Superstring theories

Interview with Michael Green, Lucasian Professor Emeritus at Cambridge University and visiting professor at Queen Mary University. He recounts his childhood in London as the child of secular Jewish parents who immigrated to London just before World War II. Green discusses his early interests in physics and the opportunities that led to his enrollment at Cambridge, and he conveys Geoff Chew’s influence with his ideas on S-matrix and bootstrap theory, which informed his thesis research on hadronic interactions. He narrates the founding ideas that led to string theory and how the work on dual models became transformed into string theory. Green describes his postdoctoral work at the Institute for Advanced Study and his interactions with Veneziano. He explains his decision to return to Cambridge and the importance of the CERN theory group for his research, and he narrates the origins of his collaborations with John Schwarz. Green connects string theory to the ideas that led to supergravity, and he explains why he does not like the term “revolution” in relation to advances in string theory to explain what was happening between 1981-1984. He explains the meaning of the pronoun “super” in relation to string theory, and he conveys his disappointment that supersymmetry has yet to be observed. Green describes the importance of AdS/CFT and his contributions to the origins of D-branes with Joe Polchinski. He discusses his increasing reliance on computers for understanding aspects of AdS/CFT correspondence. Green reflects on winning the Breakthrough Prize, and the supposed aspirational recognition on working to unify the forces which are not yet unified, and he discusses the generational de-coupling of string theory education from particle physics. He provides sociological perspective in response to the impatience that certain physicists have expressed regarding string theory. At the end of the interview, Green ponders the future relationship between string theory and quantum computing, and he describes the field as an intellectual adventure which makes it difficult to predict the significance of these changes.

Interview with Edward Witten, Charles Simonyi Professor in the School of Natural Sciences at the Institute for Advanced Study. Witten discusses his current interests in quantum information theory in gravity, and he recounts his childhood in Baltimore and the influence of his father Louis Witten, who is a physicist. He describes his undergraduate education at Brandeis, where he majored in history, a brief stint working for the McGovern campaign, and a false start in graduate school to study economics before landing at Princeton to study first applied mathematics and then theoretical particle physics with David Gross. He describes the significance of deep inelastic scattering in the emergence of QCD and his earliest exposure to the ideas that would develop into string theory. Witten describes his postdoctoral appointment at Harvard to work with Steve Weinberg, Sidney Coleman, Shelly Glashow, and Howard Georgi. He discusses t’ Hooft’s success at solving the U(1) problem and his early work in supersymmetry by the time he joined the faculty at Princeton. Witten narrates the string revolution of 1984 and the early optimism that string theory would be able to describe the real world. He describes his involvement in topological quantum field theories and he explains his decision to move to the Institute from Princeton. Witten discusses his work with Nati Seiberg on N=2 super Yang Mills in four dimensions, the origins of M-theory in the 1994 string revolution, and the impact of Juan Maldacena’s work on AdS/CFT. He describes his collaboration with Seiberg on noncommutative geometry, his interest in the Langlands program, and the role of axions in string theory. Witten conveys the sense of optimism when the LHC turned on and the significance of Khovanov homology and Morse theory. He explains the need to revisit perturbative superstring theory and the possibility that the g-2 muon anomaly experiment at Fermilab will lead to new physics. At the end of the interview, Witten reflects on how little has been seen at the LHC after the Higgs discovery, and he expresses hope that string/M-theory and quantum gravity make meaningful contact during his lifetime.

Interview with Pierre Ramond, Distinguished Professor of Physics at the University of Florida. Ramond recounts childhood in Paris, he describes his family’s experiences during World War II, and he explains that opportunities that led to his education in electrical engineering at the New Jersey Institute of Technology. He discusses his graduate degree in physics at Syracuse University to focus on general relativity and his first exposure to the earliest iterations of string theory. Ramond describes his work at Fermilab on Veneziano modelling, his postdoctoral research at Yale, and his subsequent work at Los Alamos. He describes Gell-Mann’s interest in grand unified theories and the influence of Ken Wilson. Ramond explains the excitement regarding the muon anomaly experiment at Fermilab, and he narrates his decision to join the faculty at the University of Florida. He explains how the department’s stature has risen over the past forty years, and he reflects on his involvement with the superstring revolution in 1984. Ramond describes the difference between effective and fundamental theories in particle physics and he conveys the productive intellectual ferment at the annual Aspen conferences. He describes his service work on the faculty senate and he describes his leadership position at the APS during the discovery of the Higgs. Ramond explains why he thinks supersymmetry would have been detected at a completed SSC and he reflects on receiving the Dirac medal in 2020. At the end of the interview, he discusses Einstein’s misgivings on quantum mechanics, he imagines how string theory might be testable, and he explains why he remains interested in CP violation.

In this interview, David Zierler, Oral Historian for AIP, interviews Paul Langacker, professor emeritus of physics and astronomy at the University of Pennsylvania. Langacker recounts his childhood in the Chicago area and his early interest in particle physics. He discusses his education at MIT and his graduate work at Berkeley and he describes the political situation there in 1968 , his work with Owen Chamberlain, and Mahiko Suzuki and the origins of his life-long interest in weak interactions. Langacker explains his work at Rockefeller University, which was building a program in particle physics, and the circumstances leading to his hire at Penn. He talks about his research at DESY and the tenure process, and explains what he worked to accomplish as chair of the department, and in particular, his interest in increasing the diversity of the faculty. Langacker discusses his more recent interest in connecting superstring theory to particle physics during his time at the Institute for Advanced Study. Toward the end of the interview, Langacker shares his views on string theory and its role in achieving a grand unified theory in physics.