On this thread people are pointing out many potential problems with all of these solutions. I think all have an element of validity but in the end a much bigger problem is the complete unknowns.
The good news is that there is a system for measuring the effectiveness of the potential solutions. That system is called "reality". If humanity builds a single "ark" then it is very likely to fail. The trick is that we need to get the technology to the point where we're launching dozens or hundreds of these. Only then will we discover what the actual problems and limitations are, and how many of the worries and problems will simple be irrelevant because human ingenuity will find workarounds.
Joseph Henrich, the anthropologist, characterized human technological progress and innovation by saying:
"I think that humans are pretty bad at designing institutions from the top down, but we do know how to design variation and selection systems"
We don't need one correct solution, we need some attempts and some bad copies of those attempts to collectively move towards solutions.
The generation ship in KSR's "Aurora" failed due to unknown unknowns. I'd very much hate to have lived on it as it did, and I would be unwilling to condemn tens or hundreds of thousands of people to the same fate as an experiment.
The whole oh-no-prions from hell was kinda unconvincing, as well as choosing to go back to Sol instead of just building up living space via artificial habitats in the target solar system.
If you can refuel a fucking interstellar ark in field conditions, you totally can also keep it running and expand it and your living space using local resources instead.
There were numerous ships that attempted to traverse the Atlantic to form colonies in the Americas. Many were lost, or died out, or failed to thrive for unknown unknowns. And many survived and flourished for reasons not even the settlers understood, and which frankly we will probably never understand because the moment has passed.
In Aurora society took a one-shot approach. This strikes me as unrealistic; why weren't there dozens of competing attempts? I thought the book was one of the best treatments of generation ships that I've ever seen in scifi except for this. And I don't love the "also we discovered new physics and made a sentient AI on our ship somehow" plots (the latter is also a reason I never liked "The Moon is a Harsh Mistress"). I get that it feels unjust or unfair or morally wrong to subject new generations to an experiment that they never signed up for, but that's just the way that humanity works -- all of our children are part of an experiment that they never signed up for, because none of us know (or can even conceivably know) the "right" way or environment in which to raise children.
The good news is that there is a system for measuring the effectiveness of the potential solutions. That system is called "reality". If humanity builds a single "ark" then it is very likely to fail. The trick is that we need to get the technology to the point where we're launching dozens or hundreds of these. Only then will we discover what the actual problems and limitations are, and how many of the worries and problems will simple be irrelevant because human ingenuity will find workarounds.
Joseph Henrich, the anthropologist, characterized human technological progress and innovation by saying:
"I think that humans are pretty bad at designing institutions from the top down, but we do know how to design variation and selection systems"
We don't need one correct solution, we need some attempts and some bad copies of those attempts to collectively move towards solutions.