This puzzle is known as the problem of time, and it remains one of the most persistent obstacles to a unified theory of ...

Physicists are rethinking time itself. Long treated as a basic part of the universe, time may instead be an illusion—a side effect of quantum entanglement. A new study challenges the traditional idea ...

Quantum mechanics is rich with paradoxes and contradictions. It describes a microscopic world in which particles exist in a ...

A century ago, Erwin Schrödinger came up with an equation that says how the quantum world behaves. Now scientists are asking ...

In an effort to bring together the domains of gravity and quantum theory, Albert Einstein and Nathan Rosen proposed a ...

The grandfather paradox is just one of the thorny logical problems that arise with the concept of time travel. But one physicist says he has resolved them. When you purchase through links on our site, ...

Columnist Natalie Wolchover checks in with particle physicists more than a decade after the field entered a profound crisis.