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Q & A: Higgs and photons?

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Most recent answer: 04/06/2012
Q:
Two observations on the constancy of the speed of light, and the photon's mass. The photon has an inertial mass defined by the ratio of the photon energy hv/c^2. Its 'rest' mass is, as you say, zero. Now here is a curious thing. Consider the permeability and permittivity of free space--the 'vacuum' if you will. As we know, the electromagnetic field propagates through is vacuum with the speed of light c. It is easy to construct a thought experiment 'transmission line' using the vacuum constants that constrain the EM wave to travel at c. It is possible to further speculate that photons, making up the EM wave are continuously and coherently interacting with the vacuum--possibly the Higgs field--since as I indicated, the photon has inertial mass, it follows that if the Higgs field exists then that would also be why the speed of light is not infinite. Comments?
- Peter Livingston (age 76)
Palos Verdes CA
A:
Actually, in the Standard Model the Higgs interaction is supposed to give other particles some rest mass. Photons have zero rest mass because they don't interact with Higgs. The inertial mass you mention is just required by the relativistic transforms for zero-rest-mass particles.

Mike W.

(published on 03/31/2012)

Follow-Up #1: Why is there a speed limit?

Q:
Thanks for the answer. I now understand the problem a little better. The Higgs field only confers rest mass on a fundamental particle. But you haven't addressed the root of the question: why is the speed of light what it is and not something else. I suggested a gedanken experiment in which free space acts as a transmission line with distributed inductances and capacitances according to the permeability and permittivity of free space, thus moderating the photon (EM field) rate of passage. Such a process, if it existed, would consist of some interaction of the photon field with the vacuum as yet unidentified, that would retain the EM field coherence yet delay its passage. In short, why isn't the speed of light infinite? (Apart from the fact that there would be no radiation in the universe and we would not be here to observe it.)
- Peter Livingston (age 77)
Palos Verdes CA
A:
I don't know why there's a speed limit.

As far as your model of space as a transmission line, it really doesn't make a gedanken experiment unless you draw some experimental conclusions from it. It would seem to imply that Maxwell's equations would break down on a small distance scale if you think of those electrical components as discrete objects. People have looked for that type of effect (for other reasons) and found nothing. If you think of the inductance and capacitance as being smoothly distributed properties of space, you're basically just back to standard Maxwell.

Mike W.

(published on 03/31/2012)

Follow-Up #2: Is there a deeper theory for QED?

Q:
Point taken. Thank you for your answer. Clearly I was angling for the existence of an entity with which the photons 'exchange' in such a way as to provide a speed limit. Perhaps a better way to address my question is to drill down into the meaning of the permeability and permittivity of the vacuum--which after all we are taught as being 'empty'. Of course EM theory is self consistent in which the velocity of light and the absence of a magnetic monopole is given. But don't you share a little feeling that we are avoiding some deeper question here? I don't intend an answer and I thank you for your consideration.
- Peter Livingston (age 77)
Palos Verdes CA
A:
I think most of us do share the feeling that there will be some deeper theory underlying our current laws of physics. The string theorists are attempting one approach to find it. Whether there will then be a deeper theory beneath that, and whether the layers ever stop, no one knows.

Mike W.

(published on 04/06/2012)

Follow-up on this answer.