archive: Re: SETI [Fwd: Probability of other ET Life is 1]

Re: SETI [Fwd: Probability of other ET Life is 1]

David Woolley ( david@djwhome.demon.co.uk )
Sat, 19 Dec 1998 14:42:27 +0000 (GMT)

> > P = 1 - (1-P0)^N, where P0 is the probability of life existing

Should be 1 - (1 - P0) ^ (N - 1)

Also, when you have to use such formulae, you are being very pessimistic;
the Drake equation assumes the result is very close to one and then tries
to predict how many will exist, whereas this assumes that there is a real
risk that we are the only ones.

Both are subject to unquantified parameters; this one only has two
whereas Drake's has multiple ones, so at least one can judge which factors
are wild guesses and which are known with some degree of confidence.

> Aczel is a genius. I have often had the same thoughts, but didn't have the

It's high school (A level) probability theory.