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from the out-with-the-old-priors-and-in-with-the-new dept.
New Theory Concludes That the Origin of Life on Earth-Like Planets Is Likely:
Does the existence of life on Earth tell us anything about the probability of abiogenesis — the origin of life from inorganic substances — arising elsewhere? That's a question that has confounded scientists, and anyone else inclined to ponder it, for some time.
A widely accepted argument from Australian-born astrophysicist Brandon Carter argues that the selection effect of our own existence puts constraints on our observation. Since we had to find ourselves on a planet where abiogenesis occurred, then nothing can be inferred about the probability of life elsewhere based on this knowledge alone.
[...] However, a new paper by Daniel Whitmire, a retired astrophysicist who currently teaches mathematics at the U of A, is arguing that Carter used faulty logic. Though Carter's theory has become widely accepted, Whitmire argues that it suffers from what's known as "The Old Evidence Problem" in Bayesian Confirmation Theory, which is used to update a theory or hypothesis in light of new evidence.
[...] As he explains, "One could argue, like Carter, that I exist regardless of whether my conception was hard or easy, and so nothing can be inferred about whether my conception was hard or easy from my existence alone."
In this analogy, "hard" means contraception was used. "Easy" means no contraception was used. In each case, Whitmire assigns values to these propositions.
Whitmire continues, "However, my existence is old evidence and must be treated as such. When this is done the conclusion is that it is much more probable that my conception was easy. In the abiogenesis case of interest, it's the same thing. The existence of life on Earth is old evidence and just like in the conception analogy the probability that abiogenesis is easy is much more probable."
Journal Reference:
Daniel P. Whitmire. Abiogenesis: the Carter argument reconsidered [open], Int J Astrobio, 2022. DOI: 10.1017/S1473550422000350
(Score: 2) by Thexalon on Wednesday October 05 2022, @04:58PM (1 child)
Not exactly: We have, for instance, some evidence of potential organic chemistry having happened on Mars and Venus.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 3, Touché) by Immerman on Wednesday October 05 2022, @08:16PM
Hints are not data points.
Until we can conclusively state that Mars either did or did not harbor life, any such hints are only relevant to encouraging more conclusive studies, NOT to estimating the probability.
For that matter though, we haven't even established that the Moon doesn't harbor life, much less any of the other planets. We really do only have exactly one data point from which to extrapolate, and it's positive. All we can say about the rest of the solar system is that any life present isn't super obvious.