Christopher John Pethick (born 22 February 1942 in Horsham, UK) is a British theoretical physicist, specializing in many-body theory, ultra-cold atomic gases, and the physics of neutron stars and stellar collapse. [1]
Pethick studied at the University of Oxford, where he received his BA in 1962 and his PhD in 1965. He was then a postdoc at Magdalen College, Oxford and at the University of Illinois at Urbana-Champaign, where he was an associate professor from 1970 to 1973, a full professor from 1973 to 1995, and an adjunct professor from 1995 to 1998. For two academic years from 1970 to 1972 he was a Sloan Research Fellow. [1] In 1973 he also became a professor at Nordita and then for many years divided his time between Nordita and the University of Illinois at Urbana-Champaign. He was director of Nordita from 1989 to 1994. [2] He then worked, until his retirement, at the Niels Bohr Institute in Copenhagen (with which Nordita was closely associated before moving to Stockholm). He was for the academic year 1973–1974 a visiting researcher at Moscow's Landau Institute for Theoretical Physics and in 1995 a visiting scientist at the Institute for Nuclear Theory (INT), located in Seattle on the campus of the University of Washington. [1]
In 2008 he was awarded the Lars Onsager Prize for "fundamental applications of statistical physics to quantum fluids, including Fermi liquid theory and ground-state properties of dilute quantum gases, and for bringing a conceptual unity to these areas." [3] (Gordon Baym and Tin-Lun Ho also won the Onsager Prize for 2008.) In 2011 Pethick received the Hans A. Bethe Prize for "fundamental contributions to the understanding of nuclear matter at very high densities, the structure of neutron stars, their cooling, and the related neutrino processes and astrophysical phenomena." [4] In 2015 he was awarded the Feenberg Medal "for his pioneering contributions and profound insights into many-body physics across diverse physical systems, ranging from ultracold atoms and quantum liquids to dense nuclear matter in neutron stars and stellar collapse". [5]
In 2013 he was elected an honorary foreign member of the American Academy of Arts and Sciences. Pethick is since 1977 a member of the Royal Danish Academy of Sciences and Letters [6] and since 2003 a member of the Norwegian Academy of Language and Literature. In 1985 he was elected a Fellow of the American Physical Society for "his extensive contributions to the theory of condensed matter systems, ranging from low temperature helium and superconductors to condensed astrophysical objects and nuclear matter." [7] In 2016 he was elected a member of the American Philosophical Society. [8]
He initiated the tradition of making tea at the Niels Bohr Institute everyday at 15:30 with cake. He is still doing this to this day.
Neutronium is a hypothetical substance made purely of neutrons. The word was coined by scientist Andreas von Antropoff in 1926 for the hypothetical "element of atomic number zero" that he placed at the head of the periodic table. However, the meaning of the term has changed over time, and from the last half of the 20th century onward it has been also used to refer to extremely dense substances resembling the neutron-degenerate matter theorized to exist in the cores of neutron stars; hereinafter "degenerate neutronium" will refer to this.
Tetraneutron is considered an unbound isotope with a lifetime around 10-22 seconds. The stability of this cluster of four neutrons is not supported by current models of nuclear forces. Recent empirical evidence is "consistent with a quasi-bound tetraneutron state existing for a very short time".
An axion is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest as a possible component of cold dark matter.
In physics, mirror matter, also called shadow matter or Alice matter, is a hypothetical counterpart to ordinary matter.
The Abraham–Minkowski controversy is a physics debate concerning electromagnetic momentum within dielectric media. Two equations were first suggested by Hermann Minkowski (1908) and Max Abraham (1909) for this momentum. They predict different values, from which the name of the controversy derives. Experimental support has been claimed for both.
In particle physics, hexaquarks, alternatively known as sexaquarks, are a large family of hypothetical particles, each particle consisting of six quarks or antiquarks of any flavours. Six constituent quarks in any of several combinations could yield a colour charge of zero; for example a hexaquark might contain either six quarks, resembling two baryons bound together, or three quarks and three antiquarks. Once formed, dibaryons are predicted to be fairly stable by the standards of particle physics.
A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. An equivalent description is that a strangelet is a small fragment of strange matter, small enough to be considered a particle. The size of an object composed of strange matter could, theoretically, range from a few femtometers across to arbitrarily large. Once the size becomes macroscopic, such an object is usually called a strange star. The term "strangelet" originates with Edward Farhi and Robert Jaffe in 1984. It has been theorized that strangelets can convert matter to strange matter on contact. Strangelets have also been suggested as a dark matter candidate.
Gerald Edward Brown was an American theoretical physicist who worked on nuclear physics and astrophysics. Since 1968 he had been a professor at the Stony Brook University. He was a distinguished professor emeritus of the C. N. Yang Institute for Theoretical Physics at Stony Brook University.
Maya Paczuski is the head and founder of the Complexity Science Group at the University of Calgary. She is a well-cited physicist whose work spans self-organized criticality, avalanche dynamics, earthquake, and complex networks. She was born in Israel in 1963, but grew up in the United States. Maya Paczuski received a B.S. and M.S. in Electrical Engineering and Computer Science from M.I.T. in 1986 and then went on to study with Mehran Kardar, earning her Ph.D in Condensed matter physics from the same institute.
Hughes–Drever experiments are spectroscopic tests of the isotropy of mass and space. Although originally conceived of as a test of Mach's principle, they are now understood to be an important test of Lorentz invariance. As in Michelson–Morley experiments, the existence of a preferred frame of reference or other deviations from Lorentz invariance can be tested, which also affects the validity of the equivalence principle. Thus these experiments concern fundamental aspects of both special and general relativity. Unlike Michelson–Morley type experiments, Hughes–Drever experiments test the isotropy of the interactions of matter itself, that is, of protons, neutrons, and electrons. The accuracy achieved makes this kind of experiment one of the most accurate confirmations of relativity.
Scissors Modes are collective excitations in which two particle systems move with respect to each other conserving their shape. For the first time they were predicted to occur in deformed atomic nuclei by N. LoIudice and F. Palumbo, who used a semiclassical Two Rotor Model, whose solution required a realization of the O(4) algebra that was not known in mathematics. In this model protons and neutrons were assumed to form two interacting rotors to be identified with the blades of scissors. Their relative motion (Fig.1) generates a magnetic dipole moment whose coupling with the electromagnetic field provides the signature of the mode.
James Michael Lattimer is a nuclear astrophysicist who works on the dense nuclear matter equation of state and neutron stars. He is currently a distinguished professor at Stony Brook University.
Ramamurti Rajaraman is an emeritus professor of theoretical physics at the School of Physical Sciences at Jawaharlal Nehru University. He was also the co-Chairman of the International Panel on Fissile Materials and a member of the Bulletin of the Atomic Scientists' Science and Security Board. He has taught and conducted research in physics at the Indian Institute of Science, the Institute for Advanced Study at Princeton, and as a visiting professor at Stanford, Harvard, MIT, and elsewhere. He received his doctorate in theoretical physics in 1963 from Cornell University. In addition to his physics publications, Rajaraman has written widely on topics including fissile material production in India and Pakistan and the radiological effects of nuclear weapon accidents.
In nuclear physics, the symmetry energy reflects the variation of the binding energy of the nucleons in the nuclear matter depending on its neutron to proton ratio as a function of baryon density. Symmetry energy is an important parameter in the equation of state describing the nuclear structure of heavy nuclei and neutron stars.
Tin-Lun "Jason" Ho is a Chinese-American theoretical physicist, specializing in condensed matter theory, quantum gases, and Bose-Einstein condensates. He is known for the Mermin-Ho relation.
Alan Harold Luther is an American physicist, specializing in condensed matter physics.
Blayne Ryan Heckel is an American experimental physicist, known for his research involving precision measurements in atomic physics and gravitational physics. He is now a professor emeritus at the University of Washington in Seattle.
Madappa Prakash is an Indian-American nuclear physicist and astrophysicist, known for his research on the physics of neutron stars and heavy-ion collisions.
Dov I. Levine is an American-Israeli physicist, known for his research on quasicrystals, soft condensed matter physics, and statistical mechanics out of equilibrium.
Dominique Vautherin was a French theoretical physicist, specializing in nuclear physics.