A paradox is a statement that apparently contradicts itself and yet might be true, such as a "Catch-22," in which someone is in need of something that can only be had by not being in need of it.
Fermi's paradox, named for Italian physicist Enrico Fermi (1903-54), concerns two apparently contradictory truths:
1. The universe is so large, with so many trillions of stars comparable to the sun (and, by extension, at least as many planets comparable to Earth), that it is statistically unimaginable that life is unique to our planet.
2. There is no direct evidence of extraterrestrial life anywhere in the universe.