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.