Special Relativity is the accepted and experimentally confirmed physical theory regarding the relationship between space and time. General Relativity is the geometric theory of gravitation and the current description of gravitation in modern physics. General Relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time (spacetime). The curvature of spacetime is directly related to energy and momentum of whatever matter and radiation are present.