# John H. Schwarz Wins Physics Frontiers Prize

John H. Schwarz, the Harold Brown Professor of Theoretical Physics at Caltech, and Michael B. Green of the University of Cambridge have been awarded one of three 2014 Physics Frontiers Prizes in recognition of the new perspectives they have brought to quantum gravity and the unification of the fundamental physical forces of the universe. Each Physics Frontiers Prize comes with a $300,000 award and eligibility for the 2014 Fundamental Physics Prize, which, at$3 million, is one of the largest academic prizes in the world.

The Physics Frontiers Prize is awarded each year by the Fundamental Physics Prize Foundation, which was established in July 2012 by Russian physicist and Internet entrepreneur Yuri Milner to recognize groundbreaking work in the field. Previous winners include Caltech's Alexei Kitaev, Ronald and Maxine Linde Professor of Theoretical Physics and Mathematics. He and the other laureates—including theoretical physicist Stephen Hawking—served on the selection committee for this year's prize.

Schwarz and Green were honored for developing superstring theory during their collaboration between 1979 and 1986. Its predecessor, string theory, originated in the late 1960s in response to the rapid discovery of many new particles via accelerator experiments. Theoretical physicists, says Schwarz, tried "to make order out of all this chaos" by postulating that the fundamental object of the universe is the string and that the various particles in the universe could be adequately described as different oscillation modes of the string. It was thought for a time that string theory would yield an explanation of the strong nuclear force that binds protons and neutrons together in an atom's nucleus (or even more fundamentally, the quarks and gluons that make up protons and neutrons). But then in the mid-1970s, quantum chromodynamics provided an excellent account of the strong nuclear force, and string theory fell out of favor among most theoretical physicists.

In 1974, Schwarz and his then collaborator, Joel Scherk, suggested a different possible use of string theory, and it was the granddaddy of them all, at least in the terms of modern physics: a quantum theory of gravity and the unification of all the forces in nature. To follow up on this suggestion, Schwarz began his collaboration with Green in 1979, and together they created superstring theory, a version of string theory that relies on the property of supersymmetry to relate the two fundamental types of particles in quantum theory—bosons and fermions—to one another.

According to Schwarz, this is "a very ambitious project, and not something that's going to be completed in my lifetime." But, he says, "people are making lots and lots of progress. We keep discovering new things about superstring theory, which give us the sense that we're closing in on something really important." Indeed, experimental physicists working on CERN's Large Hadron Collider may soon be able to prove the existence of supersymmetry, which, says Schwarz, "wouldn't prove that superstring theory is right, but would be extremely encouraging."

This feeling of the impending success of superstring theory has not always been shared throughout the scientific community. When Schwarz and Green began their work together in 1979, it was, says Schwarz, "not particularly fashionable or popular." But in 1984, the pair's discovery of the so-called Green-Schwarz anomaly cancellation mechanism brought new excitement to superstring theory. "It has remained popular ever since—30 years later," Schwarz remarks.

Tom Soifer, chair of Caltech's Division of Physics, Mathematics and Astronomy, says he is delighted that the Fundamental Physics Prize Foundation chose Schwarz and Green for this honor, noting that while they were developing superstring theory, "these two were in the wilderness. But at Caltech," says Soifer, "we support these solo quests and see them through to fruition."

Schwarz notes that he is especially honored because "the people who were making the selection were other theoretical physicists who've already won the prize, and they are people that I respect and admire. Being chosen by them is particularly meaningful."

The winner of the \$3 million Fundamental Physics Prize for 2014 will be announced on December 12 in San Francisco.

Written by Cynthia Eller

Caltech Media Relations