UFO attack or the Fermi paradox
 Developed by the Italian physicist Enrico Fermi in 1950, this paradox raises the question of extraterrestrial life. Several hypotheses are then put forward to answer this question:
 - Extraterrestrial life does not exist
 - Extraterrestrial life exists, but communication or stellar travel is not possible with Earth.
 - Extraterrestrial life exists, but our species, too little evolved and interesting, does not justify a connection with this superior intelligence.
 - Extraterrestrial life exists, within our civilization itself, without us realizing it.