Fermi Paradox

The Fermi paradox highlights the apparent contradiction between the high likelihood of extraterrestrial civilizations existing—given the billions of stars and potentially habitable planets in the observable universe—and the complete lack of evidence for their existence. Physicist Enrico Fermi famously posed this question in 1950 at Los Alamos, asking "But where is everybody?" Various explanations have been proposed, including that intelligent life is extremely rare, civilizations have short lifespans, or they exist but leave no detectable evidence.