Definition: Relativity, Theory of: Formulated by Albert Einstein in 1905, the famous Specail Theory of Relativity describes the motions of bodies in strong gravitational fields or near the speed of light than newtonian mechanics. Relative to the observer, both are altered near the speed of light: distances appear to stretch; clocks tick more slowly. All experiments done to date agree with relativity's predictions to a high degree of accuracy.
Relativity, Theory of
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