The Fermi paradox (or Fermi's paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity's lack of contact with, or evidence for, such civilizations.
There's a theory that the reason we haven't found other life yet is because there's a point in the existence of life where the species faces a challenge that is very, very hard to overcome. One possible reason that we haven't found other life is that we've already passed the boundary and evolved through it, unlike in other planetary systems. The other is that the boundary is ahead of us and we haven't reached it, but we'll go extinct as well when we do. Scary.
Some more possible answers to the paradox are here.
So where is all the extraterrestrial life?
There's a theory that the reason we haven't found other life yet is because there's a point in the existence of life where the species faces a challenge that is very, very hard to overcome. One possible reason that we haven't found other life is that we've already passed the boundary and evolved through it, unlike in other planetary systems. The other is that the boundary is ahead of us and we haven't reached it, but we'll go extinct as well when we do. Scary.
Some more possible answers to the paradox are here.