Quantum electrodynamics based on self-fields, without second quantization: A nonrelativistic calculation of g-2.

Bethe' first calculated the Lamb shift for the hydrogen atom in 1947, using a method that was essentially nonrelativistic (NR), but nevertheless approximately correct. In 1948, Welton gave an intuitive derivation of the Bethe result by considering the coupling of the electron to second-quantized electromagnetic vacuum fluctuations —leading to the generally held folklore that vacuum fluctuations are the physical cause of the Lamb shift. However, when the Welton approach was used to compute the anomalous magnetic moment of the electron, ' the incorrect sign for g —2 was obtained. Complementary to the vacuum fluctuation picture is the self-field picture, in which one views radiative corrections as arising from radiation reaction effects due to the interaction of a particle with its own self-field. The self-