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Null geodesics and null curves

  1. Aug 16, 2015 #1
    What is the exact difference between null geodesics and null curves? Please explain both qualitatively and quantitatively.
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  3. Aug 16, 2015 #2


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    Null geodesics are parametrised such that the tangent vector is parallel transported along it. This is not necessarily the case for any null curve.
  4. Aug 16, 2015 #3


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    Consider the path, in polar coordinates: θ = ct/R

    A circular light speed path of radius R. This is null path that is not geodesic. Light would not take such a path in vaccuo.
  5. Aug 16, 2015 #4
    ok..thanks Orodruin and PAllen.
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