Re:A 9-line summary of textbook physics
by unicas on Saturday March 19, 2022 @11:11AM
(#30734383)
There are plenty of so called "derivations of Maxwell equations", however, I would not claim that they were based on U(1) necessarily. IMO ME are just the integrability conditions for any conserved quantity (continuity equation): take a generic three-form in R^4, then dJ=0 => J=dF. F has six components corresponding to two vectofields in R^3 which depend on the fourth coordinate and satisfy the div and curl relations as in ME ;)
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Re:A 9-line summary of textbook physics
by hither_shores on Sunday March 20, 2022 @01:50AM
(#30740479)
U(1) symmetry (R also works in a classical setting: it's the Lie algebra that matters) is exactly how you get a "generic three-form" to drop out of the action.