The speed of light in a medium is inversely proportional to the refractive index of the medium, and it varies depending on the medium we perceive it to be moving through.

There are only two models that exist - the aetheric model and the atomist model. Atomists cannot define half the stuff they 'believe', and they rely on mathematical models to plug the holes in their dead-end theory. Feynman couldn't even explain magnetism, just like physicists today can't define what virtual photons or fields are.