John David Reppy (born February 16, 1931) is a

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and the John L. Wetherill Professor of Physics Emeritus at

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

. He studies the quantum properties of

superfluid Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without any loss of kinetic energy. When stirred, a superfluid forms vortices that continue to rotate indefinitely. Superfluidity occurs in two ...

s such as

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

. Reppy is also a notable

rock climber Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically an ...

of long standing. He established a number of widely known climbing routes particularly in the northeastern United States.

Early life and education

John David Reppy was born February 16, 1931 in

Lakehurst, New Jersey Lakehurst is a borough in Ocean County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 2,654,US Naval Air Station, where he worked with helium as a

lifting gas A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result. It is required for aerostats to create buoyancy, particularly in lighter-than-air aircraft, which include ballo ...

for naval lighter-than-air aviation. The family moved almost every year to follow his military placements, including an assignment to

Pearl Harbor Pearl Harbor is an American lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. It was often visited by the Naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U.S. with the signing of the R ...

prior to

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. In 1943 he was sent to the western Pacific and the rest of the family settled in Haddam Neck,

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its capita ...

. In Connecticut John Reppy became interested in herpetology,

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

and rock climbing, exploring local quarries. He graduated from high school in 1950. Reppy immediately enrolled at the

University of Connecticut The University of Connecticut (UConn) is a public land-grant research university in Storrs, Connecticut, a village in the town of Mansfield. The primary 4,400-acre (17.8 km2) campus is in Storrs, approximately a half hour's drive from H ...

, 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 David Morris Lee (born January 20, 1931) is an American physicist who shared the 1996 Nobel Prize in Physics with Robert C. Richardson and Douglas Osheroff "for their discovery of superfluidity in helium-3." Lee is professor emeritus of physics ...

, 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. In 1956, Reppy joined Cecil T. Lane's Yale Low Temperature group at

Yale University Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wo ...

. As part of his Ph.D. work, Reppy adapted a design by

Jesse Beams Jesse Wakefield Beams (December 25, 1898 in Belle Plaine, Kansas – July 23, 1977) was an American physicist at the University of Virginia. Biography Beams completed his undergraduate B.A. in physics at Fairmount College in 1921 and his mas ...

and built an apparatus for rotating a container of liquid helium in vacuum and measuring the helium's angular momentum. He completed his dissertation in 1960, and received his Ph.D from Yale University in 1961. Reppy spent 1961 working with

Nicholas Kurti Nicholas Kurti, ( hu, Kürti Miklós) (14 May 1908 – 24 November 1998) was a Hungarian-born British physicist who lived in Oxford, UK, for most of his life. Career Born in Budapest, Kurti went to high school at the Minta Gymnasium, but due ...

Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...

on a

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...

(NSF) Fellowship.

Rock climbing

In the 1950s and 60s, Reppy was active on Ragged Mountain in

where he collaborated on many first ascents and on publishing an area guidebook with Sam Streibert. The well-known Reppy's Crack on Cannon Mountain in New Hampshire bears his name and he has made first ascents as of number of routes in the Shawangunks and elsewhere. He made early attempts on Armadillo, a long alpine rock climb on

Mount Katahdin Mount Katahdin ( ) is the highest mountain in the U.S. state of Maine at . Named Katahdin, which means "Great Mountain", by the Penobscot Native Americans, it is within Northeast Piscataquis, Piscataquis County, and is the centerpiece of Bax ...

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and ...

. In addition, he has climbed extensively in England, the

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

and western America. Reppy has said his earliest interest in rock climbing as a very young teenager was related to the re-opening of small open-pit mica mines in eastern Connecticut during World War II in response to increased war-time demand for electronics materials. Reppy was among the first climbers in the United States to practice so-called "

clean climbing Clean climbing is rock climbing techniques and equipment which climbers use in order to avoid damage to the rock. These techniques date at least in part from the 1920s and earlier in England, but the term itself may have emerged in about 1970 du ...

" 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 Yvon Chouinard (born November 9, 1938) is an American rock climber, environmentalist, philanthropist and outdoor industry businessman. His company, Patagonia, is known for its commitment to protecting the environment. Chouinard is also a surf ...

and

John Stannard John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second ...

Scientific career

Reppy returned to

New Haven, Connecticut New Haven is a city in the U.S. state of Connecticut. It is located on New Haven Harbor on the northern shore of Long Island Sound in New Haven County, Connecticut and is part of the New York City metropolitan area. With a population of 134,02 ...

in 1962, and spent four years as an assistant professor at Yale University. He joined the

Physics Department in 1966, becoming the John Wetherill Professor of Physics in 1987. As physics professor at Cornell University, he studies quantum properties of superfluids with an emphasis on boundary conditions and phase transitions in systems of reduced dimensionality. Reppy's research group has close associations with

and Robert C. Richardson also of Cornell, who shared the 1996 Nobel Prize in Physics with

Douglas D. Osheroff Douglas Dean Osheroff (born August 1, 1945) is an American physicist known for his work in experimental condensed matter physics, in particular for his co-discovery of superfluidity in Helium-3. For his contributions he shared the 1996 Nobel Pr ...

for discoveries related to super fluidity in helium-3 ice. Lee, in his Nobel Prize speech, credited Reppy's "extraordinary technical ingenuity" in experiments leading to the discovery. In the speech, Lee made other references to Reppy, noting that his work helped confirm related insights. Reppy also figured at least on the fringes of the 2001 Nobel Prize for Physics which was awarded to

Eric Cornell Eric Allin Cornell (born December 19, 1961) is an American physicist who, along with Carl E. Wieman, was able to synthesize the first Bose–Einstein condensate in 1995. For their efforts, Cornell, Wieman, and Wolfgang Ketterle shared the Nobel ...

and Carl Wieman of the Joint Institute for Laboratory Astrophysics, or JILA, in Boulder, Colo., and

Wolfgang Ketterle Wolfgang Ketterle (; born 21 October 1957) is a German physicist and professor of physics at the Massachusetts Institute of Technology (MIT). His research has focused on experiments that trap and cool atoms to temperatures close to absolute ze ...

of the Massachusetts Institute of Technology.

Bose–Einstein condensation Bose–Einstein may refer to: * Bose–Einstein condensate ** Bose–Einstein condensation (network theory) * Bose–Einstein correlations * Bose–Einstein statistics In quantum statistics, Bose–Einstein statistics (B–E statistics) describe ...

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". Physicists generally agree that the atoms in

helium-4 Helium-4 () is a stable isotope of the element helium. It is by far the more abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on Earth. Its nucleus is identical to an alpha particle, and consis ...

is not a Bose–Einstein condensate in the original sense of the term because its atoms interact too strongly. Reppy studied an exception: tiny amounts of helium trapped in nanometer-sized pores of a spongelike glass called Vycor. Even though the pores keep its atoms too far apart to jostle one another much, the helium still behaves like a three-dimensional fluid. In 1983 Reppy and colleagues reported results that suggested the helium was sloshing through the glass as a true Bose–Einstein condensate. Separately, work from Cornell physics laboratories has been used to test a theory of

cosmic strings Cosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry-breaking phase transition in the early universe when the topology of the vacuum manifold associated to this symmetry breaking was not simp ...

, 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 Fritz Wolfgang London (March 7, 1900 – March 30, 1954) was a German physicist and professor at Duke University. His fundamental contributions to the theories of chemical bonding and of intermolecular forces ( London dispersion forces) are today ...

Memorial Prize in 1981 and the NASA Distinguished Public Service Medal for leadership and support to the

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

microgravity fundamental physics program in 2000. Reppy is also a member of the National Academy of Sciences (1988).

Early life and education

Rock climbing

Scientific career

Awards

References

Further reading