[tynpeddler]

I wrote a short story on this idea a while ago. Two things become clear very quickly. First, this is a very stark existence. Advanced civilization requires lots of energy and energy production requires lots of physical infrastructure. Building all that infrastructure on the home world takes time and lots of resources, building all of the infrastructure on a planet that is flying past your home world is very tricky. Second, a civilization may end up trapped on the planet. Similar to the first point, space faring capabilities require lots of material and infrastructure, and if that degrades (because they're trying to maintain other capabilities or because the chosen planet is short on raw materials), even when the planet wanders into another start system the civilization may have no capability to transfer their population to the new solar system.

[mirceal]

Transferring the population is never feasible. The amount of energy needed to bring anything from planet surface to space is huge.

I would bet on a post-biological future where the individuals can transfer themselves via information transfer so this way the amount of energy is minimal. Couple this with self replicating, terraforming machines to build the physical infrastructure and we're in business.

[swagasaurus-rex]

What if they were alien tardigrade like creatures that can hibernate for long periods?

Or alternatively, a species that has no issues sacrificing much of itself or endure hardships, because they don’t have feelings like us.