THE E.T. EQUATION, RECALCULATED

摘要

Fifty years ago, those of us who dreamed about finding extraterrestrials thought we knew where to look: planets with temperatures somewhere between the freezing and boiling points of water. Given warm little ponds, simple chemical reactions would produce life, and evolution might eventually produce intelligent creatures. While . working at the National Radio Astronomy Observatory in the 1950s, I tried to estimate the number of planets in our galaxy with intelligent, technological civilizations.