Fermi Paradox
The Fermi Paradox blows my mind. It is the contradiction between high estimates for the probability of extraterrestrial life and humanity's lack of contact or evidence for them. More and more evidence points to a startling number of planets. Either the estimates are wrong or the theories to rectify this paradox are spooky. Does civilization eventually just destroy itself? Are we living in somebody's zoo? There are lots of intriguing possibilities!