The Absolute Speed of Light

Abstract

AbstractIn the first five sections of Relativity, Einstein articulated the principle of relativity—that natural phenomena are seen to obey the same laws of motion when witnessed from any inertial frame of reference. For example, a game of billiards may be played just as easily on a uniformly moving passenger train as in the local pool hall. In other words, the billiard balls are seen to obey the principle of inertia and Newton’s other laws of motion, so the passengers have no way of discerning that they are in fact riding in a moving train by observing the billiard balls (or any of their other surroundings for that matter.) But the moment the conductor applies the breaks, the billiard balls strangely surge forward, in the absence of a recognized force acting on them, and in apparent violation of the principle of inertia. The so-called fictitious force which seems to now act on the billiard balls (and everything else on the train for that matter) is a consequence of the fact that the decelerating train is now a non-inertial frame of reference. Up until this point, Newton would have agreed with Einstein: a state of rest is equivalent to a state of uniform linear motion in that these states cannot be distinguished by observing the motion of bodies. But now Einstein takes his analysis a step further: he considers whether one can test if he or she is truly at rest or in uniform linear motion by measuring the speed of light itself.KeywordsRailway LineRailway CarriageBilliard BallLightning FlashMoving TrainThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.