> among the billion trillion stars in our past universe, none has reached the level of technology and growth that we may soon reach. May soon reach? I doubt it

> among the billion trillion stars in our past universe, none has reached the level of technology and growth that we may soon reach. May soon reach? I doubt it. I'd say there's a significant filter between our technology level and large-scale inter-solar-system colonization. It's not at all clear that there is a strong motivation for that - except for a continuous-growth economy, which is kind of unsustainable anyway. Once the population stabilizes and human civilization is basically energy-neutral (i.e. not taking more than the sun provides), where's the great need to colonize someplace else (as opposed to communicating)? And if we don't stabilize - civilization will burn itself out soon enough, colonization or no. > Even if life only evolves once per galaxy, that still leaves the problem of explaining the rest of the filter No it doesn't. It's extremely unlikely that one planet with life will travel to a different galaxy. Even with intelligent life it's extremely unlikely. Only if instantaneous travel were possible would this be likely.