The blog post was interesting, but I wouldn't say it explained "what is a photon", it explained more, why do photons have energies and propagation properties th

The blog post was interesting, but I wouldn't say it explained "what is a photon", it explained more, why do photons have energies and propagation properties that they do. The first 2/3 of it I was wondering, why go through all this intro about springs... Although, there is one thing that I have always searched for an explanation of -- why the speed of light is invariant with reference frame. The idea that space is filled with springs might help me with that. If light/photons are the passage of a wave from spring to spring, then the speed of that propagation is always at the "spring speed" however you measure it, or however fast you are going. You can only ever receive the microscopic spring transmission speed of the photon at the place you receive it. (Although it brings up the complicated followup of, how are you traveling through the "springs", etc, I guess). But I'm sure I'm wrong about that too -- if anything QM has taught me is that my attempts at physical intuitions are usually wrong about QM.