After completing his Ph.D., Weinberg worked as a
postdoctoral researcher at
Columbia University (1957–1959) and
University of California, Berkeley (1959) and was promoted to faculty at Berkeley (1960–1966). He did research in a variety of topics of particle physics, such as the high energy behavior of
quantum field theory,
symmetry breaking,
pion scattering, infrared photons and
quantum gravity (
soft graviton theorem). It was also during this time that he developed the approach to quantum field theory described in the first chapters of his book
The Quantum Theory of Fields and started to write his textbook
Gravitation and Cosmology, having taken up an interest in
general relativity after the discovery of
cosmic microwave background radiation. with the masses of the force-carriers of the weak part of the interaction being explained by
spontaneous symmetry breaking. One of its fundamental aspects was the prediction of the existence of the
Higgs boson. Weinberg's model, now known as the
electroweak unification theory, had the same symmetry structure as that proposed by Glashow in 1961: both included the then-unknown weak interaction mechanism between
leptons, known as
neutral current and mediated by the
Z boson. The 1973 experimental discovery of weak neutral currents (mediated by this Z boson) was one verification of the electroweak unification. The paper by Weinberg in which he presented this theory is one of the most cited works ever in high-energy physics. 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. Weinberg became Eugene Higgins Professor of Physics at Harvard University in 1973, a post he held until 1983. This approach allowed the development of effective theory of quantum gravity, low energy QCD, heavy quark effective field theory and other developments, and is a topic of considerable interest in current research. In 1979, some six years after the experimental discovery of the neutral currents—i.e. the discovery of the inferred existence of the
Z boson—but after the 1978 experimental discovery of the theory's predicted amount of parity violation due to Z bosons' mixing with electromagnetic interactions, Weinberg was awarded the Nobel Prize in Physics with Glashow and Salam, who had independently proposed a theory of electroweak unification based on spontaneous symmetry breaking. The theoretical physicist
Peter Woit called Weinberg "arguably the dominant figure in theoretical particle physics during its period of great success from the late sixties to the early eighties", calling his contribution to
electroweak unification "to this day at the center of the Standard Model, our best understanding of fundamental physics". Science News named him along with fellow theorists
Murray Gell-Mann and
Richard Feynman the leading physicists of the era, commenting, "Among his peers, Weinberg was one of the most respected figures in all of physics or perhaps all of science".
Sean Carroll called Weinberg one of the "best physicists we had; one of the best thinkers of any variety" who "exhibited extraordinary verve and clarity of thought through the whole stretch of a long and productive life", while
John Preskill called him "one of the most accomplished scientists of our age, and a particularly eloquent spokesperson for the scientific worldview".
Other contributions Besides his scientific research, Weinberg was a public spokesman for science, testifying before Congress in support of the
Superconducting Super Collider, writing articles for
The New York Review of Books, and giving various lectures on the larger meaning of science. His first popular science book,
The First Three Minutes: A Modern View of the Origin of the Universe (1977), described the origin of the universe in the
Big Bang.
Dreams of a Final Theory (1992) made the case for reductionism and the Superconducting Super Collider. Although still teaching physics, in later years he turned his hand to the history of science, efforts that culminated in
To Explain the World: The Discovery of Modern Science (2015). A hostile review in the
Wall Street Journal by
Steven Shapin attracted a number of commentaries, a response by Weinberg, In 2016, Weinberg became a default leader for faculty and students opposed to a new law allowing the carrying of concealed guns in UT classrooms. He announced that he would prohibit guns in his classes, and said he would stand by his decision to violate university regulations in this matter even if faced with a lawsuit. Weinberg never retired and taught at UT until his death. Weinberg recalled "I found myself so often defending the reductionist aims of high energy physics that I wrote a book about it,
Dreams of a Final Theory. Alas, funding for the Super Collider was cancelled in 1993, but even though I grieve that we physicists had failed to convince Congress, I’m at least proud that my book made it into McEwan’s canon." ==Personal life and archive ==