A long with quantum mechanics in the 1920s, Einstein's Special Theory of Relativity of 1905 and his General Theory of Relativity of 1916 stand as the supreme achievements of twentieth-century physics. Relativity is an elaborate but comprehensible explanation of these theories, both of which boosted Albert Einstein to international acclaim. In simplest terms, the theory of relativity is an approach to the measurement and study of space and time. The theory assumes that findings are based upon the relation of the frame of reference to the objects measured. The Special Theory of Relativity is primarily concerned with electric and magnetic phenomena. The General Theory focuses on gravity, not as a force as Newton postulated, but as a curved field in the space-time continuum, created by the presence of mass. Redesigned inside and out to provide a fresh, modern look, Relativity includes both explanatory illustrations and mathematical derivations of Einstein's theories. Apparent throughout is Einstein's remarkable ability to penetrate directly to the heart of the subject in a way virtually everyone can understand.Einstein, Albert is the author of 'Relativity The Special and General Theory', published 1995 under ISBN 9780517884416 and ISBN 0517884410.