Main Question or Discussion Point
I know that the speed of light in a vacuum is always measured to be the same regardless of the observer's frame of reference. My question is, does the same apply to the speed of light as it travels through any non-vacuum medium? My gut feeling tells me yes, since its speed through the medium is simply an expression of the laws of physics, just as it is with no medium, which also remain the same no matter what your frame of reference relative to them is. Am I right?