Derek Thompson writing for The Atlantic:
Enrico Fermi was an architect of the atomic bomb, a father of radioactivity research, and a Nobel Prize–winning scientist who contributed to breakthroughs in quantum mechanics and theoretical physics. But in the popular imagination, his name is most commonly associated with one simple, three-word question, originally meant as a throwaway joke to amuse a group of scientists discussing UFOs at the Los Alamos lab in 1950: Where is everybody?
Fermi wasn’t the first person to ask a variant of this question about alien intelligence. But he owns it. The query is known around the world as the Fermi paradox. It’s typically summarized like this: If the universe is unfathomably large, the probability of intelligent alien life seems almost certain. But since the universe is also 14 billion years old, it would seem to afford plenty of time for these beings to make themselves known to humanity. So, well, where is everybody?