A photon emitted from a star a billion light-years away arrives at a telescope having experienced no time whatsoever. Not ...

Did you know that moving a clock one inch toward the ground would result in a slower tick compared to the same clock positioned higher up? Gravity doesn't just pull things; it also bends time.

Tracking time is one of those things that seems easy, until you really start to get into the details of what time actually is. We define a second as 9,192,631,770 oscillations of a cesium atom.