The following is a transcript of the video. Stand on the equator and you'll be moving at 1,670 kilometers per hour — faster than the speed of sound! That's how quickly Earth rotates on its axis, from ...

Add Yahoo as a preferred source to see more of our stories on Google. Theoretical physicists have figured out how to reverse the arrow of time in a quantum system. The arrow of time marches forward.

Most of the laws of physics are the same whether you run the clock forwards or backwards. A planet that revolves around a star appears to obey the same rules as it would if you recorded it and played ...