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Would it violate any special laws, if someone were to change the axiom of SR that

"Speed of light in vacuum is the same with respect to all reference frames"

To

"Speed of light in vacuum is the same with respect to all reference frames, but it's own reference frame, where it is the minimum".

I can then assign the photon a rest mass. Of course, it will get a reference frame as well. With no direction, time or speed. I mean if I got in the concept of 0 here, then it would be possible to assign the photon a rest mass, and say that the photon exhibits both these traits. Mass and EM wave both.

The mass trait not part of an EM field.

Could factor in the extra mass in the universe, and can be checked using calculations as well I guess?

novice
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1 Answers1

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The real reason we can't assign the photon a fundamental mass is because the straightforward mass term would break the gauge symmetry on which the electromagnetic theory is based. Now, that isn't to say that it is impossible to give such a gauge particle mass, we do it to the weak force using the Higgs mechanism. I'm not sure how possible it would be to apply such a mechanism to electromagnetism, though, especially since it's a massless particle leftover from applying the process to the unbroken electroweak theory.

That said, we have very stringent observational constraints on how massive photons could be, so I find it very unlikely that we will eventually find that it has a mass.

Sean E. Lake
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  • Well, if you say it exhibits both EM wave, and mass/matter characteristics? – novice Nov 02 '17 at 22:01
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    @novice, gauge bosons must be intrinsically massless (as I understand it) and the photon is the gauge boson for the electromagnetic interaction. If the vacuum were an electromagnetic superconductor, the photon could acquire an effective mass in the vacuum much like the electroweak bosons do in the Higgs condensate (an electroweak superconductor). But then, the electromagnetic interaction would be short ranged and the world would be far different that what is observed. – Alfred Centauri Nov 02 '17 at 22:11
  • Thanks. What if it could have more than one nature? In a sense exhibit both solutions. – novice Nov 02 '17 at 22:13
  • It could have a small enough mass to meet the currently known mass constraints, and still be pretty long range. We know it's got to have at a minimum something close to the size of the universe (in distance travelled which is about 13 Gly). I think the gauge symmetry argument by @Sean Lake is a pretty good one. – Bob Bee Nov 03 '17 at 03:32
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    @BobBee I suspect that the limit is even more stringent than what is produced by direct search. See, that factor of 2 in Planck's law is a count of the number of polarization states. If photons had mass, this would be factor of 3, instead. This would affect all sorts of things through the thermodynamics of photon gases. And the lower the mass, the bigger the effect. – Sean E. Lake Nov 03 '17 at 04:00
  • @SeanE.Lake Could you please tell me a little more about it? – novice Nov 03 '17 at 20:08
  • @novice The gauge invariance stuff? I would recommend you turn to textbooks for that (e.g. Zee, Peskin & Schroeder, and Weinberg). The thermodynamics stuff is speculative, so I wouldn't want to say more. – Sean E. Lake Nov 03 '17 at 20:18
  • @SeanE.Lake Thank you! Though I suspect it might take me a long while to understand it all, but well slowly but surely. – novice Nov 03 '17 at 20:47
  • Can't @Sean Lake. I agree, there's been plenty of ways in which to constrain the phtoton mass, and I've never felt the need to do an exhaustive search. Just that there's plenty of rationale for zero mass, and simple things like direct search and gauge symmetry makes it so it is a silly thing to ask the question without just doing some simple research. It's not a hard thing to find and understand some of the basic evidence. Plenty of similar q/a's in this site – Bob Bee Nov 04 '17 at 02:31