We've all heard of relativity, but what is it? How does it relate to light and motion? So we've all heard of relativity, right? But... what is relativity? And how does it relate to light? And motion?

A cluster of recent theoretical papers has laid out mathematical frameworks for propelling spacecraft at speeds ranging from ...

General relativity and quantum mechanics seem to describe all of observable reality. Between them, general relativity and quantum mechanics seem to describe all of observable reality.

It feels so obvious that time moves forward that questioning it can seem almost pointless.

Cormac O’Raifeartaigh reviews The Perfect Theory: a Century of Geniuses and the Battle Over General Relativity by Pedro G Ferreira Fighting it out: an artist's impression of two black holes circling ...

Discover how Einstein’s theory of special relativity reshaped physics by linking space, time, mass, and energy in a universe governed by the speed of light. When you purchase through links on our site ...

Yesterday, I wrote about the core concepts needed to understand quantum physics, which is one of the two pillars of modern physics. The other, of course, is the theory of relativity, the full and ...

New impressions A visualization of a curved space–time “sea” from the general-relativity simulations carried out by the authors.(Courtesy: James Mertens) From the Genesis story in the Old Testament to ...

Entanglement, like many quantum effects, violates some of our deepest intuitions about the world. It may also undermine Einstein's special theory of relativity Our intuition, going back forever, is ...