Mike wrote:
...
Mike


Let's cut the BS and sharpen Occam's Razor a bit.

A train whistle will increase in pitch (frequency) as the train comes
towards you, and decrease in pitch as the train travels away from you.

If you mount a laser on a space vehicle capable of thousands of miles
per hour, the same doppler effect can be see. The light will switch
frequencies when viewed approaching as when seen receding.

Liken the train whistle to air, as the laser to ether. Sound cannot
propagate in atmosphere faster than a set limit. Light cannot traverse
the ether for the same reason. The change in tone is due to
"compression" of the audio frequencies due to the increase/decrease in
train motion as opposed to the limit of sounds speed in the atmosphere.
Same for the laser, the light frequencies are "compressed" due to motion.

Now, I am sure much more complex explanations can be constructed ...

JS