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F(R) gravity

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f(R) gravity is a type of modified gravity theory which generalizes Einstein's general relativity. [1]

56 relations: Accelerating expansion of the universe, Albert Einstein, Alternatives to general relativity, Auxiliary field, Brans–Dicke theory, Classical and Quantum Gravity, Conformal gravity, Connection (mathematics), Cosmological constant, Covariant derivative, D'Alembert operator, Dark energy, Dark matter, Einstein–Hilbert action, Extended theories of gravity, Fifth force, Friedmann equations, Friedmann–Lemaître–Robertson–Walker metric, Gauss–Bonnet gravity, General relativity, Gravitational constant, Gravitational wave, Graviton, Group velocity, Hagen Kleinert, Hans Adolf Buchdahl, Inflation (cosmology), Jordan and Einstein frames, Journal of Physics: Conference Series, Lagrangian (field theory), Legendre transform, Lovelock theory of gravity, Metric tensor, Metric-affine gravitation theory, Monthly Notices of the Royal Astronomical Society, Newtonian gauge, Palatini variation, Parameterized post-Newtonian formalism, Physical Review, Physical Review Letters, Physics Letters, Physics Reports, Poisson's equation, Quantum gravity, Quintessence (physics), Reviews of Modern Physics, Ricci curvature, Scalar curvature, Scalar field, Speed of light, ..., Stress–energy tensor, Structure formation, Taylor series, Wave packet, Weyl tensor, Yukawa potential. Expand index (6 more) »

Accelerating expansion of the universe

The accelerating expansion of the universe is the observation that the universe appears to be expanding at an increasing rate, so that the velocity at which a distant galaxy is receding from the observer is continuously increasing with time.

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Albert Einstein

Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics).

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Alternatives to general relativity

Alternatives to general relativity are physical theories that attempt to describe the phenomenon of gravitation in competition to Einstein's theory of general relativity.

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Auxiliary field

In physics, and especially quantum field theory, an auxiliary field is one whose equations of motion admit a single solution.

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Brans–Dicke theory

In theoretical physics, the Brans–Dicke theory of gravitation (sometimes called the Jordan–Brans–Dicke theory) is a theoretical framework to explain gravitation.

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Christmas

Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.

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Christmas and holiday season

The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.

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Christmas Eve

Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.

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Christmas traditions

Christmas traditions vary from country to country.

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Classical and Quantum Gravity

Classical and Quantum Gravity is a peer-reviewed journal that covers all aspects of gravitational physics and the theory of spacetime.

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Conformal gravity

Conformal gravity are gravity theories that are invariant under conformal transformations in the Riemannian geometry sense; more accurately, they are invariant under Weyl transformations g_\rightarrow\Omega^2(x)g_ where g_ is the metric tensor and \Omega(x) is a function on spacetime.

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Connection (mathematics)

In geometry, the notion of a connection makes precise the idea of transporting data along a curve or family of curves in a parallel and consistent manner.

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Cosmological constant

In cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: Λ) is the value of the energy density of the vacuum of space.

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Covariant derivative

In mathematics, the covariant derivative is a way of specifying a derivative along tangent vectors of a manifold.

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D'Alembert operator

In special relativity, electromagnetism and wave theory, the d'Alembert operator (represented by a box: \Box), also called the d'Alembertian, wave operator, or box operator is the Laplace operator of Minkowski space.

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Dark energy

In physical cosmology and astronomy, dark energy is an unknown form of energy which is hypothesized to permeate all of space, tending to accelerate the expansion of the universe.

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Dark matter

Dark matter is a theorized form of matter that is thought to account for approximately 80% of the matter in the universe, and about a quarter of its total energy density.

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Einstein–Hilbert action

The Einstein–Hilbert action (also referred to as Hilbert action) in general relativity is the action that yields the Einstein field equations through the principle of least action.

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Extended theories of gravity

Extended theories of gravity are alternative theories of gravity developed from the exact starting points investigated first by Einstein and Hilbert.

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Fifth force

In physics, the fifth force is a proposed fundamental force, additional to the four known fundamental forces of nature.

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Friedmann equations

The Friedmann equations are a set of equations in physical cosmology that govern the expansion of space in homogeneous and isotropic models of the universe within the context of general relativity.

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Friedmann–Lemaître–Robertson–Walker metric

The Friedmann–Lemaître–Robertson–Walker (FLRW) metric is an exact solution of Einstein's field equations of general relativity; it describes a homogeneous, isotropic, expanding or contracting universe that is path connected, but not necessarily simply connected.

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Gauss–Bonnet gravity

In general relativity, Gauss–Bonnet gravity, also referred to as Einstein–Gauss–Bonnet gravity, is a modification of the Einstein–Hilbert action to include the Gauss–Bonnet term (named after Carl Friedrich Gauss and Pierre Ossian Bonnet) G.

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General relativity

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.

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Gravitational constant

The gravitational constant (also known as the "universal gravitational constant", the "Newtonian constant of gravitation", or the "Cavendish gravitational constant"), denoted by the letter, is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general theory of relativity.

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Gravitational wave

Gravitational waves are the disturbance in the fabric ("curvature") of spacetime generated by accelerated masses and propagate as waves outward from their source at the speed of light.

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Graviton

In theories of quantum gravity, the graviton is the hypothetical elementary particle that mediates the force of gravity.

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Group velocity

The group velocity of a wave is the velocity with which the overall shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space.

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Hagen Kleinert

Hagen Kleinert (born 15 June 1941) is Professor of Theoretical Physics at the Free University of Berlin, Germany (since 1968), at the West University of Timişoara, at the in Bishkek.

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Hans Adolf Buchdahl

Hans Adolf Buchdahl (7 July 1919 – 7 January 2010) was a German-born Australian physicist.

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Inflation (cosmology)

In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe.

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Jordan and Einstein frames

The Lagrangian in scalar-tensor theory can be expressed in the Jordan frame in which the scalar field or some function of it multiplies the Ricci scalar, or in the Einstein frame in which Ricci scalar is not multiplied by the scalar field.

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Journal of Physics: Conference Series

Journal of Physics: Conference Series (JPCS) is a peer-reviewed, open-access publication from IOP Publishing providing readers with the latest developments in physics presented at international conferences.

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Lagrangian (field theory)

Lagrangian field theory is a formalism in classical field theory.

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Legendre transform

In mathematics, Legendre transform is an integral transform named after the mathematician Adrien-Marie Legendre, which uses Legendre polynomials P_n(x) as kernels of the transform.

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Lovelock theory of gravity

In theoretical physics, Lovelock's theory of gravity (often referred to as Lovelock gravity) is a generalization of Einstein's theory of general relativity introduced by David Lovelock in 1971.

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Metric tensor

In the mathematical field of differential geometry, a metric tensor is a type of function which takes as input a pair of tangent vectors and at a point of a surface (or higher dimensional differentiable manifold) and produces a real number scalar in a way that generalizes many of the familiar properties of the dot product of vectors in Euclidean space.

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Metric-affine gravitation theory

In comparison with General Relativity, dynamic variables of metric-affine gravitation theory are both a pseudo-Riemannian metric and a general linear connection on a world manifold X. Metric-affine gravitation theory has been suggested as a natural generalization of Einstein–Cartan theory of gravity with torsion where a linear connection obeys the condition that a covariant derivative of a metric equals zero.

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Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.

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New Year

New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.

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New Year's Day

New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.

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New Year's Eve

In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.

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Newtonian gauge

In general relativity, Newtonian gauge is a perturbed form of the Friedmann–Lemaître–Robertson–Walker line element.

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Palatini variation

In general relativity and gravitation the Palatini variation is nowadays thought of as a variation of a Lagrangian with respect to the connection.

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Parameterized post-Newtonian formalism

Post-Newtonian formalism is a calculational tool that expresses Einstein's (nonlinear) equations of gravity in terms of the lowest-order deviations from Newton's law of universal gravitation.

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Physical Review

Physical Review is an American peer-reviewed scientific journal established in 1893 by Edward Nichols.

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Physical Review Letters

Physical Review Letters (PRL), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society.

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Physics Letters

Physics Letters was a scientific journal published from 1962 to 1966, when it split in two series now published by Elsevier.

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Physics Reports

Physics Reports is a peer-reviewed scientific journal, a review section of Physics Letters that has been published by Elsevier since 1971.

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Poisson's equation

In mathematics, Poisson's equation is a partial differential equation of elliptic type with broad utility in mechanical engineering and theoretical physics.

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Quantum gravity

Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics, and where quantum effects cannot be ignored, such as near compact astrophysical objects where the effects of gravity are strong.

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Quintessence (physics)

In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field, postulated as an explanation of the observation of an accelerating rate of expansion of the universe.

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Reviews of Modern Physics

Reviews of Modern Physics is a quarterly peer-reviewed scientific journal published by the American Physical Society.

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Ricci curvature

In differential geometry, the Ricci curvature tensor, named after Gregorio Ricci-Curbastro, represents the amount by which the volume of a small wedge of a geodesic ball in a curved Riemannian manifold deviates from that of the standard ball in Euclidean space.

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Scalar curvature

In Riemannian geometry, the scalar curvature (or the Ricci scalar) is the simplest curvature invariant of a Riemannian manifold.

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Scalar field

In mathematics and physics, a scalar field associates a scalar value to every point in a space – possibly physical space.

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Speed of light

The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.

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Stress–energy tensor

The stress–energy tensor (sometimes stress–energy–momentum tensor or energy–momentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the stress tensor of Newtonian physics.

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Structure formation

In physical cosmology, structure formation is the formation of galaxies, galaxy clusters and larger structures from small early density fluctuations.

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Taylor series

In mathematics, a Taylor series is a representation of a function as an infinite sum of terms that are calculated from the values of the function's derivatives at a single point.

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Wave packet

In physics, a wave packet (or wave train) is a short "burst" or "envelope" of localized wave action that travels as a unit.

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Weyl tensor

In differential geometry, the Weyl curvature tensor, named after Hermann Weyl, is a measure of the curvature of spacetime or, more generally, a pseudo-Riemannian manifold.

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Yukawa potential

In particle and atomic physics, a Yukawa potential (also called a screened Coulomb potential) is a potential of the form where g is a magnitude scaling constant, i.e. is the amplitude of potential, m is the mass of the particle, r is the radial distance to the particle, and k is another scaling constant, so that 1/km is the range.

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2018

2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.

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2019

2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.

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F (R) gravity theories, F(R) gravity theories, F(R) theory, F(R)-gravity, F(r) gravity.

References

[1] https://en.wikipedia.org/wiki/F(R)_gravity

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