Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is ...

Relativity, wide-ranging physical theories formed by the German-born physicist Albert Einstein. Special relativity is limited to objects that are moving with respect to inertial frames of reference. General relativity is concerned with gravity, one of the fundamental forces in the universe.

A page of the original manuscripts of the theory of relativity developed by Albert Einstein on display at the Israeli National Academy of Science and Humanities in Jerusalem on March 7, 2010.

The theory of special relativity was introduced first and was later considered to be a special case of the more comprehensive theory of general relativity. General relativity is a theory of gravitation that Albert Einstein developed between 1907 and 1915, with contributions from many others after 1915.

Theory of Relativity – The Basics Physicists usually dichotomize the Theory of Relativity into two parts. The first is the Special Theory of Relativity, which essentially deals with the question of whether rest and motion are relative or absolute, and with the consequences of Einstein’s conjecture that they are relative.