Robert Paul Behringer, a James B. Duke Professor of Physics at Duke University, died unexpectedly on 10 July 2018 in Durham, North Carolina, following complications from surgery. At the time of his death, Bob was an active, highly respected experimental physicist in the areas of fluid dynamics and soft condensed matter; a leader in the American Physical Society (APS); a caring, successful mentor of young scientists; and a devoted husband, father, and grandfather.
Bob was born on 26 October 1948 in Baltimore, Maryland, and obtained his undergraduate and graduate degrees, both in physics, from Duke. Under the guidance of Horst Meyer, he earned his PhD in 1975 for work on critical phenomena in helium-3 and 3He–4He mixtures.
As a postdoc, Bob went to Bell Labs, where he worked with Guenter Ahlers on heat transport and the onset of Rayleigh–Bénard convection in liquid helium. In the late 1970s, there was great interest in understanding the general principles governing the properties of sustained nonequilibrium systems. Bob and Guenter published several seminal papers on the onset of irregular dynamics in fluids, including the first definitive evidence for deterministic chaos in a fluid. After spending four years as an assistant professor at Wesleyan University in Connecticut, Bob moved back to Duke in 1982 and continued his studies of transport and fluid flow in liquid helium. He remained on the Duke faculty for 36 years.
In the late 1980s, Bob became interested in techniques for observing the internal dynamics of flows in porous media and in sand. The possibility of explaining the generic emergence of power-law scaling in nonequilibrium systems enticed physicists with the promise of insights into a diverse array of systems previously studied primarily by engineers and geophysicists. Bob saw an opportunity to perform experiments that could reveal the intricate structures of stresses and flows in granular materials at the grain scale. His observations had a dramatic effect on our understanding of the rheology of granular systems and on the broader topic now known as jamming. Beginning in 2011 and continuing to the present, his group discovered and elucidated the surprising phenomenon of shear jamming in systems with densities below the critical value for random packing.
Bob’s images of force chains in two-dimensional packings of plastic disks have become icons of the science of granular materials and of the emergence of complex structures in nonequilibrium systems. Those images have captured the imagination of children and adults at science museums around the country and of physicists around the world. In recognition of his research accomplishments, Bob received the 2013 Jesse W. Beams Award from the Southeastern Section of APS.
Bob made several notable contributions to APS and to the broader scientific and engineering communities through his organizational efforts. For many years Bob helped organize the annual Dynamics Days international conference, which brings together physicists, mathematicians, engineers, and researchers in various other fields to share ideas about nonlinear and complex dynamics. He helped found the APS topical groups on statistical and nonlinear physics and on the physics of climate, and he served as chair of both groups in their infancy. Bob also cofounded the journal Granular Matter in 1998 and served as its editor-in-chief. At Duke, Bob cofounded and served as the director of the Center for Nonlinear and Complex Systems, which led to a significant boost in the university’s support of interdisciplinary science.
Bob was an exceptionally encouraging and nurturing adviser of young scientists. He saw the potential for excellence in a diverse group of advisees and exchange students, and he found ways to help them succeed. Through his Magic of Science shows, he extended his passion for science to elementary school students. Outside physics, Bob had many talents that he generously shared with others. He was an accomplished pianist and singer, and he loved French language, culture, and history.
Bob was author or coauthor of some 260 articles. He also leaves behind a rich legacy of 28 PhD students, more than 20 postdoctoral mentees and visitors to his lab, and many students, friends, and colleagues who greatly benefited from and enjoyed his mentorship, innovation, and leadership. We miss him greatly.
