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Hermann Nicolai (born 11 July 1952 in Friedberg) is a German theoretical physicist and director emeritus at the Max Planck Institute for Gravitational Physics in Potsdam-Golm.
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Hermann Nicolai (born 11 July 1952 in Friedberg) is a German theoretical physicist and director emeritus at the Max Planck Institute for Gravitational Physics in Potsdam-Golm.
At Karlsruhe Institute of Technology, Hermann Nicolai, beginning in 1971, studied physics and mathematics with a Diplom in 1975 with a doctorate in 1978 under the supervision of Julius Wess. [1] At Heidelberg University, Nicolai was from 1978 to 1979 an assistant in theoretical physics. From 1979 to 1986, he worked at CERN in Geneva as a staff member in the theory department. In 1983 he received his habilitation at Heidelberg University. He was a professor (with civil service grade C3) of theoretical physics at Karlsruhe Institute of Technology from 1986 to 1988 and from 1988 to 1997 a professor (with civil service grade C4) of theoretical physics at the University of Hamburg. At the Max Planck Institute for Gravitational Physics, Nicolai was head of the department "Quantum Gravity and Unified Field Theories" and a director from 1997 to 2020, when he retired as director emeritus. [2]
He was a member of the editorial board of Communications in Mathematical Physics from 1993 to 1995. Then, from 1998 to 2003 the editor-in-chief of the journal Classical and Quantum Gravity , and from 2006 to 2011 the editor-in-chief of the journal General Relativity and Gravitation . [2]
In 1991, Nicolai received the Otto-Klung-Award (now called the Klung Wilhelmy Science Award), in 2010 the Albert Einstein Medal, and in 2013 the Gay-Lussac-Humboldt Prize. He was appointed an honorary professor at the Humboldt University of Berlin and in 2005 at the University of Hannover. [2]
In the mid 1980s, Nicolai and Bernard de Wit developed the "N = 8 supergravity theory", [3] which arises from the dimensional reduction of the maximally supersymmetrical eleven-dimensional supergravity to four space-time dimensions (d = 4) and for which, from many plausible viewpoints, a maximal supersymmetry has a supergravity theory with a graviton and no particle with a spin greater than 2.
In the 2000s, Nicolai and colleagues investigated the behavior of gravitational equations close to a gravitational singularity such as the Big Bang; [4] these investigation lead to models with chaotic dynamical billiards, in the case of classical general relativity theory in three dimensions. In the case of eleven-dimensional supergravity, these investigations to ten-dimensional "cosmological billiards", and the infinite-dimensional hyperbolic Kac Moody algebra appears as a symmetry. contains the largest finite-dimensional exceptional semi-simple complex Lie algebra , which has been studied as a candidate for a grand unified theory (GUT]. [5] Nicolai proposed a purely algebraic description of the universe in cosmological space-time regions near the singularity (within the Planck time) using the -symmetry, whereby the space-time dimensions result as an emergent phenomenon. [6] [7]
Nicolai has also done research on a special role for in M-Theory.
He and de Wit also constructed maximally gauged (N = 16) supergravity theories in three dimensions and their symmetries. [8] Furthermore, Nicolai and colleagues examined generalizations of the variables of loop quantum gravity to supergravity / string theory.
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In addition to the publications cited in the footnotes:
General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of second order partial differential equations.
The holographic principle is a property of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region — such as a light-like boundary like a gravitational horizon. First proposed by Gerard 't Hooft, it was given a precise string theoretic interpretation by Leonard Susskind, who combined his ideas with previous ones of 't Hooft and Charles Thorn. Leonard Susskind said, "The three-dimensional world of ordinary experience––the universe filled with galaxies, stars, planets, houses, boulders, and people––is a hologram, an image of reality coded on a distant two-dimensional surface." As pointed out by Raphael Bousso, Thorn observed in 1978 that string theory admits a lower-dimensional description in which gravity emerges from it in what would now be called a holographic way. The prime example of holography is the AdS/CFT correspondence.
Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vicinity of black holes or similar compact astrophysical objects, such as neutron stars, as well as in the early stages of the universe moments after the Big Bang.
In theoretical physics, supergravity is a modern field theory that combines the principles of supersymmetry and general relativity; this is in contrast to non-gravitational supersymmetric theories such as the Minimal Supersymmetric Standard Model. Supergravity is the gauge theory of local supersymmetry. Since the supersymmetry (SUSY) generators form together with the Poincaré algebra a superalgebra, called the super-Poincaré algebra, supersymmetry as a gauge theory makes gravity arise in a natural way.
Brane cosmology refers to several theories in particle physics and cosmology related to string theory, superstring theory and M-theory.
In particle physics, the hypothetical dilaton particle is a particle of a scalar field that appears in theories with extra dimensions when the volume of the compactified dimensions varies. It appears as a radion in Kaluza–Klein theory's compactifications of extra dimensions. In Brans–Dicke theory of gravity, Newton's constant is not presumed to be constant but instead 1/G is replaced by a scalar field and the associated particle is the dilaton.
In theoretical physics, the anti-de Sitter/conformal field theory correspondence is a conjectured relationship between two kinds of physical theories. On one side are anti-de Sitter spaces (AdS) that are used in theories of quantum gravity, formulated in terms of string theory or M-theory. On the other side of the correspondence are conformal field theories (CFT) that are quantum field theories, including theories similar to the Yang–Mills theories that describe elementary particles.
GEO600 is a gravitational wave detector located near Sarstedt, a town 20 km to the south of Hanover, Germany. It is designed and operated by scientists from the Max Planck Institute for Gravitational Physics, Max Planck Institute of Quantum Optics and the Leibniz Universität Hannover, along with University of Glasgow, University of Birmingham and Cardiff University in the United Kingdom, and is funded by the Max Planck Society and the Science and Technology Facilities Council (STFC). GEO600 is capable of detecting gravitational waves in the frequency range 50 Hz to 1.5 kHz, and is part of a worldwide network of gravitational wave detectors. This instrument, and its sister interferometric detectors, when operational, are some of the most sensitive gravitational wave detectors ever designed. They are designed to detect relative changes in distance of the order of 10−21, about the size of a single atom compared to the distance from the Sun to the Earth. Construction on the project began in 1995.
Conformal gravity refers to gravity theories that are invariant under conformal transformations in the Riemannian geometry sense; more accurately, they are invariant under Weyl transformations where is the metric tensor and is a function on spacetime.
Loop quantum cosmology (LQC) is a finite, symmetry-reduced model of loop quantum gravity (LQG) that predicts a "quantum bridge" between contracting and expanding cosmological branches.
In theoretical physics, a constraint algebra is a linear space of all constraints and all of their polynomial functions or functionals whose action on the physical vectors of the Hilbert space should be equal to zero.
Marc, Baron Henneaux is a Belgian theoretical physicist and professor at the Université Libre de Bruxelles (ULB) who was born in Brussels on 5 March 1955.
Jürgen Ehlers was a German physicist who contributed to the understanding of Albert Einstein's theory of general relativity. From graduate and postgraduate work in Pascual Jordan's relativity research group at Hamburg University, he held various posts as a lecturer and, later, as a professor before joining the Max Planck Institute for Astrophysics in Munich as a director. In 1995, he became the founding director of the newly created Max Planck Institute for Gravitational Physics in Potsdam, Germany.
Bernard F. Schutz FInstP FLSW is an American and naturalised British physicist. He is well known for his research in Einstein's theory of general relativity, especially for his contributions to the detection of gravitational waves, and for his textbooks. Schutz is a Fellow of the Royal Society and a Member of the US National Academy of Sciences. He is a professor of physics and astronomy at Cardiff University, and was a founding director of the Max Planck Institute for Gravitational Physics in Potsdam, Germany, where he led the Astrophysical Relativity division from 1995 to 2014. Schutz was a founder and principal investigator of the GEO gravitational wave collaboration, which became part of the LIGO Scientific Collaboration (LSC). Schutz was also one of the initiators of the proposal for the space-borne gravitational wave detector LISA, and he coordinated the European planning for its data analysis until the mission was adopted by ESA in 2016. Schutz conceived and in 1998 began publishing from the AEI the online open access (OA) review journal Living Reviews in Relativity, which for many years has been the highest-impact OA journal in the world, as measured by Clarivate.
In mathematical physics, de Sitter invariant special relativity is the speculative idea that the fundamental symmetry group of spacetime is the indefinite orthogonal group SO(4,1), that of de Sitter space. In the standard theory of general relativity, de Sitter space is a highly symmetrical special vacuum solution, which requires a cosmological constant or the stress–energy of a constant scalar field to sustain.
In cosmology, the cosmological constant problem or vacuum catastrophe is the substantial disagreement between the observed values of vacuum energy density and the much larger theoretical value of zero-point energy suggested by quantum field theory.
Renata Elizaveta Kallosh is a Russian-American theoretical physicist. She is a professor of physics at Stanford University, working there on supergravity, string theory and inflationary cosmology.
Alessandra Buonanno is an Italian-American theoretical physicist and director at the Max Planck Institute for Gravitational Physics in Potsdam. She is the head of the "Astrophysical and Cosmological Relativity" department. She holds a research professorship at the University of Maryland, College Park, and honorary professorships at the Humboldt University in Berlin, and the University of Potsdam. She is a leading member of the LIGO Scientific Collaboration, which observed gravitational waves from a binary black-hole merger in 2015.
In theoretical physics, the dual graviton is a hypothetical elementary particle that is a dual of the graviton under electric-magnetic duality, as an S-duality, predicted by some formulations of eleven-dimensional supergravity.
Pietro G. Frè is an Italian theoretical physicist and an emeritus full professor of the University of Turin.
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