We Keep Coming Up Empty in the Search for Alien Life. Here’s What That Could Mean—and What Comes Next

Humans have been pondering the existence of life beyond Earth since ancient times. In the 1900s, scientists began actively searching for proof. Needless to say, we still haven’t found any. Although it’s only been a number of decades and technology is advancing every day, what if we continue to come up empty-handed? In a study published Monday in The Astronomical Journal, an international team of researchers tackled this question by arguing that what we don’t find can still be deeply informative. The study suggests that identifying a certain number of lifeless exoplanets could enable scientists to confidently determine whether life beyond Earth is common or rare. Specifically, the researchers used advanced statistical modeling to demonstrate that if no evidence of life is found in 40 to 80 exoplanets, we can infer that fewer than 10 to 20% of similar planets in the universe host life. While this might not seem that impressive, it would represent an upper limit for the prevalence of po ... Read full article.