[saiya-jin]

> wealthy technological races potentially stabilizing at zero population growth

It doesn't have to, in fact (relatively) endless population growth is the prime force to push even lazy non-curious fearful aliens out of their planet and sun. That and obvious unavoidable necessity of every sun eventually becoming killer of its own ecosystem, even if their planet would be super duper stable with all meteorites under total control.

The rest I agree with, even civilization having mere 100 million years of advantage on us would be able to properly colonize non-trivial part of milky way by now, we just have to abandon star trek/wars expectations of instant communication and travel which is fine. We humans are generally pretty bad at grasping true meaning of numbers when it comes to ie astronomy.

[joe_the_user]

The problem with any overpopulation or growth-limit push argument is that since interstellar travel is a very, very difficult to achieve, there's no reason to expect either humans or aliens to achieve interstellar travel at the point that they've encountered some limit to a process of out-of-control growth. Space colonization is certainly not going to solve global warming, etc.

Indeed, if human society is a guide, a society that develops interstellar travel would have to have reached a stable situation, so stable I'm not sure if massive expansion would seem desirable.