Special RelativityThe basis of Einstein's ideas is that the speed of light (in empty space) is a constant for all observers. However fast you travel, light still shoots away from you - or towards you- at the same speed of 2.99792458 x 108 ms-1. You can never ever gain on the light wave in front. Light does not obey the ordinary laws of relative motion. This led Einstein to call his theory the principle of relativity.The consequence of the principle is that distances, time intervals and the time at which an event occurs will be different for observers who move at a steady velocity with respect to each other. In time dilation, the processes take longer to happen in objects that are moving relative to us. The effect is most dramatic at relative speeds close to the speed of light. Time dilation leads to other effects: objects shrink in the direction of travel -- the Lorentz contraction - and their mass increase. From these ideas, comes the formula : E= mc2. Albert Einstein produced the theory that explained the null results of the Michelson-Morley experiment. The Lorentz - FritGerald theory was seriously flawed since it was invented to explain just one effect. Einstein produced a formula for contraction with a simpler assumption about the constancy of light. Einstein took account of the nature of light and the fact that it was an electromagnetic effect. His theory was based on two simple assumptions. The first was that physical laws - mechanical, optical, electromagnetic - are the same in all uniformly moving frames of reference. The second is that speed of light in a vacuum is the same for all observers, in all uniformly moving frames of reference. But Special Relativity did not take into account the effects of gravity, which Einstein would later include. Continue to General Relativity.
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