Steven Weinberg, named by CERN, the European Organization for Nuclear Research, as “one of the greatest theoretical physicists of all time”, died on 23 July 2021 in Austin, Texas. He was 88.
The winner of the 1979 Nobel Prize in Physics, which he shared with Sheldon Glashow and Abdus Salam, Weinberg “revolutionised particle physics, quantum field theory and cosmology with conceptual breakthroughs which still form the foundation of our understanding of physical reality,” says CERN.
“With his work, Weinberg had made the next step in the unification of physical laws, after Newton understood that the motion of apples on Earth and planets in the sky are governed by the same gravitational force, and Maxwell understood that electric and magnetic phenomena are the expression of a single force.”
Weinberg was born on 3 May 1933 in New York City. In his autobiography for the Nobel Prize organisation, he wrote, “My early inclination towards science received encouragement from my father, and by the time I was 15 or 16 my interests had focused on theoretical physics”.
After receiving an undergraduate degree from Cornell University in New York in 1954, he spent a year doing graduate study at the Institute for Theoretical Physics in Copenhagen, Denmark (now the Niels Bohr Institute), where he began to do research in physics.
He returned to the US in 1955, completed his PhD thesis at Princeton University in New Jersey, and began a journey through some of the country’s most prestigious research facilities, including Columbia University in New York, the University of California at Berkeley, Harvard University in Cambridge, Massachusetts, and the Massachusetts Institute of Technology. He also served as senior scientist at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.
In 1982 he moved to the physics and astronomy departments of the University of Texas at Austin.
In reporting his death, Physics Today magazine said Weinberg was best known for his 1967 paper, ‘A model of leptons’, published in the journal Physical Review Letters.
The UT News website, published by the University of Texas at Austin, wrote that the paper laid out “how two of the universe’s four fundamental forces – electromagnetism and the weak nuclear force – relate as part of a unified electroweak force.
“At barely three pages [it] predicted properties of elementary particles that at that time had never before been observed (the W, Z and Higgs boson) and theorised that ‘neutral weak currents’ dictated how elementary particles interact with one another.”
The first two sentences from that paper read as follows: “Leptons interact only with photons, and with the intermediate bosons that presumably mediate weak interactions. What could be more natural than to unite these spin-one bosons into a multiplet of gauge fields?”
If his meaning isn’t exactly clear to the layperson, it is interesting to note that the Kirkus review of one of Weinberg’s best-known books, The First Three Minutes: A Modern View of the Origin of the Universe, published in 1977, called it “a remarkable achievement”, suggested that Weinberg “writes with a passionate desire to communicate”, and concluded that “this is the first book in a long time that attempts to show the power of physics in explaining the glory of the universe”.
Raphael Flauger, an associate professor of physics at the University of California, San Diego, told Physics Today that Weinberg’s impact on theoretical physics “can hardly be overstated.
“While most would count themselves lucky to have one important result named after them, there are many that carry Steve’s name: Weinberg’s soft graviton theorem, the Weinberg sum rules, the Weinberg operator, the Weinberg angle…the Weinberg–Witten theorem, the Lee–Weinberg bound, and so on.
“As if this were not enough, his influence extends well beyond the reach of his research papers. Many of us have learned intricate details from his textbooks, and his popular science books have shaped how many think about physics, and about science and its place in society more generally.”
For all his influence in the study of the physical world, Weinberg is perhaps more widely known for his opinions about religion.
While at the University of Texas, he was interviewed by the US Public Broadcasting System. Asked if he thought religion had value, he replied: “I think in many respects religion is a dream – a beautiful dream, often. Often a nightmare. But it’s a dream from which I think it’s about time we awoke. Just as a child learns about the tooth fairy and is incited by that to leave a tooth under the pillow – and you’re glad that the child believes in the tooth fairy. But eventually you want the child to grow up. I think it’s about time that the human species grew up in this respect.
“It seems to me that with or without religion, good people will behave well and bad people will do evil things. But for good people to do evil things, that takes religion.”
Steven Weinberg is survived by his wife, Louise Weinberg, and their daughter, Elizabeth.