John Reppy

Early life and education John David Reppy was born February 16, 1931, in Lakehurst, New Jersey. His father was stationed at the US Naval Air Station, where he worked with helium as a lifting gas for naval lighter-than-air aviation. The family moved almost every year to follow his military placements, including an assignment to Pearl Harbor prior to World War II. In 1943 he was sent to the western Pacific and the rest of the family settled in Haddam Neck, Connecticut.

In Connecticut John Reppy became interested in herpetology, geology and rock climbing, exploring local quarries. He graduated from high school in 1950.

Reppy immediately enrolled at the University of Connecticut, beginning with summer school. He majored in mathematics but also began working for his thermodynamics instructor Charles Reynolds. At this time Reppy became friends with David M. Lee, who was also a student. Reppy received a bachelor's degree in math and physics in 1954 at University of Connecticut and a master's degree from the same school two years later. Reppy spent 1961 working with Nicholas Kurti in Oxford on a National Science Foundation (NSF) Fellowship.

Reppy was among the first climbers in the United States to practice so-called "clean climbing" techniques, which he learned in England. While most climbers of the day were hammering their way up the cliffs with pitons, Reppy helped introduce the use of nuts, which at the time consisted of hex nuts from truck wheels, strung with nylon webbing. Unlike pitons, nuts are placed and removed without the use of hammers and save the rock from permanent damage. The technique often makes placements easier and faster to achieve, and thus may make difficult climbs easier to complete. Many advances in rock climbing were made possible by this method. Among a substantial number of others deserving credit for this trend in the U.S. are Yvon Chouinard and John Stannard.

Scientific career Reppy returned to New Haven, Connecticut, in 1962, and spent four years as an assistant professor at Yale University. He joined the Cornell University Physics Department in 1966, becoming the John Wetherill Professor of Physics in 1987.

Reppy's work form 1983 also figured at least on the fringes of the 2001 Nobel Prize for Physics which was awarded to Eric Cornell and Carl Wieman of the JILA, in Boulder, Colo., and Wolfgang Ketterle of the Massachusetts Institute of Technology. Bose–Einstein condensation was predicted in 1924, and was seen decades ago in liquid helium, according to Ketterle, who acknowledged a controversial earlier claim by Reppy. Ketterle says that Reppy brought this finding to his attention, and that the priority claim was fair. "I think the results appeared conclusive", Ketterle reportedly said. Co-laureate Wieman reportedly said that Reppy's claim is "really a stretch" and that "Ketterle is being gracious".

Separately, work from Cornell physics laboratories has been used to test a theory of cosmic strings, hypothetical objects, which may have been important in the formation of galaxies, and may have arisen through "phase transitions" in a fraction of a second after the Big Bang.

Awards Reppy is the recipient of numerous awards and honors, including the Fritz London Memorial Prize in 1981 and the NASA Distinguished Public Service Medal for leadership and support to the NASA microgravity fundamental physics program in 2000. Reppy is also a member of the National Academy of Sciences (1988). In 2025, the 2026 Oliver E. Buckley Prize was awarded to Reppy, David J. Bishop, Gwendal Fève and Michael James Manfra for "groundbreaking experiments that uncovered the role of vortices in the superfluid phase transition in helium films and observed anyonic braiding statistics of quasiparticles in the fractional quantum Hall effect, thus establishing the significance of topological excitations in two-dimensions."