My mental model is that of the EM field coupling with the internal EM fields of a material to give rise to the phenomenon of index of refraction where light app

My mental model is that of the EM field coupling with the internal EM fields of a material to give rise to the phenomenon of index of refraction where light appears to move slower than the speed of light in a vacuum in said material. As I understand, a more advanced version of this occurs in superconductors which serves as a much better model of the phenomenon. At least I'm told it would if I could claim to understand it! https://physics.stackexchange.com/questions/33240/how-come-a-photon-acts-like-it-has-mass-in-a-superconducting-field https://physics.stackexchange.com/questions/33240/how-come-a... https://physics.stackexchange.com/questions/47791/what-do-massive-photons-have-to-do-with-superconductivity https://physics.stackexchange.com/questions/47791/what-do-ma...