Neat!

https://en.wikipedia.org/wiki/Fermi_paradox

The Fermi paradox or Fermi's paradox, named after Enrico Fermi, is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations, such as in the Drake equation, and the lack of evidence for such civilizations.[1] The basic points of the argument, made by physicists Enrico Fermi (1901–1954) and Michael H. Hart (born 1932), are:

  • There are billions of stars in the galaxy that are similar to the Sun [2][3] including many billions of years older than Earth.[4][5]
  • With high probability, some of these stars will have Earth-like planets,[6][7] and if the Earth is typical, some might develop intelligent life.
  • Some of these civilizations might develop interstellar travel, a step the Earth is investigating now.
  • Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in about a million years.[8]

According to this line of thinking, the Earth should have already been visited by extraterrestrial aliens. In an informal conversation, Fermi noted no convincing evidence of this, nor any signs of alien intelligence anywhere in the observable universe, leading him to ask, "Where is everybody?"[9][10] There have been many attempts to explain the Fermi paradox,[11][12] primarily suggesting either that intelligent extraterrestrial life is extremely rare, or proposing reasons that such civilizations have not contacted or visited Earth.