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...Over time an interpretation developed as to the motion of light within the solar system. The solar system including the sun, planets, moons and asteroids, is in motion with a velocity 'v' according to this analysis. Thus, if light were to travel a path of distance d from one point to another and back again as in Figure 19, it would take a total travel time for light traveling parallel to the motion of the earth of the time the light took in the forward path and the time the light took on the return path. So one uses the distance equals rate times time relationship from elementary mathematics (D=rt), to determine forwards and backwards travel times over a path d.
However, the light in the direction of motion of the solar system appears to be slowed by the velocity of the motion of the solar system 'v.' Since an observer witnesses a light speed that is slowed by the Galilean Transformations one knows that an observer determines a light speed of (c-v). Similarly, on the return journey the light appears to be going faster than it is since the solar system is approaching the light ray. Thus, by the Galilean Transformations Equations one can write that the perceived speed of light for an approaching light ray is (c+v)...
Another piece of the puzzle would be found in the year 1892 when Dutch physicist Hendrik Antoon Lorentz (1853-1928) defended the theory of the stationary ether by proposing a radical concept. Recall that the stationary ether requires an ether wind and that the Michelson-Morely experiment had failed to detect it. Thus, a mechanism had to be found to repair this glaring inconsistency between theory and experimental observation. It was Lorentz who seized and expanded upon an extraordinary hypothesis proposed by Irish physicist George Fitzgerald. He suggested that the troubling inconsistency of the Michelson-Morely experiment could be explained by the idea that movement causes contraction of space in the direction of motion.
