[GrandEagle]

The speed of light and the color of light are related.
I know I'm opening myself up here, but IF I remember my physics correctly the color's visible have to do with the frequency, of oscillation, not the speed of travel.
Be easy on me, I've not been through this stuff in quite a while AND my memory is pretty full. Consequently, when I have something new to store in memory, I have to find something old and unused to throw out. I could have thrown this information out.

[VadeRetro]

I know I'm opening myself up here, but IF I remember my physics correctly the color's visible have to do with the frequency, of oscillation, not the speed of travel.

Other things being held equal, a change in the speed of light would change the frequency of arrival of the peaks and valleys in the waveform.

Other things are not exactly equal, however, as it appears space and the light waveforms within have been stretched over time. Assuming the speed of light to be constant, that would red-shift light in transit so that objects appear redder the farther away they are. Since we indeed see a correlation between distance and redshift, it appears the universe has been expanding.

[RightWhale]

Frequency or wavelength. Since they are so closely related either is used to represent color. Einstein invented photons as a mathematical device to explain several physics problems, and all in a few years a century ago. Photons are just a device.