Steven Weinberg - Academic Career

Academic Career

After completing his Ph.D., Weinberg worked as a post-doctoral researcher at Columbia University (1957–1959) and University of California, Berkeley (1959) and then he 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. It was also during this time that he developed the approach to quantum field theory that is described in the first chapters of his book The Quantum Theory of Fields and started to write his textbook Gravitation and Cosmology. Both textbooks, perhaps especially the second, are among the most influential texts in the scientific community in their subjects.

In 1966, Weinberg left Berkeley and accepted a lecturer position at Harvard. In 1967 he was a visiting professor at MIT. It was in that year at MIT that Weinberg proposed his model of unification of electromagnetism and of nuclear weak forces (such as those involved in beta-decay and kaon-decay), 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: hence both models included the then-unknown weak interaction mechanism between leptons, known as neutral current and mediated by the Z boson. The 1973 experimental discovery of this Z boson was one verification of the electroweak unification. The paper by Weinberg in which he presented this theory was one of the most cited theoretical works ever in high energy physics as of 2009.

After his 1967 seminal work on the unification of weak and electromagnetic interactions, Steven Weinberg continued his work in many aspects of particle physics, quantum field theory, gravity, supersymmetry, superstrings and cosmology, as well as a theory called Technicolor.

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, Abdus Salam and Sheldon 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 which did not contain that model's fundamental Higgs boson.

Weinberg became Higgins Professor of Physics at Harvard University in 1973.

It is of special importance that in 1979 he pioneered the modern view on the renormalization aspect of quantum field theory that considers all quantum field theories as effective field theories and changed completely the viewpoint of previous work (including his own in his 1967 paper) that a sensible quantum field theory must be renormalizable. This approach allowed the development of effective theory of quantum gravity, low energy QCD, heavy quark effective field theory and other developments, and it 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 following 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, together with Sheldon Glashow, and Abdus Salam who had independently proposed a theory of electroweak unification based on spontaneous symmetry breaking.

In 1982 Weinberg moved to the University of Texas at Austin as the Jack S. Josey-Welch Foundation Regents Chair in Science and founded the Theory Group of the Physics Department.

There is current (2008) interest in Weinberg's 1976 proposal of the existence of new strong interactions – a proposal dubbed "Technicolor" by Leonard Susskind – because of its chance of being observed in the LHC as an explanation of the hierarchy problem.

Steven Weinberg's influence and importance are confirmed by the fact that he is frequently among the top scientists with highest research effect indices, such as the h-index and the creativity index.