3 ms·

If E = mc^2, then why does a photon contain energy?

• hilbert42 5y ago
  "The Abraham-Minkowski controversy seems to touch the argument. The permittivity of “empty“ space qualifies as a dielectric, does it not? Is the argument related to a possible ambiguity concerning photon mass? " Oh dear, I don't think I've the stamina to go through another one of these debates. I'll just say this. In SI units c^2 = 1/(ε0μ0) which implies a direct connection between the speed of light and vacuum permittivity/permeability. In Gaussian units we can equate c = 1 (as Einstein does in his 1905 paper). That changes the perspective. Where does this lead? Back to the aether argument of course, although not the debunked luminiferous aether of the 19th C. and earlier. From my observation, here there are two widely differing camps of thought and arguments always ensue when the matter is raised. My personal view is that there is a lot more to the relationship between c and vacuum permittivity and permeability than is currently discussed. In essence, there's an aether almost by definition but it's no simple matter, it has to have or present Lorentz invariance like properties consistent with relativity, etc. etc. Later, Einstein essentially admitted that the aether was a possibility. This begs the question if spacetime distorts in the presence of mass then what exactly is spacetime? It's hard to totally dismiss the notion that it's not some kind of medium. (Of course, what I've just said is a gross oversimplification that's missing many points but there ought to be enough here to buy an argument or two.)