Back to: Crib Sheet: The Fuller Memorandum | Forward to: A Bad Dream

Blogging for Orbit

I'm blogging for my UK publisher, Orbit, this week. First blog entry here: World building for Neptune's Brood.

Update: And the second part is here.



Ha! Thought that said "Blogging FROM Orbit" at first...


LOL, so thought I.


Minor nit: "star systems where multiple gas giants whirl in orbit single-digit millions of kilometres from their primary" are not actually "the new normal". I do not have a link handy, but latest estimates are that only about 1 star in 20 has a Hot Jupiter, let alone several. Hot Jupiters are over-represented among known exoplanets because they are easiest planets to see, but they are not the commonest type.

Of course "1 in 20" is still way more than "not even imagined", which is where they stood before 1995!


Are we going to be allowed a spoiler-thread for Neptune's Brood soon. Just finished and have questions ;)

As a non-spoiler observation/question... the fast/medium/slow money idea just seems so natural and "right" that I wouldn't be surprised if it turns into one of those bits of SF architecture concepts like ansibles and hyperspace jumps.


It's the only way to be sure.


Ok, I've got a minor, annoying, nitpicking quibble.

Planet detection by both radial velocity and transit light curves are biased toward finding planets that are big* and near their primaries. (Big meaning more massive for radial velocity and larger diameter for transit light curves). So the fact that we've found a whole bunch of crazy hot Jupiters and super-earths in solar systems that look nothing like ours doesn't mean that our system is unusual- it's harder to detect solar systems like ours. If Earth was in one of the systems that Kepler is looking at, Kepler might or might not detect it. So our system might be weird, but because I don't like the weak anthropic principle I'd say it's more likely that all of the hot Jupiter systems we've been finding are weird (but easy to detect) and that when we get the next generation of instruments in place we'll find a whole bunch of systems that look more like ours.


A coreless planet would also be interesting, i.e., no metallic core, just a giant rocky mantle. So the easiest, therefore most 'natural' expansion route would be to build inwards toward the core rather than outwards toward the stars.


Hot Jupiter!


My question is have you gotten any response to this book from professional economists?


Krugman had good things to say about it.


I once read somewhere or other that as the Sun ages into a giant Neptune will eventually be illuminated as intensely as Earth is now, though it will be redder. Under those conditions it seems like one of the weaker SF magic wands (say, von Neumann machines) could adjust atmospheric and ocean chemistry enough for at least some unmodified terrestrial vertebrates to live. The surface gravity would be close to Earth's, though escape velocity is more than double. It seems like it could be a fairly cozy ocean world for a few hundred million years, with surface area of 15 Earths and a variety of places to live (on the water surface, under the water, on top of any artificial land the VNMs have helpfully constructed from imported rocky materials). When I heard the title Neptune's Children I thought this might be something like the book's background, until I realized that it didn't place nearly far enough in the future for such stellar evolution.

After the Sun starts shrinking and cooling again, and the ocean world returns to ice, any remaining intelligences will have access to enough deuterium in the ice to support billions of years of post-stellar survival. Presuming that controlled nuclear fusion isn't still 50 years away. Who says that you need to escape the Solar System to survive the death of the Earth and Sun?


zorro @ 11
Err ....
Olaf Stapeldon got there first.
The last men lived on Neptune.
[ Also avialable on Project Gutenberg ]


What an odd co-incidence to find in a book. A writhing mass of detritovore worms share their name with the founder of Amazon.

Also: I was sort of hoping, by around halfway through the book, that it would itself turn out to be an advance fee fraud, with a last line something like "So here I am in X predicament, and I so nearly have my hands on the Atlantean slow cash, I just need a little money to help me out..."

Or would that have been too lame, too much like ending a book with the old "... and then she woke up and realised it had all been a dream."


No metallic core does not mean hospitable. Drilling down for habitable space isn't really that much of an option.

Ocean Planets such as Shin-Tethys are the subject of my PhD Thesis, (in progress). The high-pressure ice mantle will reach temperatures of over 2000 Kelvin, before you ever reach "rock". Just because its not molten metal doesn't mean its habitable.

Even the water is going to do nasty things to DNA. Its questionable if DNA or its equivalent can exist at the Europan moon floor, for example.


OGH donned his red cape and goggles for this one.


This following link is So Far off Topic it might as well be in Orbit, but I seem to recall that Glastonbury holds a special significance for our Gracious Host and thus he may well enjoy this post from " Diary of a Benefit Scrounger " ..


I agree completely with the comments at 3 and 6: we are not yet in any position to suggest that our system is "weird". There is definitely a selection bias in our current sample - if you look at how properties of discovered planets evolve with time, you'll find that the mean mass goes down (as our techniques improve) and the mean orbital radius goes up (as our techniques improve, and also as the length of time series of observations increases - the first planet round a "normal" star was only discovered in 1995, which is only 1.5 Jupiter years ago - for the first half of which our resolution probably wasn't up to detecting Jupiter's effect on the Sun's radial velocity anyway).

Which is not to say that using a super-Earth as a setting for a story isn't an excellent idea: they do seem to be pretty common, and some of them are indeed in the liquid-surface-water zone. They are a very diverse bunch, including some that almost certainly have substantial H/He atmospheres (not totally dominating the mass, as in gas giants, but amounting to 10 or 20% of it - see Kepler 11d, e and f).

I do worry about the stability of your system, though. Packing three giants into 5 AU sounds dynamically dodgy: it's pretty clear that gas giants are very movable feasts, and I would have thought that a >Saturn-sized object only a couple of AU away from a Neptune is bad news. I think they'd have to be in mean-motion resonances - are they?

-Susan (signing in via Google seems to have converted me into alphabet soup, sorry about that)


Regarding part II - there is a hypothesis (I'm not quite sure I'd reward it with the name 'theory' yet) mentioned in the current New Scientist that address the Moon problem.

In short, the Moon is both too big and also slowly receding from Earth, which throws out the moon-formation theories that can account for all the other moons we can see. The conclusion is that a primordial mass split into two (uneven) chunks, us and the Moon. The problem is that the original mass didn't apparently spin fast enough for the Moon to be ejected by pure centrifugal effect (nearly, but only about half the required spin rate it seems). And the collision model also has issues, to do with isotope ratios in the Moon rocks being wrong - being the same as Earth ones.

So, this new hypothesis goes 'if the Earth at 2 billion years ago was able to support the Oklo reactors, just imagine what might have been the case 4.5 billion years back'.

tl;dr - the Moon is ejecta from a massive nuclear explosion that blew a large proportion of the Earth's crust into orbit.

(And you thought the late heavy bombardment alone was unpleasant enough.)


And the collision model also has issues, to do with isotope ratios in the Moon rocks being wrong - being the same as Earth ones.

How is that an issue? With collision model isotope ratios in Earth and Moon SHOULD be the same - they started out as one body.


I think the minimum requirement for a collision is two bodies.

OK, OK, one body and a time machine if you're going to get creative.

Anyway, it's not my hypothesis.


And the article in question requires registration. Sorry.

(I get the dead tree version anyway.)


Is it just me or was there a lot of Scratch Monkey influence in Neptune's Brood? OGH has clearly been thinking about digitally transmitting personalities into waiting clone bodies for more than just a few years.


Two bodies yes, but it's not like the Moon is (or is a remnant of) the impactor. Impactor hit the Earth, two mixed together, some of the resulting mixture splashed up and became the Moon. Moon's isotope ratio is not the same as that of [i]primordial[/i] Earth, but same as resulting Earth.


Use "> $tag <" to opem HTML tags.


Make that < then >


Natural uranium on Earth contains more like 0.7% U-235 rather than 0.2%, so Shin-Tethys uranium at 1% is richer in U-235 than natural uranium than Earth but not by that much. If we apply the implied correction factor to real isotopic abundance (U-235 is 5 times more abundant on Shin-Tethys relative to Earth) then we get natural uranium at 3.5% U-235 on Shin-Tethys, ready to fuel a light water reactor or a blue smoker without further enrichment.




About this Entry

This page contains a single entry by Charlie Stross published on July 5, 2013 10:22 AM.

Crib Sheet: The Fuller Memorandum was the previous entry in this blog.

A Bad Dream is the next entry in this blog.

Find recent content on the main index or look in the archives to find all content.

Search this blog