http://www.amazon.com/Brief-History-.../dp/0553380168
Stephen Hawking, "A Brief History of Time", Chapter 3: "...we must first understand the Doppler effect. As we have seen, visible light consists of fluctuations, or waves, in the electromagnetic field. The wavelength (or distance from one wave crest to the next) of light is extremely small, ranging from four to seven ten-millionths of a meter. The different wavelengths of light are what the human eye sees as different colors, with the longest wavelengths appearing at the red end of the spectrum and the shortest wavelengths at the blue end. Now imagine a source of light at a constant distance from us, such as a star, emitting waves of light at a constant wavelength. Obviously the wavelength of the waves we receive will be the same as the wavelength at which they are emitted (the gravitational field of the galaxy will not be large enough to have a significant effect). Suppose now that the source starts moving toward us. When the source emits the next wave crest it will be nearer to us, so the distance between wave crests will be smaller than when the star was stationary. This means that the wavelength of the waves we receive is shorter than when the star was stationary. Correspondingly, if the source is moving away from us, the wavelength of the waves we receive will be longer. In the case of light, therefore, means that stars moving away from us will have their spectra shifted toward the red end of the spectrum (red-shifted) and those moving toward us will have their spectra blue-shifted."
On Hawking's interpretation, as the source starts moving towards the observer, it produces a shorter wavelength which then traverses the distance from the source to the observer. However, according to the principle of relativity, "source starts moving towards observer" is indistinguishable in any respect from "observer starts moving towards source". The principle is obviously contradicted here - as the observer starts moving towards the source, no shorter wavelength traverses the distance from the source to the observer..
Since the assumption that "a shorter wavelength traverses the distance from the source to the observer" contradicts the principle of relativity, it should be abandoned. Then it is "faster light", not "shorter wavelength", that the moving source is sending. That is, as the source starts moving with speed v towards the observer, the speed of the light relative to the observer shifts from c to c'=c+v, in violation of Einstein's relativity.
The principle of relativity is compatible with the equation c'=c+v given by Newton's emission theory of light and incompatible with Einstein's 1905 constant-speed-of-light postulate (c'=c).
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