My first thought is of the sheer quantity of extraterrestrial organisms which must exist in the incomprehensible vastness our universe.<p>Maybe the laws of physics and mortality will prevent us from meeting them, let proving their existence, but in such an ultimate vastness where we know that life does exist, <i>life must exist</i>.<p>I don’t get Fermi though. If you take the inconceivably large problem space that is “life finding other life in the universe” and cross it with the infinitesimally small amount of space-time we’ve occupied actively looking for other life, how is not having found other life yet a paradox?