Information: - Modern physics is the post-Newtonian conception of physics. It implies that classical descriptions of phenomena are lacking, and that an accurate, "modern", description of nature requires theories to incorporate elements of quantum mechanics or Einsteinian relativity, or both. In general, the term is used to refer to any branch of physics either developed in the early 20th century and onwards, or branches greatly influenced by early 20th century physics. - In theoretical physics and applied mathematics, a field equation is a partial differential equation which determines the dynamics of a physical field, specifically the time evolution and spatial distribution of the field. The solutions to the equation are mathematical functions which correspond directly to the field, as a functions of time and space. Since the field equation is a partial differential equation, there are families of solutions which represent a variety of physical possibilities. Usually, there is not just a single equation, but a set of coupled equations which must be solved simultaneously. Field equations are not ordinary differential equations since a field depends on space and time, which requires at least two variables. - General relativity (GR, also known as the general theory of relativity or GTR) is the geometric theory of gravitation published by Albert Einstein in 1915 and the current description of gravitation in modern physics. General relativity generalizes special relativity and Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or spacetime. In particular, the "" 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 partial differential equations. - In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: - In classical mechanics, linear momentum, translational momentum, or simply momentum (pl. momenta; SI unit kgm/s) is the product of the mass and velocity of an object, quantified in kilogram-meters per second. It is dimensionally equivalent to impulse, the product of force and time, quantified in newton-seconds. Newton's second law of motion states that the change in linear momentum of a body is equal to the net impulse acting on it. For example, a heavy truck moving rapidly has a large momentum, and it takes a large or prolonged force to get the truck up to this speed, and would take a similarly large or prolonged force to bring it to a stop. If the truck were lighter, or moving more slowly, then it would have less momentum and therefore require less impulse to start or stop. - Rainer K. Sachs ("Rainer Kurt "Ray" Sachs;" born June 13, 1932) is a German-American computational radiation biologist and astronomer. He and Arthur M. Wolfe were the authors of the Sachs-Wolfe effect, which concerns a property of the Cosmic microwave background radiation. He and Ronald Kantowski were responsible for the Kantowski-Sachs dust solutions to the Einstein field equation. These are a widely used family of inhomogeneous cosmological models. - In physics, spacetime is any mathematical model that combines space and time into a single interwoven continuum. Since 300 BCE, the spacetime of our universe has historically been interpreted from a Euclidean space perspective, which regards space as consisting of three dimensions, and time as consisting of one dimension, the "fourth dimension". By combining space and time into a single manifold called Minkowski space in 1908, physicists have significantly simplified a large number of physical theories, as well as described in a more uniform way the workings of the universe at both the supergalactic and subatomic levels. - Newton's law of universal gravitation states that a particle attracts every other particle in the universe using a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. This is a general physical law derived from empirical observations by what Isaac Newton called inductive reasoning. It is a part of classical mechanics and was formulated in Newton's work "Philosophi Naturalis Principia Mathematica" ("the "Principia""), first published on 5 July 1687. (When Newton's book was presented in 1686 to the Royal Society, Robert Hooke made a claim that Newton had obtained the inverse square law from him; see the History section below.) - In general relativity, a dust solution is an exact solution of the Einstein field equation in which the gravitational field is produced entirely by the mass, momentum, and stress density of a perfect fluid which has "positive mass density" but "vanishing pressure". Dust solutions are by far the most important special case of fluid solutions in general relativity. - In mathematics, a partial differential equation (PDE) is a differential equation that contains unknown multivariable functions and their partial derivatives. (A special case are ordinary differential equations (ODEs), which deal with functions of a single variable and their derivatives.) PDEs are used to formulate problems involving functions of several variables, and are either solved by hand, or used to create a relevant computer model. - In physics, special relativity (SR, also known as the special theory of relativity or STR) is the generally accepted and experimentally well-confirmed physical theory regarding the relationship between space and time. In Albert Einstein's original pedagogical treatment, it is based on two postulates: - Albert Einstein (14 March 1879 18April 1955) was a German-born theoretical physicist. He developed the general theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics). Einstein's work is also known for its influence on the philosophy of science. Einstein is best known in popular culture for his massenergy equivalence formula (which has been dubbed "the world's most famous equation"). He received the 1921 Nobel Prize in Physics for his "services to theoretical physics", in particular his discovery of the law of the photoelectric effect, a pivotal step in the evolution of quantum theory. - Arthur Michael "Art" Wolfe (29 April 1939 17 February 2014) was an American astrophysicist, professor and the former Director of the Center for Astrophysics & Space Sciences at the University of California, San Diego. Together with Rainer K. Sachs, he authored the Sachs-Wolfe effect. - In the classical physics observed in everyday life, if something has mass and takes up space, it is said to be composed of matter; this includes atoms (and thus molecules) and anything made up of these, but not other energy phenomena or waves such as light or sound. More generally, however, in (modern) physics, matter is not a fundamental concept because a universal definition of it is elusive: elementary constituents of atoms may not take up space individually, and massless particles may be composed to form objects that have mass (even when at rest). - Ronald Kantowski is a theoretical cosmologist , well known in the field of general relativity as the author , together with Rainer K. Sachs , of the Kantowski - Sachs dust solutions to the Einstein field equation . These are a widely used family of inhomogeneous cosmological models . - The Einstein field equations (EFE; also known as "Einstein's equations") are the set of 10 equations in Albert Einstein's general theory of relativity that describes the fundamental interaction of gravitation as a result of spacetime being curved by mass and energy. First published by Einstein in 1915 as a tensor equation, the EFE equate local spacetime curvature (expressed by the Einstein tensor) with the local energy and momentum within that spacetime (expressed by the stressenergy tensor). - In physics, energy is the property that must be transferred to an object in order to perform work on or to heat the object, and can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the energy transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton. After reading the paragraphs above, choose the best answer for the entity that related to 'ronald kantowski' with the relationship of 'occupation'. Choices: - acting - astronomer - astrophysicist - biologist - book - computer - cosmologist - director - general - model - physicist - physics
physicist