Who developed the theory of relativity?

Albert Einstein developed the theory of relativity. The theory consists of special relativity, published in 1905, and general relativity, developed between 1907 and 1915 and published in final form in 1916.

Einstein's work changed the Newtonian view of space, time, motion, and gravity. Special relativity showed that measurements of time and distance depend on an observer's motion and that the speed of light in a vacuum is constant for all inertial observers. General relativity later described gravity as the curvature of spacetime caused by mass and energy.

Einstein did not work in complete isolation. His theories built on earlier results from scientists including James Clerk Maxwell, Hendrik Lorentz, Henri Poincaré, and Albert Michelson. However, Einstein unified these ideas into a new physical framework and drew out their broader consequences.

A common mix-up is crediting Isaac Newton, whose laws of motion and gravity dominated physics for centuries. Newtonian mechanics remains highly accurate at ordinary speeds and scales, but Einstein's theories supersede it in extreme gravity or when objects move close to light speed.