The Clock Paradox

Science  15 May 1959:
Vol. 129, Issue 3359, pp. 1359
DOI: 10.1126/science.129.3359.1359


In two-dimensional Minkowski space a geodesic arc is longer than every other admissible arc with the same end points. Thus a particle whose worldline is a geodesic—that is, an unaccelerated particle—requires more (local) time to travel between two events than an accelerated particle. Similar results in four-dimensional Minkowski space can be established.