Time travel has shifted from pure fantasy to a serious, if highly constrained, topic in modern physics. The equations that describe gravity, quantum fields and the structure of spacetime now allow ...

Time is often treated as constant, but Einstein showed that it isn’t. Speed and gravity both affect how fast time moves, and ...

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.

The answer comes from a counterintuitive result of special relativity, a field of physics which is notoriously difficult to ...

When it comes to the idea of retrocausality in the quantum realm, how does time dilation affect entanglement? If you sent one of a particle pair much faster than the other and then measured one of ...