Physicists from JILA — a CU Boulder and National Institute of Standards and Technology institute — were able to measure an effect called time dilation at the smallest scale ever, which they say could ...

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.

OUR most accurate clocks are probing a key tenet of Einstein’s theory of relativity: the idea that time isn’t absolute. Any violation of this principle could point us to a long-sought theory that ...