Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field.This led to the development of his special theory of relativity,which he considered his masterwork. This theory found that gravity, as well as motion, can affect time and space. According to Einstein's equivalence principle--which held that gravity's pull in one direction is equivalent to an acceleration of speed in the opposite direction--if light is bent by acceleration, it must also be bent by gravity. In 1919, two expeditions sent to perform experiments during a solar eclipse found that light rays from distant stars were deflected or bent by the gravity of the sun in just the way Einstein had predicted. , which he considered his masterwork. This theory found that gravity, as well as motion, can affect time and space. According to Einstein's equivalence principle--which held that gravity's pull in one direction is equivalent to an acceleration of speed in the opposite direction--if light is bent by acceleration, it must also be bent by gravity. In 1919, two expeditions sent to perform experiments during a solar eclipse found that light rays from distant stars were deflected or bent by the gravity of the sun in just the way Einstein had predicted.
The general theory of relativity was the first major theory of gravity since