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Are photons 2 dimensional?

  1. Oct 15, 2015 #1
    String Theory speculates that extra dimensions may exist. Obviously, it would be difficult to describe or imagine that, but is it possible that there are objects or particles that exist observing LESS dimensions. For example, photons travel at c meaning that time travels infinitely slow in for all other frames; since this is also true, it exists in all places along it's path at once. Could photons actually be 2d objects?
  2. jcsd
  3. Oct 15, 2015 #2


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    The fatal flaw here is that you assumed that you can apply relativistic formulation on the frame of reference of the photon. This is a mistake.

    We have many threads, and a FAQ entry, on why you cannot do this.

  4. Oct 15, 2015 #3
    Okay, thanks for the reply, any recommended reading for this?
  5. Oct 16, 2015 #4
    In fact I can easily imagine that.

    A curved-up dimension just means that if you move along its direction, very soon you return to the same place. Like in some 2D computer games (pacman), when you cross screen boundary, you reappear on the opposite side. It's just the difference of moving along a line and on a circle.

    It's also intuitively explains why Kaluza-klein 5D gravity with one curled-up dimension is equivalent to 4D gravity + EM:
    (1) In 5D space, translation invariance still holds: you can translate along any direction, which means along that tiny circle too.
    (2) In GR, spacetime symmetries become local.
    (3) Circle translational group is isomorphic to U(1) group.
    (4) In 4D, requirement of extra local U(1) symmetry generates EM.
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