re: One thing most older SF about multigenerational starships did not address
"By the way, 500 or even 10,000 years may seem like a lot to
us short-lived creatures, but they are the proverbial drop in
the bucket compared to the galaxy or the Universe's ages."
Let me add that there could be aliens with 1000+ year lifespans. A trip between the stars might be more feasible to an alien that lives 50,000 years. If humans ever cure aging, that may become true for us as well.