Enrico Fermi  asked, why haven't we seen signs of alien civilizations at a conference in the summer of 1950. This led to the so called, The Fermi paradox, which really isn't a’ a paradox in the traditional sense of the word.

In Contact, Jodie Foster plays Dr. Eleanor "Ellie" Arroway who Carl Sagan based on the real life astronomer Dr. Jill Tarter, gives one answer: we're not ready yet.