Space

Why Does Time Exist?

Cosmologist Sean Carroll tackles a deceptively simple question: Why does time exist at all? The potential answers point to a surprising view of the nature of the universe, and our place in it.

'Hello Earth! Can You Hear Me?'

That was the tweet sent by the European Space Agency's Philae space lander on Sunday morning. Last November, after touching down on Comet 67P, Philae went silent. On Saturday night, it communicated with scientists for the first time since. NPR's Arun Rath speaks with Mark McCaughrean of the European Space Agency about Philae's wakeup.