Genius_ The Life and Science of Richard Feynman - James Gleick [202]
Suppose that historically [my equation] had been discovered before the Dirac equation? It has absolutely the same consequences as the Dirac equation. It can be used with diagrams the same way.
The diagrams for beta decay, of course, added a neutrino field interacting with the electron field. When Feynman made the necessary change to his equation, he found:
Of course I can’t do that because this term is parity unsymmetric. But——beta decay is not parity symmetric, so it’s now possible.
There were two difficulties. One was that he came out with the opposite sign for the spin: his neutrino would have to spin in the opposite direction from Lee and Yang’s prediction. The other was that the coupling in his formulation would have to be V and A, instead of the S and T that everyone knew was correct.
Gell-Mann, meanwhile, had also thought about the problem of creating a theory for weak interactions. Nor were Feynman and Gell-Mann alone: Robert Marshak, who had put forward the original two-meson idea at the Shelter Island conference in 1947, was also leaning toward V and A with a younger physicist, E. C. G. Sudarshan. That summer, with Feynman traveling in Brazil, Marshak and Sudarshan met with Gell-Mann in California and described their approach.
Feynman returned at the end of the summer determined, for once, to catch up with the experimental situation and follow his weak-interaction idea through to the end. He visited Wu’s laboratory at Columbia, and he asked Caltech experimenters to bring him up to date. The data seemed a shambles—contradictions everywhere. One of the Caltech physicists said that Gell-Mann even thought the crucial coupling could be V rather than S. That, as Feynman often recalled afterward, released a trigger in his mind.
I flew out of the chair at that moment and said, “Then I understand everything. I understand everything and I’ll explain it to you tomorrow morning.”
They thought when I said that, I’m making a joke… . But I didn’t make a joke. The release from the tyranny of thinking it was S and T was all I needed, because I had a theory in which if V and A were possible, V and A were right, because it was a neat thing and it was pretty.
Within days he had drafted a paper. Gell-Mann, however, decided that he should write a paper, too. As he saw it, he had his own reasons for focusing on V and A. He wanted the theory to be universal. Electromagnetism depended on vector coupling, and the strange particles favored V and A. He was unhappy that Feynman seemed to be thoughtlessly dismissing his ideas.
Before the tension between them rose higher, their department head, Robert Bacher, stepped in and asked them to write a joint paper. He preferred not to see rival versions of the same discovery coming out of Caltech’s physics group. Colleagues strained to overhear Feynman and Gell-Mann in the corridors or at a cafeteria table, engrossed in their oral collaboration. They stimulated each other despite the characteristic differences in their language: Feynman offering what sounded like you take this and it zaps through here and you come out and pull this together like that, Gell-Mann responding with you substitute there and there and integrate like so… . Their article reached the Physical Review in September, days before Marshak presented his and Sudarshan’s similar theory at a conference in Padua, Italy. Feynman and Gell-Mann’s theory went further in several influential respects. It proposed a bold extension of the underlying principles beyond beta decay to other classes of particle interactions; it would be years before experiment fully caught up, showing how prescient