Discover the Fermi Paradox — why, in a vast universe full of stars and planets, haven't we found extraterrestrial life? Explore the theories behind this great mystery.

Maurits Cornelis Escher, Belvedere (1958) Surrealist Treasures: The Urban S. Hirsch III Collection, Bonhams, Los Angeles, 7-17 January. Estimate: $25,000 to $35,000 ...