I was very excited about the mixing in a... some sort of generalized Yang-Mills theory, the weak and the electromagnetic interactions. I always wanted to do it. After 1957 when the weak interaction was, when it appeared that the weak interaction was vector and axial vector - confirmed later in ’58, ’59 - it became much more… much easier than when we had to cope with the scalar and tensor nonsense. So I worked on that and I endorsed Shelley’s model of how to do it... gave the speech about it in Rochester, which I think was the only intelligible presentation of… of his model. And that’s persisted to this day, that's the same model we use now: SU(2) x U(1). Then Stephen Weinberg, around 1967, added to that the soft mass mechanism that I had been advertising for... for some years using the sigma model, actually, and using the mechanism of Phil Anderson, and Higgs and Kibble and all these other people. That was a beautiful piece of work. It didn't completely clear up though all the issues. We still needed charm, and although Bjorken and Glashow had suggested charm—when was that? 1964 I believe—as an idea—they didn't propose it immediately as a solution to all the various problems of the strangeness changing neutral current. Because the charm current cancels out a lot of the problems caused by the strangeness changing… the ordinary strangeness changing neutral current. When was that? 1970 I think that..? Which, the..? That Bjorken and… and Glashow returned to… to that issue, or somebody did. Well there was the Glashow..? When was charm reasserted as the solution to the various problems? Glashow, Illiopolos and Maiani... Oh, that's what it is: Glashow, Illiopolos and Maiani. Right. Right. In '60, well...? ’70, I think. ’69. ’69 or ’70. Yeah, I was at… mid Harvard at the same time. Right, anyway that cleared up a lot of things. And all these hesitations that I had had over whether to make an analogy between three leptons and three quarks, or four leptons and four quarks and so on and so on, all of that was settled then. We definitely had four leptons, electron and its neutrino muon and its nutrino. With the charm we had four quarks and the various problems with the weak interaction theory were… were pretty much laid to rest.
