(ORDO NEWS) — Does the existence of life on Earth tell us about the likelihood of abiogenesis elsewhere? This question still baffles scientists, and everyone who is inclined to think about it.
A well-known argument by Australian astrophysicist Brandon Carter argues that the selection effect of our own existence puts limits on our observations.
Since we ended up on a planet where abiogenesis took place, no conclusions can be drawn on the basis of this knowledge alone about the likelihood of life elsewhere.
Carter believes that knowledge about life on Earth has a neutral value. Another way of looking at this is that the Earth cannot be considered a typical Earth-like planet because it was not randomly selected from among the many Earth-like planets.
However, a new paper by astrophysicist Daniel Whitmire proves that Carter used the wrong logic.
Although Carter’s theory has received widespread acceptance, Whitmire argues that it suffers from the so-called “old evidence problem” in Bayesian confirmation theory, which is used to update a theory or hypothesis in light of new evidence.
After giving some examples of how this formula is used to calculate probabilities, and the role played by old evidence, Whitmire turns to what he calls the conception analogy.
He explains, “One could argue, like Carter, that I exist whether my conception was difficult or easy, and therefore one cannot infer whether my conception was difficult or easy from my existence alone.”
In this analogy, “difficult” means using contraceptives, and “mild” means no contraceptives were used. In each case, Whitmire assigns values to these statements.
Whitmire continues: “However, my existence is old evidence and must be treated as such. Based on this, it can be concluded that it is much more likely that my conception was easy.
In the case of abiogenesis we are interested in, it is the same: the existence of life on Earth is old evidence, and, as in the analogy with conception, the likelihood that abiogenesis is easy is much more likely.
In other words, the evidence for life on Earth has no neutral value when it comes to life on similar planets. Thus, the existence of our life suggests that life is likely to appear on other planets similar to Earth.
Contact us: [email protected]