the Perimeter spring/summer 2013 Condensed Matter Xiao-Gang Wen Explores the “Frontier in the Middle” Mathematical Physics The New Face of Feynman Diagrams? From the Black Hole Bistro The Sweet Science of Chocolate Plus ... Special pull- out section: The Process of Science Pictured here, Perimeter Director Neil Turok delivers his final Massey Lecture in Toronto. In the fall of 2012, Turok delivered the five Massey Lectures to packed houses across Canada. If you missed them, you can read the collected lectures in The Universe Within: From Quantum to Cosmos, published by House of Anansi Press, or download them from iTunes. The whole series will be rebroadcast on CBC Radio this summer. cbc.ca/ideas/masseyexperience Editor-in-Chief Copy Editors Natasha Waxman Erin Bow [email protected] Mike Brown Alexandra Castell Contributing Authors Erin Bow Graphic Artist Mike Brown Gabriela Secara Greg Dick Ross Diener Photographers & Artists Cecilia Flori Jonathan Baltrusaitis Phil Froklage Luther Caverly Frederick Raab Soheila Esfahani Tracy Smith Chris Fach Natalia Toro Jens Langen Natasha Waxman Gabriela Secara Xiao-Gang Wen Carlos Tamarit Nicole Yunger-Halpern Steve Zylius Inside the Perimeter is published by Perimeter Institute for Theoretical Physics. www.perimeterinstitute.ca To subscribe, send us an email at [email protected]. 31 Caroline Street North, Waterloo, Ontario, Canada p: 519.569.7600 f: 519.569.7611 02Contact us at [email protected]. IN THIS ISSUE 04/ Lead On: Neil Turok Reappointed, Natasha Waxman 05/ Gaiotto and Hawking Awarded Fundamental Physics Prizes, Erin Bow 06/ Particles 08/ Making New Connections, Mike Brown 10/ The Frontier in the Middle, Erin Bow 12/ Beauty from the Mess: A Condensed Matter Model for the Universe, Xiao-Gang Wen 14/ Quantum Spin Liquids: A Chat with Steven White, Erin Bow 16/ Mysteries at the Tip of a Pencil, Phil Froklage 16/ Quantum Physics You Can Use, Phil Froklage 17/ Poetry for Physicists, Nicole Yunger-Halpern 18/ World’s First Glimpse of Black Hole ‘Launchpad,’ Erin Bow 19/ The Birth Cry of a Black Hole, Erin Bow 22/ Quantum Mechanics Comes On-Shell, Erin Bow 24/ The Sophistication of Symmetry, Ross Diener 26/ Conferences 28/ Contextual Truth?, Cecilia Flori 30/ Recent Perimeter Publications 34/ The Sweet Science of Chocolate, Erin Bow and Tracy Smith 36/ Using Physics to Fight Cancer, Phil Froklage 37/ Donor Profile: Dorian Hausman,Phil Froklage The Process of Science, special insert hidden wonders science works ... on long timelines shining a light on dark energy science works ... sideways science gets stuck liftoff: a scientific beginning science works ... by simplification theory leads experiment leads 03 news Lead On: Neil Turok Reappointed hen Neil Turok arrived in Waterloo in October 2008 as Institute’s Scientific Advisory Committee. Turok will also become Perimeter Institute’s new director, it was a very different the inaugural Mike and Ophelia Lazaridis Niels Bohr Chair in Wplace. Our first permanent building had just opened, Theoretical Physics. we had few students, and our faculty members still fit in one boardroom. Turok’s new term as director commences in October 2013 and runs for an additional five years. In his first five-year term as director, Turok launched the Distinguished Visiting Research Chairs program to attract world- “When we invited Dr. Neil Turok to be Perimeter’s director in leading scientists to Perimeter. He inaugurated the Perimeter 2008, we knew he was a world-class scientist and a visionary Research Chairs, wooing Xiao-Gang Wen from MIT to become leader. What he has brought to the Institute in his first term as the first chairholder. He spearheaded the creation of the Perimeter director has been nothing short of outstanding,” said Board Chair Scholars International (PSI) master’s program, a rigorous and Mike Lazaridis. “Under his direction, Perimeter has become one innovative course designed to nurture a new generation of of the leading centres for theoretical physics in the world. It is theoretical physicists. Under Turok’s leadership, Perimeter has also a special privilege for Ophelia and me to lend our name to nearly doubled in size and expanded its scope of research into this new Chair that will support Neil’s world-leading research in strategically chosen fields – you can read, for instance, about early universe cosmology.” Perimeter’s growing strength in condensed matter physics in “I am humbled and excited by this news,” said Turok. “I am this issue. In 2011, the new Stephen Hawking Centre officially especially honoured to be appointed as the first holder of the opened, making this young institute the largest centre for Mike and Ophelia Lazaridis Niels Bohr Chair and appreciative of theoretical physics in the world. Meanwhile, Turok himself was the incredible support of Mike Lazaridis and the Board. Working chosen as the 2012 Massey Lecturer. with Perimeter’s outstanding faculty and staff over the last It’s been, in short, a great five years, and now Perimeter can look several years has been intense, exciting, and hugely rewarding. forward to five more. Together, we are reinventing how theoretical physics is done. I can’t wait to get started on the next five years.” Perimeter’s Board of Directors has unanimously decided to reappoint Turok, with the full support of the faculty and the - Natasha Waxman 04 Gaiotto and Hawking Awarded Fundamental Physics Prizes erimeter Galileo Chair Davide Gaiotto Most of Gaiotto’s work takes place at the dimensional conformal field theories and and Distinguished Visiting Research intersection of quantum field theory and computing their systemically protected PChair Stephen Hawking were recently string theory. For instance, the textbook properties. awarded prizes from the Fundamental way we’ve always understood quantum Physics Prize (FPP) Foundation. fields is by writing down their Lagrangians This progress in our understanding of and using standard mathematical tools to quantum field theories has broad potential, In contrast to the Nobel, which has a strong develop our understanding of the fields because quantum fields are essential to leaning toward tangible, quantifiable or from there. In a breakthrough known many areas of physics. Particle physicists practical discoveries, FPP prizes are intended as the “class S framework,” Gaiotto use a quantum field theory called the to recognize theorists and researchers who used string theory tools to construct a Standard Model to precisely describe the are “dedicated to advancing our knowledge huge class of quantum fields that do not behaviour of all known particles. Electronic of the universe at the deepest level.” depend on Lagrangians. It’s as if all the engineers use a different quantum field Although new, these awards are already quantum fields to this point were under a theory to describe and design today’s considered major distinctions. single lamp post – and Gaiotto lit up the electronic devices. Condensed matter rest of the street. physicists use quantum field theories Stephen Hawking was given one of two to describe superconductors and other Special Prizes in Fundamental Physics – By vastly extending the canon of known exotic materials. Gaiotto’s work could the other went to the Higgs boson team field theories, Gaiotto provided a rare conceivably lead to deep mathematical at CERN. Hawking was honoured for and potentially revolutionary glimpse into advances, help us tailor exotic quantum his discovery of Hawking radiation from the structure of a generic field theory. The systems to practical applications, or black holes and for his deep contributions new framework set the stage for a flood of even advance our understanding of the to both quantum gravity and the quantum recent new results in quantum field theory fundamental laws of the universe. aspects of early universe cosmology. and string theory, both from Gaiotto and from the broader research community. “Perimeter Institute is thrilled that two of Gaiotto won a New Horizons in Physics There were even unexpected payoffs in its researchers have been recognized Prize, which recognizes exceptionally mathematics and mathematical physics. with these major international awards,” promising young researchers. In developing the class S framework, said Director Neil Turok. “Stephen’s path- breaking discoveries about the quantum Gaiotto, who is 35, does wide-ranging Gaiotto discovered several results which are now being studied by mathematicians. properties of black holes set the agenda work – a sampling of recent paper titles for much of fundamental physics and includes “Pulling the straps of polygons,” Gaiotto is currently pursuing a framework cosmology over the past three decades. “Spectral networks,” “Spectral networks analogous to the class S framework for Davide’s discoveries about quantum and snakes,” and “An E7 surprise.” There three-dimensional field theories. There fields are likewise opening the way to are also references to wall crossings, knot are surprising connections to deep more powerful mathematical descriptions invariants, superconformal indices, and mathematics, including knot theory, three- of particles and forces in the universe.” three-manifolds. The young researcher manifold invariants, and cluster algebra. is, in other words, the very model of a The physics payoff is the possibility of - Erin Bow modern mathematical physicist. mapping out a large class for three- 05 particles Mike Lazaridis named Henry Reich launches more advanced physics topics. Inspired by Susskind’s popular Stanford