One of the most basic assumptions of fundamental physics is that the different properties of mass—weight, inertia and gravitation—always remain the same in relation to each other. Without this ...

In Newtonian physics, space and time had their independent identities, and nobody ever got them mixed up. It was with the theory of relativity, put together in the early 20th century, that talking ...

When an object moves extremely fast—close to the speed of light—certain basic assumptions that we take for granted no longer apply. This is the central consequence of Albert Einstein's special theory ...

A century ago, Albert Einstein became famous. Sure, he was already well-known among physicists. But the world at large learned his name only after November 1919, when news broke that his theory of ...

General relativity states that gravity is the result of mass warping the fabric of space and time, which Einstein lumped into a four-dimensional entity called space-time. According to relativity, time ...

After two eclipse expeditions confirmed Einstein's theory of general relativity, the scientist became an international celebrity. The New York Times Archives / Photo Illustration by Shaylyn Esposito ...