The best known of the paradigm-shattering papers published by Albert Einstein in 1905, his annus mirabilis, is the one titled “On the Electrodynamics of Moving Bodies.” 1 It was there that the principle of special relativity was set forth. Einstein asserted in this paper that time is relative. That is, if two inertial observers in uniform motion at relative velocity v were equipped with identical clocks, each would judge the other’s clock to be running too slowly by a factor v 2/2c 2(excluding higher-order terms).
Einstein immediately applied that result to a pair of identical clocks, one located on the equator and the other at either of the poles. Because of Earth’s rotation relative to an almost inertial reference frame, a clock fixed at a point on the equator moves with a speed v = 0.5 km/s while a clock at the pole is essentially at...
