Time’s passage is non-negotiable. Its flow marks the progress of our lives, moving clearly in one direction. It is, by nature, asymmetrical. In this way, we perceive it to move like an arrow, ...

A new suggestion that complexity increases over time, not just in living organisms but in the nonliving world, promises to rewrite notions of time and evolution. In 1950 the Italian physicist Enrico ...

Can we turn back time? Ask a savvy physicist, and the answer will be “it depends.” Schemes for retrograde time travel abound but usually involve irreconcilable paradoxes and rely on outlandish ...

Studies of the simplest possible clocks have revealed their fundamental limitations — as well as insights into the nature of time itself. In 2013, a masters student in physics named Paul Erker went ...