[roca]

They talk about planets and generation ships. Isn't it obvious that a multimillion-year spacefaring civilization would be mostly autonomous machines that have no need for habitable planets and can sleep for aeons?

They also talk about civilization lifetime and interstellar resettlement. But interstellar resettlement doesn't make sense to me; simpler for machine civilizations to hedge their bets by putting resettlement sleeper ships in highly eccentric orbits with some desired period. Maybe there are civilization-killing effects that disable those resettlers, but they would apply to interstellar resettlement too.

[ymolodtsov]

Well, no. That assumption is as good as any.

[joe_the_user]

When one is talking aliens, some number of things might seem obvious but the reality is we're dealing from intense ignorance and the things that seem obvious to us probably shouldn't be taken at face value.