|
Graviphoton
In theoretical physics and quantum physics, a graviphoton or gravivector is a hypothetical particle which emerges as an excitation of the metric tensor (i.e. gravitational field) in spacetime dimensions higher than four, as described in Kaluza–Klein theory. However, its crucial physical properties are analogous to a (massive) photon: it induces a "vector force", sometimes dubbed a "fifth force". The electromagnetic potential A_\mu emerges from an extra component of the metric tensor g_, where the figure 5 labels an additional, fifth dimension. In gravity theories with extended supersymmetry ( extended supergravities), a graviphoton is normally a superpartner of the graviton that behaves like a photon, and is prone to couple with gravitational strength, as was appreciated in the late 1970s. Unlike the graviton, it may provide a ''repulsive'' (as well as an attractive) force, and thus, in some technical sense, a type of anti-gravity. Under special circumstances, in several natura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-gravity
Anti-gravity (also known as non-gravitational field) is a hypothetical phenomenon of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, or to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift. Anti-gravity is a recurring concept in science fiction. Examples are the gravity blocking substance "Cavorite" in H. G. Wells's ''The First Men in the Moon'' and the Spindizzy machines in James Blish's ''Cities in Flight''. "Anti-gravity" is often used to refer to devices that look as if they reverse gravity even though they operate through other means, such as lifters, which fly in the air by moving air with electromagnetic fields. Historical attempts at understanding gravity The possibility of creating anti-gravity depends upon a complete understanding and description of gravity and its interactions with other physical theories, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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 Einstein was concerned wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothetical Elementary Particles
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words "hypothesis" and "theory" are often used interchangeably, a scientific hypothesis is not the same as a scientific theory. A working hypothesis is a provisionally accepted hypothesis proposed for further research in a process beginning with an educated guess or thought. A different meaning of the term ''hypothesis'' is used in formal logic, to denote the antecedent of a proposition; thus in the proposition "If ''P'', then ''Q''", ''P'' denotes the hypothesis (or antecedent); ''Q'' can be called a consequent. ''P'' is the assumption in a (possibly counterfactual) ''What If'' question. The adjective ''hypothetical'', meaning "hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photons
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always move at the speed of light in vacuum, (or about ). The photon belongs to the class of bosons. As with other elementary particles, photons are best explained by quantum mechanics and exhibit wave–particle duality, their behavior featuring properties of both waves and particles. The modern photon concept originated during the first two decades of the 20th century with the work of Albert Einstein, who built upon the research of Max Planck. While trying to explain how matter and electromagnetic radiation could be in thermal equilibrium with one another, Planck proposed that the energy stored within a material object should be regarded as composed of an integer number of discrete, equal-sized parts. To explain the photoelectric effect, Ein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bosons
In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0,1,2 ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have odd half-integer spin (,, ...). Every observed subatomic particle is either a boson or a fermion. Bosons are named after physicist Satyendra Nath Bose. Some bosons are elementary particles and occupy a special role in particle physics unlike that of fermions, which are sometimes described as the constituents of "ordinary matter". Some elementary bosons (for example, gluons) act as force carriers, which give rise to forces between other particles, while one (the Higgs boson) gives rise to the phenomenon of mass. Other bosons, such as mesons, are composite particles made up of smaller constituents. Outside the realm of particle physics, superfluidity arises because composite bosons (bose particles), such as low temperature helium-4 atoms, follow Bose–Einst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersymmetry
In a supersymmetric theory the equations for force and the equations for matter are identical. In theoretical and mathematical physics, any theory with this property has the principle of supersymmetry (SUSY). Dozens of supersymmetric theories exist. Supersymmetry is a spacetime symmetry between two basic classes of particles: bosons, which have an integer-valued spin and follow Bose–Einstein statistics, and fermions, which have a half-integer-valued spin and follow Fermi–Dirac statistics. In supersymmetry, each particle from one class would have an associated particle in the other, known as its superpartner, the spin of which differs by a half-integer. For example, if the electron exists in a supersymmetric theory, then there would be a particle called a ''"selectron"'' (superpartner electron), a bosonic partner of the electron. In the simplest supersymmetry theories, with perfectly " unbroken" supersymmetry, each pair of superpartners would share the same mass and intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmas Zachos
Cosmas K. Zachos ( el, Κοσμάς Ζάχος; born 1951) is a theoretical physicist. He was educated in physics (undergraduate A.B. 1974) at Princeton University, and did graduate work in theoretical physics at the California Institute of Technology (Ph.D. 1979 ) under the supervision of John Henry Schwarz. Zachos is an emeritus staff member in the theory group of the High Energy Physics Division of Argonne National Laboratory. He is considered an authority on the subject of phase-space quantization. His early research involved, jointly, the introduction of renormalization geometrostasis, and the so-called FFZ Lie algebra of noncommutative geometry. His thesis work revealed a balancing repulsive gravitational force present in extended supergravity. He is co-author of treatises on quantum mechanics in phase space, Thomas L. Curtright, David B. Fairlie, Cosmas K. Zachos, ''A Concise Treatise on Quantum Mechanics in Phase Space'', (World Scientific, Singapore, 2014) . a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graviscalar
In theoretical physics, the hypothetical particle called the graviscalar or radion emerges as an excitation of general relativity's metric tensor, i.e. gravitational field, but is indistinguishable from a scalar in four dimensions, as shown in Kaluza–Klein theory. The scalar field \phi comes from a component of the metric tensor g_ where the figure 5 labels an additional fifth dimension. The only variations in the scalar field represent variations in the size of the extra dimension. Also, in models with multiple extra dimensions, there exist several such particles. Moreover, in theories with extended supersymmetry, a graviscalar is usually a superpartner of the graviton that behaves as a particle with spin 0. This concept closely relates to the gauged Higgs models. See also * Graviphoton (aka gravivector) * Dilaton * Kaluza–Klein theory * Randall–Sundrum models * Goldberger–Wise mechanism In particle physics, the Goldberger–Wise mechanism is a popular mechanism ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joël Scherk
Joël Scherk (; 27 May 1946 – 16 May 1980) was a French theoretical physicist who studied string theory and supergravity. Work Scherk studied in Paris at the École Normale Supérieure (ENS). In 1969 he received his diploma (Thèse de troisième cycle) at University of Paris XI in Orsay with and Claude Bouchiat and in 1971 he completed his doctorate (Doctorat d'État) at the same time as his colleague André Neveu. In 1974, together with John H. Schwarz, Scherk realised that string theory was a theory of quantum gravity. In 1978, together with Eugène Cremmer and Bernard Julia, Scherk constructed the Lagrangian and supersymmetry transformations for supergravity in eleven dimensions, which is one of the foundations of M-theory. He died unexpectedly, and in tragic circumstances, months after the supergravity workshop at the State University of New York at Stony Brook that was held on 27–29 September 1979. The workshop proceedings were dedicated to his memory, with a statemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graviton
In theories of quantum gravity, the graviton is the hypothetical quantum of gravity, an elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with renormalization in general relativity. In string theory, believed by some to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string. If it exists, the graviton is expected to be massless because the gravitational force has a very long range, and appears to propagate at the speed of light. The graviton must be a spin-2 boson because the source of gravitation is the stress–energy tensor, a second-order tensor (compared with electromagnetism's spin-1 photon, the source of which is the four-current, a first-order tensor). Additionally, it can be shown that any massless spin-2 field would give rise to a force indistinguishable from gravitation, because a massless spin-2 field ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metric Tensor
In the mathematical field of differential geometry, a metric tensor (or simply metric) is an additional structure on a manifold (such as a surface) that allows defining distances and angles, just as the inner product on a Euclidean space allows defining distances and angles there. More precisely, a metric tensor at a point of is a bilinear form defined on the tangent space at (that is, a bilinear function that maps pairs of tangent vectors to real numbers), and a metric tensor on consists of a metric tensor at each point of that varies smoothly with . A metric tensor is ''positive-definite'' if for every nonzero vector . A manifold equipped with a positive-definite metric tensor is known as a Riemannian manifold. Such a metric tensor can be thought of as specifying ''infinitesimal'' distance on the manifold. On a Riemannian manifold , the length of a smooth curve between two points and can be defined by integration, and the distance between and can be defined as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superpartner
In particle physics, a superpartner (also sparticle) is a class of hypothetical elementary particles predicted by supersymmetry, which, among other applications, is one of the well-studied ways to extend the standard model of high-energy physics. When considering extensions of the Standard Model, the ''s-'' prefix from ''sparticle'' is used to form names of superpartners of the Standard Model fermions (sfermions),Alexander I. Studenikin (ed.), ''Particle Physics in Laboratory, Space and Universe'', World Scientific, 2005, p. 327. e.g. the stop squark. The superpartners of Standard Model bosons have an ''-ino'' (bosinos) appended to their name, e.g. gluino, the set of all gauge superpartners are called the gauginos. Theoretical predictions According to the supersymmetry theory, each fermion should have a partner boson, the fermion's superpartner, and each boson should have a partner fermion. Exact ''unbroken'' supersymmetry would predict that a particle and its superpartners would ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
