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How Virtual Particles Give Rise to the electromagnetic force

  1. Nov 1, 2011 #1

    Recently I have learned that magnetism causes the Lorentz force. The electric force makes sense to me in terms of virtual photons. But how do virtual photons give rise to magnetism and the Lorentz force. Is it because when the charged particle moves through an magnetic field it comes into contact with the virtual photons differently. It just seems strange the Lorentz force is perpendicular to the velocity and magnetic field to me. I know virtual photons are math constructs, and the electric and magnetic force are the same, but can somemone explain the Lorentz force in terms of virtual force carriers.
  2. jcsd
  3. Nov 21, 2011 #2
    Its the right hand rule! but if you check out (Lorentz force Wikipedia) that should set you right
  4. Nov 23, 2011 #3
    What you are saying about virtual photons is true only for interacting fermions which are asymptotically free. For example, if you have an electron moving through a homogeneous electric field, the electric force is the charge multiplied by the electric field; it has nothing to do with virtual photons; electrons interact directly with the photon field which forms the electrostatic potential. If you have an electron moving through a homogeneous magnetic field, electrons interact directly with the magnetic vector potential which is formed from the photon field if you like (you can think of it as a sort of Bose condensate of real photons although to my knowledge it is not usually discussed this way).

    If you are talking about two electrons which scatter off one another, then it is true that they are repelled due to exchange of virtual photons. These virtual photons also carry spin, which gives the magnetic part of the interaction, so in your language the magnetic force between two electrons arises from the spin of the photons.
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