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posted by janrinok on Wednesday October 05 2022, @05:35AM   Printer-friendly
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


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  • (Score: 2) by legont on Friday October 07 2022, @12:36AM (1 child)

    by legont (4179) on Friday October 07 2022, @12:36AM (#1275333)

    Once again, there is no evidence life emerged here while all the building blocks of life are likely presented in comet's ice.

    As per surviving space and time, when a celestial body breaks for whatever reasons, there are small chunks and big ones. Big enough to protect life inside for indefinite time.

    Finally, folks who lived before the big bang and wanted to survive it, likely took some measures.

    Anyway, my original point was that there was not enough time for life to emerge here. The probability is just too low. See, we can't even do it on purpose.

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  • (Score: 2) by Immerman on Friday October 07 2022, @03:32AM

    by Immerman (3985) on Friday October 07 2022, @03:32AM (#1275365)

    If solid rock liquefies on impact because of the energy, or is subjected to enough temperature and pressures to convert carbon into rare forms of diamonds, then it can't protect anything. And that tends to happen even with normal asteroid strikes, much less those involving interstellar speeds. But yeah, it's not *impossible*

    Crossing interstellar distances though? And all the radiation shielding in the world won't protect you from the radiation produced by the shielding itself. Carbon, potassium, etc. - pretty much *everything* is at least slightly radioactive, and that radiation will destroy any living thing in suspended animation for millions of years. It has to be alive and active to repair the damage, which requires an extremely contrived environment when in interstellar space, where ambient temperatures are cold enough to freeze hydrogen.

    >there was not enough time for life to emerge here. The probability is just too low.
    Since we know almost nothing about the actual probabilities, and have a window of hundreds of millions of years to work with, that seems like a completely unsubstantiated statement.

    >See, we can't even do it on purpose.
    Have we tried? We certainly haven't dedicated a planet-sized laboratory to the project for hundreds of millions of years - as was available on early Earth. "We can't do it" is a horrible argument for claiming "it can't be done". Especially when talking about a field where we're only just beginning to reach the level of making crude finger paintings. We still know almost nothing about biology.