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New theory concludes that the origin of life on Earth-like planets is likely

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.


At best, he argued, the knowledge of life on Earth is of neutral value. Another way of looking at it is that Earth can’t be considered a typical Earth-like planet because it hasn’t been selected at random from the set of all Earth-like planets.


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.

然而,目前在亚利桑那大学教数学的退休天体物理学家丹尼尔·惠特迈尔(Daniel Whitmire)的一篇新论文认为,卡特使用了错误的逻辑。尽管卡特的理论已被广泛接受,但惠特迈尔认为,它受到贝叶斯确认理论中所谓的“旧证据问题”的困扰。贝叶斯确认理论是根据新的证据更新理论或假设。

After giving a few examples of how this formula is employed to calculate probabilities and what role old evidence plays, Whitmire turns to what he calls the conception analogy.


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.”