It feels so obvious that time moves forward that questioning it can seem almost pointless.

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 ...

At long last, a unified theory combining gravity with the other fundamental forces—electromagnetism and the strong and weak nuclear forces—is within reach. Bringing gravity into the fold has been the ...