Obituary Steven Weinberg (1933–2021) Theoretical physicist whose electroweak theory won the Nobel prize. teven Weinberg brought the funda- on to positions at Columbia University, New mental understanding of nature to York; the University of Berkeley, California; new levels of power and completeness. the Massachusetts Institute of Technology in He played a central part in formulating Cambridge; and, in 1973, to Harvard University and establishing theoretical physics’ in Cambridge, where he was Higgins Professor Stwo standard models — the standard model of Physics. In 1982, he moved to the University of fundamental interactions and the standard of Texas at Austin, where he remained, teach- model of cosmology. His greatest achievement ing until earlier this year. was to propose the unified theory of electro- Scientists, no less than composers, have magnetism and weak interactions, which is still styles. Einstein and Richard Feynman were in use. This won him the Nobel Prize in Phys- rebellious, most comfortable when they were ics in 1979, shared with his school classmate ‘thinking different’. Weinberg was not like that. Sheldon Lee Glashow, and with Abdus Salam. His approach was scholarly. Most obviously, he His 1967 Physical Review Letters paper, ‘A was keenly interested in the history of physics in Model of Leptons’, combined disparate ideas the West, about which he wrote several deeply about gauge symmetry, symmetry breaking researched and unashamedly ‘Whiggish’ books, and the classification of particles into an ele- most recently To Explain the World (2015). gant whole. Given the state of knowledge at He paid close attention to other people’s CERN/SPL the time, the breakthrough still calls to mind work. I remember several rather terrifying Einstein’s description of Niels Bohr’s atomic appeared in 1972, high-energy particle physics phone calls during which he quizzed me about model: “the highest form of musicality in the and cosmology were regarded as distinct sub- details of mathematical derivations in my or sphere of thought”. jects, with different cultures and communities. others’ papers. Amazingly, given its scope and ambition, After Weinberg knocked down the barriers, He would not let go of obscurities that nothing in the paper needs essential revision a new generation prospered in the border caught his attention. Several of his most today. But it was incomplete in two important zone. A central message of the book was that important investigations were sparked when ways. First, Weinberg conjectured, but could the Big Bang should be considered as a unique, he perceived gaps or unexplored conse- not prove, that his theory was ‘renormalizable’, gigantic experiment in high-energy physics. quences. His work on electroweak interactions in that incorporating quantum fluctuations He made his case by showing how hypothe- grew out of wrestling with the confused liter- would not lead to ill-defined mathematical ses about neutrino properties could be tested ature of its component ideas. If Einstein and expressions. That problem was solved for through cosmological observations. His pop- Feynman call to mind Beethoven, Weinberg quantum electrodynamics — the theory of ular book on the topic, The First Three Minutes calls to mind Bach. photons and their interactions — in the 1950s. It (1977), found a large audience. Later in his career, Weinberg extended the was even harder to crack in Weinberg’s unified Weinberg was born in New York City to ideas he had pioneered in new directions. He theory, and its solution brought in new ideas. Jewish immigrant parents. He credited his made suggestions about unified field theory, Second, it really was just a theory of lep- father with encouraging his interest in science. the nature of dark matter and the possibility tons — electrons, muons and their neutrinos. He graduated in 1950 from the Bronx High of a multiverse. These ideas, attractive but as It left out the world of strongly interacting School of Science, the city’s flagship for edu- yet unproven, continue to inspire research. hadrons, including protons, neutrons and cating young scientists. Leon Cooper and Weinberg sometimes expressed strong most of the vast zoo of particles observed in Melvin Schwartz were near-contemporaries, views against religion, such as this: “Anything high-energy accelerators. Remarkably, how- as well as Glashow, to name just those who that we scientists can do to weaken the hold of ever, quantum chromodynamics — the mod- went on to get Nobel prizes in physics. It is religion should be done and may in the end be ern theory of strong interactions, based on hard to resist the implication that it is probably our greatest contribution to civilization.” His, quarks and gluons — combines harmoniously good science policy to welcome immigrants more usual, jovial appreciation of the human with Weinberg’s model. The same is true for and bring bright children together. comedy was exemplified by the way that, given general relativity, Einstein’s theory of gravity. After undergraduate studies at Cornell the chance, he would sneak off from stiff par- Weinberg had a leading role in orchestrating University in Ithaca, New York, Weinberg ties to play games with the children. this powerful consolidation of fundamental spent a year at Nordita (the Nordic Institute physics, in particular by calculating its exper- for Theoretical Physics) in Copenhagen, Frank Wilczek is Herman Feshbach Professor imental consequences. The discovery, in the working on quantum field theory with Gunnar of Physics at the Massachusetts Institute of 1980s, of the W and Z bosons, which had pre- Källén, whom he often mentioned as a strong Technology and founding director of the cisely the masses and other properties pre- influence. He completed his PhD at Prince- Tsung-Dao Lee Institute in Shanghai, China. dicted by his model, was its crowning success. ton University, New Jersey, with Sam Treiman He has been an admiring friend of, and an The other major strand in Weinberg’s work advising on his thesis about how the strong occasional competitor with, Steven Weinberg was physical cosmology. When his land- interaction complicates the interpretation throughout his adult life. mark book Gravitation and Cosmology first of weak-interaction observations. He went e-mail: [email protected] Nature | Vol 596 | 12 August 2021 | 183 ©2021 Spri nger Nature Li mited. All rights reserved. .