Discrepancy between lack of evidence of advanced alien life and apparently high likelihood it exists
This article is about the absence of clear evidence of extraterrestrial life. For a type of estimation problem, see Fermi problem.
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence.[1][2] As a 2015 article put it, "If life is so easy, someone from somewhere must have come calling by now."[3]
There have been many attempts to resolve the Fermi paradox,[5][6] such as suggesting that intelligent extraterrestrial beings are extremely rare, that the lifetime of such civilizations is short, or that they exist but (for various reasons) humans see no evidence.