After his 1967 seminal work on the unification of weak and electromagnetic interactions, Weinberg continued his work in many aspects of particle physics, quantum field theory, gravity, supersymmetry, superstrings and cosmology. In the years after 1967, the full Standard Model of elementary particle theory was developed through the work of many contributors. In it, the weak and electromagnetic interactions already unified by the work of Weinberg, Salam and Glashow, are made consistent with a theory of the strong interactions between quarks, in one overarching theory. In 1973, Weinberg proposed a modification of the Standard Model that did not contain that model's fundamental Higgs boson. Also during the 1970s, he proposed a theory later known as technicolor, in which new strong interactions resolve the hierarchy problem.