or space contraction
In relativity physics, the shortening of an object along the direction of its motion relative to an observer.
Dimensions in other directions are not contracted. This concept was proposed by the Irish physicist George F. FitzGerald (18511901) in 1889 and later independently developed by Hendrik Antoon Lorentz . Significant at speeds approaching that of light , the contraction results from the properties of space and time, not from compression, cooling, or any similar physical disturbance. See also time dilation .