A paradox resulting from the special theory of relativity; if one of a pair of twins remains on earth while the other twin makes a journey to a distant star at close to the speed of light and subsequently returns to earth, the twins will have aged differently. The twin remaining on earth will have aged considerably more than the twin who travelled to a star. This paradox can be explained by the geometry of Minkowski (see space–time). The world line of the twin who remained at home is denoted AB, while the world line of the other twin is the sum AC + CB, corresponding to the journeys to and from the star. Such distances in Minkowski space satisfy the inequality AB > AC + CB, thus demonstrating that the time experienced by the twin who remains on earth is greater than that experienced by the other twin.