special theory of relativity

the theory proposed in 1905 by Einstein, which assumes that the laws of physics are equally valid in all nonaccelerated frames of reference and that the speed of electromagnetic radiation in free space has the same value for all inertial observers. It leads to the idea of a space-time continuum and the equivalence of mass and energy. In combination with quantum mechanics it forms the basis of the theory of elementary particles: Also called: special relativity See also general theory of relativity