Many hard-headed scientists have tried in various ways to find extra-terrestrial life. Xenobiologists try to detect microbes on Mars (not found yet), and amino acids, which are building blocks of life on comets (they have been found). Astronomers examine radio signals, hoping to decipher broadcasts from aliens.
The latest model assessing probability of life existing comes from Columbia University astronomer David Kipping.
Kipping used the statistical tools of Bayesian Inference to see if life should exist on Earth. (He knew the answer but it is a good way to test the model.) Bayesian statistics start with a hypothesis and update the
