In QFT, one can derive the equations for particles interacting electromagnetically by demanding phase invariance for the field when writing down the free field lagrangian for the klein-gordon or dirac equation.(adsbygoogle = window.adsbygoogle || []).push({});

Question: Does classical EM follow from this method also? (At least theoretically, given that you know the fine structure constant). If not what comes in the way?

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# A Can classical EM be derived from QFT?

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