Rob Leigh

1964-2026

Robert Graham Leigh passed away on April 18, 2026, at his home in Champaign, Illinois, at the age of 61, from a glioblastoma (malignant brain tumor).

Dr. Leigh received his Bachelor of Science degree in theoretical physics from the University of Guelph (Ontario, Canada) in 1986; his advisor was Professor George Leibbrandt. In 1986, he was awarded a four-year Natural Sciences and Engineering Research Council of Canada (NSERC) Postgraduate Scholarship and went on to earn his Ph.D. in theoretical particle physics from the University of Texas at Austin in 1991, working with Professor Joe Polchinski. His doctoral dissertation was titled “Topics in String Duality, CP Violation, and Baryogenesis.”

Dr. Leigh held postdoctoral research appointments at the Institute for Particle Physics at the University of California, Santa Cruz, and at Rutgers University in New Jersey. He joined the Department of Physics at the University of Illinois Urbana-Champaign in 1996 as an assistant professor. He was promoted to associate professor in 2002 and to full professor in 2008.

From 2002–2003, Professor Leigh took a sabbatical post as a scientific asssociate at the European Organization for Nuclear Research (CERN—Conseil Européen pour la Recherche Nucléaire), in Geneva, Switzerland. In 2010, Professor Leigh became an associate of the Center for Advanced Study at the University of Illinois. From 2011–2012, 2018–2019, and 2023–2025, he was a visiting researcher at the Perimeter Institute for Theoretical Physics in Cambridge, Ontario, Canada. Professor Leigh was also a member of the Illinois Quantum Information Science and Technology Center (IQUIST) in The Illinois Grainger College of Engineering.

Professor Leigh did outstanding work on string theory, supersymmetric field theories, gauge theories, and other topics in particle physics, early-universe cosmology, and condensed matter.  Professor Leigh's work still lies at the heart of current efforts to build a fundamental theory of quantum gravity.

In his first papers, Professor Leigh wrote about his discovery of D-branes and orientifolds in string theory, providing the first example of superstring duality. In this work, he derived the Dirac-Born-Infeld action describing the dynamics of D-branes. D-branes correspond to non-perturbative states unique to string theory and are analogous to magnetic monopoles in field theory. The study of D-branes is fundamental to modern string theory and its applications to particle physics, mathematics, and condensed matter physics.

Professor Leigh also did seminal work on the existence of conformal field theories and the use of intersecting branes and branes at singularities in particle physics model building. His research interests in his final years included applications of the holographic duality to study particle physics, gravity and condensed matter physics. His final paper, an essay written for the "Gravity Research Foundation 2025 Awards for Essays on Gravitation" outlined a new approach to quantum gravity that combined many of his recent efforts - including the study of edge modes in local gauge theories and operators algebra methods.

Throughout his career, Dr. Leigh was recognized as a world-class physicist with encyclopedic knowledge of the subject. By his own example, he taught his students how to be a confident theoretical physicist; he insisted that his students meet the same high standards that he demanded of his own work, while still connecting with his students on a personal level, earning both respect and admiration from his students. From 1997–2000, Dr. Leigh was named Outstanding Junior Investigator by the U.S. Department of Energy. In December 2004, the University of Illinois Urbana-Champaign awarded Dr. Leigh the Arnold O. Beckman Award, a research-support award. In 2007, Dr. Leigh became a Fellow of the American Physical Society.

For most of Dr. Leigh’s life, he was a hockey fan and an avid stamp collector and later in life amassed sizeable collections of historical postcards, postmarks, stamps, and hockey cards. For many years he was a member of and held multiple positions in the Champaign-Urbana Stamp Club, and for approximately 25 years, he was a member of the Postal History Society of Canada (PHSC), serving in the positions of vice-president, secretary, and webmaster at various times over those years. He was elected Fellow of the Postal History Society of Canada in 2018, and he was the webmaster of the ORAPEX (Ottawa Regional Association of Philatelic Exhibitions) national-level show from 2006 to 2025. He exhibited postal history at the national level and won numerous awards, including several Grand Awards. He wrote over a dozen postal history articles in BNA Topics, the journal of the PHSC, Maple Leaves, and in The American Philatelist, as well as two BNAPS (British North America Philatelic Society Ltd.) Exhibit Series publications. In September 2025, he was awarded a Lifetime Achievement Award by the British North America Philatelic Society.

Dr. Leigh’s family (and Dr. Leigh) would like to thank everyone for all their care, concern, and support over the past year while navigating the unexpected and heartbreaking journey of Rob’s illness. Whether family, friend, work colleague, or former student, your support has meant more than can be expressed.