* Einstein said it very simply: space is what we measure with a measuring rod and time is what we measure with a clock. * the first postulate Einstein made was that it was impossible to determine absolute uniform motion. Einstein showed that a moving clock marked time more slowly than one at rest. It seems as if the relativity of time poses a paradox - for how can both the passenger on the train and the person on the platform both see each other's watches slow down? by using Einstein's general theory of relativity, which applies to non uniform motions like that of the train, one can demonstrate that the twin on the train has actually aged less. * Einstein took the physics seriously: clocks really do slow down when they move. Even the order of events in time can be different for observers moving relative to one another; there is no absolute meaning to such time orderings. * simultaneity is relative. There is no universal present moment at every point of space. Events occurring at spatial separations which cannot be connected by a light signal cannot be assigned a particular chronological order which is the same for all observers in all states of motion. So one of the characteristics of the mental 'now' - that all people everywhere are experiencing the same now - is an unjustified extrapolation. There is no universal now, but only a personal one - a 'here and now'. * no physical experiment has ever been performed to detect the passage of time. * Einstein thought the universe was static and existed from an eternity in the past to an eternity in the future. * while Einstein went beyond the physics of Newton, bringing ideas of space ,time, and matter to their modern form, the framework of his physics was completely deterministic. The great clockwork of Newton's universe was altered by Einstein - the gears and the parts were different - but Einstein agreed with Newton that the motion of a clock was still completely determined into the infinite past and future. *Einstein held the classical view of determinism to the end of his life. For him, it was unthinkable that there was an arbitrariness and chance in the fundamental structure of the universe. His vision of the cosmic code - the eternal laws of nature that govern all existence - left no room for chance or the intervention of human will or purpose. He felt that the quantum theory was superficial and that beyond the random play of atomic particles it described, we would find a new deterministic physics. |