einstein's theory of general relativity, formulated in 1915, is widely acknowledged as one of the most elegant theories in physics. Einstein's special theory of relativity, formulated in 1905, replaced the Newtonian concept of space and time as absolute entities by a world-view where space and time depended on the observer. This theory was applicable only to observers at rest or in uniform motion. The general theory was an extension of the special theory to include the effects of gravitation and physics as seen by accelerated observers. The novel aspect of the general theory was the idea that gravity is a