I regard these numbers as having minimal to zero scientific significance. As yet we have NO idea whatsoever about the likelihood or probability of life arising. Were that # to be 10 -exp 22 or something, there's no life elsewhere in the universe ever. What about the probabilities for complex animal life, something that took nearly 4 exp 9 years to happen here? The probability for 'intelligence? Or better yet that for technical civs that can build radios?
On the other hand there could well be unknown to us laws of nature that drive towards biology starting, and increasing biological complexity and we could be the retards of the galaxy. WAY too early to come out with such numbers except as a fun execersize, but certainly not scientific. We're still clueless about simple stuff like the rules governing solar system formation.
Space/Science » in reply to Number of alien life forms
re: Number of alien life forms