Supersymmetry

Interview with Gerard 't Hooft, University Professor of Physics (Emeritus) at Utrecht University in the Netherlands. 't Hooft considers the possibility that the g-2 muon anomaly experiment at Fermilab is suggestive of new physics, and he reflects broadly on the current shortcomings in our understanding of quantum mechanics and general relativity. 't Hooft recounts his childhood in postwar Holland and the influence of his great uncle, the Nobel Prize winner Frits Zernike and his uncle, the theoretical physicist Nico van Kampen. He describes his undergraduate education at Utrecht University where he got to know Martinus Veltman, with whom he would pursue a graduate degree and ultimately share the Nobel Prize. 't Hooft explains the origins of what would become the Standard Model and the significance of Yang-Mills fields and Ken Wilson’s theory of renormalization. He describes Veltman’s pioneering use of computers to calculate algebraic manipulations and why questions of scaling were able to be raised for the first time. 't Hooft discusses his postdoctoral appointment at CERN, his ideas about grouping Feynman diagrams together, and how he became involved in quantum gravity research and Bose condensation. He explains the value in studying instantons for broader questions in QCD, the significance of Hawking’s work on the black hole information paradox, the holographic principle, and why he has diverged with string theorists. 't Hooft describes being present at the start of supersymmetry, and the growing “buzz” that culminated in winning the Nobel Prize. He describes his overall interest in the past twenty years in thinking more deeply about quantum mechanics and he places the foundational disagreement between Einstein and Bohr in historical context. At the end of the interview, 't Hooft surveys the limitations that prevent us from understanding how to merge quantum mechanics and general relativity and why this will require an understanding of how to relate the set of all integer numbers to phenomena of the universe.

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 John Ellis, Clerk Maxwell Professor of Theoretical Physics at King’s College London, and Visiting Scientist at CERN. Ellis discusses the g-2 experiment at Fermilab and where he sees current efforts geared toward understanding physics within the Standard Model, and pursuing new physics beyond it. He recounts his childhood in a small town north of London and his innate interest in physics before he understood that it was a proper field of study. Ellis discusses his education at Cambridge and the department’s strength in particle physics, general relativity, and cosmology, and he explains the relevance of the deep inelastic scattering research at SLAC for his thesis on approximate symmetries of hadrons. He describes the intellectual influence of Bruno Zumino and his decision to go to SLAC for his postdoctoral research to work on scale invariance. Ellis discusses his subsequent research at Caltech and he explains why he would have appreciated more the significance of asymptotic freedom had he better understood field theory at that point. He discusses his subsequent position at CERN and is collaboration with Mary Gaillard on semileptonic decays of charm. Ellis narrates the famous “penguin diagram” that he developed with Melissa Franklin and his interest in grand unification and how it differs from the so-called “theory of everything.” He describes the optimism in the 1980s that supersymmetry would be found and its possible utility in the search for dark matter. Ellis discusses his involvement with LEP and axion physics, and he reflects on the spirit of competition and collaboration between ATLAS and CMS in the run up to the Higgs discovery. He explains the new questions that became feasible as a result of the discovery and his interests in both gravitational waves and supernovae. Ellis describes the AION experiment, the important physics research currently in the works in China, and key recent developments in quantum gravity. At the end of the interview, Ellis conveys his belief in the importance of science communication, he minimizes the importance of the h-index as a measure of excellence, and in reflecting on his own career, he cautions against younger physicists becoming overly-specialized. 

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 Sylvester James Gates, Jr., Ford Foundation Professor of Physics and Director of the Theoretical Physics Center at Brown University. Gates discusses his preparations to lead the APS and the value of his service for PCAST for this new role. Gates recounts his family heritage and he discusses his father’s military service and the death of his mother. He explains how his family navigated racist challenges during his upbringing in El Paso and then in Orlando and how he navigated his own intellectual abilities in school. Gates explains his interest in physics in high school and the opportunities that led to his admission at MIT for his undergraduate work. He recounts the many mentors who made a positive impression on him and he explains his realization that his specialty would be at the boundary between math and physics. Gates describes his earliest interactions with string theory and he explains his decision to remain at MIT for his graduate work to work with Jim Young on supersymmetry. He paints a broader picture of supergravity research at this time and the rising importance of computers for this work. Gates describes his postdoctoral research at Harvard as a Junior Fellow, where he worked closely with Warren Siegel, and he describes his decision to join the faculty at MIT after a subsequent postdoctoral position at Caltech. He addresses Shelly Glashow’s criticism of string theory, and he explains his decision to leave MIT for a faculty position at the University of Maryland. Gates reflects on his teaching and mentoring career at Maryland, he describes his time at Howard University, and he discusses the broader issue of diversity in physics and AIP’s TEAM-UP Report. He describes his more recent interests in graph theory and the broader effort to unify gravity with the other forces. Gates reflects on how he became an advisor to President Obama for PCAST and how he worked with John Holdren to translate reports into policy changes. He explains his decision to go emeritus at Maryland and to take a new position at Brown, and why joining the Watson Institute was an attractive part of the offer. Gates reflects on assuming leadership at APS during the twin crises of Covid and racial strife, he surveys the state of string theory and high energy physics, and he explains why supersymmetry might offer a path to understanding dark matter. At the end of the interview, Jim conveys his hope that his work in math will yield deep insights into nature, and he considers the possibility of pursuing an autobiographical project.

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.

Edward “Rocky” Kolb is the Director of the Kavli Institute for Cosmological Physics at the University of Chicago and the Arthur Holly Compton Distinguished Service Professor of Astronomy at the University of Chicago. In this interview, Kolb explains how he acquired his nickname and he recounts his upbringing in New Orleans and his habit of spending time in the local library, where he developed his interest in science. He describes the financial constraints that compelled him to attend the University of New Orleans for college, and he characterizes his education there as broad but not deep, which caused him to consider a wide range of specialties for his graduate research at the University of Texas. Kolb describes working with his graduate advisor Duane Dicus in applying particle physics to cosmological questions, and he summarizes his dissertation research on the effects of axions in stars. He discusses his postdoctoral research with Willy Fowler at Caltech, and he emphasizes the influence of Allan Sandage on his decision to focus on cosmology.  Kolb describes his second postdoctoral fellowship at Los Alamos where he joined the burgeoning astrophysics group in the Theoretical Division to work on Big Bang nucleosynthesis.  He explains his decision to join the astrophysics group at Fermilab, where he collaborated closely with Michael Turner and benefited from the support of Leon Lederman. He describes his developing interest in supersymmetry and neutrino oscillations, he describes the impact of Alan Guth’s lectures on inflation, and he explains his increasing involvement with the astronomy and astrophysics department at the University of Chicago culminating with an offer for him to become chair of the department.  He describes his objectives and achievements in that position, he explains how he maintained research interest in creating particles from the vacuum, and he describes how this research could be of value in the ongoing quest to understand dark matter. At the end of the interview, Kolb reflects on the different approaches that religion and science take to understanding reality, and he explains why he is most optimistic that understanding dark matter is the most likely major future breakthrough in his field.

This is an interview with David Kaplan, Professor of Physics and Astronomy at Johns Hopkins University. He recounts his childhood in New York and then Seattle, and he explains his complex Jewish-Israeli family roots. Kaplan describes his early aptitude for math, and he discusses his education at Chapman College and his transfer to Berkeley, where he completed his undergraduate degree in physics. He explains his near-accidental entrée into the graduate program in physics at the University of Washington, and he describes the formative influence of Ann Nelson. He conveys the excitement surrounding supersymmetry during his time in graduate school and his research on quark masses, and he recounts his postdoctoral research, which was split between Argonne Lab and the University of Chicago. Kaplan discusses the crisis of confidence he felt in his early career and he describes his second postdoctoral appointment at SLAC where he worked with Savas Dimopoulos on supersymmetry and became involved in the B physics endeavor. He conveys his long-held contempt for string theory and attacks it on both sociological and scientific grounds, and he explains the circumstances leading to his hire and tenure at Johns Hopkins. Kaplan describes how he used startup funds to invite speakers to the department, and he explains how imposter syndrome affects faculty members as much as anyone else. He explains the various issues surrounding the cancellation of the SSC, the viability of the LHC, and the prospects of the ILC, and he offers his view on what these projects say about the state of particle physics globally. Kaplan discusses the significance of WIMP dark matter, and why more physicists should work on issues beyond string theory and collider physics. At the end of the interview, Kaplan describes how he tries to make his research an antidote to the problems he sees in the field, and he discusses his ongoing interest in general Higgs decays.