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Can space-time homogeneity put limits

  1. Dec 13, 2006 #1

    dextercioby

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    ...on the gauge-invariance of classical electrodynamics ?

    I'm thinking of flat Minkowski space-time of SR in which a charged particle moves and generates an electromagnetic field described by the well-known Lie/nard - Wiechert potential.

    In this situation can we say all spacetime is homogenous ? If so, then can we infer that the gauge freedom of the L-W potential is disturbed, meaning that the gauge-parameter is necessarily 0 ?

    If you think the questions and the whole subject of this post are idiotic, then the same label can be ascribed to the article phys:0609152 available at www.arxiv.org.

    Daniel.

    P.S. I share your feeling: WTF ? :surprised
     
  2. jcsd
  3. Dec 13, 2006 #2

    pervect

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    AFAIK, space-time is only homogeneous in the large. I.e. we have large lumps of matter (planets, galaxies, stars). We say that space-time is homogenoeous only when averaging over a large volume. In the later case we make this sort of averaged homogeniety "the cosmological principle" http://en.wikipedia.org/wiki/Cosmological_principle

    The same sort of principle applies to charge. The flux tubes around Jupiter illustrate that there can be important electromagnetic inhomogoneities locally. It's only on the "grand scale" that we expect homogeneity.

    Basically, if there is a conflict, gauge invariance trumps homogeneity.
     
  4. Dec 14, 2006 #3

    dextercioby

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    So you're saying the article is not a bunch of crap. Ok. then.

    Daniel.
     
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