[alnorth]

I've thought about this a few times before.

I do not believe in the theory that there's a lot of civilizations out there who choose not to talk to us and who we can't notice. I also think the theory that civilizations naturally destroy themselves is dumb. Even if you think humans are assholes, some portion of intelligent species out there would be enlightened enough not to kill themselves.

I believe there is a great filter, and that the filter is ahead of us. I think that filter is simply "unable to travel near the speed of light, and unable to warp space".

If you can't travel near or faster than the speed of light, then the mind-boggling vastness of space really puts a damper on any civilization's ability to survive the death of their star, much less colonize other planets.

If we're still alive when our star gets perilously close to cooking our planet during its red giant phase, I imagine we'll try sending out generation ships out of desperation, and they'll probably fail. The End.