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Reducing the speed of light

  1. Apr 10, 2013 #1
    is it possible that gravity reduce the speed of light, and addtionally does anyone know an equation to calculate the exact deflection of light due to gravity.
  2. jcsd
  3. Apr 10, 2013 #2
    It does not reduce the speed but does reduce the energy.

    Note that specifically gravity doesn't deflect light. Light follows geodesics, which are "curved" by gravity.

    Specifically gravity curves spacetime, light travels geodesic paths through spacetime.
  4. Apr 10, 2013 #3
    thanks alot but so is there a fairly simple to equation that some what accurately predict the bend in the light
  5. Apr 10, 2013 #4


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    Staff: Mentor

    It is with astounding self-restraint that I resist the temptation to answer exactly the question you asked (The answer is "yes") and instead suggest that if you google for "gravitational deflection of light" you'll get many references at various levels of complexity.

    The very last equation at http://www.theory.caltech.edu/people/patricia/lclens.html [Broken] is probably pretty close to what you're looking for.
    Last edited by a moderator: May 6, 2017
  6. Apr 10, 2013 #5
    Yes it would be a simple equation, that said I'd imagine a GR approach would be very complicated.

    I don't know of a common way to calculate, surely though there are many different ways to.
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