivial.

149:

I am aware of that, but I am also aware of its relative rarity among the communities to which I belong, and later onset - and I am 68, with that community being of comparable age. Note that I said 70% of lifetime as productive, but that was (a) for the population, (b) was NOT thinking of simply extending working life, and (c) was NOT assuming the 'preserve heartbeat at all costs' dogma. For example, teaching would be largely done by the elderly - which, inter alia, reduces dementia significantly. And I would make more productive use out of those in training, much as is done in some communities today (NOT as in industrial revolution sweatshops).

The harder job is making more of the population usefully employable.

150:

I'm not sure about use it or lose it.

I don't have any real evidence, but still. A couple of things occur to me.

Alice is still teaching at an advanced age, watch how Alice's teaching job protects her from dementia. Bob retired 3 years ago, he's on the downhill now... poor Bob.

That's how the fables go, but did Bob retire because he was having trouble organising lessons? Did he stop enjoying teaching because it was getting too hard? Untangling cause and effect is tough when people self select their paths through life.

Then there's another related issue that I have some experience with. I was really really good at operating when diving on air at considerable depths. I was pretty regularly air diving for fun in the 70 to 80 metre range with occasional excursions below 80. Not in clear tropical ocean but in things like old cable tunnels, shipwrecks and restricted caves. Thinking at that depth is virtually impossible, so I didn't. I had all sorts of well practised routines that I would call if required but my capacity for original thought or 'on the fly' planning was approximately nil. I would literally write what to do when on my hand and follow the instructions my thinking self had laid down. Unexpected situations were handled very very badly or not at all.

How much of what someone who is 'using it' is doing, is actually just coping tricks rather than thinking on the fly? It's hard to tell from the outside.

In all the use it or lose it idea seems a little short on evidence and anything that could collect evidence would be just absurdly unethical.

151:

I was aware that even getting to "assembler" (never mind 'for what machine'; I'm talking about it as a concept) was a step on from dip switches. Hence the question about using punched media, since this is the point where we can sensibly create an assembly language, and maybe even start thinking about things like keyboard and screen drivers. (BTW I share an office with an old 12" demountable single platter magnetic disc with a totally classic head crash on it; one of my first tasks in this job was to destroy punched media for our DEC PDP-7; I share the building with a 1960s Data General that needs booted up from 0.5" 9 track magnetic tape...)

152:

I suggest looking up the evidence - it's overwhelming. This is NOT about personal protection from dementia, nor about eliminating it, but about reducing it in the population and as a drain on society. Your argument from anecdata is, at best, misleading. The currently most practical key to reducing and slowing dementia is staying physically and mentally active (both are important).

153:

Yes. Those are second generation, perhaps even third :-)

155:

Oh I agree. In fact, IIRC from the likes of Colossus, the "Turing Bombes" etc, the first generation is really more "computing engines" which are hard wired to a single task but since we positively know the history I was hoping to use it to skip hard-wired and just use dip switches to develop the drivers for I/O devices and channels.

156:

Note also the recent research suggesting that some forms of Alzheimer's might well be renamed "Type-III Diabetes"; insulin is present as a CNS neurotransmitter and there are tantalizing hints that there's an autoimmune effect present in dementia, just as in Type-I diabetes.

There's a huge amount we don't know about the dementias because dementia is a symptom, not a disease process in its own right, and it's really hard to study a living brain non-destructively. (Similarly, it's only in the past decade that we've begun to grapple with cancer at the genetic level, recognizing that some "types" of cancer actually emerge from five different genetic malfunctions that manifest the same way, for example.)

158:

Right. Type II diabetes and many forms of cancer have a lot in common - i.e. we could reduce them somewhat by some draconian social engineering, but that would still not eliminate them. The anti-smoking campaign being a classic example, though not as draconian as it could be. I was assuming just the methods that are known to work at a population level, to reduce the cost (to society) of dementia to significantly less than it is today. But not to a small fraction of its current cost, because we don't know how to do that.

159:

You have just demonstrated my points! Those aren't the techniques, and they wouldn't help with the problems that arise in practice. Programming languages? Interrupt tables? You have a LONG way to go before you get there.

Ah, no - interrupt tables wouldn't be a thing with that processor. It was just something that I did play with a long time ago.

Programming without a compiler, on a (simple) processor I have planned and built myself, from for example those relays? I'd still be fairly certain I could do it. If I had punch paper tape readers and writers (which were in use *before* the computers) I'd probably use those and start with something with little memory, stack or anything else fancy - but even those are not impossible.

A computer like this would be quite large, obviously.

The main thing here is that I know what is possible and what has been already done, even if I don't remember the specifics.

160:

Any big space system that's useful for beamed power is going to be fun as a weapon. Heck, I think Niven even pointed out any nifty space propulsion is weapon. Everything from torchship exhaust to kinetic impact, to orion fission weapons, to beamed power arrays.

I like beamed power from solar because done right, its an amazing tool for solar system infrastructure as well as launching probes. The problem is the easiest and best infrastructure tools are series of mirrors which re-direct solar energy. Using a series of collector, you can put a lot of energy on small asteroids to mine them. (and use a spin to separate the resulting compounds by weight). It's gonna be hard to run it over large enough space though due to speed of light lag (John Ringo loved the concept in his life free or die books, which he used imported alien FTL comms to get around). I think though you could get a fair amount of power even with those limits by restricting the distance involved between collectors.

Alas the power I describe is pure sunlight, not coherent and thus unsuitable for deep space work. Otoh you might be able to beam the light to power your giant laser. Still is a big death ray as well as an infrastructure tool. Niven loved them in 'Madness has its Place'.

Orion is still probably the only near term technically feasible interstellar tech. But I don't think any other contenders would be politically feasible either.

Maybe we'll be lucky and find some Kerr-newman black holes and manipulate their spin as a drive ala the McAndrew stories.

161:
Information propagation by means of some cultural institution devoted to continually re-copying it lasts only as long as does the culture supporting the institution.

Obviously DNA doesn't have any "institution" to ensure copying. Computers automatically handling copying can ensure continuity. Does this require an institution? I don't think so, but clearly institution owned server farms will help to ensure that copying continues on a large scale.

That's all Folks...

A reference to an SF short story about the remains of a Disney cartoon being interpreted by Venusians?

162:

Getting back to planet habitability

http://www.businessinsider.com/goldilocks-exoplanet-habitability-internal-heat-2016-8

I wonder how long until we have a telescope capable of confirming plate tectonics on nearby worlds?

163:

Yes, you could do it - even someone with no experience could - but it's non-trivial to reinvent the tricks, and there are quite a lot that don't scale up beyond very small-scale systems. The system I used allowed the inspection and setting of any (most?) store locations; you can do it without, if you can execute an instruction to load them into the accumulator and inspect that. But without either of those? Yes, it can be done, but the time needed hits the ceiling. As you said, knowing that something can be done and vaguely how saves a LOT of time.

164:

I was thinking in the nearer future than you are. At 50-70 years out, I'd expect sets of cloned humans to be the first space colonizers in order to reduce the biological unknowns these travelers might have to deal with. 'Reference' clones would remain on Earth, probably in isolation.

Senility ... the immune system (and diabetes is one of the immune disease) apparently plays a part in overall mental health/fitness. Interestingly, there's some research that shows that when allergies act up, so does neurogenesis. There's also some research about how some older antihistamines can screw up the brain, specifically memory encoding. Imagine if we could control our immune systems to rev up production of specific antibodies or whatever signalling compounds, we could self-engineer ourselves on demand.

About the infant brought to hospital with malnutrition from vegan diet: Since my digestive system includes organs designed to digest/process different categories of foods/nutrients, it only makes sense to provide it with the full range of foods so as to keep those organs healthy/functional. At the same time, my body has its own bunch of sensitivities/allergies, so it's also thanks very much, but I'll take a pass on XXX even if everyone else swears it's the ultimate health or super-food.

165:

You still find it in Anime and Video games. Gundam series are still almost always about Earth versus colonies. The classic timeline had them as O'Neil colonies.

There's plenty of demand for people in space in the future, but mostly industrial. Space mining is potentially the ecological savior as we can push most of the pollution into space. Might take centuries for that to happen as it requires cheaper lift though to make it really work.

But there will still be a desire for boots on the ground exploration of mars and the major gas giant moons. Especially Titan and Europa.

166:

The play "Wine of India" solves the problem of decrepitude by medical intervention. Your body stays young, but you have to voluntarily die at age 70. We seem to be moving forward with improvement in slowing aging, although we haven't yet come to grips with dying on demand.

I do think the concept of sending living, humans to the stars as colonists makes no sense with current physics. Despite the objections of artificial wombs and decent AI caregivers, this is going to be the only way to do it if you want humans on other worlds. Otherwise just leave them to the AIs. Our technology development will solve machine intelligence and bootstrapping machine development probably long before we solve how to ship large numbers of humans in ships with titanic energies to propel them for many decades, centuries or millennia.

167:

Re: Information storage & retrieval in the distant future

Even if no apocalypse, I'd think that you'd need to make this information as simple to retrieve and understand as possible. At present, mostly for economic/market reasons, we're changing the tech for data encoding/transmission/storage every few years thereby promulgating incompatibilities. Also, as much/most of the 'data' being produced by humans is garbage, we'd need some type of sophisticated editing system to pare this down to most salient components only.

So the question becomes: What's the simplest and most durable tech vs. What's the most sexy tech.

168:

Reference article re: allergies & neurogenesis ...

http://journal.frontiersin.org/article/10.3389/fncel.2016.00169/full


'Allergies and their characteristic TH2-polarized inflammatory reactions affect a substantial part of the population. Since there is increasing evidence that the immune system modulates plasticity and function of the central nervous system (CNS), we investigated the effects of allergic lung inflammation on the hippocampus—a region of cellular plasticity in the adult brain. The focus of the present study was on microglia, the resident immune cells of the CNS, and on hippocampal neurogenesis, i.e., the generation of new neurons. C57BL/6 mice were sensitized with a clinically relevant allergen derived from timothy grass pollen (Phl p 5). As expected, allergic sensitization induced high serum levels of allergen-specific immunoglobulins (IgG1 and IgE) and of TH2 cytokines (IL-5 and IL-13). Surprisingly, fewer Iba1+ microglia were found in the granular layer (GL) and subgranular zone (SGZ) of the hippocampal dentate gyrus and also the number of Iba1+MHCII+ cells was lower, indicating a reduced microglial surveillance and activation in the hippocampus of allergic mice. Neurogenesis was analyzed by labeling of proliferating cells with bromodeoxyuridine (BrdU) and determining their fate 4 weeks later, and by quantitative analysis of young immature neurons, i.e., cells expressing doublecortin (DCX). The number of DCX+ cells was clearly increased in the allergy animals. Moreover, there were more BrdU+ cells present in the hippocampus of allergic mice, and these newly born cells had differentiated into neurons as indicated by a higher number of BrdU+NeuN+ cells. In summary, allergy led to a reduced microglia presence and activity and to an elevated level of neurogenesis in the hippocampus. This effect was apparently specific to the hippocampus, as we did not observe these alterations in the subventricular zone (SVZ)/olfactory bulb (OB) system, also a region of high cellular plasticity and adult neurogenesis.'

169:

The currently most practical key to reducing and slowing dementia is staying physically and mentally active (both are important).

Agreed. Studies have indicated the most likely cause of death for people in white collar engineering type jobs is retirement.

But one thing I've seen is there are a huge number of elderly who just want to sit around and watch TV. They have absolutely no interest in "doing things". And yes they are a drain on society. (And their relatives if they stay involved.) Now this is based on my personal experience and that of friends but this still casts a wide net. When a friend is a cardiologist he gets a fairly broads overview of many of the elderly. But a systematic study of how many people WANT to stay active I've not seen. And just asking the question doesn't get it. Many of the elderly SAY they want to do things but when you keep being turned down when you work to do things they say they want you begin to get the idea they don't really mean it.

Me, personally, I don't see a reason to "retire". Unless retirement is not earning income they same way as I have for 30 years. To me the only way I'd consider retirement is if I was infirm mentally. Physically I could still do a lot of things related to my current work. Being self employed helps with this.

I suspect I got this from my father. His idea of a summer project in retirement when in his 70s was to dig out and timber and fence a spring, install a automatic remote control lift pump, run 200' of line up to a storage and distribution system for an 8 zone irrigation system for his home/yard. I feel like a slacker compared to him.

My grandfather actively ran his farm until he broke his hip at the age of 92. By actively I mean went out everyday to supervise the work around the farm and slaughter house.

Anyway I agree with your point. But don't believe society has a way to get people to want to be active. At least not our western first world society.

170:

I'm sorry for the misattribution.

171:

"My parents' generation are now all dead, but several of their deaths were a merciful release after some years of misery."

I was in hospital recently for a few days, surrounded by men younger than me whose quality of life was appalling. A couple were discussing suicide, and I helpfully pointed out that you need to kill yourself while relatively healthy. By the time you are stuffed full of tubes in a hospital bed it is too late.
The prospect of no euthanasia option in the NHS I find horrific.

I have a well defined cutoff point for me, when it is time for a walk in the snow with some whisky and codeine.

172:

well jesus, this conversation got bleak as fuck

173:

Nothing like death and colonization to make everybody all plucky and cheerful.

174:

About the infant brought to hospital with malnutrition from vegan diet

I'm married to someone who's been vegan for 20+ years.

From the top: non-batshit-crazy vegans are fine with feeding their babies breast milk until they're ready to wean, and non-batshit-crazy vegans accept powdered infant formula as a fallback in event of lactation failure. Humans are mammals: our neonates are specifically adapted to digest milk, and don't acquire the flexibility to tackle other foodstuffs for quite some time.

Next: non-batshit-crazy vegans don't suffer from malnutrition because, like everybody else who isn't batshit-crazy, they eat a balanced diet. (Hint: there was a case recently of a bunch of college frat boys in the USA who came down with Scurvy, of all things, from a diet of beer and vegetation-free pizza. It cuts both ways.) Meat is not the only source of protein available to the human diet; we are not obligate carnivores. Go back a ways and most humans couldn't digest dairy produce -- milk/cheese as part of a diet is a relatively recent adaptation common in societies that domesticated cattle (before which, it wasn't necessary or practical). Again, eggs only became a routine part of our species' diet with the domestication of fowl.

What's going on in Italy (and France) is basically your standard moral panic by old folks terrified of a fad spreading among the young folks (and, incidentally, threatening the revenue of some bits of the agricultural industry); in France it also interlocks with the national cult of Laicete and the issue of religious diets in school meals -- some folks can't tell the difference between a strict muslim diet (no pig products) and a vegan one, especially because if vegetarian food is available but the school won't cater to muslims, the muslim kids will go vegetarian to avoid the taboo animal. As with all moral panics, the headlines latch onto a handful of barking mad outliers and ignore the 1-10% of the population who are practicing whatever cultural activity it is quietly and without annoying/injuring anybody.

Just say "no" to moral entrepreneurs, okay?

PS: Yes, I eat bacon in front of my wife. I also periodically spend days at a time eating vegetarian or vegan, because why not?

Maybe I ought to add to the moderation policy: trolling people on the basis of their diet is an offense (notable exception: cannibalism).

175:

re. vegans: What Charlie said.

As Frances Moore Lappé noted back in 1971 ("Diet for a Small Planet"), the vast majority of the world's population has survived for millennia on a primarily vegetarian diet. Details of her conclusions have been modified extensively over the years as a result of subsequent nutrition research (e.g., vegetarians have to keep an eye on things like B12 intake to avoid deficiencies*), but on the whole, have stood the test of time.

* Note that carnivores can suffer from deficiencies too. I eat a diverse and balanced diet, but still ended up with a deficiency. I'm now on supplements, and am feeling much better.

I eat a ton of vegetarian food, but I'm not fanatic about it. I enjoy a good burger as well as the next carnivore. (Heh. Editor, edit thyself: to avoid any misunderstandings, that should probably say "me and the next carnivore both enjoy burgers". I haven't, to the best of my knowledge, devoured any carnivores.)

Enjoying vegetarian meals is all about being willing to spend 30 seconds with your favorite search engine finding tasty recipes. Apart from the ethical considerations (including both animal welfare and greenhouse issues), it's healthier and makes for a more interesting diet.

176:

Not quite. Primates (including chimpanzees and bonobos) eat eggs when they find them, and oophagy predates the domestication of chickens by millions of years. We are NOT adapted to a vegan diet, and it causes serious dietary deficiencies (mainly B12), but the incidental invertebrates in organic vegetables are really all we need. A largely vegetarian diet is fine, but the simple fact is that we (as a species) need either some animal protein or adequate artificial substitutes.

177:

To be fair to SFReader, I brought up the yegan diet thing as a substitute for raising a kid on a raw diet, because at that point, I didn't think anyone was crazy enough to try to raise a child on a raw foods diet and didn't check Google.

Turns out, I was wrong, so I'm at fault here. My apologies.

Then again, we're not talking about raw food, chimpanzee style,* here, and the struggles the parents have had trying to raise their kids on raw foods is instructive. Even when successful, it ain't cheap or easy.

And I still think we're coadapted with fire as a species.

*One aspect of Tarzan's upbringing that's seldom discussed nowadays. I'll bet he didn't have any trouble with impacted wisdom teeth.

178:

"there was a case recently of a bunch of college frat boys in the USA who came down with Scurvy, of all things, from a diet of beer and vegetation-free pizza."

Isn't that an urban legend? I heard it when I was at university: "...and then one day he coughed and his mouth was full of blood. He'd got Scurvy!!!"

(FWIW my own diet is somewhat similar - porridge, meat pies, and microwave curries, plus gallons of tea. Only noticeable deficiency seems to be plain calories: I have no arse, and too much sitting on an office chair produces sores over the protruding pelvic bones if I don't add extra cushioning.)

179:

You could implant a small explosive charge in your skull, set to go off if it fails to detect the correct code tapped on your head with your knuckles with appropriate regularity. Doesn't have to be a messy skull-burster, just has to set up enough of a shock wave.

180:

Hmm. Cannibalism.

I was there watching the Worldcon panel with OGH and Paul Krugman when Charlie came up with cultured human tissue burgers as an example of weird SFnal shit that was on the cutting edge of current scientific progress.

181:

No. I know someone who was diagnosed with it, and its mild form is common; I suffered badly from it (mouth ulcers) at school. Rickets is also common in the UK, due to our near-total lack of sunlight in winter, and even things like beri-beri have been seen.

182:

Uh? Computers require maintenance, both of themselves and of their power supplies, which in turn requires the technological capability to produce the spare parts, and the capability to produce the spare parts for the machines that produce the spare parts... etc. Keeping that going for multiple thousands of years while the sands of the desert bury the relics of the civilisation that set it up doesn't sound very possible to me...

Yes, that was the reference :)

183:

Even if the organisms have DNA, proteins, and carbohydrates that all have the opposite chirality to ours, there are going to be microbes that can use bits of us for substrate...
Space Gangrene is likely a bigger threat than Space Flu.

I am somewhat skeptical of this idea. Most bacterial diseases that affect humans have, to the extent that we can trace them, mammalian origins. We don't usually worry about bacteria that infect plants attacking humans, and there are no chirality barriers there...

And if you postulate chirality barriers, then the natural trend of evolution would be to eliminate those organisms which did tend to try attacking humans and Earthlife, because they'd be wasting their energy doing so. How can Space Gangrene grow on you if your dead cells provide no food?

Elderly Cynic's suggestion of allergic reactions (Space Hay Fever?) makes some sense, because that's your immune system overreacting to random things, and we know that people can have allergic reactions to completely artificial substances.

184:

Rickets? I don't think I've ever seen anyone with bendy-outy legs apart from someone who'd been kneecapped. Are we using different definitions of "common" or is it my perception that bendy-outy legs are an inevitable symptom (indeed, pretty much the defining one) that's at fault?

185:

I was pretty regularly air diving for fun in the 70 to 80 metre range with occasional excursions below 80. Not in clear tropical ocean but in things like old cable tunnels, shipwrecks and restricted caves. Thinking at that depth is virtually impossible, so I didn't. I had all sorts of well practised routines that I would call if required but my capacity for original thought or 'on the fly' planning was approximately nil. I would literally write what to do when on my hand and follow the instructions my thinking self had laid down. Unexpected situations were handled very very badly or not at all.

First... you are nuts. Never mind nitrogen narcosis, 80 meters on air is well into range of CNS oxygen toxicity, a.k.a. "sudden convulsions and drowning". But you are obviously alive, so congratulations!

Second -- what for? If you cannot think at that depth, how can you remember what you had seen?

186:

we're going to leave bugger-all behind for our successors, because essentially all of our writing is on media that fall apart after years to a few centuries.

Physical survival of writing only matters if the culture itself doesn't continue in some fashion.

People today don't know about The Iliad or The Aeneid because we have surviving 8th BC scrolls of the former or 1st Century B.C. scrolls of the latter (we don't); they know about it because they were valued and kept getting copied.

If the Phoenicians had survived as a distinct culture -- if Carthage had not been conquered and assimilated by the Romans -- there would probably be a lot more surviving Phoenician literature.


One big barrier right now is around 12th Century BC. With the Bronze Age Collapse, we lost continuity of most Mediterranean cultures aside from Egypt. That was at least 2,000 years of culture gone, and beyond that point, we depend on archaeology more than history

Assyria and much of Mesopotamia carried on with relatively little disruption. What we mainly lost were the Mycenaeans, the Hittites, and some of the coastal Levant.

The real problem is probably not the Late Bronze Age Collapse, it's the later social and technological changes that led to writing Sumerian and Akkadian in cuneiform being replaced by writing Aramaic in an alphabetic script (on papyrus or leather), which meant that all the accumulated Akkadian (and Sumerian) cuneiform literature gradually became lost, because almost no one could read or write it any more.

187:

Whoa, that's rather a big claim re. rickets. Are you sure you aren't recalling your own childhood a century ago or more?

A search of the internet using google scholar finds things like this:
http://adc.bmj.com/content/89/8/699.full.pdf

which found that between 20 and 34% of children in the ethnic groups studied had concentrations of vitamin D low enough to be in the deficiency region.
Bear in mind that immigrant populations from the Indian subcontinent have apparently been recognised as having greater incidence of rickets, this isn't really evidence for it being very common.
Then there's this BMJ article,
http://adc.bmj.com/content/89/8/699.full.pdf
from 2004, which sort of argues that it has made a bit of a come back, but isn't very clear on the numbers involved.

Fortunately, this one from 2014 has some numbers on incidence of hospitalisations due to rickets, and it has increased, from 2 per 100,000 at the end of the last century to more like 5.
http://www.thelancetnorway.com/journals/lancet/article/PIIS0140-6736(14)60211-7/fulltext
Obviously there'll be more cases than are hospitalised, but I really don't think there's the one in a thousand cases or such that many of us might consider more common.

188:

There was a story going around when I was in Uni, of a young man who blued all but ten pounds of his first grant Cheque on a sound system, and spent the remaining ten pounds on a 50 pound bag of oats. As this was his sole form of nutrition, he managed to come down with Rickets and became a minor celebrity at the local teaching hospital as every med student wanted to have seen a case of rickets
I am sure it's not true, but it should be

189:

I was going to say the same thing, but I was half asleep. I got up to find you'd said what I was thinking but better. Particularly the stuff about moral panic.

190:

"Second -- what for? If you cannot think at that depth, how can you remember what you had seen?"

Short answer...It was fun and I enjoyed the company of the people I was doing it with and enjoyed the challenge.

Long answer, I didn't remember much, nor did I 'see' much. Seeing is a combination process between your eyes and your brain. Brain wasn't really turning the images that came down the optic nerve into anything sensible. I couldn't take photos because operating a camera was beyond me at that depth. I didn't even try, not that I could have afforded a housing that worked at that depth anyway. Peripheral vision was pretty much toast as the work of breathing air at that depth meant I was borderline hypercapnic the whole time. I didn't worry about O2 tox as in those days O2 wasn't considered any problem at all until you hit a PPO2 of about 2 and most people thought that 2.8 was fine for short exposures. I never spent more than 20 minutes below 70 metres so that was ok (as best I knew then)

You might note that my name is now gasdive... I switched to helium based breathing media well before anyone else I knew. I can't remember the exact date, but early early early in the piece. I was writing my own tables by reverse engineering the Comex helium tables and the USN tables into some sort of mishmash. It was sort of instructive in that I discovered that the USN tables that I'd thought were Gospel didn't reverse engineer at all. They were clearly a model that had then been hacked with some real world experience. Nothing much lined up between the NDLs and the long exposures.

Things improved mightily when I got hold of Sheck Exley's DrX and I also got access to Nitrox. Until then I'd been diving Heliair with Air and O2 deco.

Anyway, I can *clearly* remember the first dive I took on Heliair. It was the wreck of the Koputi, which is, if memory serves, in 78m of water off Sydney. The guys I was diving with (none of us 'buddied' on the idea that if one of us got into trouble, there wasn't really anything that any of us could have done to save them) just swam around bumping into things and generally looking like they were asleep. The way I could actually *see* the wreck was a revelation. I had many many dives on that wreck and it was completely different on gas. That was pretty much the end of my deep air days. The down side of course was that our deco was a bit on the hit and miss side. We were generally getting mild DCI hits about every other dive. Chamber rides were a bit problematic too as the local chamber was getting panicked about the idea of helium bends turning up on the doorstep. They didn't really feel they could treat them (there was a tonne of misinformation floating around in those days) so we were doing a fair bit of in-water treatment or turning up at the chamber and lying through our teeth about what we'd been doing. Of the two, IWR had way better results than going to the chamber. I ended up having a meeting with them about it all and their attitude was that they were there to keep divers out of their chamber so it could be reserved for emergencies. I got as far as an agreement that if I turned up and vouched for a diver they'd blow them down, otherwise they'd continue with their own protocol, which was to put them in a normal bed on 6 lpm O2 and see if symptoms improved in an hour (which is about as effective as examining chicken entrails as far as diagnosis is concerned) Still dirty about that...

Ahh, those were the days eh?

191:

PS:

"

First... you are nuts."

You're not the first to have noticed this.

192:

Remember, not every molecule is chiral, and earthly bacteria metabolize all sorts of weird substrates.

Where we could get into trouble is with the equivalent of a biofilm that somehow doesn't get broken down by our immune system. I'm not enough of a molecular biologist to figure out what would be targeted, beyond things like blood plasma, but I suspect there's a big list of things that could potentially get gummed up. And yes, we could end up being allergic to them as well.

The critical thing is that we tend to focus on viruses and other parasites as SF alien horrors (see the movie Alien for example). At least for the first few thousand years, parasites won't be a problem (they need to coevolve with us to the point where they can overcome our defenses first*). Rather it's the oddball decomposers, the biofilms, the odd fungoids that find us tasty for whatever reason, and other random generalists, irritants, and species that tolerate hard vacuum that will be the problem for us first.

*Probably our first alien parasites will be social parasites. They'll be just so incredibly cute/beautiful/desirable/profitable that we'll fall all over ourselves making more habitat for them and defending them from their enemies. We're suckers for that sort of thing already, and we're getting worse).

193:

For information to be preserved over long periods requires it to be in some form that will endure regardless of curation - whether that's carving on stone tablets,...

stop right there we have a winner. Stone tools have been found that were made by hominids older than a million years, so that proves durability of the medium. Modern gravestones can also be produced with photographic images etched into them, and a typical sized gravestone could hold maybe a photocopy of one printed encyclopedia page. Twenty thousand of those in a medium to large cemetery sized plot could display the Encyclopedia Britannica for what to our point of view would be all eternity. Naturally it won't outlast the planet, but future archeologists could find them buried under sedimentary layers as long as they had ground penetrating radar.

194:

Over the last few decades it has become to most anyone who might read sf or watch a tv show that people can't live anywhere else in the solar system AKA "The Martian Chronicles". This was still made into a TV mini series (in the US at least) in the later 80s. Today it just would not fly.

I agree on the facts -- back in the '30s-'60s when a lot of Science Fiction's important founding texts were written, it's certainly the case that we didn't know a lot about the rest of the solar system, so it was relatively plausible to the audience that we might find Mars and Venus to be habitable and full of exotic alien wildlife. In more recent decades, people tend to learn about the planets in school so these stories look very dated now.

On the other hand, though, people certainly knew back in the day that the Moon, asteroids, Jupiter's moons and the like were not at all habitable, and yet there are still many famous stories about colonizing those places. Certainly we've had literature since the '30s describing the colonization of the void, not just an endless fanciful series of mythical Earth substitutes.

So I don't really buy this idea that because we know that Mars and Titan also require high technology to live on, that it's somehow unbelievable. What's wrong with writing stories about people living in caves on Mars? I mean, it's not like we didn't have stories about living in caves on the Moon...

If I was going to guess, I think I'd point my finger more at TV and movies. People aren't used to seeing depictions of a realistic space civilization, so we're fighting against that cultural baggage.

195:

Maybe we won't have to make giant leaps to actual stars. Maybe we can take small steps to "Brown Dwarfs" (can't we come up with a cooler name, like Dark Stars?) that occupy the vast space between the stars. Who knows, there may be dozens of BDs between the stars for every visible star:

http://nextbigfuture.com/2009/11/could-nasa-wide-infrared-survey.html

"The other headline would be the discovery of a brown dwarf that is even closer to Earth than the nearest star, the Alpha Centauri system at 4.3 light-years. Brown dwarfs are objects that form along with stars but do not have enough mass to trigger or sustain nuclear fusion. They are so cool and dim very little is known about their distribution in the galaxy"

and:

http://www.scifi.com/sfw/issue183/labnotes.html

"What if space is littered with these failed stars, scattered between the bright ones like a stellar Polynesia, making interstellar travel a series of short hops, rather than a single gigantic one? What if a simple fusion reactor carried just enough fuel to push a spacecraft to our solar system's Planet X in reasonable time? What if it could refuel there, harvesting just enough hydrogen or deuterium or helium to limp along to another dark neighbor, and another, and another? Granted, it would take a long, long time to get to Alpha Centauri that way, and probably a much, much longer time to find a planet somewhere that looked even remotely like our rain- and sun-drenched Earth. But given the likelihood of tidally warmed moons, and the obvious possibilities for life there, we may just find that the cold, dark spaces are where most of the action is anyway."

There may be dozens or hundreds of mini-solar systems between Sol and Alpha Centauri. With the discovery of BDs, free floating planets between the stars, and extra-solar planetoids like Sedna, future space explorers may find plenty to keep them occupied in our own solar neighborhood for centuries to come. While not the galaxy spanning empires and federations of science fiction, it would be enough for our species to explore far into the future.

And since these mini-solar systems and planets are a stone's throw away, they can be reached without exotic warp drives or hyperspace. Simple solar sails, laser sails or nuclear rockets will do just fine. Exploration missions can visit and return in a matter of years, instead of centuries or millennium. Interstellar "empires" and "federations" can be created using slower than light space travel.

Maybe Capt. Kirk and Obi Wan Kenobi wouldn't be impressed, but we’ll be half way to Alpha Centauri.

196:

We're getting very close to the Vernor Vinge game about how to bootstrap a medieval culture into technological advancement in the minimum number of steps.

So if we can etch stuff on rocks, what blueprints do we leave for our descendants? Probably best to start out with a system of measurement that works...

197:

Protect against impacts from interstellar dust particles at relativistic speds the same way tanks protect against armor piercing rounds: sloped armor.

Take a miles long nickel/iron asteroid and reshape it into the the shape of a spike or a needle (like the wedge shape imperial cruisers in Star wars only more so). The result is a frontnose surface with an impact angle of only a few degrees with a forward surace made of a solid metal shield hundreds of feet thick.

Hollow out its cylindrical main body for habitable space, set it spinning to provide artifical gravity. Include self replenishing bio habitat to taste.

Attach an Orion pusher plate on the aft end, load up with thousands of nuclear charges for propulsion and away you go at 0.1c.

Slow down by deploying a boron drogue chute, use a few thousand nuclear charges to slow down faster (like the Medusa concept which uses a parachute in tension for propulsion).

Easy peasy.

198:

Sorry. I was reading the comments while in real life are dealing with burnout of my wife dealing with her mom and realized I've never heard of anyone addressing this in their space colonization operas. Dementia in all it's variations will occur in almost any group of more than 10 people who live into their 60s and later. There was that NIH or similar official who came down with early onset in his 50s and how his wife dealt with it.

Are the Mars colonies or future star ships going to have a wing where they handle these folks or Eskimo them on the ice floes.

199:

Actually, aerogel or a whipple shield works better.

IIRC, if something's moving at ridiculously high speeds, heavy armor just means more stuff turns to plasma when it hits. A Whipple shield is a stack of fairly thin aluminum plates, while aerogel, is...aerogel. What happens when a high speed thingie hits one of these is that it turns to a ball of plasma. Since there's not much there to turn to plasma, it's a small ball, and it's relatively easily absorbed by the plates beneath it.

Now these are used at interplanetary velocities. At interstellar velocities you'll want that kind of shielding, but perhaps also a nice electromagnetic shield that charges the incoming particles and either moves them out of the way or directs them at a sacrificial anode or whatever, just so you don't get hit by the darned things. Of course, this creates a tremendous amount of drag, so it's best to deploy something like this when you want to slow down.

Again, this is why science fiction got into FTL in such a big way. Getting around problems is preferable to beating your way through them.

200:

Out of curiosity:

When did you start scuba diving?

How many dives do you have?

(in my case, it is 2000, and about 350)

201:

It's not bootstrapping but the course below has been designed to give todays CS students insight about what is going on under the hood.

nand2tetris

202:

Starships won't be launched until the solar system spanning civilization runs out of easily exploited resources nearby and sees an economic or political interest in expanding to other nearby systems. A thriving solar system spanning civilization will have solved little things like senile dementia.

Sustainable interplanetary colonies won't be founded until the human component is superfluous supercargo. Robots will have everything set up before people actually move in, and the people won't have much work to do. Seniles won't be any more useless than anybody else.

203:

Like when combining sheet metal with phone books makes a car bulletproof (until the system ablates). How about keeping your unused (deceleration)reaction mass (liquid hydrogen) in a big fuel tank forward of the payload (inhabited) compartment, on the end of a long pole? And what about projecting high speed particle beams in front of your starship? They hit stuff a long way in front of the starship and deflect it, plus the particle beam is constantly renewing. Of oourse that amounts to a low powered retrothruster (equivalent to drag) that your main thrusters (throwing out hot protons backwards at relativistic speeds) have to overcome.

204:

As well as does the next carnivore?

205:

Didn't Artthur C Clarke write a (very) short story about cannibalism? Or rather, the discovery that a future world's favourite culture-grown tissue tasted of people?

Must go digging in the library...

206:

"It cuts both ways"
Saw an article somewhere a few years ago about a very old find of humans in Colorado, like Clovis point era, so not too many generations removed from the first people to wander into the new world on land. These people had holed up in a cave over the winter and lived on nothing but meat, of which they had huge quantities (megafauna and such). But they died of malnutrition because humans need carbohydrates. So the article said. One might think other deficiencies would also be involved.

207:

I'm in my fifties and retired from the US Military (at about the lowest rank you can retire at). People older than me are always implying that I have some kind of moral duty to get a job. For example, I go into Home Depot to gets materials for some project I'm working on and the cashier, a woman still working in her 60s, is like, "You're too young to be retired". Being someone's modern day wage serf is not my idea of a moral duty. The game has rules, I played them smart, and now I don't have to work for anybody, so I do what I want. Nya nya. I intentionally picked a career that still has a traditional pension. I lived in the barracks and saved my pay (instead of spending it on sportcars, prostitutes, and other luxuries like many of my peers) then rode the stock market up and down intelligently (instead of buying in at the top and selling out in a panic like many of the idiots still working in their sixties). So I own my home mortgage- free, have a nest egg I will never spend, and have a pension I can live on. Why do I have some kind of moral duty to be employed? Because I'm "living off the government"? Color me an evil parasite. Just like your boss. I won.

208:

But - we are NOT "Carnivores" - we are Omnivores.
So, usually a "balanced" diet will involve some meat/fish/eggs .... and since settled agriculture, animal products, as well.
However, as you know, I don't have any problem with other people being Vegan/Vegetarian ... as long as they don't try to preach at me.
The "Meat is Murder" people produce the usual reaction in me - I want to go & eat a dripping steak in front of them, simply because .... [ Like telling marxists that I never read religious tracts, in fact ]

210:

It's interesting how Mikko and I tackled the problem slightly differently, but both clearly have an idea of the sorts of issues we have to address, and how to tackle getting to the point where we can load an OS kernel and then use that to "run code" (for values that include screen and keyboard drivers, text editors, compilers and debuggers as "code").

211:


So, IYO, is "studying what you want when you want, and maybe doing some 'pin money work' " the same as "being retired"?

212:

Maybe; I heard "something similar" whilst at school, but it involved some children who'd spent the Summer with their grandparents and living on a diet of Scotch pies, chips, sodas and ice cream.

213:

Rickets was (were?) verbally reported as "being common" on some housing estates around Scotland in the 1970s.

215:

I looked at basic logic things a bit (to brush up, I haven't been using this knowledge in years), and while it's only two relays (or transistors) to make a NAND gate, making a half-adder is five NAND gates, and any computer, even a toy one, would need a lot more than that.

So, in the foreseaable future I'm not making a hobby computer out of relays or transistors. ;) If somebody would pay me a working salary to do that, yeah, possible, but I have too many conflicting hobbies anyway.

216:

And it's MORE common today! The skin cancer hysteria is one reason, the increase in dark-skinned people another, and the wearing of all-over garments a third. Yes, it is a good reason to ban niqabs and similar extreme garments for anyone under 18. Pigeon has been reading too many Victorian novels - the mild form of rickets (which is what is common, and I have, for truly exceptional reasons) isn't visible except on close inspection, and is a pretty minor handicap. I have a slight stoop, slight bow legs, slight hyperlordosity etc., but I carried a 25 Kg pack over the Highlands at 67.

217:

Who knows, there may be dozens of BDs between the stars for every visible star

I'm afraid not. The best current evidence (from WISE, the space telescope that the first article you linked to is speculating about) is that it's more like the other way around: stars significantly outnumber brown dwarfs, so that there are several stars for every brown dwarf.

http://www.nasa.gov/mission_pages/WISE/news/wise20120608.html

218:

On the staying active into old age front, a family friend is 81 and competes in ultramarathons and ironman races. He's been winning his age category by default for almost 15 years now, in many cases the "senior" category starts at 50, and he didn't start racing until 55! Seriously switched on too, he's one of those really canny wiry old buggers who gets gnarled not old.

On the other hand a good friend of mine was extremely active into old age, then broke his hip. He was gone within two years, the lack of mobility removed the drive to live.

219:

Oh how I love rough fractions of lightspeed calculations.

If you ever read the worldbuilding sub on stackexchange you get non-science types writing their stories asking for reality checks and about 95% of the time if they include any fraction of lightspeed that doesn't have a very big denominator then you can quickly run the numbers to show that their high speed ship/planet/ark/etc will be glowing hotter than the surface of the sun purely from impacts with interstellar gas.

220:

No :-) You don't hospitalise people with rickets unless it's severe - indeed, I doubt that most people with it realise they have it! See my response to paws4thot. All that it is, is the result of vitamin D deficiency during the growth phase; if it is diagnosed and not too severe, the treatment is simply vitamin D supplements. From the figures you quote, at least 5% of UK children are at risk of rickets - while I don't know how many of the deficiency cases manifest as skeletal effects (i.e. rickets), I would guess quite a high proportion. That's common.

221:

Did you ever see the Mega Processor, a hand made 16 bit machine?

40,000 transistors, 10,000 LEDs and over a million solder joints.

There's always someone just mad enough to make something cool.

222:

Yes. As you two show, the knowledge has not yet been completely lost, but my point was that it is getting very rare. And, as I said, this is a very simple (almost trivial) case, because the techniques don't have a long chain of prerequisites, each of which needs something from later in the chain! It's the geology, metallurgy and chemistry bootstrapping that is the really nasty one, especially if most of the 'easy' ores have been mined out.

223:

Did you ever see the Mega Processor, a hand made 16 bit machine?

No, I haven't seen it before. Thank you for pointing it out. Also, yeah, not something I want to dedicate the living room for, nor the time to solder it together...

224:

WOW!!

I mentioned sharing the building with a 1950s DG earlier? The Mega Processor's RAM bank was instantly recognisable, although the DG only has enough LEDs to display the status of one register.

225:

Remember, not every molecule is chiral, and earthly bacteria metabolize all sorts of weird substrates.

Also: remember we exist in a predominantly matter universe (not 50/50 matter-antimatter, i.e. one that at this point would be 100% gamma radiation and neutrinos because of mutual annihilation)? Parity is not conserved in all force interactions, and IIRC I've seen a news piece whizz past in the last couple of years that suggests biomolecules in interstellar gas clouds are not racemic mixtures because underlying physical chemistry constraints going all the way back to symmetry breaking favour L-amino acids and R-monosaccharides.

I suspect if this is true, we will find life on other planets uses the same chirality and many of the same amino acids and saccharides -- but more complex structures such as nucleotides may vary, and in particular, the base codon alphabet will be unrecognizably, randomly, different.

So ... we may have problems digesting polysaccharides because the alien equivalents of cellulose or starch use a different bond structure, and we may not be able to play well with their proteins (ranging from bizarre immune reactions or non-reactions up to unable-to-degrade or they-use-nitrile-groups-for-WHAT?), and in particular their viruses will be unable to get a toe-hold on us, but there'll be some cross-over, mostly at the microbiological level, and it's going to be messy.

226:

There is a huge difference between "being retired" (doing nothing but sit at home in front of the TV waiting to die), "working" (at assigned tasks that you would not voluntarily undertake without a fiscal reward dangling in front of your nose), and the curious, liminal state some of us occupy if we're very good at what we do, and very lucky: being paid to do something we'd do anyway as a hobby in the absence of money (albeit swearing, having to work at a wage-earning job, and doing a lot less of it as a result).

That's me. I like what I do; it took me 20+ years of "work" before I got a chance to do it full-time: and I don't intend to "retire". I may do so eventually, but if so it'll be a response to terminal illness/decline -- I'll end up sitting and watching TV all day in the hospice, in other words, and not before. I will reduce my output rate, though, because I don't have the stamina of a thirty-something any more, and by the time I'm past 60 I don't expect to be publishing two novels a year (as I am at present) and past 70 I'll be lucky to make one a year.

Clear.

227:

Cannibalism is going to split out into the acceptable and unacceptable versions. I anticipate two distinct forms of the acceptable.

Firstly, the middle-classes will be able to have meat cultured from their own DNA; at dinner parties, the hosts will serve this meat to their guests.

Secondly, celebrities will have lines of food. For example, a Tom Cruise burger, or a Taylor Swift steak. People will buy these at the supermarket and at home will eat their chosen celebrity.

228:

See also "The State of the Art" by Iain M. Banks, "Transmetropolitan" by Warren Ellis, etc.

229:

Not to mention the pirated lines.

Safeguarding your DNA is more than a little tricky, as forensic specialists will be happy to attest. Would you, superstar, prefer to live inside an isolation bubble, or grin and bear the thought that someone out in the favelas is culturing your tissue? It's bad enough with the papps selling pictures of your knickers.

(Okay, so who was that who just applied for the Beefcake trademark? You're sick, do you hear me, sick!)

230:

In my life, I have invented the following things:

The bicycle.
Networking cables.
The holographic lens.
VAT-grown human meat for public consumption.

Sadly, I invented none of these things first.

231:

Get real.
If you want to commit suicide doing so in a certain-to-die, relatively pain free and easily contrived manner is very hard.
That's why overdose and hanging are old favorites, although not necessarily certain or pain free.
And seriously, Dignitas is too expensive for the average person.

232:

Color me elitist, but not being able to continue what I am now doing intellectually is one of those "lines in the snow" points where I take the long walk.
As I occasionally say: The only cure for average intelligence is a bullet.

233:

I wasn't trying to say people should not "retire". You had a plan and implemented it and I assume you're happy. Great. I just can't imagine that I would "retire" and go fishing every day and sit around watching TV when not fishing. Or some such.

And it sounds like you're not sitting around doing nothing.

Anyway each to their own.

234:

No. There are a lot of people who can't wait to "retire" and watch TV all day. When not sitting in a boat fishing. Or attending concerts in Branson.

I can't imagine that "retirement".

As to your description. For a large part of my adult life my work sounded like that. My wife and I raised two kids while both earning a living and no day care. Which meant that most of the 20 years or so of time this took we were not really employed compared to many people. Both of us averaged part time work.

235:

I looked at basic logic things a bit (to brush up, I haven't been using this knowledge in years), and while it's only two relays (or transistors) to make a NAND gate, making a half-adder is five NAND gates, and any computer, even a toy one, would need a lot more than that.

Back in 1972 a few of us teens though about building a computer out of 74xx logic. (The big boys were doing it so why not us.) The biggest stumbling block was the cost of the 74181 4 bit adders. The rest of it wasn't too hard. Now you could get 4 NAND, OR, AND, or NOR gates on a chip fairly cheaply. And if limited to NAND only you would wire up the rest. Flip flops on a chip were also a time and space saver. But it could all be done without toooooooo many 4 NAND chips. The biggest issue would be the slower speed do to all the interconnects.

Any way with 74xx logic and the short cut of 74181 adders you could lay out a "reasonable" computer in about 1.5 meter square.

236:

I seem to recall a study from the UK suggesting that the duration of the average successful suicide process was on the order of 7 hours. Skewed by drug overdoses, of course -- paracetamol (acetaminophen) is notoriously slow, with overdose victims taking 2-6 days to check out -- but even "fast" methods (opioid overdose, slashed wrists) can take hours.

On this morbid subject, if you want a guaranteed pain-free and rapid check-out, probably the ideal way would be a scuba tank and regulator loaded with pure nitrogen: unconscious within seconds without respiratory distress, brain dead 4-8 minutes later. Alternatively, use a pistol ... but that's going to leave a very unpleasant mess for somebody to clean up.

On a spaceship, I'm pretty sure a space suit rigged with an opaque visor and no oxygen in the life support pack would be a good way to spare the sensibilities of everyone else. If you had spares you could even use it as a coffin, giving the deceased a burial in space.

Now, can we please drop this subject?

237:

Alpha particles aren't penetrating: flip side, they dump all their energy in the top couple of millimetres of the shield, which gets hot. This is not good.

The atoms in the shield might also transmute (e.g. from aluminium to phosphorus), which is also not good!

238:

I'm not sure that's a possible transmutation, and even if it were phosphorus doesn't burn in the absence of oxygen!

239:

Re: Cannibalism.

ISTR seeing a news item on TV years ago about how cannibalism had persisted in the British Navy. I was fortunately able to find a transcript, which follows.

"Well first of all I'd like to apologize for the behaviour of certain of my colleagues you may have seen earlier, but they are from broken homes, circus families and so on and they are in no way representative of the new modern improved British Navy. They are a small vociferous minority; and may I take this opportunity of emphasizing that there is no cannibalism in the British Navy. Absolutely none, and when I say none, I mean there is a certain amount, more than we are prepared to admit, but all new ratings are warned that if they wake up in the morning and find any toothmarks at all anywhere on their bodies, they're to tell me immediately so that I can immediately take every measure to hush the whole thing up. And, finally, necrophilia is right out."

240:

Not only is it possible, the result is radioactive.

(It's what the Curies got the 1935 Nobel for doing)

241:

A crash helmet lined on the inside with a thin layer of C-4 plus detonator is probably the fastest and most painless way to go since the shockwave will outrrun the neuronal activity in the brain that's saying that it hurts. There's also no chance of a well-meaning bystander attempting and succeeding in resuscitation after the brain damage has been done unlike assorted gassings, pills etc.

242:

A company I worked for hired a young woman who built an 8-bit processor from TTL gates and chips as a hobby. She only had an HND and not the usual degree required by the HR people but it was a nice bit of design and implementation and boded well for the work she was being hired to do. The microcode was in an EPROM and she did use regular static RAM rather than doing everything in only basic gates but the CPU was all hand-rolled and it worked.

243:

Pardon me - the Joliot-Curies, not the previous generation.

244:

That's from a Monty Python sketch. Amazingly, can't find a you tube of the exact clip. Enjoy this instead:
https://www.youtube.com/watch?v=deoNAOfkXxc

245:

Do not go gentle into that good night,
Old age should burn and rave at close of day;
Rage, rage against the dying of the light.

246:

Didn't Artthur C Clarke write a (very) short story about cannibalism?
Wiki link is below (Ruth S. at #214). Endless riffs possible on e.g. vat-grown celebrity (or alternatively, infamous person) meat. Also, various religious prohibitions (about forbidden meats of various species) could (potentially at least) revisited, again and again. (And that's only thin slice of the cultural possibilities.)

247:

Ah, #227/#228 got there first. Should have read the thread first.

248:

Actually, as I was walking last night I contemplated the possibility of having some sort of foam extruder on the front of a spaceship, the foam acting as a Whipple shield. Stuff hits it, bubbles burst in a cloud of plasma, but the ship just bubbles out more suds of whatever-it-is that makes good suds in a vacuum.

Then I started thinking of a nice, foamy pint...It's close to probability zero, but who knows? Perhaps something like beer foam will turn out to be a workable micro-debris shield. If so, it's yet another way that beer might help us conquer space.

249:

No worries ... Also, I agree in principle with Charlie about diet. My beef (ahem) is when diet (or any other behavior) becomes religion. Over the years I've met (and even married and produced) humans who had specific dietary needs. After a very young relative was hospitalized after eating a common healthy/organic cereal grain, seeing my best friend get violently ill at the slightest hint of a particular herb, I now always, always ask about food sensitivities, etc.

Something else that people sometimes forget is that our major esp. Western cities have become more ethnically diverse, therefore different food sensitivities and nutritional needs are bound to crop up. So please ease up on there being only 'the one true/good diet'.

BTW, I've enjoyed almost all of the 40+ different ethnic cuisines I've tried. Okay, I've never tried fried/grilled insects but heh, since I already eat the slimy sea stuff (oysters, sea weed, etc.), I'll probably try the crunchy stuff one of these days.

250:

Also Larry Niven. His Gligstithoptok asked for copies of our DNA, grew brainless human bodies for meat, and paid us a royalty. They were very nice people, just don't ask what kind of meat is in their sandwiches.

251:

What transmutation do we want? We build the shield out of the right material and... bingo! We arrive on site with x tons of the right stuff.

252:

Actually, phosphorus wouldn't be bad if we were planning to commit agriculture.

253:

Secobarbital Sodium is now the drug of choice in the US for death with dignity (Pentobarbital is second). Thank god I live in a state where it's an option. Oregon keeps good records back to legalization in 1998, and there's been about ~800 deaths with ~20 known complications.

254:

I like it, a tombstone/thuktun, and you could pick the concept you wanted to illuminate for future generations. How antisocial would it be to choose PUREX as the industrial process to grave on your stone?

255:

Yes, you can find a clip by googling "expedition to Lake Pahoe".

I got the 'transcript' from Monty Python's Just the Words website.

256:

You see this a good deal with certain professions. Especially in law. Lawyers spend their entire lives building their career, and even if at the end they're mostly doing dog and pony shows for clients, you'll get 80 year olds coming into the office to do something related to an case with origins in the dawn of time.

You see it too with judges in the US. Law schools had mandatory retirement at 70 commonly until 1994. Federal judges sit for life, and some are blessed with long lives :Wesley Brown was hearing cases at 104, and Stevens at 96 could in theory hear cases if he chose to (but won't because of politics and fairness concerns).

It's actually a great resource since these old guys have the strangest stories and so much practical knowledge. Otoh its also an issue when they have a lot of control and are resistant to social changes.

257:

I endured a mild, accidental hydrogen sulfide intoxication when I was 20. I became dizzy and couldn't smell the rotten eggs any more. It went away when I hastily shut down the apparatus and retired to outdoors. There were no lasting ill effects AFAICT. That's the way I would go if I had to take care of things myself and couldn't get a proper self-euthanasia drug prescription (but I live in a state where I could just get a prescription, if I were terminal at least).

You can order sodium sulfide online as a darkroom chemical, buy calcium polysulfide solution ("lime sulfur") intended for pest/fungus control on trees, or make sodium polysulfide at home by stirring calcined sodium bicarbonate into molten sulfur. Any one of these three will release copious quantities of hydrogen sulfide on exposure to an acid solution such as lemon juice. Hydrogen sulfide is roughly as toxic as hydrogen cyanide by inhalation, quick acting, and gives little-to-no pain as "warning" on the way to unconsciousness. It stops stinking once the concentration gets dangerously high. That's why it can also be so deadly in industrial accidents.

258:

One of Bob Shaw's Serious Scientific Lectures postulated a space drive powered by beer drinkers, utilising the odd property of beer in that drinking one pint of beer results in more than one pint of used beer (or Tetleys as it's known) being evacuated. The ship's toilets would be connected a purification plant connected to a brewery which produced the requisite beer with surplus fluid being used as an inexhaustible source of reaction mass.

The prototype ship was to be called the "Yurin-8".

259:

Agree that we're nowhere near understanding all of the -omes we depend on. That's why a few topics back I'd suggested taking 'core cuttings' (scoops) of 100 yards - 1 mile diameter living/thriving sections of our Earth to transplant onto whatever planet humans wanted to terraform. Basically, I'm unconvinced that the test tube chemistry approach that much of SF uses would work at all. Or, if it did work, it would take a few millions of years to do any good.

That said, if you're only interested in sustaining someone's life for a while and have very little cargo space or possibility of setting up more complex nutrient vats or systems, TPN is an option.

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

260:

or Tetleys as it's known Titbread Wankerd, actually ....

261:

It used to be possible to get the proverbial "good pint of Tetleys" when I was a young 'un in Leeds, but never more than 10 miles from the brewery, and only from pubs where someone knew how to manage the cellar properly. A long-range or otherwise borked pint of Tetleys invariably tasted like stewed tea brewed with soapy wash-up water.

Then they closed the old brewery and moved it up to Newcastle and the rest is history ...

Like the proverbial pint of cask-conditioned Guinness that allegedly could be had in the head brewer's office at the plant in Dublin, all the rest being pasteurized and crappified to within an inch of its life. And then they did away with that.

262:

One of the few beers I liked was unpasteurised Carlesberg Hof.
I once worked as a chemist at one of their breweries

263:

Yep. And you can get antigravity by strapping a slice of bread butter side up on the back of a cat and getting them spinning.

So we have a ship powered by continuous beer drinking to feed into the fusor (or is that the fizzer), and then we have a room full of dropped, cat/bread units. As long as we can properly control the cat/bread spin rate, I think we've got a good anti-gravity drive.

Maybe this is what Alcubierre was thinking of, with the breadcats acting as the strange matter? If so, we can conquer the galaxy with enough cats and enough beer.

264:

Hah! As if we will be the ones to conquer, lashed to the yoke to provide fuel for our supernatural spinning cats' galaxy spanning ambitions.

265:

NoNoNo, feline antigravity isn't used for the warp drive, it's used for the grav field generator that keeps everyone's feet on the ground as the starship accelerates at right-angles to the vertical!

266:

odd property of beer in that drinking one pint of beer results in more than one pint of used beer (or Tetleys as it's known) being evacuated.

Why is that odd? Beer (or sugary soda) is water + carbohydrates. Carbohydrates plus oxygen equal more water plus CO2.

267:

Anyone know of a source that's not so hyperbolic about this? The way Business Insider spins it, Defcon just invented soft AI

http://www.businessinsider.com/forallsecure-mayhem-darpa-cyber-grand-challenge-2016-8

268:

Speaking of cask-conditioned beer, which is far more interesting than euthanasia, it's well worth seeking out. I first encountered this as Dogfish Head's "Palo Santo Marone" (http://www.dogfish.com/brewery/beer/palo-santo-marron), which is remarkable.

Locally, we have a tiny microbrewery called Le Castor ("the beaver"... Canadian, eh?) that's growing like kudzu (http://www.microlecastor.ca/?lang=en). They have a range of barrel-aged ales that are to die for. The Wee Heavy Bourbon and Wee Heavy Rhum are enough to justify the trip to Montreal, though at 11% A.B.V., they're definitely for sipping, and you might want to appoint a designated driver first.

269:

Indeed, but absent actual figures, I'll just say that at risk from is not the same as suffering from, therefore you overstated yourself.

As for retirement and activity, the retired for several years father of a friend of mine, seems to mostly watch television all day, apart from spending some time rebuilding the kitchen. APparently he commented once that he wished he'd taken the electrician vocational route not the joinery one, 45 or 50 years ago, because that way his joints wouldn't be in such a state.

I'm sure Dirk will have some studies or such about why some people are very sprightly into old age and some aren't, even if they have had similar work lives.
One I heard of was Nigel Tranter, in his 80's he was climbing over stone walls to visit castles and suchlike. Then he got a bad bout of flu and died. Or indeed one man I know, is mid 80's, I recall reading something about his retirement 20 years ago. A couple of weeks ago he was joining in on a tug of war!

But it certainly helps if you have a more sedentary lifestyle than say our miner forefathers.

270:

Forgot to specify dropped, spinning cats. The critical part is to gain differential control of breadcat spin, either through mechanical means (drones?) or possibly by invoking some descendant of the Schroedinger's cat principle and merely making carefully timed observations to get the proper spin rate. I suspect you could do the latter by having a way of controlling the picture-taking rate on a camera focused on each cat.

And, incidentally, if you can control the rate of breadcat spin and even precession, you get fine control over antigravity on all three axes of the ship, so it's not just artificial gravity for the beer drinkers.

By the way, what are we calling this whole setup, the schizomemic stardrive?

271:

Hey, looks like I was wrong re. vitamin D defiency, but then so was elderly Cynic. If you believe the figures the government gives from a survey, it's more like 25% at risk of deficiency:
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/213703/dh_132508.pdf

Of course the further question would be, how does this translate into actual deficiency, all it says is "which means they
are at risk of the clinical
consequences of vitamin D deficiency"
i.e. could develop rickets, but presumably from the wording, don't actually have it.

272:

A note about aging and health: Most of the comments neglect the importance of genetic factors, which you can't really do much about yet. If you win the genetic lottery, you can remain vigorous and mentally competent into your 90s and beyond; if you lose the genetic lottery, doesn't much matter whether you live a healthy and active life. That Huntingdon's chorea or early-onset Alzheimers will get you anyway.

Assuming you're more in the winner than loser category, eating healthily and remaining mentally and physically vigorous through exercise and learning new things will definitely prolong your healthy lifespan. Perhaps more importantly, since you can't predict whether you're a genetic winner or loser, this approach will improve the quality of whatever lifespan your genes will grant you. That alone is a good reason to recommend that lifestyle.

273:

it certainly helps if you have a more sedentary lifestyle than say our miner forefathers.

Yup. One of my grandfathers worked on the railway and died shortly after retiring. He was profoundly deaf from work, and it's good that he died when he did as he also had "minor" asbestosis and a range of other ailments that would have been crippling within a decade or two. He wasn't happy before he died, just like my other grandfather, who died of accumulated war injury complications (the pain just kept getting worse).

The grandmothers were much better off. Actually, thinking about it, all my grandparents died with their brains pretty much in working order, of assorted physical problems. The recipe "broken hip/femur plus two years = dead" applies. It does mean that I have to plan for a life extending into my 90's, because I have skipped both the hard manual labour and the workplace explosions paths.

I do wonder what the crossover between VR and ageing is going to look like. At some point I expect it will be possible for quadriplegics to use VR, which will mean you can just immerse yourself in VR let your body decay into a puddle (a la Wall-E). That will probably reveal that bodily activity is as important as some of them medical boffins say it is, I think. So more likely some kind of baby-style walker harness/2D treadmill plus VR, if you want to live more than a year or two.

274:

According to my doctors, actual rickets is the acute end of vitamin D deficiency. Deficinecy levels that don't present visual symptoms still have all kinds of nasty effects. Apparently vitamin D turns out to be active in all sorts of things beyond bone growth, including a bunch of subtle metabolic stuff. And Vitamin D also apparently suppresses some precancerous cells.

It was implied that standard requirements, being keyed to preventing ricketts, were probably way too low.

275:

At some point I expect it will be possible for quadriplegics to use VR, which will mean you can just immerse yourself in VR let your body decay into a puddle (a la Wall-E).

I wonder more about Surrogates.
http://www.imdb.com/title/tt0986263

276:

"When did you start scuba diving?"

About 1975. I got certification in 1979 (I think)

"How many dives do you have?"

I don't have a good handle on that. I've been a bit slack on logging and it depends on how you define a 'dive'. I've also been a bit variable on intensity. None since I got back from a cave diving trip to Florida in 2002. During the trip I was diving about every 28 hours (Cave diving is great in that you can go any time of the day and my natural sleep/wake cycle is 28 hours). So one dive per 28 hours for about 4 months running. About 2 hours at 30-33m depth (which was the depth of the bedding plane I was diving in that area) with about 3 hours deco. Maybe a hundred ish there?

I had two years or so professional diving, so 5 days a week and that would vary from a one dive a day that starts in the morning about 8am and finishes at about 12am through to dives of about 2 minutes each, but 100 odd dives in a day when doing things like inspections or sediment sampling. So less than 10 000 and more than 1000 depending on how you define a dive. I've been told that PADI says a dive of a couple of minutes isn't a dive. I don't care, I still got paid! From memory I think I logged about 70 000 minutes under pressure in 2 years.

For about 5 years I did a deep/wreck dive every saturday and sunday morning. Most of the wrecks around Sydney are in the 50-80m range and bottom times varied between about 12 minutes out to an hour at 50 metres. Run times (total time in the water) was usually 80 minutes but of course for dives that are an hour at 50 metres you need over an hour of deco, so they tended to be rare. Getting the boat to hold over you for 2-3 hours is a weekday thing, they're too busy on weekends. So a few hundred of them.

Bottle dives in the harbour or just evening strolls around the coast (get in the water in one bay, swim out to sea, go north or south and come ashore in the next bay over for a couple of hours of peace and quiet) once or twice a week for a few years. No real idea on numbers.

Holiday dives as well I suppose. I couldn't hazard a guess on the numbers. Even if I went inland, I'd dip myself in lakes and rivers.

277:

I feel I ought to point out some problems with the panifelicogyre proposal...

1) The antigrav effect of a panifelicogyre is exerted upon itself, and is relative to the local floor. Coupling the force to the spaceship is likely to result in no net effect as the panifelicogyre/floor spacing remains constant. It is also an unsolved mechanical problem; one experimental proposal has been made based upon a modified version of the standard adjustable dog-carrier, but nobody has yet been found who is willing to carry out the experiment (see also point 2).

2) The panifelicogyre antigrav effect is still purely hypothetical, and has not been experimentally verified. All experimenters to date have died in the course of the attempt, from such causes as cranial trauma secondary to slipping on butter on the floor or blood loss from multiple massive lacerations. This is for reasons related to point 3.

3) The panifelicogyre antigrav hypothesis is commonly misconceived, due to popular focus on the result to the exclusion of the context (much as with Schroedinger's cat). Since it depends upon Murphy's law as applied to buttered bread, brief consideration of basic Sod theory makes it clear that the result is only valid if the piece of bread becomes attached to the cat's back accidentally, and the fall of the cat must similarly be accidental. Sod theory precludes any useful result from setting up a suitably hazardous environment, so the spaceship would be dependent on spontaneous natural panifelicogyre events, which are not frequent enough to be useful. More importantly, any attempt to put Sod phenomena to useful purpose such as driving a spaceship is practically certain to involve catastrophic consequences up to and including total existence failure.

I would like to propose, therefore, the simple modification to the proposal that the antigrav and drive units should be not panifelicogyres, but laithodynes, which have similar force characteristics but without the dangerous dependence on Sod results. A laithodyne consists of a robot effigy of Eric Laithwaite waving a great big flywheel about, using the principle that gyroscopes wielded by Laithwaite can alter the action of Newton's third law to provide any desired amount of reactionless thrust.

278:

Even worse, when I was a student in Manchester in the mid-60's no-one would drink Tetley's ...
But, visiting Leeds, you had virtually no choice - & it turned out to be drinkable(!)
Because it came from a different brewery - in those days we didn't understand the goings-on of the "Big Brewers" ... what we were avoiding in Manchester was labelled Tetley's, but brewed in Warrington, yuck.
I'm pleased to say that Hydes' Ales are unchanged to this day, though .....

279:

#203, RDSouth

How about keeping your unused (deceleration)reaction mass (liquid hydrogen) in a big fuel tank forward of the payload (inhabited) compartment, on the end of a long pole? And what about projecting high speed particle beams in front of your starship? They hit stuff a long way in front of the starship and deflect it, plus the particle beam is constantly renewing.

#248, Heteromeles:

Actually, as I was walking last night I contemplated the possibility of having some sort of foam extruder on the front of a spaceship, the foam acting as a Whipple shield. Stuff hits it, bubbles burst in a cloud of plasma, but the ship just bubbles out more suds of whatever-it-is that makes good suds in a vacuum.

Pellegrino made the suggestion that you could use a fountain at the prow of your starship that would combine the functionality of a droplet radiator and a shield. His Valkyrie designs had the engines at the front of the ship, towing the cargo a long way behind, so they needed big heat radiators up there anyway. You get some wastage of coolant, of course, but your front shielding will be ablated anyway over an interstellar flight.

If you're not familiar with the Valkyrie design, it is worth a look. It appeared recently as the basis for the ISV Venture Star in Avatar, which is probably one of the most (if not the most) plausible starship designs to appear on the big screen.

(oh, and if you're not familiar with liquid droplet radiators, they're well worth reading up on, too, as they're a good way of making lightweight yet very high surface area radiators)

280:

Define "sedentary"
I avoided all spurts at school if I possibly could, yet I'm certainly in the top 5% fitness cohort for my age (70). Very few of the jobs I've had involved sitting down for any lenght of time, either, but neither were they "extreme" in terms of exertions - lots of gentle exercise, in other words.
But, I still cycle a bit, walk quite a lot, keep an allotment & dance, of course.
In fact I'm off to Germany tomorrow for a long weekend of dancing & beer-consumption.

281:

Given the time I spend in the open-air (allotment) I don't think I'm going to get Vit-D deficiency!

282:

You probably are, unless you work bare chested every day all year round. Skin synthesis of vitD drops in efficiency with age. RDA VitD is 400 units, which is about 10x too low. I take 5000 units per day.

283:

I do wonder what the crossover between VR and ageing is going to look like. At some point I expect it will be possible for quadriplegics to use VR, which will mean you can just immerse yourself in VR let your body decay into a puddle (a la Wall-E).

You've never used a VR rig, have you?

Hint: in a decade's time, competitive VR gamers (competitive computer gaming is already a sport today) are going to be as ripped as gymnasts or martial arts experts. Using a Vive is intensely physical -- not force-intensive, but requiring rapid and coordinated movement and reflexes.

(Yes, immersive interfaces that have input methods suitable for paraplegics will be a thing, too. But that's not where mainstream VR is going.)

284:

Yeah, friend of mine (late 50's) was diagnosed last year with deficiency. He walks outdoors for about an hour every day, shorts and tee shirt. Very fair skin, but still deficient in Vitamin D. We live in Port Macquarie. 31 degree latitude. It's almost like we didn't evolve to live indoors 23 hours a day.

285:

The vive is quite a nice piece of kit. Very well balanced, good tracking, acceptable image quality. Best VR rig out there at the moment imho. The people selling high end professional HMDs should be worried!*

The two big improvements it needs are getting the weight down and losing the cables. Inertia is a problem with fast head movements and you can't really have an immersive experience if you can get tangled up.

I'm fairly confident both of these will happen in the next couple of iterations.

*They wont be. They will insist that their image quality is better and ignore the "crap" competition. Worked out well for 3dlabs and sgi.

286:

I think we now think this is radio-phosphorus, which is possibly an issue, if not the one you first thought.

287:

This may also be a way of providing a hyperdrive, given sufficient drinkers, an adequate level of intoxication per drinker, and the existence of the "beer scooter effect"?

288:

For those who are interested, Ars Technica now has a nice write-up on the paper by Hoang et al. discussing the interstellar travel dangers that Dave @ 68 linked to above.

Here's a relevant comment from the paper itself:
"To prevent damage by gas bombardment, the spacecraft can be protected with a thin layer of 0.01 mm made of highly conducting material, such as graphite or beryllium. For dust bombardment, the crater formation is insensitive to the material because it is determined only by the binding energy and the total thickness of protective shielding. Our results suggest that a shield made of graphite of ∼ 1-3 mm thickness will be required to prevent the melting by dust bombardment."

289:

I think we now think this is radio-phosphorus ...

Yes -- the suggestion was Al 27 (the most common isotope) being hit with an alpha particle, which turns it into P 30 (plus a free neutron), which decays with a half-life of 2.5 minutes into Si 30 (which is stable). So it's a way of turning aluminum into silicon, if that's what you want...

290:

Which also caused me to wonder what effects multiple spacecraft of that sort of type flying similar courses would have on "their course's local environment"?

Would sufficient particles be annihilated to make the local density of space lower, or would outgassing from the ship (presuming its skin isn't perfectly impermeable) and the shield cause the local density to rise?

291:

I was always convinced that there was a connection with the other Tetleys (which I don't like, either), and the used teabags were recycled to add flavour to the beer.

292:

The second reference you gave showed that, in its sample, nearly 3/4 of the children with vitamin D deficiency DID have rickets, as observed by radiology. As I said, there is ample evidence. I have a friend's son who is just doing a medical degree, and he was taught about a massive rise in (minor) rickets. From the references you gave alone (I don't have time to do a better search), it affects several percent of UK children (perhaps even 5%). From what I know, almost all of those cases are either undiagnosed or would simply be treated with vitamin D pills. That's common. OK?

293:

Ok, so we get aluminium to phosphorus to silicon, plus neutrons and? I'm thinking gamma particles?

294:

They misled you or you misunderstood. The bones are a calcium reserve and vitamin D is used for many purposes, so rickets IN ADULTS is the acute end stage. IN YOUNG CHILDREN, however, the skeletal malformation happens very readily, because bone growth is a main use of the calcium and, if it is short, they don't form correctly. This is unlike scurvy, beri-beri and most other deficiency diseases, because the normal form of rickets in adults is the result of a deficiency at an earlier time, not of an ongoing one.

295:

Because somebody will almost certainly play word games with what I wrote, I should have written "active rickets IN ADULTS".

296:

However, diet is also important & for that reason I still don't think I'm going to get Vit-D deficiency.

297:

Ok, so we get aluminium to phosphorus to silicon, plus neutrons and? I'm thinking gamma particles?

It's
27Al + 4He --> 30P + n
and then
30P --> 30Si + e+

So, no gamma rays directly, though you would get some from the positrons annihilating with nearby electrons (as happens in positron emission tomography), assuming the positrons don't escape into space first, as some probably will.

298:

Thanks; the last time I actively used radiochemistry was in school, around 1979.

I understood you perfectly, but couldn't have reproduced the decay states and products.

299:

I suspect so. To go from P 30 to Si 30, you need to convert a proton into a neutron. AIUI, this involves emission of a positron to carry away the charge. Yon positron will then annihilate on contact with an electron, and that should produce your gamma ray.

300:

Remember, not every molecule is chiral, and earthly bacteria metabolize all sorts of weird substrates.

But amino acids and sugars, for example, are.

If you turn it around and consider the War of the Worlds scenario -- how would Earth bacteria deal with invaders from an alien ecology? -- then the bacteria are going to have a lot of trouble growing and reproducing if they can't metabolize any amino acids to make their proteins, because the invaders have opposite-chirality amino acids.

Since some Earthly bacteria can form biofilms on inorganic surfaces, that would be a potential issue. I think that's maybe a better way to look at things: from the point of view of Ecosystem A, invaders from Ecosystem B may be analogous to rocks or plastic: some organisms can grow on them, but most cannot, and few will be able to "metabolize" or do much damage on short time scales.

301:

"I still don't think I'm going to get Vit-D deficiency."

You won't know unless you are tested.
Low VitD is associated with just about every major disease of ageing. Correlation only, or some causation?

302:

Well given that there's about 250 different bugs that can live on a diet of nothing but jet fuel and water, I think Earth bugs could make a feast of just about anything. Jet fuel has no natural immunity to infection by Earth bugs and it's a bit of an issue for aviation.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC546914/

303:

Right. And I will bet that at least some of those produce toxic or allergenic waste or decomposition products. Damn hay fever - think of farmers' or bagpipe lungs. Several SF authors have noted that point, but most have associated it with multicellular invaders. As you and others say, it's the surface-living decomposition organisms that are most likely to survive.

304:

Bacteria also colonize the plastic microbeads that litter the ocean (https://www.sciencenews.org/article/oceans-plastics-offer-floating-fortress-mess-microbes). It's unclear whether they're actually metabolizing the plastic (if so, right now it's at too slow a rate to declutter the oceans), but the second order effects are fairly messy.

In general you're right. Where microbes, alien or otherwise, are most problematic is in systems with high purity ingredients that cannot tolerate contamination. That pretty much describes spacecraft. I suspect that we live in a bit of a golden age, because technology evolved so fast that microbes are only beginning to catch up. Over deep time (millennia), I suspect that they'll figure out how to take really good advantage of our industrial materials, and the utility of those materials will decline accordingly.

Getting back to science fictional plots, I don't remember anyone using this in a story, but being part of a newish starfaring culture, and exploring an ancient culture (or the remains thereof) might be dangerous to your technology, even if the microbes in the system don't think you're terribly edible personally.

305:

Would sufficient particles be annihilated to make the local density of space lower, or would outgassing from the ship (presuming its skin isn't perfectly impermeable) and the shield cause the local density to rise?

Not really. While the ship would temporarily sweep clean its path through the interstellar medium, the surrounding medium would expand into the swept-out vacuum quite rapidly (typical particle speeds in the ISM are a few kilometers per second, so even the path of a kilometer-wide spaceship would be refilled in a few seconds).

Any outgassing would quickly mix into the surrounding ISM, and would be a trivial addition in any case.

306:

This sounds sort of like a Joan Slonczewski type plot?

307:

So about as useful as following another car in dense fog then? (not very)

308:

Oh, yes, it has. Unfortunately, I cannot remember the names of the stories or the authors!

309:

Well, aside from ancient alien (nano)technology chewing up your stuff, which is a standard horror and SF going back to, well, Cthulhu.

What I'm thinking of is specifically the notion that if you leave a lot of some novel substrate lying around, if anything can make a living metabolizing it, eventually something does. This is especially true if, as with jet fuel, there's some energy to be had from metabolizing it and doubly true if there's a lot of oxygen present. Therefore, exploring in an environment that's had very long term exposure to the kinds of technological substrates you depend on might be hazardous to your technology, if not your body.

This is also a bit different than the first book I wrote, about people colonizing a world where the organisms naturally produced things we considered industrial polymers, so as a result, plastic, rubber, and lubricants broke down rather rapidly and technology had a short service life.

310:

Totally unrelated, but interesting, especially for those who think that doing pharmacy is sort of like software development, but with molecules:

http://blogs.sciencemag.org/pipeline/archives/2016/08/16/rules-for-modern-drug-development

(warning, real science content. PK is pharmacokinetics)

The comment thread is interesting too.

311:

Back to the OP: the official paper on Proxima Centauri b is now out: Nature 536, 437–440. I haven't linked it because it's probably paywalled, and it seems to be so new that half the links to it get 404s, but here's the BBC News article.

Brief details: minimum mass (that's what you get from a radial velocity detection—better than transit, where you get no mass at all) 1.3 Earths; orbital period, 11.2 days (this is good, as the star's rotation period is known to be about 83 days, so this doesn't look like something resulting from stellar variability); distance from star, 0.05 AU (1 AU = Sun-Earth distance). Irradiance at that distance about 65% of what Earth gets. Equilibrium effective temperature estimated as 220–240 K, but that neglects any greenhouse effect. Data are from the HARPS precision spectrometer at ESO. Signal is weak but looks real.

Things we don't know: the actual mass (would need a transit; probability that we are that lucky is 1.5%), the radius and hence density (ditto—but for something this low mass to be other than rocky would be unexpected), the eccentricity of the orbit (fit says <0.35, but that's a big range), and whether or not it's 1:1 tidally locked so that one face always faces Proxima—you'd expect it to be, but if the orbit is significantly eccentric it might wind up in some other resonance, like Mercury.

312:

Just back from Worldcon.... They also note that it's allegedly unnamed.

Geez! Talk about ignorant! Older folks here in the US know perfectly well it's name: Rann.

Paging Adam Strange! Your zeta beam is here.....

mark

313:

ESO is hosting a PDF version of the paper here.

314:

Ah! You know this stuff really well. So here's the hypothetical: We're going to build a generation ship. It will have shielding against highly energetic particles. While we're in transit, and the shield is being bombarded by highly energetic particles, we want the shield to be transmuted into some chemical which will be useful upon arrival. What materials do we start with, and what do we end up with? Or can we use multiple materials and get more interesting results?

315:

You can get around the paywall by inserting ".sci-hub.cc" after the "nature.com".

It is a good paper with a lot of detail in a supplementary Methods section.

316:

The 1970s British SciFi tv series "Doomwatch" had an episode "The Plastic Eaters"[?] about bugs rapidly eating plastics. The tv remake of "The Andromeda Strain" made a big deal about the organism digesting plastic.
However the most memorable for me was an episide of 1960's British SciFi tv series "Out of the Unknown" where an interstellar survey team land on an inhabited planet where the aliens clearly understand how to use advanced technology, but live is primitive conditions. The problem was a bug that ate metal, which ultimately strands the ship and crew. Unfortunately this is an episode that was lost by the BBC's decision to reuse videotape. This is goes back to the pronlem of long term information transmission. Reusing videotape is like grinding off the hieroglyphs on stone monuments to make way for new "important" statements.

317:

Videotape and obsolete file formats are artifacts of a period of rapid development. Now that electronic information technology is more mature things are settling down. For example, in a hundred years you will be able to open a pdf, txt, mp3, mp4, or probably even doc. At least things are slowing down enough that software for using these formats will be around and there will be operating systems that can run it--or at least there will be copies of the operating systems and there will be computers that can run the operating systems. Or else somebody will find the Windows XP Toughbook I keep in a metal box in the basement with a bunch of gold plated archive DVDs.

The mere fact that people are concerned about this, and doing things like the seedbank, shows that efforts will be made to preserve much of our culture, know how, and history. Of course it will be spotty, and there will be missing chunks, like what we have from the classical world. But with superior awareness (benefit of seeing the past), and superior technology, that point may take 20000 years rather than 2000. And here's the kicker. Part of what we archive will be what we have from the classical world, and part of what they archive in 20000 years will be their own stuff plus what they have from us. I think we've reached escape velocity and will manage to not fall back.

318:

If memory serves, Larry Niven described a future earth where a micro organism had developed a taste for polyethylene, drastically reducing it's utility.

319:

"Missing chunks." For example, we have 6 epics and 45 plays from ancient Greece. That's out of who knows how many (hundreds? thousands?) of pieces produced over a period of centuries, about 2800 to 2200 years ago, and that's using a much more durable technology than digital media. Indeed, we're still using writing, and people still read ancient Greek.

Missing chunks, in this case, means missing almost everything.

320:

Interesting blog - thanks for posting!

Found this article referenced/linked by one of the commenters re: AD individualized therapy examines many variables including diet (includes case studies). Might be of interest to folk here. My take-away is: AD is a complex disease (syndrome?) and that may be why single-shot therapies just don't work. (And why BIGpharma R&D haven't been successful in finding THE magic bullet/pill?)

https://s3-us-west-1.amazonaws.com/paperchase-aging/pdf/NjJf3fWGKw4e99CyC.pdf

321:

Hint: in a decade's time, competitive VR gamers (competitive computer gaming is already a sport today) are going to be as ripped as gymnasts or martial arts experts.

Meanwhile, half the population is obese and regard a flight of stairs as a significant physical barrier. What athletes do and the mass market are essentially uncorrelated.

My expectation is that the more strenuous VR stuff will be less popular as personal experience than the Wii and will probably peak in the same market (kids/youth, plus geriatrics), and the great majority will use it the way they use headphones today - as a way to consume passive media privately. I reckon the peak physical activity will closer to Pokemon Go than Paris-Brest_Paris.

322:

Anything digest fluorinated plastics?

323:

Not that I've heard of, and I'd hate to lose my nonstick cookware. But we've been offering a steady supply of plastics to soil organisms for a long time, it shouldn't be too surprising if something develops a taste for them.

324:

Some microorganisms seem able to develop a tolerance for fluoride. [See below.] Didn't find anything re: organisms specifically designed to remove fluoride from water, soil, etc.


http://www.ncbi.nlm.nih.gov/pubmed/19457531

Abstract

Fluoride is a common contaminant in a variety of industrial wastewaters. Available information on the potential toxicity of fluoride to microorganisms implicated in biological wastewater treatment is very limited. The objective of this study was to evaluate the inhibitory effect of fluoride towards the main microbial populations responsible for the removal of organic constituents and nutrients in wastewater treatment processes. The results of short-term batch bioassays indicated that the toxicity of sodium fluoride varied widely depending on the microbial population. Anaerobic microorganisms involved in various metabolic steps of anaerobic digestion processes were found to be very sensitive to the presence of fluoride. The concentrations of fluoride causing 50% metabolic inhibition (IC(50)) of propionate- and butyrate-degrading microorganisms as well as mesophilic and thermophilic acetate-utilizing methanogens ranged from 18 to 43 mg/L. Fluoride was also inhibitory to nitrification, albeit at relatively high levels (IC(50)=149 mg/L). Nitrifying bacteria appeared to adapt rapidly to fluoride, and a near complete recovery of their metabolic activity was observed after only 4d of exposure to high fluoride levels (up to 500 mg/L). All other microbial populations evaluated in this study, i.e., glucose fermenters, aerobic glucose-degrading heterotrophs, denitrifying bacteria, and H(2)-utilizing methanogens, tolerated fluoride at very high concentrations (>500 mg/L).


Don't know enough physiology to guess at what this means for real-life consequences, i.e., whether that drink of fluoridated water before HIIT is counterproductive. (If this is true, then you may also want to switch from tea to coffee. Tea made from older tea leaves has high fluoride content.)

325:

Drug development is easily as time consuming and complex as programming, and probably with as many undesired and unforeseen outcomes. Except they are more serious.
The first article you linked to didn't define what "best" is in the drug research world. Fortunately the paper it links to discusses that in more detail.

The odd thing I've noticed in my new job, being involved as it is with High throughput screening on the supply of compounds to be screened end, is that huge pharma basically went into HTS in a big way a decade or more ago, but didn't get quite the return it expected from it. Instead, what we're seeing now isn't massive 100,000 compound screening runs, but much smaller, 1k compound runs, and the compounds picked on the basis of how they match specific known molecules that affect target receptors or suchlike, in order to otimise our knowledge of the shape and size of the receptors and how they work, so as to work towards molecules and fragments of molecules which do the job best.

But even after that there's no guarantee that the best molecule will be safe to use or actually possible to administer to a human.

To avoid some of the problems, datasets and groups of molecules have been identified which have a known broader effect, say on the human heart, so should be avoided when trying to come up with a drug.


As for the immune system, I'm sure catinadiamond was there decades ago, but on radio 4 this evening they had a segment talking about how researchers are finding some forms of psychotic break and depression are linked to the immune system and ceratin antibodies within it, i.e. something causes the antibodies to be produced, then once in your system they mess with the brain, causing the problems.
So yet another form of therapy to be explored, which at least suggests that rather than doping people up with broad spectrum brain bashers, the specific stuff at the molecular level can be disposed of, leading to a large reduction in symptoms. Of course this wouldn't deal with every sort of depression or psychosis, but it would appear a promising start on some forms of them.
I have gotten the impression over the years that the human system brain-body, is, as a system, vulnerable to a lot of different perturbations that manifest as similar enough symptoms, despite having different original causes.

326:

Sure dude, whatever.

327:

Aliens are just empty calories. Remember to eat your tholin salad.

They Came To Eat Our Brains, We Gave Them Diabetes.

Cthulhu has a sweet tooth.

328:

Come to think of it, didn't Ringworld have superconductor-chomping microbes that caused civilization to collapse on it?

Oh well, nothing new under the sun.

329:

Videotape and obsolete file formats are artifacts of a period of rapid development. Now that electronic information technology is more mature things are settling down. For example, in a hundred years you will be able to open a pdf, txt, mp3, mp4, or probably even doc.

I have PDF files that I can't read right now. They require an older version of Acrobat Reader than will run on even my oldest computer.

I have files on floppy disks (5¼” and 3½”) that I can no longer read — no functioning floppy disk reader that I have access to.

I have Word files inherited from a coworker that the current version of Word won't open — they are too old. (Charlie wrote an essay about this once.):
http://www.antipope.org/charlie/blog-static/2013/10/why-microsoft-word-must-die.html

330:

Have you tried your old Word files in LibreOffice? I've had good luck salvaging text that way -- sometimes you lose some of the original formatting from some of Microsoft's more perverse stuff, but you may be able to get at the information from the text.

Once they figure out how to read a MS format, the developers don't discard the knowledge.

331:

Panfelicogyre? I forgot to comment earlier, but that's an excellent name! And we can use the Laithodyne as the updated prototype for a Spindizzy, correct?

Personally, I figure that running FTL or antigravity on a misapplication of Murphy's Law is at least as plausible as most of the designs out there (cough, stutterwarp, cough, bloater, cough...)

332:

I was thinking there must be a way to use Internet Trolls to power an interstellar drive. Maybe we could design something which runs on malice...

333:

AS Elyse says, or OpenOffice for the same reasoning? After all, they're both free downloads.

334:

How about using Nigerian scammers, phishers and trolls as reaction mass?

335:

OpenOffice development went to Oracle during the Sun take-over; the folks who were serious about it walked, forked the codebase, and named their fork LibreOffice.

Generally the code quality of LibreOffice is way ahead of OpenOffice these days, and it's receiving bugfixes and new functionality on an ongoing basis.

So you probably want to remove OpenOffice from your computery gizmos and install LibreOffice instead at this point.

336:

"Out of the Unknown" was probably based on one of the stories I can't remember the name of - I have it in one of my books, but can't remember which!

337:

I believe that there is a tropical fungus that secretes hydrofluoric acid - I have half a pair of binoculars, with the etchings clearly visible, which I was told was from that cause.

338:

Thanks; that's well work knowing in my case, (but may be less relevant in Robert's since we're effectively trying to find him a reader).

339:

Not sure what contitutes "hysteria" over there, but melanoma is very serious, the metastasis is often deadly. Sure I live in the place with the highest incidence in the world, so covering up is sort of second nature and I accept that this doesn't work the same way in dark, damp and cold places. Just another reason to question why people think such places are habitable, Shirley. You mean to say it's so dimly lit that you need to get (mostly) naked and go for a run in the snow just to avoid vitamin D deficiency? Madness!

340:

That's an excellent idea. Now all I need to do is persuade our IT crowd to install LibreOffice…

(We have some good people working in IT, but they seem outnumbered, or at least outranked, by those who passed a MS course by rote and only know one way of doing things with no understanding why. For example, passwords must be exactly eight characters with at least one number and no special characters, because this apparently gives us the highest level of security.)

Sarcasm about Dilbert Zone IT aside, thanks for the suggestion. The formatting is critical, so it may not work, but I'll try it after the holidays.

341:

Dead file formats are why open standards are hugely important. We've mostly transitioned to a worlds of "it's just a collection of bits" and underlying physical formats are starting to become less significant. How those bits are organised is still damned significant. Doing so in an easily and freely understood manner keeps information from evaporating in the future.

342:

Something must be done. This is something. Therefore this must be done.

There is significant evidence that the melanoma 'epidemic' has been, in a large part, caused by the sunscreen campaign. The early sunscreens protected against burning more than against melanoma, so people spent longer under the sun. This was predicted as a possible outcome right at the start (the 1960s?) by quite a few people, me included. The researchers I have spoken to were funded (one by HMG) on conditions that they did NOT publish, to avoid the manufacturers being sued. Also, melanoma is weakly associated with excessive sunlight on untanned skin - a (real) suntan is protective, to some extent.

In the UK, I believe that vitamin D deficiency is a MORE serious problem than melanoma, or even all skin cancers, and probably always was. Inter alia, as someone said, it is one factor in a both causing and failing to recover from a large number of serious problems, including cancers. And, in a UK winter, if you are dark skinned, yes, you do indeed have to spend much of the day outside, naked, in order to get enough sunlight.

343:

Wasn't that "Something must be done. This is something. Therefore we must do it!" in the original?

344:

Could be. The form I quoted is the one that is used most often in practice, and makes more sense. But I have no idea where it originated, and it's probably older than the source that popularised it (like many such quotes).

345:

Yes. I have been meaning to mention this; apart from the causality problems, some forms of FTL drive have problems with conservation laws as well. This applies to pseudospeed drives like the stutterwarp (oldie but goodie RPG game fodder!) and EE Smith's inertialess drive. It goes like this:

Run out from the inner drive limit (which is ill-defined; the higher the gravitational gradient, the slower the drive is) of a large body such as a gas giant. Switch off drive, let yourself fall under gravity, switch drive back on, rinse and repeat. Gravity can accelerate you to an almost arbitrarily high speed, certainly a fair fraction of the speed of light. Where has the kinetic energy come from? Not the drive, for sure.

One can do much the same with the drive conceived of by the sainted Dr. Smith. In both cases (explicitly stated by Smith, not so clear in Traveller 2300) objects have an intrinsic velocity which is not affected by the stardrive; long, arduous and complicated inertial manoeuvres are required when arriving almost anywhere, from anywhere.

That's the problem, in general, with fictional FTL drives. Just about all of them break physics. Of course, that's assuming we know all the physics there is to know; that is an exceedingly arrogant and potentially dangerous assumption.

346:

In the UK, melanoma is a pretty low risk - the low angle of the sun means you have to try pretty hard to get burned and it's repeated exposure that adds up to an increased risk. The UV index peaks in summer at around 6, which is around 30-40 min burn time, and that gets increased by the amount of air pollution which varies but is noticeable year round.

Australasia on the other hand has a UV index starting at around 5-6 on a sunny day in midwinter, peaking in summer in NZ at around 12-13, and in northern and central Australia at 14-16. With the general lack of dust and pollution in the air, burn times can be as low as 5 min on fair skin on a bad day. In the clear airs out on a boat or on the mountain glaciers and the sun is seriously fierce.

Sunscreens designed for European conditions were notorious in the 80s and 90s for being worse than useless, with anything under SPF 30 being a recipe for pain and these days SPF 45 is more common.

There are valid reasons that melanoma is a huge concern for fair skinned people in the South Pacific, with the hole in the ozone layer only the most prominent one of them.

347:

Yes, but that wasn't the aspect I was referring to. My point was that their use INCREASED the risk of melanoma, everywhere, INCLUDING in Australia, for the reasons I gave - they included carcinogenic chemicals, too, but I believe that was a minor factor.

348:

There are valid reasons that melanoma is a huge concern for fair skinned people in the South Pacific, with the hole in the ozone layer only the most prominent one of them.
Ok, I'll bite. Is Australia in the Arctic, the Antarctic, or Tibet? ;-)

349:

Plus some folk happen to be very allergic to PABA one of the major active ingredients used in the first sunscreens marketed. BTW, if you happen to be 'allergic' to PABA in sunscreen, you're also probably 'allergic' to PABA-based local/topical anesthetics such as benzocaine. (Found this out the hard way in hosp.) Like most health-related stories, not enough press/attention paid to subgroup analysis, effectiveness/safety ranges, etc. On the flip-side, some folk need PABA supplementation for various (serious) health conditions. Ditto for sun exposure: since news of the sun exposure/melanoma connection first broke, MS and SAD incidences have increased. Conclusion: Again, no one-size-fits-all when it comes to human health.

350:

There was NO attention paid to that - the 'policy' was to implement the first something that came to hand, amply supported by the 'sunscreen' profiteers, and suppress any dissent. That's why Those With Clue predicted problems. And, as you say and I said, the lack of sunlight in the UK is a very serious health problem. I don't think that SAD is a major problem in Australia, though :-)

351:

Elyse wrote: Have you tried your old Word files in LibreOffice?

I more than second that. Just late last year, I finally picked up my late wife's writing, to finish it and sell it (we worked on them together, beyond that, long very spooky story (cue the Twilight Zone theme)). At any rate, its response, when asked to open early/mid-nineties WordPerfect documents was, "sure, why, did you think there'd be a problem? what else would you like me to open...?"

mark, currently looking for an agent for straight adult SF

352:

Of course star drives all break physics. That's kind of a given. It's also kind of a given that me talking about the realities of interstellar transport is a bit like an atheist pondering God.

On the other hand, SFF literature is all about the "here be dragons" blank spots on the map. That's where we postulate dragons and write stories about them.

Right now, physics can't really tell us what (they say) 96% of reality is, so you can do whatever you want with dark matter. I hear it makes excellent exhaust for starship engines--you can blast it out your ship engines, and only its gravity affects anything. The nice thing is that dark matter is a yuuuge realm of unknown stuff to play with. Perhaps it has dragons, or photino birds. Is it the signature of hyperspace? Could be. Is dark matter the gravitational signature of our space being so folded on itself in higher dimensions that we can wormhole across and save millennia in transit (and dark energy is the universe trying to lie flat)? Also possible, albeit totally improbable. The universe of dark matter and energy, so far as SFF artists are concerned, is a motherlode of potential bullshit, in the technical use of the term.

Ditto with quantum gravity. When some theorists are talking about doing away with a temporal dimension to create a grand unified theory, potentially there's something like whatever Brin's Time Drop drive hiding out there in theory space, or those other "T goes to zero, V goes to infinity" space drives that are out there. Maybe we can use the observer effect to arbitrarily redefine where a ship is in four-space (the big jump method). Or maybe we can make starships do high frequency quantum tunneling and get that stutterwarp jittering along, like a monstrous quantum bristlebot.

Perhaps, ultimately, the Fermi Paradox will turn out to be a real paradox, and not merely a sign that interstellar travel is impossible and detection is impossibly difficult.

And so forth. There's ample room to BS your way to the stars. The problem is, we've been doing it for so many decades now that there seems to be a bit of BS fatigue out there. Still, it looks like publishers are betting on a space opera revival being the Next Big Thing. Let's hope they're right, and another black swan like Harry Potter doesn't come along and drink their milkshakes for them. We can hope, and in the meantime, we can invent panfelicogyres.

353:

>>>Hint: in a decade's time, competitive VR gamers (competitive computer gaming is already a sport today) are going to be as ripped as gymnasts or martial arts experts. Using a Vive is intensely physical -- not force-intensive, but requiring rapid and coordinated movement and reflexes.

I'd like VR where I can pretend to be super-human, preferably without getting tired in the process...

354:

Hmm, I'm not so certain that sunscreens particularly increased melanoma risk in and of themselves.

Go back to the 1700s/1800s and most white people wore long sleeved clothes at all times. Early 1900s and that started to reduce, 1940s onwards and beach culture as we know it starts to exist.

So people are wearing less clothing, and spending more time in the sun. They are dying less of everything that previously killed them, and have settled in places that were previously the domain of people with much more melanin. That makes it a perfect breeding ground for new things to die of, and melanoma is just one of them.

That being said, I don't know enough to speak to the potential snakeoil history in the early development, but can easily believe there were lots of problems swept under the rug in the name of sending troops into hot places...

355:

Another totally different topic, inspired by Proxima Centauri B:

About the planet's weather...

Once they announced the Prox B's putative characteristics, I immediately started worldbuilding. Then I ran into trouble, and that's what I wanted to kick to the crowd here, although it's too bad we don't have any meteorologists in attendance.

One is this idea that having a tidally locked planet means that there's a perpetual storm under the noon sun, a perpetual icecap under the midnight stars, and a perpetual flow of moist air from day to night, culminating in all the water ending up on the night side as some gynormous ice cap.

That sounded reasonable until I thought of Hadley Cells On our world, the sun heats the tropical air. It picks up water from the ocean, rises, cools, and when that air gets below freezing, all the water condenses out into those huge stormclouds. The now very dry air flows polewards, where, about 30 degrees off the equator, it drops down, forming deserts like the Sahara as the dry, hot air falls to make persistent high pressure zones (the Ridiculously Resilient Ridge in the Eastern Pacific could be a Hadley Cell moving north, IIRC).

You don't get a huge storm under the noonday sun on Proxima B unless the air has shed all its water to make those clouds in the first place. The air that flows away from that huge storm will be dry, not wet, and I'm not sure how humid air is supposed to flow from the dayside to the nightside.

Equally, I'm not sure what the equivalent of a Hadley Cell would look like on Prox B. Because the daystorm area is stationary and there's no Coriolis effect, the air is moving out from the storm in a circle, but equally, it's getting drawn back in in an circle. My first guess is that it's going to be pretty chaotic, with cyclone-ish things (do they spin without a strong Coriolis effect?) boiling up and spinning out in random directions until they've dumped their rain in the deserts beyond, but I really don't know. This is where I wish a meteorologist with an interest in SF would suddenly appear and straighten me out.

And that's not all of it.

There's another problem with the whole flare-star thing. IIRC one reason they didn't get a good look at the x-ray universe until the Chandra satellite was that our atmosphere is really good at blocking x-rays. And it blocks a fair amount of UV too, especially where there are clouds. I also remember getting into a discussion one Christmas with a space physicist about how the magnetic fields of Jupiter and her moons are linked. I suspect that the magnetic fields of Prox B and Proxima Centauri would be linked in some sort of really complicated way that would make sorting out the effects of Proxima Centauri flares on Prox B a non-trivial exercise.

Then there's the whole "no moon" problem. Here, I'm not thinking about rotational hijinks or tides, but that Earth's Moon was formed by blasting a fair amount of Earth's crust off and putting it into orbit. At a first guess, Prox B is going to have a thicker crust than Earth would (more stuff on top). If it does, this also means that its mountains will be taller, and possibly (depending on what you believe about water and volatiles) that it will have a deeper ocean and thicker atmosphere to go along with that. Super Polynesia? Possibly. Possibly not. If there's more water, the oceans at the noon and midnight points will be so many kilometers deep (due to the gravitational influence of Proxima Centauri) that there's no chance of land under the sun. Along the dawn/dusk line, though, the water will be kilometers shallower, and there may in fact be a ring continent at the 90th meridians, blocking oceanic circulation from the day side to the night side.

Where did I get all this? A lot of it comes from working out the physics of a habitable moon circling a gas giant back about 7 years ago. This is the same situation, only bigger, and in some ways, simpler.

My biggest complaint was that I was hoping that Proxima Centauri would be this swollen red brooding presence in Prox B's sky. No such luck. It's about 1.5 degrees across. Prox B's sky will likely be a washed out blue, it's sun kinda wan. If you've been out on a clear winter's day, you've seen that sky already. Sadly unexotic.

356:

As I said, I have spoken to a few people who researched this area, and their results showed clearly that the use of sunscreen did, by the mechanism I described. As I also said, you won't find this published ....

The standard clothing of the hotter parts of the Empire was shorts and short-sleeved shirts, sometimes topless for men (especially for boys), and melanoma was less prevalent before the hysteria compared to afterwards. Yes, the WWII troops sent to North Africa got a lot of melanomas (one of my uncles was one), but that's a different era from the 'epidemic'.

357:
this also means that its mountains will be taller,

Wouldn't the higher gravity of the more massive world have the opposite effect?

There have also been quite a few theoretical studies of atmosphere dynamics on exoplanets, including tidally locked ones. The possible space of outcomes is quite large depending on atmosphere composition and density, axial inclination, orbital eccentricity, where situated in the HZ etc. probably worth looking at a few if you haven't already done so, if just for ideas.

358:

You are right that there would be major differences, but I suspect that there will be more circulations than that. Of course, the proportion of ocean will have major effects, especially whether or not the poles are part of a connected ocean or not. As you say, this needs a specialist to make an intelligent guess at the details.

359:

You don't get a huge storm under the noonday sun on Proxima B unless the air has shed all its water to make those clouds in the first place. The air that flows away from that huge storm will be dry, not wet, and I'm not sure how humid air is supposed to flow from the dayside to the nightside.

A couple of other considerations:

Proxima Centauri is a red dwarf, very cool compared to our sun, but it's an X-ray flare star, producing nearly as much X-ray flux overall as our own star. Solar UV splitting is one of the main causes of loss of water/hydrogen from planetary atmospheres -- absorption of UV by water vapour in the high stratosphere/ionosphere results in splitting to hydroxyl radicals plus hydrogen (which rapidly dimerizes), and the hydrogen is light enough that solar UV can kick H2 molecules right out of the high ionosphere and into space/the solar wind. I'm not sure, but I'm going to guess that atmospheric absorption of X-rays results in significant ionization effects, and solar X-rays are therefore equally potent at splitting water molecules; Prox A's proximity to Proxima Centauri suggests that the effects of those flares on the upper levels of the atmosphere could be savage.


About Alpha Centauri: Proxima is 15,000 AU +/- 700 AU from Alpha. Note that Pluto orbits roughly 40 AU from Sol. That's a horrendous distance -- 0.23 light years!

360:

Which might lead to a situation like Venus: where have all the H'atoms gone?

361:

Gonna depend on the atmospheric makeup I think. X-rays do have more energy, but a shorter wavelength (so great odds of a hit) and enough energy so that the x-rays are absorbed by atoms rather than molecules.

In our atmosphere, x-rays actually have a very low penetration compared to most other wavelengths since oxygen will absorb it and kick out an electron resulting in fluorescence.

I'm betting James Webb and TESS, in combination with various other telescopes will all be looking to see if there is x-ray absorption on Proxima B. From what I've read, those flares from Proxima are often enough that we can get some great data.

Also I'm wondering about the orbital mechanics for this planet having a moon. Far as I can tell the techniques involved so far cannot tell if its a planet, a planet and moon or even something like a double planet.

362:

I would expect that the electron-bashing will cause quite a lot of UV, but I am just speculating. My understanding is that such a close planet cannot keep a moon for long, because you can't have both the planet and moon tidally locked and the distances are such that it is inevitable. While I have seen quite a lot of SF that talks about close-in double planets, I am not sure that it's plausible, on the same grounds. But I don't remember having seen a proper analysis, though I am sure that some exist.

363:

I'm sure that incorrect sunscreen use may have very slightly complicated the problem, but I doubt it was or is statistically significant and it certainly wasn't an underlying "cause". On the other hand the "Slip, slop, slap" campaign was among most successful public health campaigns anywhere, ever (arguably more successful than the "Grim Reaper" campaign).

Many fair-skinned people just don't tan enough for this to offer significant protection. Those who try end up a sort of permanent burnt-orange rather than brown. You used to see it a lot with people who worked outside, and such people as a rule died young. In addition to the factors Mayhem described, I would also draw attention to detection rates, which increased dramatically in the middle of the 20th century in most places in the world.

364:

First two papers on weather on tidally locked papers I found, not read yet:
https://arxiv.org/pdf/1405.1025.pdf
http://mnras.oxfordjournals.org/content/453/3/2412.full


I really don't understand Hadley cells. I think the crucial question for us is why the subtropical high pressure belt is where it is, on earth. Would it be at 30° on a tidally locked planet?

What would be a mechanism that transports water from the cold side to the warm? If there is none (most water frozen), the atmosphere will be very dry and the planet might keep it's water (because it's safe in the shadow, not in the stratosphere).
But the question of water crucially depends on the weather systems and on what shape and size Hadley cells assume.

Another idea to safe water (not really plausible - spot the chicken and egg problem): Oxygen is even more abundant that on earth, so there's a thick ozone layer that slows water loss.


365:

The X-ray flux from Proxima Centauri to Prox B, on a first guess, is about 8 times what we experience on Earth from the Sun. The way I calculated this is to use the formula for the surface area of a sphere (4pi*r^2). The flux coming off the surface of a sphere is the same flux that's found in a sphere of a much larger diameter further out, so the flux of the sun (of 1.0 solar radii) is much smaller when it reaches the orbit of the earth (a sphere with a radius 1 AU). Now, Prox B orbits at about 0.05 AU from Proxima Centauri, but Proxima Centuri is 0.141 solar radii. Just taking the ratio of squares and assuming I didn't screw up, it looks like there's about 8 times the X-ray flux, or a bit less than experienced by Mercury.

So savage X-rays? Unclear. Ditto with the UV and anything resembling a coronal mass ejection at the same time, although the last is due to whatever interactions are going on between the magnetospheres of Prox B and Proxima Centauri, and since I know people that work on that stuff in our solar system, I know how complicated that mess is.

It's also unclear whether those X-rays would be splitting water in Prox B's atmosphere or, as elfey1 noted, causing oxygen to fluoresce in the high atmosphere. It looks like there is water vapor up in the stratosphere on Earth, but when we're talking about relative humidity falling linearly with altitude and atmospheric pressure falling nonlinearly, it's not clear what we're talking about in terms of the absolute amount of water high up. It's an important issue for modeling greenhouse gases, but it's not a simple one to discuss.

One thing I did biff up on is that Prox B does have a coriolis effect. Since the planet orbits Proxima Centauri in about 11.2 days, it has about 1/11 the spin. At a WAG, that's enough to start something like convection cells going, but that also depends (again) on the placement of mountains, continents, and other things that shape both air and water currents.

Things get weird with a tidally locked planet, because longitude matters more than latitude for determining the weather. The North Pole, South Pole, and Equator at the dusk/dawn terminator all have the same amount of sunlight coming in. However, coriolis effect depends on latitude, so it's more likely for storms to blow along the equator or "subtropical latitudes" more than due north over the poles. However, the equator at the terminator isn't tropical, because it's not getting direct insolation, so any equatorial cyclone spawned in the hot waters directly under the sun will hit a lot of cold water and dry air before it hits the terminator and goes over to the darkside, meaning it won't hit land as a cyclone, and will dump a lot of water on the cooler dayside oceans first. If there is a lot of topography on the terminator (and there should be, because the ocean is kilometers shallower), then you get all sorts of orographic effects pushing storms up and forcing them to cool and dump precipitation on the mountains before they get to the darkside.

I'm not sure what darkside storms would look like, but there might be the possibility of the occasional "perfect storm" when dayside and darkside storms somehow combine at some point over the terminator.

The other thing is that while the surface of the darkside ice is presumably very cold (unless there's a big greenhouse effect on, as with Paleocene Antarctica), but there's still a lot of planetary heat under the ice, which suggests strongly that the ice is sitting on water. If there are channels for that water to flow back to the dayside, it probably will. If nothing else, you get all sorts of weird stuff going on when you try to float a huge glacier on kilometers of water. Whatever else, it's not going to stay static.

Fun stuff. I wish more of it was captured in the astrobiology papers I've seen so far.

366:

I think what happens in order is a solar x-ray photon smacks an oxygen atom's electron cloud, freeing an electron from an inner shell. The oxygen then experience an outer shell election collapsing to the inner shell. This generates another photon to balance the energy. This photon should be an X-ray as well, but its lost some eV. Its also emitted, so its scattering. The new X-ray will likely hit another oxygen atom, reducing further the energy as the process repeats. I'd have to really look and do math I've not done in 10 years here to figure out what's likely.

Eventually you might get some UV, but even if that strips H from H2O, each of those ionizing interactions produced free oxygen.

As for the shape, prolly need to check the the roche limit. Might end up being close enough to cause any planetary mass to distort. Also depends quite a bit on density.

367:

Ozone depletion is asymmetric and affects the southern hemisphere more than the northern, and the Antarctic ozone hole is so large that at times it crosses populated areas. Here the vernacular is to refer to "the hole in the ozone layer", though usually that covers a range of things. Key point is there isn't a discrete boundary. See https://www.environment.gov.au/protection/ozone/ozone-science/ozone-layer

368:

Hm. I'm still wading through that second paper but by eye is caught by the wind speed chart. Apparently slow rotation planets are not stuck with constant hurricanes; just the opposite, weather may tend to be quite slow and gentle when the temperature only changes over many hours. That's interesting and, unlike so many of our exoplanet discoveries, not disappointing to those of us who would like to see extrasolar life.

369:

I wonder about the need for something like our moon and the effects if brings as a precondition for "advanced" life to develop, and on whether habitability is even feasible in the most optimistic terraforming sense. Is there a good source on that?

370:

Another idea to safe water (not really plausible - spot the chicken and egg problem): Oxygen is even more abundant that on earth, so there's a thick ozone layer that slows water loss.

Above a partial pressure of oxygen of 30%, even waterlogged organic tissue burns like dry wood; you get rampaging forest fires from lightning strikes and animals that go up like torches. Makes life on land impossible.

You also need to oxidize the entire upper lithosphere (assuming you've got plate tectonics) before you can get there.

371:

Once they figure out how to read a MS format, the developers don't discard the knowledge.
That's the truth. Yeah, that file format knowledge was often hard won, and much of it written down. Still have a 1995 "File Formats Handbook" hardcover on my shelf. Mainly useful as a heavy flat weight, but you never know. (It's fairly valuable as a used book so there's that too.)

For the early/mid versions of MS Word (Excel etc) the description of the file format was quite literally Microsoft's reference (code) implementation. I had to sign a 5 year non-compete (essentially, and long since expired) with MS just to be a backup (who could look at this code) for a person who was working more directly with parsing of MS documents.

372:

It's the Rabid Trombone Reality Check that depresses me.

373:

We (almost) got there in the Carboniferous, thanks to some over-enthusiastic plants sequestering lots of carbon and releasing lots of oxygen. The evidence for charcoal midst the Carboniferous coal is reportedly quite plain.

Fortunately, we managed to avoid that particular catastrophe. I suspect that it's one of those things that's a temporary disaster, not a permanent one, simply because there are so many things for free oxygen to react with.

As you've noted before,most of Earth's history (the 4 billion years or so that life's been around) seem to have been about dealing with oxygen. Before the cyanobacteria came along, this planet had a *lot* of reduced chemicals, and it took a very, very long time (as in most of the history of this planet) to oxidize them thoroughly.

374:

I had the usual problem of them being long on "saying stuff" and very short on "showing stuff". Perhaps you'd like to point out Australia, or even New Zealand, in the illustration at the top of https://en.wikipedia.org/wiki/Ozone_depletion ?

375:

The X-ray flux from Proxima Centauri to Prox B, on a first guess, is about 8 times what we experience on Earth from the Sun.

No, it's about 400 times what we experience on Earth. Your argument assumed that Proxima Centauri produces the same amount of X-rays per unit surface area as the Sun. However, Proxima Centauri is a different type of star than the Sun; as Charlie pointed out, it actually produces about the same total X-ray luminosity as the Sun, despite being much smaller and lower mass. Since Proxima b is 20 times closer to Proxima Centauri, the result is an X-ray flux that's about 400 times higher.

IIRC one reason they didn't get a good look at the x-ray universe until the Chandra satellite was that our atmosphere is really good at blocking x-rays.

Yes, although there were in fact quite a lot of X-ray space telescopes before Chandra, starting back in the 1960s.

376:

I'm not sure, but I'm going to guess that atmospheric absorption of X-rays results in significant ionization effects, and solar X-rays are therefore equally potent at splitting water molecules...

Basically, yes. Splitting a molecule (or ionizing an atom or molecule) requires delivering enough energy in one blow to equal or exceed the binding energy of the molecule (or electron in an atom). Generally, the energy required to do this corresponds to a UV photon. Since X-rays (and gamma rays) are higher-energy photons, they can easily do this, too.

In practice, the cross-section for interaction between photons and atoms or molecules tends to be highest right at the binding energy, and decreases for more energetic photons. So a UV photon with enough energy to photodissociate a molecule is more likely to affect the first molecule it encounters, while an X-ray photon may zip past five or ten before it interacts with one. However, since planetary atmospheres are (by astronomical standards) really thick, an X-ray photon hitting a planetary atmosphere will interact with a molecule sooner or later. (As well as the possibility of ionizing an atom within a molecule and freeing an electron with enough energy to dissociate another molecule, etc.)

377:

I agree that there is an excessive extent to which organisations ram their conclusions down your throat, and obfuscate or hide the data. The paper Damian quoted claimed a 5-9% drop in ozone over Australia, which I believe corresponds to a small integer factor increase in high-energy UV flux at the surface. But the less technical papers describing both the absorption and which frequencies are associated with melanoma are bloody awful, for the above reason, so it's quite a project to work out what the factor really is. You CAN get at the actual facts by decoding research papers, which rarely misrepresent data, but it's bloody hard work. Or you can talk to researchers in a relevant area, which is where I have got much of my information from.

Summary: in this case, I believe that Damian was right in principle, but obfuscated the situation. The 'hole' isn't hard-edged and is global in effect, and the pretty pictures are an artifact of the presentation intended to promote a political message.

378:

The key point is that while the main hole is over Antarctica, pockets of reduced ozone spin off and move north on a daily basis. Which way the pockets go is random, but they tend to rotate clockwise around the southern ocean over the course of a week or so then dissipate. here is one over NZ, here over Tasmania, and here is the opposite, with a thickening over NZ and the big hole heading to South Africa

All three images are in the past month, I can't be bothered hunting for specific examples of bad cases for you.

379:

Nitpick: I didn't cite a paper at all, I just linked the front the Australian federal environment department's page on the topic, which itself links a bunch of things. If you're after hard data I'd regard that as a starting point for someone unfamiliar with the problem. For most people's practical purposes the BoM is the goto site these days: http://www.bom.gov.au/uv/

Anyhow, I don't see how I'm obfuscating anything there. Images like the one paws4thot linked are just visualisations - there are no discrete edges, the area of very thin ozone changes size constantly to rough seasonal cycles and also rotates and moves.

More to the point, I'm not really arguing any case here. I'm just pointing out the things Mayhem was saying have been non-controversial for 20-30 years, so arguing against it is a bit... well whatever. No disrespect intended anyway.

380:

a (real) suntan is protective, to some extent

Not really. A suntan amounts to an equivalent of 2-3 SPF (or less if you get it from a tanning salon).
http://www.scientificamerican.com/article/fact-or-fiction-a-base-tan-can-protect-against-sunburn/

381:

That I agree with. Ok, the visualisation does depend on a colour key to tell us how much thinner the ozone is where, but it's obvious that darker blues are thinner and brighter reds are thicker.

What it also illustrates is that there is no permanent hole by the time you reach Oz; just temporary thin patches that spun off the main hole.

382:

If it does, this also means that its mountains will be taller, and possibly (depending on what you believe about water and volatiles) that it will have a deeper ocean and thicker atmosphere to go along with that.

As Alex Tolley pointed out (#357), it's the other way around. Proxima Centauri b has a mass of at least 1.3 times the Earth (probably somewhere in the 1.5-3 Earth-mass range). Higher surface gravity means less extreme topographic variations: compare Earth and Mars.

(Also, I don't know why you're supposing that Proxima b can't have suffered a protoplanetary collision similar to Earth's.)

383:

Yep. It's also seasonal, this is the cover over NZ in January and this one in march, when the sun is at its peak. Contrast with July which is winter.

The sun risk has been common knowledge for years, with UV pictures in the weather sections of the papers or evening news. Weather is a big thing in NZ, as it changes so fast, so the populace is reasonably well informed.

384:

While we're in transit, and the shield is being bombarded by highly energetic particles, we want the shield to be transmuted into some chemical which will be useful upon arrival. What materials do we start with, and what do we end up with?

Actually, I don't know radioactive decay chains all that well, so I can't really suggest anything interesting off the top of my head. (You'd have to worry about whether the decay processes produced any dangerous radiation along the way, as well as how the decay products from the intermediate processes might cause transmutations themselves...)

Also, your shielding is being continually eroded by collisions with dust particles, so most of your interesting decay products will probably be lost along the way.

385:

a (real) suntan is protective, to some extent
Not really. A suntan amounts to an equivalent of 2-3 SPF

Hmmm. One data point.

In my foolish youth I mowed fields in the summer typically wearing nothing but shorts shoes and hat. No sun screen. I would burn early in the summer. Once. Then just be dark the rest of the summer. Why no more burns?

386:

It's not just one data point. Those of us who have lived in the tropics know that effect well - back in the 1950s, almost nobody used sunscreens, and they were pretty useless when they could be obtained. Some people didn't tan enough to resist sunburn, and pretty well every white would burn when exposed to excess, but most people who had lived there for some time had no trouble. The Geekish Merkin is not a reliable source. In any case, I was talking about melanoma, and the effect is well-known to oncologists, because of the relative frequency in different locations - to remind people, I said 'to some extent'.

387:

Possible moons around Proxima b:

The Hill radius radius for Proxima Centauri b, which sets the basic limit on how far out a moon could stably orbit around Proxima b, would be something like 100,000 to 200,000 km, depending on the mass of Proxima b (more massive planet = larger radius) and the eccentricity of its orbit (more eccentric = smaller radius; all we know right now is that the eccentricity is less than 0.35). More detailed calculations suggest that half the Hill radius may be a more realistic number, so let's say 50,000 to 100,000 km.

The Roche radius for Proxima b, inside of which the moon would be torn apart by the tidal forces, would be something like 10,000 to 25,000 km (depending on the the planet's mass and the density of the moon).

So the basic stability criteria allow Proxima b to have a moon with an orbital radius between roughly 20,000 and 100,000 km. The corresponding orbital periods for such a moon would be roughly 0.1 days to 6 days. Assuming Proxima b is tidally locked to the star, any moon in a stable orbit would be orbiting faster than Proxima b's rotational period, and so -- if it was orbiting prograde -- would experience tidal deceleration (the opposite effect of the Earth-Moon system, where the Earth spins faster than the Moon's orbital period). How long this would take before the moon's orbit shrank down to the Roche radius and it was torn apart depends on a lot of poorly determined parameters, although smaller moons would last longer. Based on the calculations for lower-mass planets with small orbits about their parent star in this paper, I'd tentatively say any moon currently orbiting Proxima b would need to be less than 10-4 times the planet's mass, and so would be pretty small. (For comparison, our Moon is about 0.01 times the Earth's mass.)

388:

>Excel

https://www.washingtonpost.com/news/wonk/wp/2016/08/26/an-alarming-number-of-scientific-papers-contain-excel-errors/


An alarming number of scientific papers contain Excel errors
By Christopher Ingraham August 26 at 6:17 AM

A surprisingly high number of scientific papers in the field of genetics contain errors introduced by Microsoft Excel, according to an analysis recently published in the journal Genome Biology.

A team of Australian researchers analyzed nearly 3,600 genetics papers published in a number of leading scientific journals — like Nature, Science and PLoS One. As is common practice in the field, these papers all came with supplementary files containing lists of genes used in the research.

The Australian researchers found that roughly 1 in 5 of these papers included errors in their gene lists that were due to Excel automatically converting gene names to things like calendar dates or random numbers.

389:

Excel is also notorious for numerical unreliability, including replacing errors by bogus values without comment, and has been since it was perpetrated.

390:

Related to this; Excel can (will?) not correctly render and store Latitude or Longitude values in DD:MM:SS or DD:MM.9 formats, only in DD.9.

This appears to be a side effect of it using day numbers from 01 Jan 1900 as "day 1", and presuming that a value entered as 99:99:99 format must be a time of day, with a maximum value of 23:59:59(.999), so that, say, 57:30:00 is read as 03/Jan/1900 at 09:30:00 rather than Latitude 57.5 North.

Incidentally Excel also incorrectly treats 1900 as a leap year, but that's actually Lotus Software's fault because they made that mistake in 1-2-3 and Microsoft noted the bug but retained it for compatibility.

391:

I can attest to that exact problem. Working with another bioinformatician I was writing some analysis code for him and had to get him to re-create the input data a couple of times because of various excel data-modification bullshit.

I'm from a software background so some of the checking code caught it but I can easily imagine it making it into the final analysis with someone from a stats or bio background.

Most of the time it wouldn't have made a difference to the analysis but it's an absolute pain in the ass. I'm sorta tempted to make a list of genes with names which excel will mangle and see if there's any low hanging fruit of things missed due to the problem.

392:

Though I should note, it's not a problem unique to excel, any system which attempts to figure out data stored in an unknown format in a string can screw things up the same way.

I once hit something similar with some legacy code which attempted to look for formatting in emails which was incorrectly matching on certain number combinations in emails and mangling emails as a result.

393:

Gravity will haul down mountains, but gravity isn't destiny for mountain height. Mercury, the Moon, and Venus have proportionally lower mountains than does Earth, while Mars, Pluto, Io, Vesta, and Ceres have proportionally taller mountains. source: https://en.wikipedia.org/wiki/List_of_tallest_mountains_in_the_Solar_System).

Earth is the heaviest rocky body in the solar system, so we don't have good information about what happens with even bigger worlds.

We also don't have good information for mountain height across Earth's history. Were the Appalachians once higher than Everest? Were the Alps? There's no good way to tell. That's the difference between an active crust and a static crust.

But yes, the argument about crustal thickness supporting taller mountains is dubious. It works for Everest and Mt. Olympus (both of which rest on thick crusts), but it doesn't work for Mauna Loa, which rests on thin crust. Gravity plays a role in mountain heights, but the forces that build up mountains (continental collisions, vulcanism, major asteroidal impacts) play much bigger roles.

394:

With regard to Excel, Mark Lieberman has some comments here
http://languagelog.ldc.upenn.edu/nll/?p=27730

395:

Re 373: "We (almost) got there in the Carboniferous, thanks to some over-enthusiastic plants sequestering lots of carbon and releasing lots of oxygen. The evidence for charcoal midst the Carboniferous coal is reportedly quite plain."

It strikes me that if anything like our biology developed there, and the O2 went up, all the fires would have pulled out O2, lowering the percentage. Seems like a natural check and balance.

mark

396:

I was thinking about economic opportunities, (assuming interstellar travel at some significant fraction of light speed.) Something like "We know the Epsilon Eridani colony is short on This_Material, so we'll build our radiation shielding of That_Material, which will turn into This_Material due to radioactive decay. Upon arrival at Epsilon Eridani, we will sell our shield at a profit and build a new shield."

397:

Radioactive decay doesn't work that way, and transmutation and fission are not radioactive decay.

398:

We now know that the mass of the new world can't exceed 2-3 Earth masses

http://www.space.com/33845-why-proxima-b-exoplanet-hard-to-find.html

399:

Back to VitD ... this ties in with retirees/seniors who prefer to just sit in front of a TV all day. If your bones haven't fused properly, and (consequently) muscle development is just so-so even during your youth (because your skeleton is too feeble to bear more muscle mass), then what chance do you have to do much more than watch TV in your old age. The below also suggests (to me) that hip fractures would be far likelier among the VitD deficient group. Further, because the bone matrix is so crappy, these folks' bones wouldn't mend nearly as well or as fast.

'By definition, rickets occurs in children whose growth plates have not fused. These children are often found to have started walking late or prefer to sit down for prolonged periods. In adults, vitamin D deficiency results in osteomalacia, which presents as a poorly mineralized skeletal matrix. Adults in these cases can experience chronic muscle aches and pains.[6]'

Oh, and tanning beds (UVB) are a recognized therapy for VitD deficiency.


And there's a link between maternal (first trimester) VitD deficiency and ADHD/hyperactivity in children.

http://www.medscape.com/viewarticle/864249

Coverage from the European Congress of Endocrinology (ECE) 2016

Medscape Medical News > Conference News
Maternal Vitamin D Deficiency and Behavioral Issues in Offspring

Becky McCall
June 03, 2016

Maternal vitamin D deficiency in early pregnancy is associated with an increased risk of behavioral issues and attention-deficit/hyperactivity disorder (ADHD)–like symptoms in preschool children, according to new data from a birth cohort study in Greece.

But no association was found between maternal vitamin D deficiency and cognitive scores in the children at age 4, reported Vasiliki Daraki, MD, an endocrinologist from the University of Crete, Heraklion, Greece, who led the analysis, which was a poster presented at the European Congress of Endocrinology 2016.

"Given the high prevalence of vitamin D deficiency among pregnant women, these findings could have important clinical and public-health implications," said Leda Chatzi, MD, coauthor of the poster and director of the Rhea mother-child pregnancy cohort, which was started in Crete in 2007.

Ironically, even in countries with abundant sunshine like Greece, vitamin D deficiency is a growing public-health issue, and there is no recommendation for pregnant women to take supplements. In fact, in this analysis, Dr Daraki and her colleagues showed that 60% of pregnant women were vitamin D deficient. "This is concerning, because the fetus is dependent on the supply of vitamin D from the mother," she said.

And "a recent study from Spain has also shown that vitamin D deficiency during the first trimester was associated with ADHD," Dr Daraki told Medscape Medical News.

First-Trimester Vitamin D Deficiency and Behavioral Problems

The Rhea longitudinal, prospective pregnancy cohort study aims to evaluate the nutritional, environmental, biological, and psychosocial exposures in the prenatal and early childhood periods of 1300 mothers and their children to the age of 7 years. This particular analysis was designed to investigate the associations between maternal 25-hydroxyvitamin D [25(OH) D] levels in early pregnancy with offspring neurodevelopment at 4 years of age.

A total of 471 mother-child pairs were included in the analysis. Maternal vitamin D status was measured by plasma concentration of 25(OH) D at the first prenatal visit (around 13 weeks). The levels were rated according to the 2011 Endocrine Society categories: sufficiency (> 75 nmol/L), insufficiency (52.5–72.5 nmol/L), or deficiency (

At 4 years of age, the children were evaluated for cognitive and motor functions using the McCarthy Scales of Children's Abilities (MSCA), and their emotional and behavioral development was assessed using two questionnaires: the Strengths and Difficulties Questionnaire (SDQ), and the Attention Deficit Hyperactivity Disorder (ADHD) Test. Multivariable linear regression analyses were used to estimate the effect of maternal vitamin D status on child neurodevelopment.

The analysis showed that maternal vitamin D levels lower than 50 nmol/L during the first trimester of pregnancy were associated with increased behavioral problems and ADHD-like symptoms among the offspring.

"The lower the mother's vitamin D levels, the higher the child's hyperactivity and inattention," reported Dr Daraki.

The most notable findings comprised a 2-point higher score in the SDQ scale of behavior problems (25-item scale; β-coef, 2.07) and a 5-point increase in score in the ADHD-like symptoms scale (36-item scale; β -coef, 5.36).

"This ADHD score is significant," remarked Dr Daraki.

The association of vitamin D deficiency in pregnancy with peer-group relationship problems was less pronounced, with only a 0.58-point increase in score.

"But in another analysis, when we examined mothers with even lower levels of deficiency, we did see a stronger relationship with peer-relation problems," she noted.

Cognitive function in the children was not found to be associated with vitamin D deficiency in pregnancy, however.

Maternal thyroid function in pregnancy or maternal obesity did not modify the observed associations.

"I think the role of vitamin D in the developing brain is in neuronal differentiation and axon development, and these are more important for behavioral problems than for cognition," Dr Daraki added.

In the future, she and her colleagues intend to measure the cognitive function and behavioral status at the age of 7 years and determine whether the results still hold at the later age.'

400:

Radioactive decay doesn't work that way, and transmutation and fission are not radioactive decay.

Well, many forms of radioactive decay involve transmutation (e.g., 40K to either 40Ca or 40Ar, or 14C to 14N), and spontaneous fission is usually considered a form of radioactive decay.

401:

We now know that the mass of the new world can't exceed 2-3 Earth masses

Actually, no... the statement in that article was clearly referring to the lower limit on the planet's mass, from earlier (unsuccessful) observations.[*]

Prior to the recent study, you could rule out a planet with mass > 2-3 M_earth / sin i, where i is the inclination of the orbit (90 degrees for edge-on, 0 degrees for face-on). Now the mass is known to be about 1.3 M_earth / sin i, which means 1.3 M_earth if the orbit is edge-on, up to (for example) about 7.5 M_earth if the inclination is only 10 degrees. (Because we can only measure the Doppler shift, which comes from the part of the planet-star motion that in our direction. If the orbit is edge-on, then at the right point in the cycle, all of that motion is in our direction. But if the orbit is inclined by i degrees, then we can only see sin i times the velocity.)

[*] OK, "clearly" if you know how the observations and measurements are done; kind of misleading if you don't.

403:

Speaking of neglected tropical diseases [402]:
http://www.sabin.org/programs/global-network-neglected-tropical-diseases

For the cost of a typical Starbucks drink, you can make half a dozen lives far less miserable, while also flouting Big Pharma.

404:

Interesting. Thanks!

Let's see, a large majority (more than 75%, IIRC) of drug development costs are salaries, and some unknown chunk of the retail cost (1/3?) is advertising. Getting salaries down and foregoing advertising makes a non-trivial difference in the cost of drugs.

They're also getting costs down by making combinations of existing drugs, rather than trying truly novel products. The latter take a lot more work.

That said, I've seen this in my own field. As a consultant, no one can afford me wasting my time doing real science, let alone anything exploratory or inventive. I'm about ten times too expensive. That's what grad students and research assistants are for. They're cheap, young, and disposable to some degree. That's why there's so gosh darn many of them in the system.

405:

I really don't understand Hadley cells. I think the crucial question for us is why the subtropical high pressure belt is where it is, on earth. Would it be at 30° on a tidally locked planet?

Fundamentally it's the result of conservation of angular momentum on a rotating planet: even if you have zero initial wind speed, with increasing latitude conservation of that equatorial angular momentum results in rapidly increasing zonal wind speeds. For rapidly rotating planets (such as Earth) the velocities get to be large (hundreds of km/hour by a latitude of 30°) and such flows are highly susceptible to instabilities.

The details are a lot more complicated than this, of course, but there are reasonable, pretty simple models that predict a Hadley cell width in latitude of about 30° for the Earth's parameters. For a non-rotating planet, you would expect the Hadley cell to extend all the way to the pole. Of course, tidally-locked planets are not non-rotating; whether they are rapid or slow rotators depends on their orbital parameters.

406:

LibreOffice. I downloaded and am trying out LibreOffice because of the recommendations here. The first frustration I found is that I have not been able to figure out how to remove tables from a document. In Word I can copy and select 'keep text only' when I paste the information back into the document. I have looked everywhere I can think of, and even consulted Help, but I could not find any mention anywhere of how to delete a table. (People overuse tables in formatting documents, I have never been able to figure out why.)

So, how do I remove tables in LibreOffice? (Without crashing it. I crashed it twice by trying out options it did not like.)

407:

Didn't know that. Thanks.

408:

Select the table

from the menu Table>Convert>Table to text

It gives you some options about wanting tabs etc. Hit ok

Done

409:

Another thing to consider. I haven't read past 360 so I don't know if anyone mentioned it.

Let's say you have the scenario other people outlined, where cyclones move the water towards a super glacier in the night sky. The thing is that compression will liquify the water at the bottom of the super glacier, which will then flow back to the day side.

410:

https://www.newscientist.com/article/2102267-interstellar-probes-will-be-eroded-on-the-way-to-alpha-centauri/

Now Avi Loeb at Harvard University, who heads Milner’s scientific team, has completed the first of these studies, looking at the effects of collisions with the interstellar medium of dust and gas. “We did a thorough analysis, taking all the relevant physics into consideration,” he says. “We didn’t see any showstoppers.”

411:

I'm not sure you can get ice liquefaction if you compress it hard. The reason there's water at the base of glaciers is that ice is a very good insulator, and the Earth is warm, due to having a molten core.

It's not clear to me why you get permafrost sometimes (presumably because it's waterlogged soil, rather than bedrock), but apparently, if you have ice resting on bedrock, enough heat can get through the bed rock to melt a bit of water on the bottom of the glacier.

This is the mechanism implicated in things like Heinrich Events, where Hudson's Bay rapidly purged itself of glacial ice and triggered a rapid, short-term warming during the last ice age. These happened fairly regularly, and the temperature swings recorded in ancient ice suggest that the problem with the ice ages wasn't that it was cold, it's that the climate unstably and rapidly (on order of years to decades) varied among three metastable states. While this didn't trigger a mass extinction, amazingly enough, it may have kept our species from developing agriculture and civilization for most of our species' history.

Anyway, I did mention it back up there, but that's okay. The key trick here is that there needs to be a way for water to flow from the dark side to the day side. If so, then you can get ice deposited on the top of the darkside glaciers and groundwater or meltwater flows heading back towards the day sides.

I suspect it's also possible to get cold, darkside storms to cross the terminator and leave precipitation where it can drain back onto the dayside. It may also be possible to get a "perfect storm" of a darkside cold storm combining with a dayside hot storm. That would be messy, just as "the perfect storm" and Superstorm Sandy were.

413:

Have wondered about the role of the equator in weather overall given that hurricanes can't cross because of the Coriolis effect. More specifically, wonder how much Coriolis effect is needed to prevent this. Could be relevant in SF world-building scenario. (Have also wondered whether current glacial melting has been adding to our planet's waist line sufficiently to alter its CE and rotation.)

414:

I'm not sure you can get ice liquefaction if you compress it hard. The reason there's water at the base of glaciers is that ice is a very good insulator, and the Earth is warm, due to having a molten core.

The melting temperature of water does go down with pressure, and so increased pressure at the bottom of a glacier can and does allows melting.

From Clarke (2005), Annual Reviews of Earth and Planetary Science, "Subglacial Processes":

The fact that the ice melting temperature decreases with increasing pressure underlies the glaciologically important process of regelation. If ice at temperature T is in thermodynamic equilibrium at its melting temperature then T = Tm; if pressure is increased, the melting temperature is reduced so that, in effect, T > Tm and to restore equilibrium ice must melt. As melting proceeds, the ice temperature drops until a new equilibrium is established. A vivid example of the regelation process is provided by the classroom experiment of drawing a thin metal piano wire through a block of ice. Melting occurs on the leading face of the wire and the same pressure gradient that sets the conditions for melting and freezing drives meltwater from the upstream face to the downstream face where it freezes.

Here's a nice demo of the "classroom experiment" he's talking about (using a guitar string instead of a piano wire):
https://www.youtube.com/watch?v=gM3zP72-rJE


Obviously, what matters is the interaction between the pressure-based melting point and the local temperature, which of course varies a lot over the surface of a planet. and is generally going to be lower for ground under a glacier than for ground outside, because the glacier reflects or blocks sunlight from reaching the ground beneath it, and insulates the ground from potentially warmer air above.

415:

Restating OGH@35 in more emphatic terms: the critical path in any "let's travel to the stars" scenario is building a civilisation that can remain stable enough for the tech to remain operational for the time required to achieve target velocity, and then to decelerate at the other end. We only have a few examples that have lasted longer than about four generations, and even then complex technology preservation was not a priority;

A society living in space will come up with with efficient ways to maintain complex technology because it is of the utmost priority that it is maintained. Without it death will soon follow. Anyone fancy a caste system to keep it going?

416:

The papers Martin mentioned up in 364 are useful, especially the second one. It's a model of planets of various sizes and rotation speeds. There are actually a bunch of ways that the winds can work, depending on how heavy the planet is and how fast (or slow) it is rotating.

417:

Thanks for straightening that out. It looks like the melting point of ice decreases by about 1oC per 100 bars increased pressure, so with glaciers that are kilometers deep, the freezing temperature can be substantially depressed.

It's also interesting to me that areas with reportedly really deep permafrost (like Antarctica and the Tibetan Plateau) don't seem to have massive glaciers, while other areas did or do. I don't know enough to know if permafrost and huge glaciers are mutually exclusive, or if they're just not found together now. If they're not mutually exclusive, then we've got the added complexity of frozen soil holding up the more pure ice of the glacier, and bedrock holding it up elsewhere.

418:

Antarctica does have glaciers, around the seacoast and just inland which calve off icebergs and provide sea-ice coverage. The central areas of the continent are effectively a desert with very little precipitation each year (approx. 10cm per annum at the pole IIRC) because there's no open water for thousands of kilometres nearby to provide evaporation and the air is so cold (well below freezing all the time) it doesn't hold moisture very well.

In the case of the Tibetan plateau the same applies although the main driver of low humidity is the effect of altitude, same with the Atacama plateau in Chile and other similar places.

419:

A thought on water cycles: Water flows downhill but look at the Nile and for how long it flows basically paralell to a large sea. Local topology matters very much. So it could be conceivable that water from the glaciers somehow finds it way to the dayside, but 'downhill is very much defined by local topography and I would find it plausible that a very large glaciers sits on a large resorvoir of water that can escape at only a few places, because said glaciers is sort of a stopper on the water basin.
OTOH, if you have an equator crossing (or touching) ocean, you could have a very liveley water cycle, which would equalize temperatures between day and night side a bit. The I would imagine that the climate on the equator is very much defined by the water flows nearby.

Could a tidally locked planet have plate tectonics? Far less so than earth to presume since only the tidal energy provided by planet-moon interaction + decay is available, or do I grossly misunderstand tectonics?

About the size of that ocean: If you tidally lock earth to sun so that the pacific is (roughly) the night side, could you fit all of earth water in a large pacific ice shield? The pacific has more than half of the earth water and a mean depth of slightly less than 4km (wiki says so), so for it to have all the water there would be an iceshield towering a total of 8 km from ground to top. hmm.

420:

A society living in space will come up with with efficient ways to maintain complex technology because it is of the utmost priority that it is maintained. Without it death will soon follow. Anyone fancy a caste system to keep it going?

Again, this brings to my mind first the Adeptus Mechanicus of Warhammer 40 K... Though they have changed their priorities during their existence a lot.

422:

And, of course, the interior of Antarctica is basically one big ice sheet, which is a glacier writ (very) large.

423:

For us, again so far as I know, the tides aren't the major source of energy for plate tectonics. Apparently, there are two major factors: the heat from radioactive decay of metals like uranium that preferentially segregate with iron and therefore ended up mostly in Earth's core, and the large amount of water on Earth, which makes the crust more plastic than it would be otherwise (and I'm less sure about this second one, but the crust of Earth acts very differently than do the crusts of Venus and Mars, and water is probably one issue).

Plate tectonics is basically about melting rocks and having them solidify again. It's sort of like a pot of porridge, except it's a big ol' molten glob hanging in space. So long as the core is molten enough, the heat will pop up in hot spots and add rock to the surface, either in a spot (a volcano) or along a line (a rift) Additionally, when you've got one slab of slag (a continental plate) that's more dense than another slab (oceanic crust is much denser than continental crust, albeit thinner), then when the two crusts hit, the denser one goes down under the lighter one, and we get subduction (if they're equal density they ram into each other and ruck up, making things like the Himalayas and more exotic formations). Because of subduction and rifting, you get plates moving away from rifts and towards subduction zones (this is grossly simplified--we've also got faults, because the world is curved, so forces don't propagate smoothly along straight lines).

If the Earth was tidally locked, it would likely still have plate tectonics, since it's a hot place. What's more in question is whether it would have a magnetic field, since it would be rotating much more slowly. A planet that's close in to a red dwarf might also have a magnetosphere, if it's big enough to have a molten core, and is going around the star fast enough to have some sort of rotation (remember, the planet rotates through 360 as it goes around the star, because that's the only way to have one face continually pointing towards its sun).

Things get weirder if you've got multiple planets in close, harmonic orbits, as with the Galilean moons of Jupiter. Then you also get strong tidal effects as the planets pass close to each other. This is one of the things keeping Io molten and probably keeping Europa liquid. Again, this adds heat, not magnetism. It could keep active plate tectonics going on a planet without a working magnetosphere. However, when you talk with people studying the magnetosphere of Jupiter, they start mumbling, because magnetospheres and solar winds are a lot more complicated than that. Probably this is true for red dwarves and their close-in planets.

424:

So there's two main sources for water under glaciers. Year round you get a very thin layer from the weight of the ice compressing everything down and the movement along the ground heating it by friction, that acts as a lubricant. This water fills any cracks in the rocks around the glacier and refreezes and is another factor in glacial bed erosion.

And in summer you get rain and ice melting on the surface, which over time works down through the surface cracks and erodes bloody great rivers under the ice. That's where the main meltwater streams come from. Depending on the surrounding environment that meltwater may completely drain over winter and stop flowing, but usually it maintains a minimum flow from melting at the fringe.

And while the glaciers in Antarctica are technically only on the fringes, they are still utterly enormous. The largest is something like 400km long and 100km wide, and dozens are over 100km long.

425:

Apparently, there are two major factors: the heat from radioactive decay of metals like uranium that preferentially segregate with iron and therefore ended up mostly in Earth's core...

You'd think that, but apparently most of the radioactive metals (uranium, thorium, and potassium) are in the mantle and crust, not the core. I believe this has to do with the chemical properties of the elements: the core is full of iron and things that like to bond with iron (siderophiles), while U, Th, and K are among the elements that like to bond with oxygen, and thus tend to end up in rocks (lithophiles).

Also, radioactive decay produces about half the heat; the other half is residual heat left over from the Earth's formation (accretion of planetesimals), plus some contribution from the siderophiles sinking into the core.

426:

#426

No joke revolving around "Fear of a Black Planet YT: Music: 3:37 and all those X-rays.


Sigh.

427:

IIRC, the South Pole is still around 2700 meters, and that's mostly ice.

The concerning thing are these pretty blue meltwater lakes in East Antarctica. Worse, it looks like they're near an area where some modelers think that the glaciers would remain even during severe climate change. (http://wwwice.lowtem.hokudai.ac.jp/~sugishin/research/hokudai2/langhovde/glacier/glacier.html)

428:

"an area where some modelers think that the glaciers would remain even during severe climate change"

If your models are predicting remaining glaciers in severe climate change, your models are broken and need fixing.

History shows no ice in Antarctica above 1000ppm. If your models predict something different to what nature does, it's not nature that has it wrong.

429:

Not my models. Real climatologists, like David Archer, who's done most of the deep time projections for future climates, have a remnant ice cap on East Antarctica in their latest paper. I haven't yet asked him why, but when I do a rewrite of Hot Earth Dreams, I'm going to see if I can get an interview and get straightened out on the latest work. Hot Earth Dreams was based substantially on Archer's work from the early 2000s, and if new models are leading him and others to change their mind about the presence of glaciers in a really hot Antartica, it would be great to have a good explanation. And yes, this is glacial ice with way over 1000 PPM CO2e in the atmosphere. It's basically an update of his earlier, cruder models.

Note that under Archer et al's newer models, most of East Antarctica would indeed lose its glaciers, and there would be something like 40-50 m of sea level rise globally (I'm pulling this from memory, I don't remember the exact figure). With Antarctica totally deglaciated, we'd be looking at 60-65 m sea level rise, so that is a substantial amount of ice, but it's still a bad amount of sea level rise.

The meltwater lakes I mentioned appear to be coastward of the remnant glaciers, and I have no clue whether they are part of the same ice sheets or not. Still, that's not where any of us want to see meltwater lakes, predictable as they are.

430:

I didn't mean 'you' as in 'Hereromeles', I meant 'you' as in 'anyone'.

First you guess, then you calculate the consequences of your guess, then you compare your calculations to nature.

I'd be very interested in the interview. They must of course know that Antarctica at 1000ppm has a had climate like Brisbane or Savannah. Presumably they have some reason to trust their models more than nature. That implies that they have some reason to think that the example from history is not applicable to the future. Which is in and of itself interesting.

The cap is indeed high and thus cold, so it could remain as a remnant in the same way that Greenland is a remnant of the last ice age. However Greenland's icecap sits in a sort of craterish shaped land mass that prevents warm seawater getting under the ice, whereas Antarctica is an archipelago like northern Canada. No continent size icecap in Canada anymore. Warm sea water will undercut the glaciers. Once that happens they'll slide into the sea and they won't be high (and thus cold) in the way that the Greenland cap is. Maybe some glaciers like the ones on the South Island of New Zealand? Still, even that seems unlikely to me. I think they were talking about sea temperatures around 25C in Antarctica ~35 mya (when land was in about the same configuration as present day). The idea of a remnant glacier on an island, surrounded by 25C water seems far fetched to me.

431:

Adeptus Mechanicus, Warhammer 40 K?

Not familiar with that and a few clicks determined that it is going to stay that way.

432:

Warhammer 40K is a series of games, originally from Games Workshop, who nowadays mostly make miniature war games for the IP. Mainly the Adeptus Mechanicus are an order of tech priests who keep the technology of an empire running mostly by rote.

I admit that it's not everybody's cup of tea - I'm not that enthusiastic about it either, but there are some edges which are entertaining to me.

433:

Yep, the vast majority of East Antarctica is between 2000 & 3500m, with a rise of over 4000 in the middle, and an average ice thickness of 1.5-2.5 km.

The South Pole isn't actually near the middle, which is partly why we were able to reach it so easily. But the meltwater lakes are on the fringes, where the glaciers drop from 2000m to sea level in a 50-150km stretch. So they are an indication of summer melting, but not one of impending doom of the great ice sheet. Yet.

Arguably surface lakes are a sign of ice health underneath, since it means there aren't the cracks for the water to flow into, but if they persist longer then the water will find a way.

West Antarctica is a whole different ballgame, being mostly on water not on land.

434:

Heteromeles wondered: "I'm not sure you can get ice liquefaction if you compress it hard. The reason there's water at the base of glaciers..."

Yes, and you do get liquefaction due to pressure under glaciers. For a familiar example with far less pressure, that's how ice skates work. Pressure from the overlying ice is generally the primary factor in subglacial ice. Subglacial heat (Iceland) and rain are other significant factors in some areas.

H: "It's not clear to me why you get permafrost sometimes (presumably because it's waterlogged soil, rather than bedrock)"

Waterlogging is usually secondary. All that's essential for permafrost to form is sufficiently low surface temperatures that the soil freezes to a certain depth. That depth is defined by the heat-transfer characteristics of the surface soil: the permafrost layer lies below the maximum depth that summer heat can reach and still melt the frozen soil. Simplistically, the colder the summer, the less heat enters the soil and the closer the permafrost lies to the surface. Global warming appears to be proceeding much faster at high elevations so (for example) the Qinghai Tibetan Plateau is losing its permafrost at an alarming rate. As the summers warm and grow longer, heat has more time to penetrate deep into the soil.

As for tidally locked planets, it seems highly likely that you'll still get significant circulation, though perhaps not the classical Hadley cells we see on Earth and probably not the hurricane winds that are often proposed. (Specifically, after a few million years, most of the air will have been chased away from the hot pole, establishing a slower and less violent equilibrium circulation pattern.) Air that is warmed at the hot pole facing the star will rise up (convection) and cool as it does (adiabatic cooling). Increased pressure produced by the rising air will force the warmed air to flow away from the hot pole towards the cold pole. Where it will descend depends on the cooling rate and the size of the planet: it may not descend until it reaches the cold pole, or it may form one or more additional convection cells in different latitude bands. Details of what will happen depend on complex calculations of relative heating and cooling rates and on the pressure gradients that develop; I suspect there isn't any one universal pattern for all such planets. Speaking of pressure:

At the cold pole, even frozen substances are likely to sublimate (transform from solid to gas without passing through a liquid phase) at a significant rate that will depend on the gases involved and temperature and pressure conditions. In many regions on Earth, sublimation causes faster loss of snow than melting. (Blew my mind when I learned this.) Pressure generated by descending and cooling air pushed from the hot pole towards the cold pole is likely to push pools of cold sublimated air away from the poles and back towards the hot pole, where it will be heated and renew the cycle. Some kind of complex equilibrium flow will eventually develop.

Also, a note on drug costs: A significant chunk of the cost arises from egregious inefficiency and flabby budget control. First-hand evidence from someone I'll anononymize to protect their identity and that of their top-five Big Pharma employer: When they were moved to a new city, the company literally offered to pay to transport their newly purchased patio bricks to their new home. I'm not joking. They also gave them a per diem large enough to feed a small African country so they could buy food during the first weeks of their stay in their new home. I exaggerate, but only slightly. Most egregiously, the Big Pharma profit model requires huge profits to keep C-level execs and stockholders happy.

436:

I'm not sure that's the entire explanation for permafrost, as the permafrost in places like the Qinghai plateau is hundreds of meters thick. I think the record is Siberia, where it's apparently over a kilometer thick in parts. Heat diffuses pretty slowly through soil at the best of times, so meters down, the heat wave from last summer may still be propagating, in an attenuated form, in the soil. At some depth, the temperature evens out, since all the pulses are too attenuated to make that much of a difference. Presumably, with deep permafrost, the average soil temperature is at or below freezing. Considering that temperatures get rather hot a kilometer down, I'm not sure how permafrost that deep stays frozen, which is why I'm not sure we've got a full understanding.

There's a whole long conversation about whether all permafrost can disappear during severe climate change when some of it is so deep (the answer is quite possibly not, although the soil will keep melting for quite a long time, and building on the resulting thermokarst will be fun), but I'm not going there. What I wanted to point out is the oddity that the really deep permafrost seems to occur in places where there's not a history of enormously big glaciers. That may well be a false perception on my part, but it seems odd.

437:

Apparently some of those East Antarctic Lakes are suddenly disappearing, so don't be too sure it's a healthy system. Still, I'm not familiar enough with East Antarctica's geography to know whether there's a range of hills beneath the ice between the new lakes region and the big sheets. Hopefully there is one...

438:

Thanks for the clarification.

One thing to realize is that land gets depressed under glaciers, so land beneath sea-level now might eventually be above sea level as the ice melts. That makes the drainage a bit more complicated than simply stripping off the ice and figuring out where the ocean will go.

That said, there's a troublesome bit of Greenland about 70oN where there might be a subglacial connection between the ocean and the central depression (https://en.wikipedia.org/wiki/Greenland_ice_sheet). If a durable water link dvelops between that central depression and the sea, Greenland's ice sheet might go really fast.

So far as East Antarctica goes, see https://en.wikipedia.org/wiki/Antarctica and especially https://en.wikipedia.org/wiki/File:AntarcticBedrock2.jpg. The remnant ice sheet is proposed for the region at about 1 pm on the jpg. Note that this map isn't corrected for isostatic rebound, but it is fairly elevated, and presumably it will get higher. If there's any place on Earth that might retain an ice sheet, I'd suggest that this is it. High cold places tend to create their own weather, as you can see in Tibet, which is on the border between temperate and subtropical latitudes.

439:

I suspect there isn't any one universal pattern for all such planets.

Your intuition is almost certainly correct. The scientific paper linked above describes three classes of climates for tidally locked planets that have been explored in simulation. I'll go so far as to guess that the phase space contains some modes that we haven't found yet, but for now the answer seems to clearly be 'at least three.'

440:

I could see, maybe some glaciers, but I can't imagine an icecap like Greenland's surviving. There's some lovely crinkly fjords along the Antarctic Peninsula in the image you linked to, and some more along the Transantarctic mountains, but they're not 'icecap' now. '1pm' seems to equate to Dome Fuji, but the land under that is only about 2000ft high. It will get higher, but I don't know how fast the land rebounds. I gathered 'not very' certainly by human timescales. Isn't Canada still rebounding from events 10 000 years ago?

Still interested to hear how they can model any kind of icecap remaining.

441:

We're pretty much in agreement: I'm pretty sure that the Greenland and West Antarctic ice sheets are what the firefighters call "historical structures" in wildfires (meaning they'll be history). The Fuji Dome area does seem to have a bunch of mountains between it and the equator, and that might be part of the puzzle, or not. My comment about Greenland is that the central depression may turn into a route for rapid melting, rather than the last redoubt of the Greenland ice sheet.

Another factor with Dome Fuji area is that there are reasonably tall mountains between that ice and the equator, which means part of it will be in semi-permanent shade. That might matter, because glaciers tend to make their own weather to some degree. The other factor is that, if the air is more moist, because the sea is closer after East Antarctica starts melting, then there might be more snow. They're already seeing that, with parts of the East Antarctic ice cap actually growing, because more snow is falling as the air gets warmer. Getting back to the Dome Fuji area, if more snow falls throughout the year than evaporates in the summer, that's the definition of a glacier, and the ice will remain where that happens.

442:

Re post 432: "Mainly the Adeptus Mechanicus are an order of tech priests who keep the technology of an empire running mostly by rote."

By Saint Vidicon, what an unusual idea,

mark "why, what is this Centicles of Liebowitz?"

443:

In somewhat-exoplanet-related news, there are now reports of an "interesting signal" from a 0.99 solar mass star about 95 light years away.

How interesting? Well, it's certainly not proof of anything, but it's interesting enough that at least some SETI people want to redirect other telescopes to keep a permanent watch on the (presumed) origin. (If the origin is something beyond that star, then wow that'd be a terrifyingly powerful beam at source.)

444:

1 out of 39 broad band measurment scans that passed over the star showed a signal at ~4.5x the mean noise power and a profile that kinda sorta looks like a beam profile.

SETI@Home has returned literally millions of potential signals with similar characteristics

But it is a slow news day (or at lest the news there isn't what they want to cover) and so the media has seized on this. And since business runs on media, everyone will look at it: Arecibo, Breaktrhough, ATA, SRI International, etc, are all going to hop on board, trot out some scientists to nod knowingly at the "potential" and speculate about this being the "most important event ever in human history" and "could you re-up our grant please? And maybe throw in some extra so we can look at some interesting stuff at meter+ wavelengths?"

And it will turn out to be absolutely nothing. Just like the other literal millions of similar signals.

445:

I'd somehow misunderstood the article I linked to as saying that there was a second (independent) confirming report, which would have made it much more interesting than it actually looks to be. So yeah, probably just a(nother) blip.

446:

So long as it's not someone making microwave popcorn...again.

Updated: 'Leaked' space signal report has SETI groups scrambling

447:

Well, we know of one way to generate 10^100 watts in a single signal peak:

"I felt a great disturbance in the Force, as if millions of voices suddenly cried out in terror and were suddenly silenced..."

Or is that one of those forbidden, crossing-the-streams sort of explanations?

448:

Since this discussion has moved towards the environment, is this statement true?

Scotland has less heavy metal pollution now than in the iron age

449:

Interesting news with emdrive. I would really like to believe it works as advertised but suspect at best it is just conventional radiation pressure
http://www.ibtimes.co.uk/emdrive-nasa-eagleworks-paper-has-finally-passed-peer-review-says-scientist-know-1578716

450:

Yes & no ....
It is a differential radiation pressure,IF I've understood it correctly.
It's a sort of e-m versio9n of an hydraulic jack is my best analogy of the mechanism .....

Note, however, that Shawywer states that "Good for NASA - but they are still behind the curve, if only because of partly-justified scepticism.
We will know within a year of 5, won't we?

451:

The (unofficial) thrust measured was around 1mN IIRC, or a pressure of about 100mg force. Too high to be conventional radiation reaction

452:

Ah, thanks, didn't spot that bit.
I note that Shawyer is now talking about (possibly) force-outputs of over a kg .....

If NASA & others do reproduce his results, it's going to be very embarrassing for some people, but OTOH IF (And a very big if it is too) then Sawyer will deserve a Nobel.

453:

DNA Data storage is already (nearly) a thing.


http://www.seattletimes.com/business/microsoft/uw-microsoft-claim-big-breakthrough-with-data-storage-using-dna/

If you accept we had a really high level of civilisation before (for the sake of argument) then it could be we already have the high tech info (FTL tech even!) encoded into our own bodies, just don't have the tech to read it.

454:

Has anyone done a SETI search within the genomes of various organisms?

455:

If Shayler is correct, from an historical perspective this is a bigger deal than the steam engine or powered flight.

456:

I would really like to believe it works as advertised but suspect at best it is just conventional radiation pressure...

The claimed power consumption is far too low to generate the claimed thrust by pure radiation pressure, as I recall from the last time the emdrive came up. It would certainly be nice if the emdrive is not the Dean drive of the current generation. I'm left skeptical by the combination of extraordinary claims and a lack of good explanation of how, clearly and without bullshit, this thing is supposed to work anyway.

457:

The short answer is, "what for?"

If you're looking for a series of DNA that, when rastered properly, shows a four-color picture of a cute little alien, then the answer is no. I don't think mutation and natural selection would let something like that sit unmodified in any case.

If you're asking whether some organism has been found whose DNA doesn't fit on our tree of life, the answer appears to be no. The caveat is that if the aliens got here 4 billion-odd years ago, then we've got a situation of panspermia and we're running on alien DNA, but we can't diagnose that from the evidence on hand.

If you're looking for evidence of alien DNA, don't be absurd. The problem isn't the DNA, because I suspect that versions of this chemical are extremely widespread in the galaxy. Instead, the problem is in the coding. Our DNA code appears evolved and somewhat random. There's no obvious reason why DNA from another planet would have anything resembling our code. If it's inserted into our genome, it's at best junk, and will be treated as such by evolution. This is something that I mentioned upthread, about why I'm not worried about alien viruses.

458:

What we would be looking for is something like Pi encoded with a lot of error correction.

Inserted anytime in the last million years or so

459:

If the thrust could be scaled up to the Newton range it would be beyond doubt. I'll wait for that before declaring space is now open to all.

460:

The problems with Pi (or any bit of information), is that it will get altered.

For one thing, there will be point mutations. For another, some part of it might code for some sort of junky amino acid. If that part causes trouble, there will be selective pressure to get rid of it. The RNA transcript may have some weird folding pattern too. Sometimes these are useful, sometimes they're useless, but unless they're selectively neutral, they'll get selected for or against.

That's the problem. DNA is great for information storage, but plunking a chunk in a cell and assuming that it will continue to exist for thousands of generations unaltered is absurd. The only case that happens in is when the code is so vital that changing it kills the carrier. Unfortunately, there's nothing in encoded pi that seems to meet that category.

461:

But that ( Thrust in whole numbers of Newtons) is what Shayler is claiming, right now, admittedly in experimental rigs.

464:

Ha ha, I would *love* to see that.

Not that I'm advocating diverting funds from cancer research or anything.

But if you have a hammer in your hand everything looks like...

465:

H: 'If you're looking for a series of DNA that, when rastered properly, shows a four-color picture of a cute little alien, then the answer is no'

FM: We don't need to go that far, our feline overlords have already made that much clear. Look out your window or into your lap!

466:

On a more serious note tho, here's where I am touched by your faith in our current state of science but am going to have to disagree with you.

You haven't even mentioned mtDNA here and the very few 'Eve's' who we are all related to no matt