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I How can photons interact if they travel at the speed of ligh

  1. Apr 29, 2016 #1
    I was listening to a podcast about the solar neutrino problem, and they discussed how we have deduced that neutrinos are not massless due to the fact that they interact with other particles (even if this interaction occurs rarely). I paraphrase: "a particle traveling at the speed of light is frozen in time and is frozen in its state. It can never change states." If that is the case, then how come we can see photons coming into and out of existence on Feynman diagrams? If they travel at the speed of light how is it possible for them to interact and change states?
     
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  3. Apr 29, 2016 #2

    Orodruin

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    You are misinterpreting what they are saying. They are not saying a massless particle cannot interact. They are also hugely oversimplifying what neutrino oscillations are.
     
  4. Apr 30, 2016 #3
    What do you think they mean by "frozen in its state"?
     
  5. Apr 30, 2016 #4

    Orodruin

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    A more accurate (although still very over simplified) description would be that if all the mass eigenstates travel at the same velocity, which they would if they were massless, they cannot acquire a relative phase. It is the mass eigenstates acquiring different phases that is the basis of neutrino oscillations.
     
  6. Apr 30, 2016 #5
    which podcast is this?
     
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