The contraction of a moving body in the direction of its motion. It was proposed independently by H. A. Lorentz and G. F. Fitzgerald (1851–1901) in 1892 to account for the null result of the Michelson–Morley experiment. The contraction was given a theoretical background in Einstein's special theory of relativity. In this theory, an object of length l0 at rest in one frame of reference will appear, to an observer in another frame moving with relative velocity v with respect to the first, to have length l0√(l − v2/c2), where c is the speed of light. The original hypothesis regarded this contraction as a real one accompanying the absolute motion of the body. The contraction is in any case negligible unless v is of the same order as c.