Physicist Shapes Modern Thought

Kenneth G. Wilson ’56 was part of the generation of scientists who revolutionized physics in the 1970s and confirmed the quantum theories of physicists from the early 20th century including Niels Bohr and Albert Einstein.

Wilson won the 1982 Nobel Prize in physics for his development of the Renormalization Group (RG) into a central tool in physics.

Wilson’s father, E. Bright Wilson Jr. was a professor of chemistry at Harvard. As an undergraduate, Wilson concentrated in mathematics, though he also studied physics. He won the prestigious Putnam fellowship, awarded to high scorers on a national collegiate math competition.

Wilson described his time at Harvard as a “stimulating environment.”

“The extraordinary members of the faculty I had access to, the fellow undergraduates that I knew, plus opportunities to participate in track and field and in the Harvard-Radcliffe Orchestra, all contributed to my overall experiences,” he writes in an e-mail.

Returning as a Junior Fellow in 1959, Wilson was unsatisfied with the weakness of theoretical physics at Harvard.

He received a doctorate from the California Institute of Technology in 1961, and joined the physics faculty at Cornell University in 1963.

“I accepted the [job] offer because Cornell was a good university, was out in the country and was reputed to have a good folk dancing group, folk-dancing being a hobby I had taken up as a graduate student,” he wrote in his autobiography on the Nobel Prize website.

Until Wilson’s work in the seventies, the theories of particle physics had remained nearly unchanged for 50 years.

However, the accepted quantum field theory developed by Bohr and Einstein half a century earlier was straining under the fact that many of its predictions seemed impossible.

Quantum field theory describes subatomic particles as waves which derive their properties from the amounts of energy they carry.

Before Wilson’s discoveries, many physicists thought quantum field theory had to be discarded, because so many of its calculations generated infinite values—which are physically impossible. Wilson’s RG theory not only explained these infinite values, it showed that they contained information which allowed for a fuller understanding of the relevant physics.

Wilson was among the physicists of the 1970s who developed Standard Theory, the current model of particle physics that refined quantum field theory.

Michael E. Peskin ’73, who was Wilson’s doctoral advisee at Cornell and is now a professor at the Stanford Linear Accelerator Center, recalls how Wilson synthesized all of elementary particle physics into the Standard Theory at a seminar in 1974.

Wilson drew boxes on a long blackboard, and each box contained some known concept about elementary particles. Then he drew arrows between all the boxes, explaining the connections between concepts that seemed unrelated or even contradictory.

“It was just one of the most amazing experiences of my life,” says Peskin. “He was saying, ‘I see the big picture. You can see it too. Here’s how it goes.”

The basic idea of RG theory is to study the variation in the importance of certain properties at a smaller or larger scale. For example, think of a large pile of tuna sandwiches. On a small scale, there are large differences in the consistency of this pile—the bread is different from the tuna, which is different from the tomato slices and the lettuce. However, on a larger scale, the pile is consistent, because each sandwich is the same. The pile of sandwiches can be described in terms of how the consistency of the pile changes as you zoom in or out looking at it.

This method is applied to particle physics through the concept of lattice gauge theory. According to Peskin, the basic idea of lattice gauge theory is that the infinities that appeared to be flaws in quantum field theory are actually the data you need to move from one scale to another.

This development allowed researchers to calculate physical properties at one scale from those of a smaller scale. RG theory implies that, with enough computer power, it would be possible to describe such large-scale phenomena as the boiling of water in terms of the interactions between fundamental subatomic particles.

“Wilson is famous for understanding how, in transitions from one phase of matter to another, there are quantities that are completely independent of the details of the states of matter,” says Mallinckrodt Professor of Physics Howard Georgi ’67.

He explains that Wilson’s work was valuable not only in the field of phase changes, for which Wilson won the Nobel Prize, but had much broader applications for all of modern physics.

It is a crucial component of our understanding of quantum chromodynamics (QCD)—the strong nuclear force that holds quarks together within protons and neutrons, for which the most recent Nobel Prize in physics was awarded, Georgi says.

In the seventies, Georgi used Wilson’s renormalization group in his formulation of a grand unification theory which would describe three of the four fundamental interactions in physics—electromagnetism, QCD, and the weak nuclear force—as different manifestations of the same interaction.

In 1975, Wilson was elected to the National Academy of Sciences and the American Academy of Arts and Sciences, and in 1984 to the American Philosophical Society. Together with Michael Fisher and Leo Kadanoff, he was awarded Israel’s Wolf Prize in Physics in 1980. Wilson is currently at the physics department of Ohio State University.

In recent years, Wilson has devoted himself to education reform. He co-directs Learning by Redesign, an organization that explores of novel ideas in elementary and secondary education.

In a September 1998 interview with NEA Today, the magazine of the National Education Association, Wilson explained his interest in K-12 education.

“If your aim is to have an impact on science literacy... you need to rivet your attention on the 46 million students in our public schools, not on graduate students in our universities,” he said.

—Staff writer Virginia A. Fisher can be reached at vafisher@fas.harvard.edu.