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Force Carrier for Electromagnetism

  1. Jan 7, 2012 #1
    Can anybody give me or point me to a model that describes how electromagnetism works from a photon force carrier perspective. I like to know how the virtual photons are generated around an electron. Also why electromagnetism is polar. I am also confused why moving electric fields create magnetic fields, and why the magnetic field creates the Lorentz force. The force carrier model seems simple when shown the Feynman diagrams but electromagnetic waves and magnetism confuse me under this model.
     
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  3. Jan 7, 2012 #2

    jedishrfu

    Staff: Mentor

    you know thats an interesting question and Im not sure physicists know this to the level you're asking.

    electrons changing to a lower energy state emit a photon I don't think we can delve into the interaction other than it changes state and a photon of a certain energy is created. Similarly when an electron jumps to a higher state it has absorbed a photon of the exact energy needed to jump. I'm not sure if it can use a photon with a little added energy, absorb it and then spit out a lower energy photon once its made its jump but I don't think its disallowed.

    Similarly pulsating EM fields produce radio waves which are photons but how it actually happens is a mystery part of the wave particle duality.

    Maybe this will come together once we understand how space is quantized if it is that is.
     
  4. Jan 7, 2012 #3

    Drakkith

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    Staff: Mentor

  5. Jan 7, 2012 #4

    jedishrfu

    Staff: Mentor

    drakkith that looks right. The last section of the wiki talks about using photons in combination where each would be insufficient.

    But I'm thinking the actual creation of a photon is the real mystery may be like asking how an ocean wave is formed the moment its formed.
     
  6. Jan 7, 2012 #5

    Drakkith

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    What do you mean?
     
  7. Jan 7, 2012 #6

    jedishrfu

    Staff: Mentor

    i was thinking more of the white crests of the waves as being something that comes into being but really isn't there.

    like constructive interference of waves.
     
  8. Jan 9, 2012 #7

    Bill_K

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    Science Advisor

    AustinLee, It's important to realize that even now, after the advent of Quantum Field Theory, Maxwell's Equations have not yet been repealed! :wink: So the answers to most of your questions simply fall out from classical electromagnetism. The electromagnetic field is still described by a vector potential Aμ, the difference being that it is now an operator. The interaction is JμAμ, total charge is the integral of J0 which may be either positive or negative, and the Lorentz transformation properties of the electromagnetic field Fμν = Aν,μ - Aμ,ν imply that electric fields become magnetic fields and vice versa in a moving frame.

    As to the first question, "how the virtual photons are generated around an electron", it's because in the presence of the interaction term, a bare electron is no longer an eigenstate of the Hamiltonian. The corresponding eigenstate of the full Hamiltonian is a dressed electron, namely a superposition of the electron along with a cloud of one or more photons. (This state is time-independent, so there is no 'emitting' or absorbing' going on, it is simply a superposition.)
     
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