[Analemma_]

I don't think you can treat those as equivalent. The arguments against airplanes were about physics, which is comparatively easy. The whole point of this essay, and KSR's companion novel Aurora, is that people who get excited about generation ships tend to only think about the physics and engineering problems, and handwave away the problems of ecology, biology, sociology, ethics (!), and politics (!!) because they don't find them interesting, even though these problems are actually much harder to solve. His complaint is that by sweeping the hard problems under the rug, people are making this out to be a much more feasible operation than it actually is.

In order to prove him wrong, you'd have to really grapple with the question of how to have a self-sustaining ecology in space. This is something I basically never see in online space boosterism, and note that empirical attempts to answer it like Biosphere 2 ended in complete failure (and those were on Earth, which is orders of magnitude easier).

[t43562]

Physics might seem easy to you now but flying was an impossible dream for most of history.

The other problems may become more amenable - one just can't know what will happen. Amazing things like CRISPR - an incredible tool that lets us edit genes - appear suddenly and change everything.

Sequencing a Genome once seemed a massive task and now it's no big deal - so perhaps some of these problems will end up like that.

We can also re-engineer ourselves and that might help a lot.

[issa]

I just think it is a case of thinking small. A few key advances and all the problems are solved. For example:

- Increased lifespan making the trip possible in 1 generation - A hollowed out asteroid or other extremely large biosphere. It is not hard to imagine something large enough to overcome the ecological problems - Virtual reality (the holodeck) if you're still worried about social issues in a large space. BTW, most teens today would be happy to stay in a closed room, as long as they had a phone. (I exaggerate, but only a little)

All of these things are reasonable extrapolations of existing tech. In 200 years, I'm sure a whole lot more will be possible.

[tivert]

> A few key advances...

Understatement of the year.

[XorNot]

The ethics of generation ships always seems like a ridiculous issue to worry about: no one born today for a say in the circumstances of their birth, nott the ideology they get raised in. And there's a lot of bad options if that's anywhere on Earth.

[Analemma_]

That's not the same thing and you know it. If you were resentful at having been born into a sealed can the side of a large office building, with a meager lifestyle and-- by necessity-- an authoritarian government that chooses your occupation, spouse, etc., and you heard about the paradise of Earth, you know perfectly well your anger wouldn't be assuaged by "no one born there has a say in their circumstances either".

[XorNot]

People are born everyday on Earth into far worse circumstances then "we live in this spaceship". The spaceship by comparison is paradise (though it's also worth noting you thought the point wasn't quite strong enough if you didn't start adding modifiers: no democracy, the government must be authoritarian...)

[issa]

Exactly. If growing up on a spaceship was all you ever knew, it wouldn't seem like a problem. It only seems like a problem to people who grew up with a lot of choices on Earth. Most people on our planet don't have a lot of choices in how they live their life.

[Terr_]

Coincidentally, I'm reading A City On Mars (by the husband and wife team behind Saturday Morning Breakfast Cereal comics [0]) and it's pretty much all about poking at those legal, sociological, and medical problems that keep getting skipped over.

[0] https://smbc-comics.com

[johnnyanmac]

Well the big flaw here is that he just outright throws away the idea of FTL travel. A lot of that friction will be reduced if we ever figure out how to break that (which yes, is extremely tricky. Even IF we figure it out we'd need to also counter time dilation to properly verify).

Now sure, the politics on who and what gets to go to thr next world will doom many. But physics can alleviate the whole "we'll tear each other apart over 200 years of space travel" part

[layer8]

FTL implies time travel. The into-the-past kind. Good luck with that.

[johnnyanmac]

I won't be the one to solve it, but we thought the sound barrier was unbreakable a few centuries ago. I won't underestimate human ingenuity.

I think more likely is we figure out wormholes. If we can't go light speed we can instead fold space like a piece of paper and reduce the space we need to Traverse. That may or may not be as easy as FTL.

[layer8]

Wormholes imply time travel in much the same way as FTL. There is no escape from this, for very simple geometric reasons.

[johnnyanmac]

If space compression is time travel, sure. It's not like we can't time travel right now (to the future).

I obviously don't have the finer details in line.