M-theory is a theory in physics that unifies all consistent versions of superstring theory. Edward Witten first conjectured the existence of such a theory at a string theory conference at the University of Southern California in 1995. Witten's announcement initiated a flurry of research activity known as the second superstring revolution. Prior to Witten's announcement, string theorists had identified five versions of superstring theory. Although these theories initially appeared to be very different, work by many physicists showed that the theories were related in intricate and nontrivial ways. Physicists found that apparently distinct theories could be unified by mathematical transformations called S-duality and T-duality. Witten's conjecture was based in part on the existence of these dualities and in part on the relationship of the string theories to a field theory called eleven-dimensional supergravity.
String field theory (SFT) is a formalism in string theory in which the dynamics of relativistic strings is reformulated in the language of quantum field theory. This is accomplished at the level of perturbation theory by finding a collection of vertices for joining and splitting strings, as well as string propagators, that give a Feynman diagram-like expansion for string scattering amplitudes. In most string field theories, this expansion is encoded by a classical action found by second-quantizing the free string and adding interaction terms. As is usually the case in second quantization, a classical field configuration of the second-quantized theory is given by a wave function in the original theory. In the case of string field theory, this implies that a classical configuration, usually called the string field, is given by an element of the free string Fock space.
Michael James Duff FRS, FRSA is a British theoretical physicist and pioneering theorist of supergravity who is the Principal of the Faculty of Physical Sciences and Abdus Salam Chair of Theoretical Physics at Imperial College London.
In theoretical physics, type I string theory is one of five consistent supersymmetric string theories in ten dimensions. It is the only one whose strings are unoriented and the only one which contains not only closed strings, but also open strings.
Joël Scherk was a French theoretical physicist who studied string theory and supergravity.
Tamiaki Yoneya is a Japanese physicist.
In theoretical physics, the anti-de Sitter/quantum chromodynamics correspondence is a goal to describe quantum chromodynamics (QCD) in terms of a dual gravitational theory, following the principles of the AdS/CFT correspondence in a setup where the quantum field theory is not a conformal field theory.
Bernard Julia is a French theoretical physicist who has made contributions to the theory of supergravity. He graduated from Université Paris-Sud in 1978, and is directeur de recherche with the CNRS working at the École Normale Supérieure. In 1978, together with Eugène Cremmer and Joël Scherk, he constructed 11-dimensional supergravity. Shortly afterwards, Cremmer and Julia constructed the classical Lagrangian for four-dimensional N=8 supergravity by dimensional reduction from the 11-dimensional theory. Julia also studied spontaneous symmetry breaking and the Higgs mechanism in supergravity
The history of string theory spans several decades of intense research including two superstring revolutions. Through the combined efforts of many researchers, string theory has developed into a broad and varied subject with connections to quantum gravity, particle and condensed matter physics, cosmology, and pure mathematics.
David Ian Olive ; 16 April 1937 – 7 November 2012) was a British theoretical physicist. Olive made fundamental contributions to string theory and duality theory, he is particularly known for his work on the GSO projection and Montonen–Olive duality.
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.
Warren Siegel is a theoretical physicist specializing in supersymmetric quantum field theory and string theory. He was a professor at the C. N. Yang Institute for Theoretical Physics at Stony Brook University. He retired in Fall of 2022.
André Neveu is a French physicist working on string theory and quantum field theory who coinvented the Neveu–Schwarz algebra and the Gross–Neveu model.
Ferdinando Gliozzi is a string theorist at the Istituto Nazionale di Fisica Nucleare. Along with David Olive and Joël Scherk, he proposed the GSO projection to map out the tachyonic states in the Neveu–Schwarz sector.
Werner Nahm is a German theoretical physicist. He has made contributions to mathematical physics and fundamental theoretical physics.
Peter Christopher West, born on 4 December 1951, is a British theoretical physicist at King's College, London and a fellow of the Royal Society.
Claus Kalevi Montonen is a Finnish theoretical physicist, most known for his work with British physicist David Olive in proposing the Montonen–Olive duality.
Eric D’Hoker is a Belgian-American theoretical physicist.
Hermann Nicolai is a German theoretical physicist and director emeritus at the Max Planck Institute for Gravitational Physics in Potsdam-Golm.
Costas Christou Kounnas was a Cypriot theoretical physicist, known for his research on string theory, supersymmetry, supergravity, GUTs, and quantum chromodynamics.
