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Is Extraterrestrial Life More Whimsical Than Plausible?
coondoggie writes "Princeton University researchers are throwing some cold water on the hot notion that astrobiologists and other scientists expect to one day find life on other planets. Recent discoveries of planets similar to Earth in size and proximity to the planets' respective suns have sparked scientific and public excitement about the possibility of also finding Earth-like life on those worlds, but the expectation that life — from bacteria to sentient beings — has or will develop on other planets as on Earth might be based more on optimism than scientific evidence."
It's statistical probability, you Philistine!
"The researchers used a Bayesian analysis—which weighs how much of a scientific conclusion stems from actual data and how much comes from the prior assumptions of the scientist—to determine the probability of extraterrestrial life once the influence of these presumptions is minimized."
Source
Which amounts to, "my filter hasn't found any papers on extra-terrestrial life we've found yet, so clearly no evidence of extra-terrestrial life exists." I don't need a Bayesian filter to figure that one out, and it's actually pretty stupid to use one. We already know that we haven't found any life outside the Earth.
That said, the existence of life on Earth is all the evidence you need for life elsewhere. The chance of life arising is bigger than zero, and the amount of planets is large enough that for anything with probability not zero, it's going to happen more than once. The only valid question is just how full of life is the universe? Is it mostly lifeless or chock-full of it?
And having read the link, I can only say that my own statistical analysis shows with a high degree of confidence that every earth-centric or earth-is-unique argument made so far has been proven wrong. Therefore, expectations that this particular view will endure are probably based on optimism rather than evidence.
There is no support either for or against the existence of life on other planets. Bayesian analysis doesn't transform that lack of knowledge into evidence against life. After Bayesian analysis, people still don't have any facts.
However, I'd say things certainly look better now than they did a few decades ago, given that we have discovered both vast amounts of organic molecules in space, as well as lots of planets in the Goldilocks zone.