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US Nobel-prize-winning physicist Steven Weinberg dies aged 88

26 Jul 2021 Michael Banks
Steven Weinberg
Particle pioneer: Steven Weinberg's work became a cornerstone of the Standard Model of particle physics. (Courtesy: CERN/Maximilien Brice)

The US physicist Steven Weinberg, who shared the 1979 Nobel Prize for Physics for his theoretical contributions to the Standard Model of particle physics, died on 23 July aged 88. In the 1960s Weinberg’s work was instrumental in understanding the weak interaction in particle physics, which is best known for its role in nuclear decay. He shared the 1979 Nobel prize equally with Sheldon Glashow and Abdus Salam.

Born in New York on 3 May 1933, Weinberg attended the Bronx High School of Science, which has seen seven former pupils go on to win physics Nobels. In 1954 Weinberg received a degree in physics from Cornell University and after a year at the Institute for Theoretical Physics in Copenhagen (now the Niels Bohr Institute), he returned to the US to compete his PhD at Cornell University, graduating in 1957.

After a stint at Columbia University, in 1959 Weinberg went to the University of California, Berkeley, before heading to Harvard Univeristy in 1966. A year later, Weinberg became a visiting professor at the Massachusetts Institute of Technology where he carried out much of his pioneering work in unifying the weak and electromagnetic interaction.

Unifying forces

In 1967, at the age of 34, Weinberg published his groundbreaking work. Entitled “A Model of Leptons” and barely three pages long, it became a cornerstone of the Standard Model of particle physics – and one of the most highly-cited papers in physics. The work predicted the existence of the W and Z bosons, which carry the electroweak force, and also theorized that “weak neutral currents” dictated how elementary particles interact with one another.

Working independently to Weinberg, Glashow (who was in the same year group as Weinberg at the Bronx high School), and Salam made their own contributions to the model, which later became known as the Salam-Weinberg theory. However, at the time it was not taken seriously by some in the community because it seemed impossible to subject the theory to the usual “renormalisation” procedure. This meant it generated infinite and therefore meaningless expressions, so it seemed impossible to perform accurate calculations with it.

That particular issue was overcome in 1972 when the Dutch physicists Matinus Veltman and Gerardus ‘t Hooft showed how to carry out this renormalisation and used their theory to make precise calculations of particle properties. A year later and physicists working at the CERN particle-physics lab near Geneva announced the discovery of weak neutral currents — interactions that are governed by the Z boson. In 1979 Glashow, Salam and Weinberg were awarded the Nobel Prize for Physics for “for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current.” The W and Z particles were then detected for the first time in 1983 at CERN.

[Weinberg was] one of the most accomplished scientists of our age, and a particularly eloquent spokesperson for the scientific worldview

John Preskill

In 1973 Weinberg went back to Harvard where he also held a position at the Smithsonian Astrophysical Observatory. In 1982 he moved to the University of Texas at Austin, where he spent the remainder of his career. Weinberg was a vocal advocate for the proposed $4.4bn Superconducting Super Collider – a huge 87.1 km circumference circular collider to be built in Waxahachie, Texas – that failed to receive funding and was cancelled in 1993. He also had a long-time interest in nuclear proliferation and served as a consultant for the US Arms Control and Disarmament Agency.

Book and prizes

Weinberg never retired and worked in many areas of physics throughout his career. One of which was cosmology — an interest that he developed in the 1960s. Weinberg published numerous books including the popular-science account The First Three Minutes (1977), which told the story of the origin of the universe as well as Dreams of a Final Theory (1993), in which he wrote about his belief that physics was on the verge of discovering a theory that would unite physics.

One of his last books —  To Explain the World: the Discovery of Modern Science (2015) – examined the history of physics from the ancient Greeks to the present day. Yet it was criticised by some science historians and philosophers given that it judged the past from the standpoint of the present – known as “Whig interpretation”. Weinberg knew, however, that the book would ruffle feathers telling attendees at the American Physical Society meeting in Baltimore in 2016 that he was “being naughty” with the approach. He added that without the perspective of where we are now, “the story we tell has no point”.

Weinberg unlocked the mysteries of the universe for millions of people, enriching humanity’s concept of nature and our relationship to the world

Jay Hartzell

Weinberg was the recipient of numerous prizes including the National Medal of Science in 1991 and the Benjamin Franklin Medal for Distinguished Achievement in Science in 2004. Last year, he received a Special Breakthrough Prize in Fundamental physics – and with it $3m – for his contributions to physics.

A ‘colossal’ loss

Physicists have voiced their admiration for Weinberg’s work and life. John Preskill from the California Institute of Technology (Caltech), who was supervised by Weinberg as a PhD student at Harvard, says Weinberg’s death is an “immeasurable loss”. “[Weinberg was] one of the most accomplished scientists of our age, and a particularly eloquent spokesperson for the scientific worldview,” adds Preskill. “[He] remained intellectually active to the end.”

That view is backed by fellow Caltech physicist Sean Carroll who says Weinberg is 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.” Brian Greene, from Columbia Univeristy, meanwhile, says that Weinberg had an “astounding ability to see into the deep workings of nature” that “profoundly shaped” our understanding of the universe. “His passing is a colossal loss to science and the world,” adds Greene.

“Weinberg unlocked the mysteries of the universe for millions of people, enriching humanity’s concept of nature and our relationship to the world,” noted Jay Hartzell, president of the University of Texas at Austin, in a statement. “From his students to science enthusiasts, from astrophysicists to public decision makers, he made an enormous difference in our understanding. In short, he changed the world.”

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