Hello everyone, I was thinking about the Doppler shift of light and I had a disturbing thought. It seems that the only way that light could maintain a constant speed and have shorter or longer wavelengths is if it is being carried by some kind of ether, which has long since been rejected. For example, if you're standing beside a train track on a windless day and a train is approaching, the sound from the train will have a higher pitch because the train is moving relative to you and to the stationary air(ether). The sound will have a higher frequency and shorter wavelength, but the two effects will cancel each other to produce a constant speed. It seems that if there is no ether, then the light will always have the same wavelength, but then the frequency would need to remain constant in order for the light to have a constant speed. Have I misunderstood something? Any thoughts on this anyone?