Steven Weinberg ’54, the theoretical physicist whose Nobel Prize-winning work transformed scientists’ understanding of fundamental forces, died on July 23. He was 88 years old.
“[His work] is basically the foundation of everything we do in particle physics, what we now call the Standard Model, ”said Professor Csaba Csaki, Physics. The Standard Model explains the fundamental particles and interactions that make up the universe.
In his most important work, the former Cornell student and former guest lecturer proposed the electroweak force, which unifies electromagnetic and weak forces, two of the fundamental forces that explain the behavior of all particles in the universe.
Electromagnetic force is the push or pull that occurs between charged particles, while weak force is responsible for radioactive decay, according to Csaki. In his revolutionary theory, Weinberg suggested that these two forces are identical at very high energies.
To reach this conclusion, Weinberg relied on the Higgs mechanism, which explains how particles that carry fundamental forces and allow the exchange of energy acquire mass.
“Weinberg took the Higgs mechanism and applied it to [develop] a theory that correctly describes nature, ”Csaki said.
Weinberg predicted the properties – including mass – of a force-carrying particle known as the Z boson in a 1967 paper. Bosons are elementary particles – particles that cannot be broken down into sub-parts. smaller – which carry the fundamental forces.
“The funny thing is when he wrote this article, no one took him seriously,” Csaki said.
“For five or six years there were hardly any quotes. Then, around 1973, experiments and theoretical advances appeared, and they began to show that the world really is as Weinberg predicted.
This evidence included the work of Nobel Laureate Gerardus’ t Hooft and Martinus Veltman, who developed a mathematical theory that validated Weinberg’s prediction in the early 1970s.
As new evidence for Weinberg’s theory mounted, the initial skepticism he faced began to fade. In 1979 he received the Nobel Prize in Physics for Electroweak Unification, along with contributors Sheldon Lee Glashow and Abdus Salam.
Since then, physicists have continued to verify Weinberg’s theory of electroweak interactions. In 1983, the Z boson was observed for the first time, and its properties were exactly as Weinberg predicted. The discovery of the Higgs boson – another force-carrying particle – in 2012 provided additional experimental evidence for the mechanisms underlying Weinberg’s theory.
Csaki explained that Weinberg also laid the groundwork for an effective field theory, which describes another fundamental force, the strong interaction. The strong force is what binds the nucleus of an atom together.
Weinberg’s theoretical advances revolutionized particle physics and continue to define the path of the field.
Its influence can be seen in current efforts to develop a theory that adds strong force to its unification of electroweak force, according to Csaki. This theory would show that the three forces are identical under certain conditions.
Beyond his Nobel Prize-winning work, Weinberg has contributed to some of the most important areas of modern physics, including general relativity, cosmology, and quantum field theory. According to Csaki, Weinberg’s three-volume textbook on quantum field theory is considered one of the most comprehensive works on the subject.
Csaki added that Weinberg’s success as a scientist was in part due to his open-minded nature and his desire to keep learning, even late in life. Weinberg’s interest in theoretical physics dates back to childhood – he became interested in the subject at the age of 16, motivated by his father’s encouragement.
“He was always broadening his point of view, even at an advanced age, by volunteering to teach a class slightly. [outside] his expertise, using it to really deeply [delve] in the subject and then writing the manual on it, ”Csaki said.
Weinberg was also passionate about bringing science out of the classroom and into contexts accessible to a more general audience. His 1977 book titled The first three minutes gives a glimpse of the first moments of the universe.
Weinberg received his undergraduate degree from Cornell and went on to earn his doctorate. in Physics at Princeton University in 1957.
In 2007, Weinberg returned to Cornell and lectured on the history of science as part of the University’s Messenger lecture series, which highlights topics understandable to the general public.
Weinberg is survived by his wife Louise and daughter Elizabeth.