, Nobel laureate and a professor emeritus at the 91̽��, died in Cambridge in the U.K. on April 6, 2019. He was 84 years old.

Thouless was a theoretical physicist whose most well-known work focused on the properties of matter in extremely thin layers. His research explained the behavior of matter in some of its most unusual states — including superfluidity and superconductivity. For these efforts, in 2016 he was awarded the along with his collaborator of Brown University and of Princeton University.

Thouless was the seventh 91̽��faculty member to receive a Nobel Prize, and the second 91̽��physics laureate.

“It really meant a lot to him that he won the Nobel Prize,” said Helen Thouless, his daughter.

Thouless’ career included stays on both sides of the Atlantic, but he spent more than three decades — the latter half of his career — as a 91̽��faculty member. One reason he and his wife, Margaret Thouless, a 91̽��professor emeritus of pathobiology, made Seattle their final academic home were the opportunities that the 91̽��provided for Thouless to enjoy a more collaborative approach to research.

“He really wanted to be part of a team — not necessarily the person leading the pack,” said Helen Thouless. “The 91̽�� offered a very collegial, very friendly setting. That’s why they stayed, I think.”

Thouless was a professor in the 91̽��Department of Physics from 1980 until his retirement in 2003.

“David Thouless was not only a scholar of the highest caliber, he was a gentleman, a wonderful department citizen and an inspiration to all of his colleagues,” said , chair of the 91̽��Department of Physics. “He will not be forgotten.”

David James Thouless was born on Sept. 21, 1934, in Bearsden, Scotland — the second child of Priscilla Thouless, a teacher, and Robert Thouless, a psychologist and professor. From an early age Thouless showed interest in numbers and arithmetic. According to his Nobel , his childhood pursuits included trying to determine how far numbers went by counting them and calculating how many seconds there are in a year.

Thouless attended St Faith’s School in Cambridge from 1942 to 1947, when he earned a scholarship to Winchester College in Hampshire. At school, he fostered other lifelong interests, including history and literature. Even outside his career in theoretical physics, Thouless enjoyed learning.

“He was always reading something. Growing up, our house was filled with books,” said Helen Thouless.

He studied at Trinity Hall at the University of Cambridge, graduating with a Bachelor of Arts degree in 1955. With support from the Fulbright Program, Thouless then crossed the Atlantic on the RMS Queen Elizabeth to study at Cornell University under future Nobel laureate . At Cornell, Thouless also met Margaret Scrase, a biology student. They wed in 1958, the same year Thouless graduated from Cornell with his doctoral degree.

After Cornell, he spent a year as a postdoctoral researcher at the Lawrence Radiation Laboratory — now the Lawrence Berkeley National Laboratory — before returning to the U.K. to work with , a world-renowned physicist at the University of Birmingham. Thouless joined the faculty at Birmingham in 1965 as a professor of mathematical physics.

In 1970, Thouless began a critical collaboration with Kosterlitz on phase transitions of matter. Solid ice melting to liquid water is an example of a phase transition of matter. Thouless and Kosterlitz took on a prevailing theory of the day, which stated that matter in flat, nearly two-dimensional systems undergoes no phase transitions. Their theories concluded that phase transitions are actually possible in flat environments, which helped explain properties such as superfluidity and superconductivity in these systems.

“We worked well together, since I had the broad ideas and tried to understand the big picture, whereas Mike would find the holes in my arguments and ways to solve the problems I had ignored,” said Thouless later, according to his Nobel biography.

The Nobel Committee for Physics cited these efforts in awarding them the physics prize in 2016.

Thouless left the University of Birmingham in 1978 and, after briefly working at Yale University, arrived at the 91̽��in 1980. In 1982, he and three postdoctoral researchers published a paper in which they used topological methods — a branch of mathematics describing properties that change in a stepwise manner — to explain another two-dimensional phenomenon called the .

This work was also cited by the Nobel Committee for Physics and is “seen nowadays as the starting point for the discovery of many new topological phenomena, including topological insulators and topologically protected quantum phases,” said , a 91̽��professor of physics who was one of the postdoctoral co-authors on the 1982 paper.

“David Thouless was the cornerstone of the condensed matter theory group in the 91̽��Department of Physics for many years,” added Den Nijs. This year, the 91̽��physics department founded the .

Thouless became a fellow of the U.K.’s Royal Society in 1979, a fellow of the American Academy of Arts and Sciences in 1981 and a fellow of the American Physical Society in 1987. In 1990, he shared the prestigious with , another future Nobel laureate. In 1995, Thouless was elected to the National Academy of Sciences.

Outside of his academic interests, the Thouless family enjoyed the fruits of life in the Pacific Northwest – including hiking, skiing and sailing — as well as arts at the UW, particularly opera and early music.

In addition to Margaret Thouless, his wife of more than 60 years, and daughter Helen Thouless, a lecturer and researcher at the Institute of Education at the University College London, survivors include two sons — Michael Thouless, a professor of mechanical engineering at the University of Michigan, and Christopher Thouless, a strategic advisor with Save the Elephants and director of the Elephant Crisis Fund — as well as four grandchildren and a bounty of friends. Thouless was preceded in death by his parents and his sister Susan.

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Days of festivities for the culminated on Dec. 10 with an and banquet in Stockholm hosted by the Nobel Foundation and the Swedish Royal Family. On stage at Stockholm Concert Hall before an audience of dignitaries and guests, , 91̽�� professor emeritus of physics, received the Nobel Prize in Physics from King Carl XVI Gustaf of Sweden.

Half of this year’s physics prize went to Thouless, with the other half shared between professors of Brown University and of Princeton University. The three received the prize “for theoretical discoveries of topological phase transitions and topological phases of matter,” according to the Oct. 4 .

At the Dec. 10 event, Professor of Stockholm University and the Royal Swedish Academy of Sciences presented Thouless, Kosterlitz and Haldane to the assembly.

“They have set the stage for a new way of describing matter,” Hansson said. “They have given us a rich mathematical language with deep and beautiful abstract concepts.”

Concluding that the laureates’ contributions represent “theoretical physics at its best,” Hansson invited each to come forward and receive a Nobel medal and diploma from the king. Thouless led the way.

As a professor at the University of Birmingham in the 1970s, Thouless began to explore the unique properties of matter that become exposed in flat, two-dimensional environments.

This type of work continued when Thouless joined the 91̽��faculty in 1980, with three postdoctoral researchers, including  , who is now a 91̽��professor of physics. Ultimately, they were able to describe the “exotic” properties of matter in these “flatlands” using topological methods — a branch of mathematics that describes properties which change in a stepwise manner.

These were complex undertakings, and in a Nov. 30 with Smithsonian Magazine Kosterlitz lauded Thouless for his ability to “understand the contradictions, and puzzle them out.” They upended existing ideas on the behavior of matter in the flatlands. Their theories and practices form the basis of today’s scientific quests for new materials with exotic properties.

Events of also included public lectures on the discoveries that were made this year’s laureates. Speaking before two such presentations on the physics prize, Hansson described Thouless as “a legendary person” who has made contributions to theoretical physics and mathematics even beyond the work cited by this year’s prize announcement. Thouless’ contributions to intermediate-scale physics and quantum mechanics — or mesoscopic physics — “might be as important as the work that we are celebrating today,” Hansson said.

Thouless retired from the 91̽��in 2003. He resides in the United Kingdom with his wife, Margaret Thouless, who was a 91̽��associate professor of pathobiology.

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Thouless splits the prize with Professor of Princeton University and Professor of Brown University “for theoretical discoveries of topological phase transitions and topological phases of matter,” according to the from the Academy. Half the prize goes to Thouless while Haldane and Kosterlitz divide the remaining half. Thouless is , and second in physics after Hans Dehmelt in 1989.

“Prof. Thouless’ work is a perfect example of why curiosity-driven basic science is so vital,” 91̽��President . “Not only did his discoveries open up entirely new fields of research, but they also have had implications for the electronic devices that power our world today and those that may do so in the future — everything from advanced superconductors to quantum computers to other applications we can hardly imagine. We are tremendously proud of this recognition of the seminal importance of his work.”

Born in 1934 in Bearsden, Scotland, Thouless earned his undergraduate degree in 1955 from Cambridge University and a doctorate degree in 1958 from Cornell University, where he studied under physicist and Nobel laureate . Thouless was a postdoctoral researcher at the University of California, Berkeley, before returning to the United Kingdom to work with world-renowned physicist Rudolf Peierls at the University of Birmingham.

At Birmingham, where he was a professor of mathematical physics from 1965 to 1978, Thouless began a pivotal collaboration with Kosterlitz which overturned prevailing theories on how matter behaves in flat, two-dimensional environments. As the explains they and Haldane discovered that, in these extreme “flatland” settings, matter explained only using complex topological methods.

Topology is the branch of mathematics dealing with properties that change in a stepwise fashion. And it turns out that the promise of new materials and methods for manipulating matter lie within these “flatlands,” where quantum mechanics is exposed and matter assumes more “exotic” states than the typical solid, liquid or gas. Their theories and practices have revealed new ways to understand physical interactions in this “exotic” state.

All matter rests on a bed made by the rules of quantum mechanics. Larger and bulkier forces like gravity often obscure these quantum-level interactions — just as a sturdy mattress, fluffy pillows and thick quilts obscure the underlying bedframe. But that frame is still there, and forms the foundation of the larger, overlaying structure.

In the flattened, 2-D realm of their investigations, these scientists were able to describe new and unique behaviors of physical matter under these conditions.

“It is the foundation for new technologies we are exploring today, using 2-D surfaces using graphene and other ‘new materials,’” said , a 91̽��professor of physics who has known Thouless for 35 years. “This award was a long time coming. He’s a brilliant scientist and wonderful person.”

In work beginning in the 1970s, Thouless and Kosterlitz showed how matter in the flatlands can transition between phases, and does so using fundamentally different interactions than in our more familiar 3-D realm.

After a brief stint at Yale University, Thouless moved to the 91̽��physics department in 1980 and used topological methods to explain what physicists call the . This phenomenon was described in a pioneering experiment by physicist and Nobel laureate , but could not be explained using theories at the time.

Thouless used topological methods to explain von Klitzing’s results, showing that quantum mechanics reigned supreme in the flatlands. He did this work with three 91̽��postdoctoral researchers, including Den Nijs.

These lines of research set the stage for today’s quests in physics and materials sciences for innovative approaches to electronics and computing. They all depend on a thorough understanding of topological interactions in flat, 2-D realms. In other words, today’s materials and computers make use of quilts and pillows on the bed, while tomorrow’s will exploit the bedframe itself.

“There is no greater honor for a physicist and scholar than winning the Nobel Prize,” said Robert Stacey, Dean of the 91̽��College of Arts & Sciences. “We are thrilled and deeply honored to celebrate Professor Thouless’ lifetime contributions to his field. His work epitomizes the 91̽��’s deep commitment to world-class research that stretches our understanding of exotic matter and the complex universe around us. And it reminds us how important fundamental scientific research and education are to our society, even when the practical applications of such research take decades to emerge.”

Thouless has received many awards and honors for his groundbreaking discoveries. He became a Fellow of the Royal Society in 1979 and, in 1981, a Fellow of the American Academy of Arts and Sciences. In 1987, he became a Fellow of the American Physical Society and earned the prestigious Wolf Prize for Physics in 1990. Thouless retired from the 91̽��in 2003. Thouless’ wife Margaret was an associate professor of pathobiology at the 91̽��from 1980 to 2004.

The first 91̽��Nobel laureate was , who won the prize for physics in 1989. Aside from Dehmelt and Thouless, the remaining 91̽��Nobel laureates won the prize in physiology or medicine: in 1990; and in 1992; in 2001; and in 2004. At the time of their awards, Thomas, Hartwell and Buck were also faculty researchers at the Fred Hutchinson Cancer Research Center in Seattle.

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For more information, contact James Urton in the 91̽��Office of News & Information at 206-543-2580.