Matthew W. Choptuik | |
---|---|
Born | 1961 (age 62–63) |
Nationality | Canadian |
Alma mater | University of British Columbia |
Scientific career | |
Fields | Theoretical physics |
Thesis | A Study of Numerical Techniques for Radiative Problems in General Relativity (1986) |
Doctoral advisor | W. G. Unruh |
Doctoral students | Frans Pretorius |
Matthew William Choptuik (born 1961) is a Canadian theoretical physicist specializing in numerical relativity.
Choptuik graduated from University of British Columbia with a master's degree in 1982 and a Ph.D. advised by William Unruh in 1986. He became an associate professor in 1995 at the University of Texas at Austin. In 1999 he became a member of the Institute for Theoretical Physics at the University of California, Santa Barbara and in the same year he became a professor at University of British Columbia.
In 1993, [1] he discovered critical phenomena in gravitational collapse [2] via numerical studies. He showed—under non-generic initial conditions [3] —the possibility of the occurrence of naked singularity in general relativity with scalar matter. This had previously been the subject of a bet between Stephen Hawking, Kip Thorne and John Preskill. Hawking lost the bet after Choptuik's publication, but renewed it under non-generic initial conditions. [4]
Choptuik was the 2001 awardee of the Rutherford Memorial Medal. In 2003 he received the CAP-CRM Prize in Theoretical and Mathematical Physics. In 2003 he became a fellow of the American Physical Society. In 2002, he became an honorary doctor of Brandon University.
A black hole is a region of spacetime where gravity is so strong that nothing, not even light and other electromagnetic waves, is capable of possessing enough energy to escape it. Einstein's theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. A black hole has a great effect on the fate and circumstances of an object crossing it, but it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly.
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch is believed to have lasted from 10−36 seconds to between 10−33 and 10−32 seconds after the Big Bang. Following the inflationary period, the universe continued to expand, but at a slower rate. The re-acceleration of this slowing expansion due to dark energy began after the universe was already over 7.7 billion years old.
The weak and the strong cosmic censorship hypotheses are two mathematical conjectures about the structure of gravitational singularities arising in general relativity.
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.
In general relativity, a naked singularity is a hypothetical gravitational singularity without an event horizon.
A gravitational singularity, spacetime singularity or simply singularity is a condition in which gravity is predicted to be so intense that spacetime itself would break down catastrophically. As such, a singularity is by definition no longer part of the regular spacetime and cannot be determined by "where" or "when". Gravitational singularities exist at a junction between general relativity and quantum mechanics; therefore, the properties of the singularity cannot be described without an established theory of quantum gravity. Trying to find a complete and precise definition of singularities in the theory of general relativity, the current best theory of gravity, remains a difficult problem. A singularity in general relativity can be defined by the scalar invariant curvature becoming infinite or, better, by a geodesic being incomplete.
The Large Scale Structure of Space–Time is a 1973 treatise on the theoretical physics of spacetime by the physicist Stephen Hawking and the mathematician George Ellis. It is intended for specialists in general relativity rather than newcomers.
The no-hair theorem states that all stationary black hole solutions of the Einstein–Maxwell equations of gravitation and electromagnetism in general relativity can be completely characterized by only three independent externally observable classical parameters: mass, electric charge, and angular momentum. Other characteristics are uniquely determined by these three parameters, and all other information about the matter that formed a black hole or is falling into it "disappears" behind the black-hole event horizon and is therefore permanently inaccessible to external observers after the black hole "settles down". Physicist John Archibald Wheeler expressed this idea with the phrase "black holes have no hair", which was the origin of the name.
Kip Stephen Thorne is an American theoretical physicist and writer known for his contributions in gravitational physics and astrophysics. Along with Rainer Weiss and Barry C. Barish, he was awarded the 2017 Nobel Prize in Physics for his contributions to the LIGO detector and the observation of gravitational waves.
Jacob David Bekenstein was a Mexican-born American-Israeli theoretical physicist who made fundamental contributions to the foundation of black hole thermodynamics and to other aspects of the connections between information and gravitation.
Micro black holes, also called mini black holes or quantum mechanical black holes, are hypothetical tiny black holes, for which quantum mechanical effects play an important role. The concept that black holes may exist that are smaller than stellar mass was introduced in 1971 by Stephen Hawking.
Numerical relativity is one of the branches of general relativity that uses numerical methods and algorithms to solve and analyze problems. To this end, supercomputers are often employed to study black holes, gravitational waves, neutron stars and many other phenomena described by Einstein's theory of general relativity. A currently active field of research in numerical relativity is the simulation of relativistic binaries and their associated gravitational waves.
Demetrios Christodoulou is a Greek mathematician and physicist, who first became well known for his proof, together with Sergiu Klainerman, of the nonlinear stability of the Minkowski spacetime of special relativity in the framework of general relativity. Christodoulou is a 1993 MacArthur Fellow.
In theoretical physics, particularly fringe physics, polarizable vacuum (PV) and its associated theory refer to proposals by Harold Puthoff, Robert H. Dicke, and others to develop an analog of general relativity to describe gravity and its relationship to electromagnetism.
Robert M. Wald is an American theoretical physicist and professor at the University of Chicago. He studies general relativity, black holes, and quantum gravity and has written textbooks on these subjects.
The initial value formulation of general relativity is a reformulation of Albert Einstein's theory of general relativity that describes a universe evolving over time.
Tsvi Piran is an Israeli theoretical physicist and astrophysicist, best known for his work on Gamma-ray Bursts (GRBs) and on numerical relativity. The recipient of the 2019 EMET prize award in Physics and Space Research.
Frans Pretorius is a South African and Canadian physicist, specializing in computer simulations in astrophysics and numerical solutions of Einstein's field equations. He is professor of physics at Princeton University and director of the Princeton Gravity Initiative.
Stuart Louis Shapiro is an American theoretical astrophysicist, who works on numerical relativity with applications in astrophysics, specialising in compact objects such as neutron stars and black holes.
Richard Alfred Matzner is an American physicist, working mostly in the field of general relativity and cosmology, including numerical relativity, kinetic theory, black hole physics, and gravitational radiation. He is Professor of Physics at the University of Texas at Austin where he directed the Center for Relativity. In 1993 he organized and was Lead Principal Investigator of an NSF/ARPA funded computational Grand Challenge program involving ten university teams seeking computational descriptions for the interaction of black holes as potential sources for observable gravitational radiation. His work leading what became known as the Binary Black Hole Grand Challenge Alliance featured in Kip Thorne's Nobel Prize lecture, including when Matzner and Alliance collaborators wagered Thorne that numerical relativity would produce a simulated waveform comparable to observation prior to the first LIGO detection. Matzner and colleagues eventually won, Thorne saying he "conceded the bet with great happiness."