Thursday, June 27, 2013

Kenneth Wilson, Nobel Physicist

Kenneth Wilson, Nobel Physicist, Dies at 77

Cornell University
Kenneth Wilson in 1982, the year he won the Nobel Prize. He determined how to calculate tricky moments in physics.
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Kenneth G. Wilson, who was awarded the 1982 Nobel Prize in Physics for showing how to calculate tricky moments like when ice melts or an iron bar loses its magnetism, died on Saturday in Saco, Me. He was 77.
The cause was complications of lymphoma, according to Cornell University, where he had been a professor for 25 years.
His colleagues hailed Dr. Wilson as a legend who had changed how theoretical physicists went about their work, especially in particle physics, the study of the elementary and fundamental constituents of nature. He was also a pioneer in using computers and then supercomputers to study the properties of quarks, the building blocks of protons and neutrons.
“He’s a giant in theoretical physics,” said Frank Wilczek, a Nobelist at the Massachusetts Institute of Technology, calling his work “quite profound.”
Steven Weinberg, a Nobel winner at the University of Texas at Austin, said, “Ken Wilson was one of a very small number of physicists who changed the way we all think, not just about specific phenomena, but about a vast range of different phenomena.”
Kenneth Geddes Wilson was born on June 8, 1936, in Waltham, Mass., the first of three children of Edgar and Emily Buckingham Wilson. His father was a chemist at Harvard. His mother had been a physics graduate student before marrying. One grandfather was an engineering professor at M.I.T. and the other the speaker of the Tennessee House of Representatives.
Kenneth Wilson entered Harvard at 16, majored in math and ran the mile. He obtained his Ph.D. at the California Institute of Technology under the legendary theorist Murray Gell-Mann, then did postdoctoral studies at Harvard as a junior fellow that included a year at CERN, the European nuclear research organization in Geneva. He joined Cornell as a physics professor in 1963.
He later said he was drawn to Cornell by, among other things, the folk-dancing scene in Ithaca, N.Y. It was at a folk dance that he met Alison Brown, who was working in the university’s computer center. They were doing a Swedish dance called the hambo. “His hambo and my hambo fit together really well,” she said.
They married in 1982. She survives him, along with a brother, David; a sister, Nina Cornell; a half sister, Anne Goldizen; two half brothers, Paul and Steven Wilson; and a stepmother, Thérèse Wilson.
Dr. Wilson arrived at Cornell already famous for his mathematical prowess. At Harvard he had proved a conjecture by the renowned mathematician Freeman Dyson while sitting around waiting for an M.I.T. computer to finish a job for him.
From the start, Dr. Wilson was drawn to difficult problems that could take years to solve, said Kurt Gottfried, a Cornell colleague. One such problem was phase transitions, the passage from water to steam or atoms lining up to make a magnet. At the critical point — the temperature at which the change happens — orderly behavior breaks down, but theorists had few clues to how to calculate what was happening.
Dr. Wilson realized that the key to the problem was that fluctuations were happening on all scales at once — from the jostling and zooming of individual atoms to the oscillations of the entire system — something conventional theory could not handle.
At the heart of Dr. Wilson’s work was an abstruse mathematical apparatus known as the renormalization group, which had been conceived by his thesis adviser, Dr. Gell-Mann, and Francis Low in 1951. They had pointed out that fundamental properties of particles and forces varied depending on the scale over which they are measured.
Dr. Wilson realized that such “scaling” was intrinsic to the problems in phase transitions. In a series of papers in the early 1970s, building on the work of Michael Fisher and Benjamin Widom at Cornell and Leo Kadanoff, then at the University of Illinois, he applied the renormalization idea to show how the critical phenomena could be solved by dividing the problem up into simpler pieces, so that what was happening at the melting point, for example, could be considered on one scale at a time.
The results showed that many seemingly unrelated systems — from magnets to liquids — could exhibit the same characteristic behavior as they approached the critical point. The concept proved to be of wide relevance in physics and was cited by the Royal Swedish Academy of Sciences in presenting the Nobel.
Dr. Wilson went on to apply the same divide-and-conquer strategy to quantum field theory, the mathematical language that underlies the study of the most elementary particles and fundamental forces in nature. The theory was plagued by such vexing issues as infinities and other mathematical absurdities when physicists tried to calculate something like the mass of an electron. A method had been developed to work around these anomalies, but many physicists worried that they were just sweeping a fatal flaw in physics under the rug and that, in the words of Dr. Wilczek, “quantum field theory was doomed.”
Dr. Wilson’s new technique banished the infinities for good, putting the theory on a sounder footing. As the Caltech physicist John Preskill put it in a blog post, “Wilson changed that.”
Dr. Wilson’s ideas played a major role in the development of quantum chromodynamics, the branch of quantum theory that describes the behavior of quarks and the gluons that stick them together to form protons and neutrons. In 1974, in order to solve the equations of this theory numerically and gain a more precise understanding of this process, he invented a digitized version of the theory called lattice gauge theory, in which space is imagined as a kind of finely resolved jungle gym where every intersection of the bars represents a point in space-time.
Such computations required supercomputers, and Dr. Wilson was instrumental, his colleagues said, in establishing a national supercomputer center — one of five sponsored by the National Science Foundation — at Cornell.
In 1988, Dr. Wilson and his wife, Ms. Brown, moved to Ohio State University, where he helped found the Physics Education Research Group. Ms. Brown became the assistant director of a new supercomputer center.
They moved to Maine in 1995, drawn there in part by the kayaking. Dr. Wilson was associated with Ohio State until 2008, when he retired.
Ms. Brown said that Dr. Wilson’s health had begun to fail after he fell while hiking last year in the Southwest. Dr. Wilson liked to chew over physics problems as he walked.
Friends described him as a modest and informal man. At one conference in the 1960s he chose to camp out on the beach with graduate students, talking physics, rather than stay in a hotel with other faculty members.
“Ken was the most lacking in small talk of anyone I ever met,” Ms. Brown said. When he died, she sent an e-mail to friends, saying: “Ken died last evening. He always liked to do things quietly and without fuss, and that’s how he left us.”

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