From: Russell Standish <[EMAIL PROTECTED]> > I've just finished reading "Extraterrestrials: Where are they?" by > Zuckerman and Hart. It really scotches the idea that SETI might > actually be successful, even though the Fermi paradox is a bit > overdone "Any ET civilisation of substantial duration would have > colonised the Galaxy by now. So where are they?" > > However, Gott raises an interesting point. Anthropic reasoning eg > Doomsday argument really rules out galactic colonisation - at least > for our reference class. It would appear that the Doomsday argument is > in direct contradiction with the Fermi paradox. I am rather > uncomfortable about this, and my preference would be to accept the > Fermi paradox argument over the anthropic reasoning.
I must be missing something here. Isn't the obvious answer for both Doomsday and Fermi that civilisations don't last long enough to colonise? Standard responses to the Fermi paradox include self-destruction, colonisation apathy, and clandestine spread in our area (for ethical or scientific reasons). My own favoured explanation is simply that intelligent life (not necessarily any life) is sufficiently rare (<1 per galaxy) that visitations haven't happened yet. There are counters to DA. Alastair
