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Electromagnetism and Feynman diagrams

  1. Mar 23, 2008 #1


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    1. Feynman says all of electromagnetism follows from Maxwell equations.
    2. Somebody (Pointing to a Feynman diagram of a photon/electron reaction) said all of electromagnetism is in that one diagram. So, can anyone help me with these two questions: how does point 1 come from point 2. And, how does a photon come from an EM field just by using it in a Langragian form?
  2. jcsd
  3. Mar 23, 2008 #2
    I remember when I asked one particle physicists, that "how does Coulomb's force follow from that diagram?". The response was "no... we use these to calculate particle collision cross-sections". That's the unpleasant, but simple, truth :wink: You are not getting electromagnetism out of particle exchanges.
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