science-junkie: The Physics of Extraterrestrial Civilizations The late Carl Sagan once asked this question, “What does it mean for a civilization to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical
science-junkie: The Physics of Extraterrestrial Civilizations The late Carl Sagan once asked this question, “What does it mean for a civilization to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical
