The life and scientific work of Steven Weinberg (a proposed op-ed)

STEVEN WEINBERG (1933-2021) NOBEL LAUREATE (1979) AND PHYSICIST EXTRAORDINAIRE

Nobel Prize winning physicist and one of the most influential theoretical physicists of the twentieth century Steven Weinberg passed in July 23, 2021 in Austin, Texas, where he had been professor of physics and founder of the theoretical physics department at the University of Texas, Austin. Weinberg shared the 1979 Nobel Prize in physics with Sheldon Glashow and Abdus Salam for their construction of the unified electro-weak theory of the weak and electromagnetic interactions. Their work was associated with the correct identification of the mathematical structure of the underlying symmetries governing these interactions, and the incorporation of the Higgs mechanism into their model that would make the force carriers massive, and the mixing between them, which is characterised by the `Weinberg angle’.

Weinberg was born on May 3, 1933 in New York City and studied at the Bronx High School of Science, a school that produced a large number of gifted student of science. Glashow and Weinberg were from the same graduating class. Weinberg obtained his undergraduate degree at Cornell University and spent a year at the Niels Bohr Institute in Copenhagen, Denmark after which he returned to the USA to pursue his Ph. D. at Princeton University under the supervision of Sam Trieman. He worked at Columbia University, MIT, and Harvard University before moving to the University of Texas. Over the course of his career Weinberg was considered a great teacher of physics, expositor, and also a supervisor for several Ph. D. students.

Weinberg worked in virtually all the important topics in the field of elementary particle physics, namely the phenomenology of the (electro-)weak and strong interactions and quantum field theory, where he has innumerable results which are named after him. In 1967 he wrote a short paper `A Model of Leptons’ which was his Noble Prize winning paper, which is one of the highest cited papers in the field in history. Weinberg was initiated the programme of `phenomenological lagrangians’ which was a framework that required one to use partial knowledge of elementary particles and their interactions at lowenergies even if a full theory that would reveal itself only at higher energies. He pursued the programme of renormalisation vigorously, studied CP violation, implications of phase transitions in the early universe, supersymmetric models to name some examples. After the Veneziano model was proposed, the precursor to string theory, Weinberg co-authored a paper with Gabriel Veneziano to improve its properties. Weinberg actively encouraged the study of string theory by appointing several persons to his group in Texas, thereby illustrating his genuine commitment to the growth of theoretical physics in every possible manner. Weinberg was intimately aware of experimental data and its implications to theory. He was also interested in physical cosmology and followed the subject.

Weinberg is also known for his monumental books on many technical fields, on field theory and particle physics, as well as on gravitation and cosmology. He also wrote popular books, The First Three Minutes, the story of the big bang and its aftermath being a huge best-seller. In his later years, he put forward his views on the evolution of western science.

Not a stranger to controversy, Weinberg was an avowed rationalist and atheist, and a defender of reductionism in science, which made him a proponent of the Superconducting Super Collider, a high energy collider in the US which eventually was cancelled due to the expense. He pioneered the debates around such topics and participated in them, especially regarding collective effects in physics, such as in the phenomenon of superconductivity. A key notion of `spontaneous symmetry breaking’ was proved by him with Jeffrey Goldstone and Salam in relativistic field theory, supporting the hypothesis of Yoichiro Nambu (Nobel Prize 2008), which is a manifestation of collective effects. These debates continue to this day.

Weinberg also did not shy away from his duties as a scientist and citizen. He advised his country’s government whenever called upon, including as a member of Jason, an elite group of scientists. He was a vocal supporter of Zionism by his own admission and protested against what he considered an unfair targeting of Israel for international sanctions.

The life and work of Steven Weinberg stand as a sacrament to all those who are committed to knowledge and science and its application. In the present era, where collaboration and team work is more the order of the day, one can learn the importance of understanding a subject from a very fundamental point of view, which was the hallmark of his style and approach (many of his papers are single-authored and have few references). The legacy of Weinberg will be one which brought simplicity and order to the world of elementary particle physics.

B. Ananthanarayan is Professor and former Chair of the Centre for High Energy Physics, Indian Institute of Science, Bangalore. A B. Tech. in Chemical Engineering from IIT Madras (1985) he obtained his Masters (1988) and Ph. D. (1991) from the University of Delaware in physics. He is an author of over a 100 refereed publications in international journals in elementary particle physics and field theory, and held the MSIL Chair of the Div. of Physical and Mathematical Physics, IISc (2015-18) and serves on the board of Springer Publications and was Associate Editor of Current Science. He is also a keen populariser of science and is active on Social Media.