The explanations for Special Relativity given by others tell the results of applying Einstein’s Special Relativity ideas. However, there is a slightly different view on Einstein’s work. The term, “Relativity” is a statement of the fact that information is relative to an observer. Einstein’s ideas relate, if carefully examined, how that information may be distorted when it is transmitted from an observed to an observer along a carrier wave. In the case of our Universe, the Universe with which Einstein dealt, this carrier wave is electro-magnetic energy which has a maximum velocity, called in his equations, “c.”
Now the equations which describe this distortion can be applied to ANY TRANSMITTER/ RECIEVER SITUATION INVOLVING A CARRIER WAVE VELOCITY. That is, the equations could be used to analyze Sonar results if the transmitter and receiver had a relative velocity to each other close to the speed of sound in water at the depth studied. They could be used in a “Perceptual Universe” where the maximum transmission speed was the speed of nerve impulses, etc. (The appropriate carrier wave speed would, of course, have to be substituted for “c” in the equations.)
That is, Einstein’s Special Relativity Theory is not a “Theory.” It is an accurate description of how information is distorted by relative motion of a transmitter and receiver in one of an unlimited number of “Perceptual Universes,” the particular Perceptual Universe having an observation point here on Earth and a limiting velocity of the Information Carrier Wave of the speed of light.