When energy propagates through a medium, it travels as a wave. This is true of light as well as sound. The fact that light behaves as a wave is well supported by scientific evidence (it also can behave as a particle in some situations, but in general it acts like a wave).
The Doppler Effect applies to all types of waves, so it applies to light.
If that isn’t enough, we have scientific evidence from observations of the universe that the doppler effect applies to light. In astronomy, we know that due to the expanding universe, stars or galaxies that are far away should be red shifted due to the Doppler Effect. When we evaluate all the stars and galaxies that we can see using telescopes, we find that the farther away they are, the redder they are, indicating a red shift is occuring.
Latest Answers