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Experiment: Photon propagating trough dense neutrino beam

  1. May 23, 2014 #1


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    Greetings. I thought about how/ why light propagates slower trough matter than vacuum. Generally it is excepted that it happens because photons are absorbed and then emitted by the atoms and it kinda makes sense. But I see other possibilities.
    I propose and experiment:
    How about shining photons trough a dense beam of neutrionos - the stuff that only interacts with gravity [and strong.. or week nuclear force?] - if the beam is slowed down [and the angle is changed] then there would have to be another explanation for why light slows down, wouldn't there?

    A possible alternative could be, for example, that gravity on the really small scale doesnt follow the inverse square law and gets way stronger - curving the space much more and, like all gravity does, creating a region of .. well.. "larger on the inside", which means more time for light to pass trough.
  2. jcsd
  3. May 23, 2014 #2


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    Personal pet theories are not really allowed here at PF, so unless you have some sources talking about your "alternative" then, I think this thread might get closed.

    Photons travel through a "dense" (depending on your definition of dense of course) beam of neutrinos all the time. There are ~10^11 neutrinos per square centimeter traveling through the surface of the Earth per second.
  4. May 23, 2014 #3


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    Photons interact with charged particles. Neutrinos have zero charge. And extremely small masses, so their gravitational interaction would also be immeasurably small. In fact, the gravitational interaction of all elementary particles is immeasurably small.
  5. May 23, 2014 #4
    Neutrinos _can_ interact with photons.

    Since neutrinos participate in weak interaction, they have quantum corrections in a form of W boson loops. And those particles, being charged, interact with with photons.

    But the probability of this particular virtual interaction is astronomically tiny because of W boson mass, the correction to vacuum spped of light will be similarly astronomically tiny.
  6. May 23, 2014 #5

    Vanadium 50

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    This thread got off to a bad start and is getting worse.

    As pointed out, we don't discuss personal theories here.
    Also, the sort of quantum corrections described by nikkom are zero for the neutrino because of the gauge invariance of electromagnetism.
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