 | This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages)
|
Robert G. Leigh | |
|---|---|
| Born | |
| Alma mater | University of Guelph University of Texas at Austin |
| Scientific career | |
| Fields | particle physics |
| Institutions | University of Illinois at Urbana-Champaign |
| Doctoral advisor | Joseph Polchinski |
Robert Graham Leigh is a Canadian physicist working on string theory.
Leigh obtained his B.Sc. degree from the University of Guelph in 1986, and his Ph.D. from the University of Texas at Austin in 1991, working with Joe Polchinski. After postdoctoral positions at Santa Cruz and Rutgers, he has been a professor at the University of Illinois at Urbana-Champaign since 1996. Since 2007, he has been a Fellow of the American Physical Society. [1]
Leigh discovered, in association with Dai and Polchinski, an important class of extended objects in string theory, the D-branes.
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity.
In string theory, D-branes, short for Dirichlet membrane, are a class of extended objects upon which open strings can end with Dirichlet boundary conditions, after which they are named. D-branes are typically classified by their spatial dimension, which is indicated by a number written after the D. A D0-brane is a single point, a D1-brane is a line, a D2-brane is a plane, and a D25-brane fills the highest-dimensional space considered in bosonic string theory. There are also instantonic D(–1)-branes, which are localized in both space and time.
Joseph Gerard Polchinski Jr. was an American theoretical physicist and string theorist.
Cumrun Vafa is an Iranian-American theoretical physicist and the Hollis Professor of Mathematics and Natural Philosophy at Harvard University.
In string theory, a heterotic string is a closed string (or loop) which is a hybrid ('heterotic') of a superstring and a bosonic string. There are two kinds of heterotic superstring theories, the heterotic SO(32) and the heterotic E8 × E8, abbreviated to HO and HE. Apart from that there exist seven more heterotic string theories which are not supersymmetric and hence are only of secondary importance in most applications. Heterotic string theory was first developed in 1985 by David Gross, Jeffrey Harvey, Emil Martinec, and Ryan Rohm (the so-called "Princeton string quartet"), in one of the key papers that fueled the first superstring revolution.
Andrew Eben Strominger is an American theoretical physicist who is the director of Harvard's Center for the Fundamental Laws of Nature. He has made significant contributions to quantum gravity and string theory. These include his work on Calabi–Yau compactification and topology change in string theory, and on the stringy origin of black hole entropy. He is a senior fellow at the Society of Fellows, and is the Gwill E. York Professor of Physics.
Shamit Kachru is an American theoretical physicist, a professor emeritus of physics at Stanford University, and a former Wells Family Director of the Stanford Institute for Theoretical Physics. He served as the Stanford Physics Department Chair from 2018 to 2021. He retired in 2023.
Eva Silverstein is an American theoretical physicist, cosmologist, and string theorist. She is a professor of physics at Stanford University and director of the Modern Inflationary Cosmology collaboration within the Simons Foundation Origins of the Universe initiative.
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 perturbatively contains not only closed strings, but also open strings. The terminology of type I and type II was coined by John Henry Schwarz in 1982 to classify the three string theories known at the time.
Petr Hořava is a Czech string theorist. He is a professor of physics in the Berkeley Center for Theoretical Physics at the University of California, Berkeley, where he teaches courses on quantum field theory and string theory. Hořava is a member of the theory group at Lawrence Berkeley National Laboratory.
Stanley Mandelstam was a South African theoretical physicist. He introduced the relativistically invariant Mandelstam variables into particle physics in 1958 as a convenient coordinate system for formulating his double dispersion relations. The double dispersion relations were a central tool in the bootstrap program which sought to formulate a consistent theory of infinitely many particle types of increasing spin.
The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next is a 2006 book by the theoretical physicist Lee Smolin about the problems with string theory. The book strongly criticizes string theory and its prominence in contemporary theoretical physics, on the grounds that string theory has yet to come up with a single prediction that can be verified using any technology that is likely to be feasible within our lifetimes. Smolin also focuses on the difficulties faced by research in quantum gravity, and by current efforts to come up with a theory explaining all four fundamental interactions. The book is broadly concerned with the role of controversy and diversity of approaches in scientific processes and ethics.
The Type 0 string theory is a less well-known model of string theory. It is a superstring theory in the sense that the worldsheet theory is supersymmetric. However, the spacetime spectrum is not supersymmetric and, in fact, does not contain any fermions at all. In dimensions greater than two, the ground state is a tachyon so the theory is unstable. These properties make it similar to the bosonic string and an unsuitable proposal for describing the world as we observe it, although a GSO projection does get rid of the tachyon and the even G-parity sector of the theory defines a stable string theory. The theory is used sometimes as a toy model for exploring concepts in string theory, notably closed string tachyon condensation. Some other recent interest has involved the two-dimensional Type 0 string which has a non-perturbatively stable matrix model description.
Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings.
Paul Kingsley Townsend FRS is a British physicist, currently a Professor of Theoretical Physics in Cambridge University's Department of Applied Mathematics and Theoretical Physics. He is notable for his work on string theory.
Raphael Bousso is a theoretical physicist and cosmologist. He is a professor at the Berkeley Center for Theoretical Physics in the Department of Physics, UC Berkeley. He is known for the Bousso bound on the information content of the universe. With Joseph Polchinski, Bousso proposed the string theory landscape as a solution to the cosmological constant problem.
Ryan Milton Rohm is an American string theorist. He is one of four physicists known as the Princeton string quartet, and is responsible for the development of heterotic string theory along with David Gross, Jeffrey A. Harvey and Emil Martinec, the other members of the Princeton String Quartet.
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.
Gary T. Horowitz is an American theoretical physicist who works on string theory and quantum gravity.
João Miguel Augusto Penedones Fernandes is a Portuguese theoretical physicist active in the area of quantum field theory. He is currently an associate professor at the École Polytechnique Fédérale de Lausanne (EPFL).
| International | |
|---|---|
| Academics | |
   | This article about a Canadian scientist is a stub. You can help Wikipedia by expanding it. |
 | This article about a physicist is a stub. You can help Wikipedia by expanding it. |
