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According to Brandon Carter’s theory, the fundamental principles governing the appearance of life on Earth and the possibility that it could exist on other planets would be based on a selection effect, linked to a series of very rare and very precise. However, this theory would suffer from a lack of “old evidence”, and recent discoveries in the field of astrobiology seem to point in the opposite direction. Daniel Whitmire, a retired astrophysicist, has come up with a new hypothesis that abiogenesis is ultimately not so unlikely, and that the existence of life on other planets is instead governed by the analogy of design — especially if we base ourselves on the fact that abiogenesis on Earth is not a neutral argument.
Carter’s theory that the existence of life on Earth is governed by a selection (survival) effect and based on a Bayesian analogy. From this analogy derive the two fundamental principles of the theory: the weak and strong anthropic principles. The first means that our position in the Universe is privileged and is compatible with the conditions necessary for our presence as observers, otherwise we would not be there to observe. The second states that the Universe must have fundamental laws and parameters for life (including observers) to exist. Our existence — generated by abiogenesis (the appearance of life from inanimate matter) on our planet — would not therefore necessarily mean that it is probable that life is also present on other planets.
In summary, this theory suggests that the observation of life on Earth does not represent exhaustive information regarding the probabilities of abiogenesis on other relatively similar planets. Thus, we cannot rely solely on the information we have on terrestrial abiogenesis to estimate the probabilities of the appearance of life on other planets.
This theory seems to affirm that the appearance of life would result from a process of selection linked to survival. The probability that it could exist elsewhere would therefore be low and certain Earth-specific conditions would impose constraints on the Universe. If the Sun were not located exactly (and consistently) at the “edge” of our galaxy between two of its arms, for example, the Earth would be bombarded with deadly radiation and cometary dust. And if the amount of dark matter in the Universe varied only very slightly, the Earth would not be suitable for life, because its inertia would be modified.
Although accepted by many scientists, the probabilities arising from Carter’s theory would however suffer from lack of old evidence. Whitmire’s new hypothesis, presented in the journal Cambridge University Press, then seems to suggest the opposite. Much evidence in favor of off-Earth abiogenesis has notably come to light during this decade. Among these numerous proofs, it was discovered that the presence of liquid water on other planetary bodies of the solar system is not as rare as previously thought. To formulate his theory, Whitmire then considered this evidence in his calculations, integrating it into a new method of analyzing probabilities.
A theory based on the analogy of design
After considering how the existence of ancient evidence might influence the probabilities of abiogenesis, Whitmire relied on “the analogy of conception.” According to the latter, Carter’s theory would be interpreted as follows: I exist regardless of whether my conception was difficult or easy, and therefore nothing can be inferred whether my conception was difficult or easy from my mere existence “. In this specific case, “difficult” means that the parents would have used a method of contraception, and “easy” would mean the opposite.
However, according to this new hypothesis, existence itself constitutes old evidence that must be taken into account. From this, one could conclude that the probability that the conception was easy is much higher. If one were to apply this analogy to abiogenesis by considering the existence of life on Earth as ancient evidence, the odds that it could exist on other planets also increase.
Thus, the existence of life on Earth would not be a “neutral proof” according to Whitmire, and the abiogenesis on other planets which are more or less similar to it would be relatively “easy” (to use the terms advanced in the article). ‘study). Moreover, according to his calculations, the time necessary to bring together the right conditions for abiogenesis would be less than that which the Earth would have needed to bring together all the conditions of habitability. ” The existence of life on Earth is ancient evidence, and just like in the conception analogy, the odds of abiogenesis being easy are much higher. “, he concludes.