On The Alien Question: Where Are They?

The great physicist Enrico Fermi asked this question in the 1950s. There are more than 50 possible "solutions" to Fermi's Paradox: Here, astrophysicist Marcelo Gleiser explores a few.(Image credit: Ken Brown/Getty Images)

Source: NPR Health and Science - November 14, 2017 Category: Consumer Health News Authors: Marcelo Gleiser Source Type: news