Got to start somewhere... Light is supposed to travel at c regardless of the motion of the source, right? Then how do you explain the Doppler effect? The shift in frequency should occur not because the wavelength changes, but because we are gaining or receding (c+v or c-v), and therefore percieve a different frequency. In Einstein's example of a railway embankment, with simultaneous flashes of light at points A and B, there is an observer on the rail car midway between points A' and B' who sees one flash first because she is moving toward it, and the other flash second as she recedes from it. I don't understand why our observer would not have some tools with her, and notice that there is a Doppler shift on each of these two flashes, and do some simple additive and subtractive calcuations to verify that the two flashes did indeed occur at the same time, but were in motion relative to the observer. What am I missing? (a brain?) I tried to find an explanation of DeSitters observations of binary stars that proves light travels at c regardless of the motion of the source, but no luck. Help? Other proofs? Since my math is stale, I also tried to find a layman's explanation of the Maxwell-Lorentz equation and Lorentz transformation. Help?