This topic goes back to my M.Sc. thesis, when my supervisor, Prof. Christie Eliezer (2nd from left in the photo), who was one of Dirac's very few research students, told me about the Dirac-Sommerfeld paradox. He thought it might be pertinent to my thesis.
Being a physics "genius", I didn't pursue it because I assumed it had been resolved by more modern developments like, Quantum Field Theory — a subject that neither Eliezer nor I knew much about. I was wrong. Very wrong!
