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- Newsgroups: sci.physics
- Path: sparky!uunet!snorkelwacker.mit.edu!galois!riesz!jbaez
- From: jbaez@riesz.mit.edu (John C. Baez)
- Subject: Re: Defining Photons
- Message-ID: <1992Jul27.233934.12465@galois.mit.edu>
- Keywords: Relating photons E=MC^2 criticism
- Sender: news@galois.mit.edu
- Nntp-Posting-Host: riesz
- Organization: MIT Department of Mathematics, Cambridge, MA
- References: <26JUL199218561022@zeus.tamu.edu> <1992Jul27.033211.26912@Princeton.EDU> <24927@dog.ee.lbl.gov>
- Distribution: na
- Date: Mon, 27 Jul 92 23:39:34 GMT
- Lines: 23
-
- In article <24927@dog.ee.lbl.gov> sichase@csa3.lbl.gov writes:
- >You will find that serious attempts at quantizing photons in a rigorous way
- >actually treat the photon as massive (to elimate certain problems which
- >arise from gauge transformations) and then discard the unphysical part of the
- >resultant fock-space which results from the unphysical degrees of freedom.
- >(The phrase "Buela-Gupta quantization" pops into my head.)
-
- Bleuler-Gupta pops into mine.
-
- >The massiveness
- >in no way interferes with the photon's quantization or its behavior in the
- >classical limit.
-
- Indeed, if one is only worried about free photons there's not even any
- need to treat the photon as massive at any stage, or screw around with
- "indefinite metrics" in Hilbert space and such. It's just another
- unitary irreducible representation of the Poincare group and one just
- pops it into the general machinery for quantizing unitary
- representations. If one is worried about interacting photons then of
- course there is no rigorously worked out theory, since there's no fully
- worked theory of interacting QFT's in 4-d. But there is a workable
- perturbation theory and while the masslessness of the photon causes
- nasty infrared divergences the experts tell me this doesn't faze them.
-