The essence of Einstein’s thinking is that time is relative. “Time is relative” is a short way of saying that clocks on two bodies in relative motion cannot be synchronized. In his original work, in 1905, Einstein uses a concept of synchronization that is shown to be ambiguous and erroneous. Counter examples are given to show that clocks on two bodies in relative motion can in fact be synchronized.
Einstein believes that synchronization cannot be divorced from communication. It is by separating these processes that synchronization becomes possible. None of his arguments – about simultaneity, about the Michelson-Morley Experiment, about the Lorentz Transformation, and about the ‘red shift’ is free of ambiguities and false inferences.
This much is certain: His two basic principle of Special Relativity Theory (SRT) are contradictory. The result of the Michelson-Morley experiment contradicts his second principle, the assertion that the speed of light is independent of the motion of the source.
There is no such evidence against Einstein’s first principle. The first principle implies the symmetry of source and receiver as far as movement is concerned in two inertial systems. For the Doppler effect this is shown to yield a formula that depends only on the separation rate of source and receiver. While this is true as well under SRT, the formula under Newtonian thinking yields a dramatically different result for velocities approaching the speed of light.
The theory of relativity leads to an interpretation of recent astronomical data that puts the age of the universe at over 12 billion years. This is based on an interpretation of the Doppler shift based on SRT. Without SRT, a reasonable interpretation of type 1A supernovae is obtained by adding the age when these stars were formed, (near the beginning of time), to the life time of stars whose supernovae are now visible, (about three billion years), and adding the time for the light to reach us (based on the minimum red shift, also about three billion years).
This gives us an estimate about half that age. That is the estimate we get if we take ‘time’ as universal, and the speed of light as constant, but only as measured by an observer at rest with respect to the source. The Doppler effect, under Newtonian thinking, related to the data of type 1A supernovae, suggests that the initial expansion velocity of the universe at the time of the ‘big bang’ was nearer to half the velocity of light, c/2, than to c.
The forces generated by radiation pressure are generally too small to be detected under everyday circumstances; however, they do play a crucial role in some settings, particularly astronomy and astrodynamics. For example, had the effects of the sun’s radiation pressure on the spacecraft of the Viking program been ignored, the spacecraft would have missed Mars orbit by about 15,000 kilometers.[