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Photons + Gravity

  1. Apr 9, 2009 #1
    hi. so if a photon doesnt have a mass why can you attract it with gravity as in the case of gravity lensing. does some quality of the photon allows it not to be affected by the higgs field and therefore has no mass and travel at the speed of light.?

    and having said that. in degenerate matter light slows down, would you say that since superluminal travel requires no mass, if you slowed down light the photon would gain mass and interect with the higgs field.

    or would you say that the higgs field and electromag field are at right angles in a vector sence and never interact.... or both and the universe freaks out and turns off the higgs field.. just joking??
  2. jcsd
  3. Apr 9, 2009 #2


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    Please read several entries in the FAQ thread.

  4. Apr 9, 2009 #3
    yeah i get that if a phton has energy it has mass in some way. im not a scientist so i didnt get the destincttion between the different kinds of masses, i assume you cant weigh a photon with a set of scales .. what i mean is it doesnt have a mass that you could feel pushing against your hand towards earth.
  5. Apr 9, 2009 #4


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    Gravity doesn't only act on massive particles, it can also acts on massless particles (provided that they have a momentum). Put simply, energy and momentum distort space-time and it is this disortion that results in gravitation.

    All particles (not under the influence of any forces such as EM) follow geodesics and the geodesics are not generally flat in non-euclidean (curved) space-time.
    A massive photon would contradict the requirement of a local gauge symmetry.
    Photon's do not slow down, they always travel at c. It is a common misconception that photons slow down in dispersive media. Check out the FAQ sticky in this forum for more information.
  6. Apr 9, 2009 #5
  7. Apr 9, 2009 #6
    ahh i c. but the material i am talking about is a degenerative one like the material of a neutron star or similar. .. is it the same kind of thing absorbtion and emittance?

    http://www.hno.harvard.edu/gazette/1999/02.18/light.html [Broken]
    Last edited by a moderator: May 4, 2017
  8. Apr 9, 2009 #7
    I'm not sure that's quite right. In principle, if I shine a light on you, you'll feel a push.
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