[deleted]
Georgina,
Let's take just the blue-green spectral line of hydrogen. The only way we can detect Doppler Shift is by it's position in what would always appear to be a continuous visible spectrum. Light is going to go at light velocity. So...at velocity, if a star were viewed as it moved very rapidly away from us, even though hydrogen would emit that BG wavelength, by the time it was through the Transition Zone of emission, it would be 'stretched out' and the absorption spectral line would be detected in a region more towards the red end of visible. But we would know it by its position among its companion Hydrogen spectral lines. All the other emissions would do likewise, so ultra violet would become visible while red would become infrared. (The Transition Zone of 2 wavelengths is it's own theoretical study)
Likewise, light going at light velocity, would be encountered more rapidly by an approaching receiver. What slays people is that at velocities at the very high end of the velocity scale, the receiver physically compresses along the direction of motion. All of which physically preserves the electrodymanics of the induction of the 'leap-frog' electro-magnetic reaction to the absorption of energy by that c proportional difference between the electric field and its companion magnetic field.
Doppler shift of sound in not the same thing. What your sensory organs do with that electromagnetically induced reaction, that you become consciously aware of is 'information'. You may wish to ascribe information to reactions that you are unaware of, but then the onus is upon you to physically prove what that is. In physics, they are known as properties, having known characteristic results.
How we become 'informed' is still a great mystery in neural-physiological research. I'll accept their findings.
Sorry to wear an old hat, but it's well sweat-stained and I like the darned thing. :-) jrc