Life on other Planets?

Almost certainly (and I only include the "almost" out of due deference to tentativity)Now, how much of this life has developed into something more complex than a basic microbial stage is another question entirely...Basic reasoning for the above (off the top of my head):Abiogenesis is a physical process and thus we can assign a gross probability, p, to the probability that abiogenesis occurs in a single trial.The number of trials appropriate to p is roughly the number of stellar systems to +/- an order of magnitude or so.Let us consider just the Observable Universe. That gives an n of around 10²². Let X be the number of abiogenetic events.If p>10^-22, then E(X)>1 and P(X=1) is very small.
If p~10^-22, then E(X)~1, but still P(X>1) > P(X=1), and suggests a level of "fine-tuning" which would require further explanation.
If P<10^-22, then E(X)~0 and P(X=1)>>P(X>1), but P(X=1)<<1 and thus X=1 is a highly significant event which requires further explanation.Edited by cavediver, : No reason given.

Sorry, standard stats notation - E(X) is the Expectation of X, otherwise known as the mean in other contexts, and E(X) = n x p in this context. P() is simply the probability of the condition in the brackets.Example with dice: X is rolling a six; n is number of rolls, p is probability of rolling a six.So with p=1/6, n=6E(X)=1 (i.e. we expect to get 1 six when rolling a die 6 times)P(X=1) = 0.4 (but the probability of getting 1 six is actually only 0.4, so even though we "expect" 1 six, we are more likely to get something else!)

Count up the probabilities: six rolls, so the six could occur on any one roll.P(six on 1st roll, and not a six on other five rolls) = 1/6 x 5/6 x 5/6 x 5/6 x 5/6 x 5/6
P(six on 2nd roll, and not a six on other five rolls) = 5/6 x 1/6 x 5/6 x 5/6 x 5/6 x 5/6
P(six on 3rd roll, and not a six on other five rolls) = 5/6 x 5/6 x 1/6 x 5/6 x 5/6 x 5/6
etc...These are mutually exclusive probabilities, so they can be added up to giveP(six on just one roll, and not a six on the other five rolls) = 0.40 (2 d.p.)We can condense the arithmatic by using the mathematics of the Binomial Distribution:P(X=r|n, p) = p^r(1-p)^(n-r)Cⁿ_rIn this case, we haveP(X=1 | 6, 1/6) = (1/6) x (5/6)⁵ x C⁶₁ = 0.40 (2 d.p.)Oh, and...