Physicists have demonstrated with unprecedented accuracy that the speed of light remains constant. In 1887, a landmark physics experiment was carried out by American researchers Michelson and Morley.

A POPULAR exposition of the doctrine of Relativity and what it implies: for this the world has been crying since the astronomers announced that the stars had proved it true. Here is an excellent ...

General relativity describes gravitation in a geometrical framework generalizing special relativity and classical mechanics. This term includes theoretical studies of gravity, experimental studies of ...