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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


Original Submission

 
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  • (Score: 2) by Immerman on Tuesday October 11 2022, @08:41PM

    by Immerman (3985) on Tuesday October 11 2022, @08:41PM (#1276118)

    I just gave you the timeline. When the first generation hypergiants started exploding is when the first *everything* became available - from lithium to uranium and beyond. About 100M years after the big bang, or 13.7 billion years ago. But the amounts were pretty low.

    Third-generation stars like ours, whose planet systems probably have element ratios similar to our own, started forming about 9 billion years ago, though the concentrations of heavier elements might not be quite as high as here, depending on the specifics of the protostellar cloud formation.

    Where are you getting your numbers from?

    Life started on Earth at least 3.42 billion years ago - the age of the oldest fossils, and it's suspected that the last common ancestor of all Earth (LUCA) life actually lived between 3.71 and 4.41 billion years ago - as early as a hundred million years of the formation of Earth, and about the same time liquid water began to form. https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life [wikipedia.org]

    Meanwhile, the sun is roughly the same age as the Earth and other planets, between 4.5 and 4.6 billion years old. Planets form from the same protostellar cloud as their suns, and once the sun ignites most of the remaining cloud is blown away by the photon pressure. Though the gas giants may have caught much of it as it blew out past them - the process likely took several million years.
    https://en.wikipedia.org/wiki/Sun#Formation [wikipedia.org]
    https://www.worldatlas.com/articles/how-old-is-the-sun.html [worldatlas.com]

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