June 5, 2014 – In the journal Challenges the authors of a study entitled “Assessing the Possibility of Biological Complexity on Other Worlds, With an Estimate of the Occurrence of Complex Life in the Milky Way Galaxy,” report that planetary conditions within the galaxy indicate that organic life conditions exist on at least 100 million planets. That doesn’t mean complex life or intelligent life. It just means that the conditions are favorable for at least microbial life or better.
How did the scientists come up with the number? The paper’s authors, from Cornell, University of Texas at El Paso, University of Puerto Rico at Arecibo and Washington State University, surveyed more than 1,000 planets. They created a mathematical formula that incorporated planet density, temperature, chemistry, age and distance from a star, and whether the planet was largely liquid, solid or gas. From this they devised what they call the Biological Complexity Index (BCI).
Between 1 and 2% of the planets had a BCI rating greater than Jupiter’s moon, Europa. They then took the number of stars in the Milky Way and multiplied them by that percentage which gave them the 100 million number.
Maybe that’s why SETI scientists are convinced we will find intelligent life on an exoplanet within the next 25 years. It seems the odds are pretty good.