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Background-independent
Background independence is a condition in theoretical physics that requires the defining equations of a theory to be independent of the actual shape of the spacetime and the value of various fields within the spacetime. In particular this means that it must be possible not to refer to a specific coordinate system—the theory must be coordinate-free. In addition, the different spacetime configurations (or backgrounds) should be obtained as different solutions of the underlying equations. Description Background independence is a loosely defined property of a theory of physics. Roughly speaking, it limits the number of mathematical structures used to describe space and time that are put in place "by hand". Instead, these structures are the result of dynamical equations, such as Einstein field equations, so that one can determine from first principles what form they should take. Since the form of the metric determines the result of calculations, a theory with background independence is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Loop Quantum Gravity
Loop quantum gravity (LQG) is a theory of quantum gravity that incorporates matter of the Standard Model into the framework established for the intrinsic quantum gravity case. It is an attempt to develop a quantum theory of gravity based directly on Albert Einstein's geometric formulation rather than the treatment of gravity as a mysterious mechanism (force). As a theory, LQG postulates that the structure of space and time is composed of finite loops woven into an extremely fine fabric or network. These networks of loops are called spin networks. The evolution of a spin network, or spin foam, has a scale on the order of a Planck length, approximately 10−35 meters, and smaller scales are meaningless. Consequently, not just matter, but space itself, prefers an atomic structure. The areas of research, which involve about 30 research groups worldwide, share the basic physical assumptions and the mathematical description of quantum space. Research has evolved in two directions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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String Theory
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 acts like a 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. String theory is a broad and varied subject that attempts to address a number of deep questions of fundamental physics. String theory has contributed a number of advances to mathematical physics, which have been applied to a variety of problems in black hole physics, early universe cosmology, nuclear physics, and condensed matter ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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String Field Theory
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. The principal advantages of the formalism are that it allows the computation of off-shell amplitudes and, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Theoretical Physics
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict List of natural phenomena, natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena. The advancement of science generally depends on the interplay between experimental studies and theory. In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations.There is some debate as to whether or not theoretical physics uses mathematics to build intuition and illustrativeness to extract physical insight (especially when normal experience fails), rather than as a tool in formalizing theories. This links to the question of it using mathematics in a less formally rigorous, and more intuitive or heuristic way than, say, mathematical physics. For example, while developing special relativity, Albert E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Open Court Publishing Company
The Open Court Publishing Company is a publisher with offices in Chicago and LaSalle, Illinois. It is part of the Carus Publishing Company of Peru, Illinois. History Open Court was founded in 1887 by Edward C. Hegeler of the Matthiessen-Hegeler Zinc Company, at one time the largest producer of zinc in the United States. Hegeler intended for the firm to serve the purpose of discussing religious and psychological problems on the principle that the scientific world-conception should be applied to religion. Its first managing editor was Paul Carus, Hegeler's son-in-law through his marriage to engineer Mary Hegeler Carus.Fields 1992, pg. 138 For the first 80 years of its existence, the company had its offices in the Hegeler Carus Mansion. Open Court specializes in philosophy, science, and religion. It was one of the first academic presses in the country, as well as one of the first publishers of inexpensive editions of the classics. It also published the journals ''Open Court' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Kluwer Academic
Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in Berlin, it expanded internationally in the 1960s, and through mergers in the 1990s and a sale to venture capitalists it fused with Wolters Kluwer and eventually became part of Springer Nature in 2015. Springer has major offices in Berlin, Heidelberg, Dordrecht, and New York City. History Julius Springer founded Springer-Verlag in Berlin in 1842 and his son Ferdinand Springer grew it from a small firm of 4 employees into Germany's then second-largest academic publisher with 65 staff in 1872.Chronology ". Springer Science+Business Media. In 1964, Springer expanded its business internationally, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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University Of Pittsburgh Press
The University of Pittsburgh Press is a scholarly publishing house and a major American university press, part of the University of Pittsburgh. The university and the press are located in Pittsburgh, Pennsylvania, in the United States. The press publishes several series in the humanities and social sciences, including Illuminations—Cultural Formations of the Americas; Pitt Latin American Series; Pitt Series in Russian and East European Studies, Pittsburgh Series in Composition, Literary, and Culture; Pittsburgh/Konstanz Series in Philosophy and History of Science; Culture, Politics, and the Built Environment; Central Eurasia in Context, and Latinx and Latin American Profiles. The press is especially known for literary publishing, particularly its Pitt Poetry Series, the Agnes Lynch Starrett Poetry Prize, and the Drue Heinz Literature Prize. The press also publishes the winner of the annual Donald Hall Prize, awarded by the Association of Writers & Writing Programs and the w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Advanced Science Letters
''Advanced Science Letters'' was a peer-reviewed scientific journal published by American Scientific Publishers. The editor-in-chief was Hari Singh Nalwa. Publishing formats include full papers, short communications, and special sections consisting of various formats. The journal was established in June 2008, and is published by American Scientific Publishers, a company identified by Jeffrey Beall as a predatory publisher. Although the journal received a 2010 impact factor of 1.253, it ceased to be indexed the following year. The journal was discontinued in 2019. Scope Coverage included joining basic and applied original research across multiple disciplines. These are the physical sciences, biological sciences (including health sciences and medicine), computer sciences (including information science), agriculture sciences, geosciences, and environmental sciences (including environmental engineering Environmental engineering is a professional engineering Academic discipli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Quantum Field Theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and in condensed matter physics to construct models of quasiparticles. The current standard model of particle physics is based on QFT. History Quantum field theory emerged from the work of generations of theoretical physicists spanning much of the 20th century. Its development began in the 1920s with the description of interactions between light and electrons, culminating in the first quantum field theory—quantum electrodynamics. A major theoretical obstacle soon followed with the appearance and persistence of various infinities in perturbative calculations, a problem only resolved in the 1950s with the invention of the renormalization procedure. A second major barrier came with QFT's apparent inabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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General Covariance
In theoretical physics, general covariance, also known as diffeomorphism covariance or general invariance, consists of the Invariant (physics), invariance of the ''form'' of physical laws under arbitrary Derivative, differentiable coordinate transformations. The essential idea is that coordinates do not exist ''a priori'' in nature, but are only artifices used in describing nature, and hence should play no role in the formulation of fundamental physical laws. While this concept is exhibited by general relativity, which describes the dynamics of spacetime, one should not expect it to hold in less fundamental theories. For matter fields taken to exist independently of the background, it is almost never the case that their equations of motion will take the same form in curved space that they do in flat space. Overview A physical law expressed in a generally covariant fashion takes the same mathematical form in all coordinate systems, and is usually expressed in terms of tensor fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Coordinate-free
A coordinate-free, or component-free, treatment of a scientific theory A scientific theory is an explanation of an aspect of the universe, natural world that can be or that has been reproducibility, repeatedly tested and has corroborating evidence in accordance with the scientific method, using accepted protocol (s ... or mathematical topic develops its concepts on any form of manifold without reference to any particular coordinate system. Benefits Coordinate-free treatments generally allow for simpler systems of equations and inherently constrain certain types of inconsistency, allowing greater mathematical elegance at the cost of some abstraction from the detailed formulae needed to evaluate these equations within a particular system of coordinates. In addition to elegance, coordinate-free treatments are crucial in certain applications for proving that a given definition is well formulated. For example, for a vector space V with basis v_1, ..., v_n, it may be tempting to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |