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The physical meaning of a symmetry

  1. Aug 18, 2011 #1
    I know that the physical meaning of SU3 and SU2 - you can change the places of the quarks or/and leptons and you will get the same results.

    What is the physical meaning of U1, and O3,1 (Lorentz group if im not wrong)?

    I know U1 is connect with the Polarization of the light.

    Thanks very much to the people who will answer... (sorry about my bad english)
  2. jcsd
  3. Aug 18, 2011 #2
    It seems many of the laws of physics originate in symmetries.

    You might find Nother's Theorem of interest:


    where different symmetries are shown to underly different conservation "laws".
  4. Aug 20, 2011 #3
    U(1) is isomorphic to SO(2), the 2D rotation group.

    The connection with the polarization of light is that the polarization of massless fields in n space-time dimensions lives in the (n-2) transverse dimensions, in this case, 2. So the transverse-dimension rotation group in 4D is SO(2).

    The Lorentz group is indeed SO(3,1) -- the numbers are because the space-time metric's signature is +++- or ---+, depending on the convention.
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