Life on Earth can help determine if there is life on other planets

A popularly held argument, Carter's belief, is that the knowledge of life on Earth makes our opinion neutral. Since we already live on a planet where abiogenesis has happened, we can’t predict probability of life existence on other planets from our observation.

An old theory debunked

Now, a new study by Prof. Daniel Whitmire, an astrophysicist who teaches math at the University of Arkansas, argues that Carter's theory was based on faulty logic. Whitmire explains that the theory suffers from 'the old evidence problem' in Bayesian confirmation theory which is essentially a means for updating theories in the light of new information.

Whitmire gives examples of how the formula is used to calculate probabilities and the role old evidence played in Carter's theory.

Using conception analogy, Whitmire makes his point. “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,” says the professor. In his comparison, 'hard' means contraception was used and 'easy' means there was no contraception.

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.”

Observing planets for life

Daniel Whitmire's explanation essentially means that we are not neutral when observing other Earth-like planets for life. This is because other observers like us could possibly exist- just as we can observe them, they too could observe us. Although most planets are barren.

This analysis by Whitmire suggests that an update in Carter’s widely accepted theory would need to be made as we gain new information, suggesting that “the observation of life on Earth is not neutral but evidence that abiogenesis on Earth-like planets is relatively easy.”

Better yet, Whitmire believes that life is even more likely to exist on other planets because of our life and existence. This is a huge shift in argument from the once commonly believed theory by Carter that our existence negates the inference about the probability of biogenesis and life on Earth-like planets.

Whitmore says that we have the ability to find life on other planets and believes we are not alone.