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← New Drake Equation To Quantify Habitability?

mmurray's Avatar Jump to comment 23 by mmurray

The question is whether it's more reasonable to assume that Earth is the only planet with life than it is to assume that other life-bearing worlds are out there. Personally, given the immense number of stars out there , and the possibly even more immense number of planets that are likely to be in orbit of them, assuming that Earth is the only one with life is a bit of a stretch, in my opinion.


The immense number of stars isn't an argument by itself. If N is the number of stars and p the probability of there being life on a planet orbiting that star then the expected number of stars with life is Np. Sure N is like 10^22 but I don't think we know much about p. It seems clear that once life gets going it's pretty tenacious and can survive in a range of environments but I don't think we know how hard it is for it go to get going. I'm no expert in abiogenesis and would be happy to hear arguments for p > 10^{-22}. At the moment I just don't think we can decide what is reasonable because we don't have decent estimates of p. Better theories of abiogenesis would help, life on Mars that didn't come from earth would be great, earth like planets around nearby stars that seem to exhibit seasonal changes caused by life would be great ... I just hope we discover some of these in my lifetime.

Michael

Wed, 23 Sep 2009 10:52:00 UTC | #400135