Time travel has shifted from pure fantasy to a serious, if highly constrained, topic in modern physics. The equations that ...

Contemporary physics has learned to describe the universe with unprecedented precision. Yet when it tries to say what time is, it stumbles again and ...

Sara Imari Walker receives funding from the National Aeronautics and Space Administration and the John Templeton Foundation relevant to the work in this article. She is also a member of the External ...

With everyone trading electronically, it’s easy to think that trades and quote changes happen simultaneously. But they don’t. In fact, all data is delayed. Even proprietary feeds. It’s just physics.