Having finished her law degree, Louise takes up work at a Boston law firm; they are not returning to Berkeley after all, so Weinberg resigns his professorship there. At MIT, he continues teaching graduate courses on general relativity, with an emphasis on cosmology. He spends the spring of 1971 in Paris, making comparisons between the academic characters of Paris and Boston. Gerard ’t Hooft and Martinus Veltman renormalize Weinberg’s theory of leptons, showing an experimental route to proving the theory. Weinberg starts to consider the extension of the electroweak theory to strongly interacting theories. Electroweak theory starts to receive a lot more attention from theorists. His first book, Gravitation and Cosmology, is published in 1972. Weinberg is offered the Higgins Professorship at Harvard, and accepts.

Now in Boston, Weinberg describes how his earlier work on current algebra led to effective field theory. With the Vietnam War going on, JASON work focuses on the war effort. In 1967, Weinberg takes up a lectureship at MIT and published his most-cited paper, “A Model of Leptons,” which heralded electroweak theory. He attends the Solvay conference in Brussels in 1967, but misses being in the group photo. Back in Boston, Weinberg discusses making friends through his election to the American Academy of Arts and Sciences. He becomes involved in an independent study of the US’ anti-ballistic missile program, concluding that this would hasten the arms race between the US and the Soviet Union.

Time reversal symmetry violation in the eletroweak interactions provides evidence for an asymmetry of time itself, given the Representation View.