The nature of time is an age-old conundrum for physicists, philosophers, biologists and theologians. The Newtonian picture of time—a kind of cosmic clock that ticks off time in a manner that applies identically to everyone and everything—tightly aligns with our experience. But with special and general relativity, Einstein showed the fallacy inherent in experience: the rate at which time elapses depends on circumstance and environment. These discoveries raise even more basic, long-standing puzzles: What is time? Is it a fundamental feature of reality or something we humans impose on experience? Does time come into existence with the universe or does it transcend it? Why does time exist at all?
This program is part of the Big Ideas series.