query: when was the theory of general relativity published

pos: History of general relativity Switzerland to accept a professorship at his "alma mater", the ETH. Once back in Zurich, he immediately visited his old ETH classmate Marcel Grossmann, now a professor of mathematics, who introduced him to Riemannian geometry and, more generally, to differential geometry. On the recommendation of Italian mathematician Tullio Levi-Civita, Einstein began exploring the usefulness of general covariance (essentially the use of tensors) for his gravitational theory. For a while Einstein thought that there were problems with the approach, but he later returned to it and, by late 1915, had published his general theory of relativity in the form in which

neg: Relativity: The Special and the General Theory Relativity: The Special and the General Theory Relativity: The Special and the General Theory began as a short paper and was eventually published as a book written by Albert Einstein with the aim of giving: It was first published in German in 1916 and later translated into English in 1920. It is divided into 3 parts, the first dealing with special relativity, the second dealing with general relativity and the third dealing with considerations on the universe as a whole. There have been many versions published since the original in 1916, the latest in December, 2011. The work has been

neg: Relativity: The Special and the General Theory labeled unique in that it gives readers an insight into the thought processes of one of the greatest minds of the 20th century. Relativity: The Special and the General Theory Relativity: The Special and the General Theory began as a short paper and was eventually published as a book written by Albert Einstein with the aim of giving: It was first published in German in 1916 and later translated into English in 1920. It is divided into 3 parts, the first dealing with special relativity, the second dealing with general relativity and the third dealing with considerations on the universe

neg: Theory of relativity 1915. The final form of general relativity was published in 1916. The term "theory of relativity" was based on the expression "relative theory" () used in 1906 by Planck, who emphasized how the theory uses the principle of relativity. In the discussion section of the same paper, Alfred Bucherer used for the first time the expression "theory of relativity" (). By the 1920s, the physics community understood and accepted special relativity. It rapidly became a significant and necessary tool for theorists and experimentalists in the new fields of atomic physics, nuclear physics, and quantum mechanics. By comparison, general relativity did

neg: Introduction to general relativity nature of singularities and the fundamental properties of Einstein's equations, and ever more comprehensive computer simulations of specific spacetimes (such as those describing merging black holes) are run. More than ninety years after the theory was first published, research is more active than ever. "Additional resources, including more advanced material, can be found in General relativity resources." Introduction to general relativity General relativity is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915. According to general relativity, the observed gravitational effect between masses results from their warping of spacetime. By the beginning of the 20th

neg: General relativity of research. 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. 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. Some

neg: General relativity 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. 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. Some predictions of

neg: Relativity priority dispute to mistakes of Whittaker, like predating Lorentz's 1904 paper (published April 1904) to 1903. Views similar to Holton's were later (1967, 1970) expressed by his former student, Stanley Goldberg. In a 1965 series of articles tracing the history of relativity, Keswani claimed that Poincaré and Lorentz should have the main credit for special relativity - claiming that Poincaré pointedly credited Lorentz multiple times, while Lorentz credited Poincaré and Einstein, refusing to take credit for himself. He also downplayed the theory of general relativity, saying "Einstein's general theory of relativity is only a theory of gravitation and of modifications in the

neg: Course of Theoretical Physics listed. Covers classical mechanics without special or general relativity, in the Lagrangian and Hamiltonian formalisms. Covers relativistic mechanics of particles, and classical field theory for fields, specifically special relativity and electromagnetism, general relativity and gravitation. Covers quantum mechanics without special relativity. The original edition was two books, labelled part 1 and part 2. The first had general aspects of relativistic quantum mechanics and relativistic quantum field theory, leading onto quantum electrodynamics. The second continued on with quantum electrodynamics and what was then known about the strong and weak interactions. These books were published in the early 1970s, at a time

neg: Moshe Carmeli He took Einstein's theory of general relativity and extended it into five dimensions, adding the radial velocity of galaxies expanding in the Hubble flow as the fifth dimension. This fifth dimension is known as "space-velocity". He published his initial special relativistic version of the theory in 1997 in his book "Cosmological Special Relativity: The Large-Scale Structure of Space, Time, and Velocity". He then developed the complete general relativistic theory called cosmological general relativity, publishing several papers on its implications over the next decade. Complete lists of Carmeli's works can be found at Microsoft Academic Search (with links), or at his

neg: Albert Einstein in the development of quantum theory. Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led him to develop his special theory of relativity during his time at the Swiss Patent Office in Bern (1902–1909), Switzerland. However, he realized that the principle of relativity could also be extended to gravitational fields, and he published a paper on general relativity in 1916 with his theory of gravitation. He continued to deal with problems of statistical mechanics and quantum theory, which

neg: The Einstein Theory of Relativity The Einstein Theory of Relativity The Einstein Theory of Relativity (1923) is a silent short film directed by Dave Fleischer and released by Fleischer Studios. In August 1922.."Scientific American" published an article explaining their position that a silent film would be unsuccessful in presenting Albert Einstein's theory of relativity to the general public. They argued that only as part of a broader educational package including lecture and text would such film be successful. "Scientific American" then went on to review frames from an unnamed German film reported to be financially successful. Six months later, on February 8, 1923, the Fleischers

neg: Alfred Bucherer 1940, when similar experimental equipments were sufficiently accurate to confirm the Lorentz-Einstein formula, see Kaufmann–Bucherer–Neumann experiments and Tests of relativistic energy and momentum. Bucherer (1906) was the first who used — during some critical remarks on Einstein's theory — the expression "Einsteinian relativity theory / theory of relativity" ("Einsteinsche Relativitätstheorie"). This was based on Max Planck's term "relative theory" for the Lorentz-Einstein theory. And in 1908 Bucherer himself rejected his own version of the relativity principle, and accepted the "Lorentz-Einstein theory". Later (1923, 1924), Bucherer criticized general relativity in some papers. However, this criticism was rejected because Bucherer misinterpreted Einstein's

neg: Introduction to general relativity of quantum physics to produce a complete and self-consistent theory of quantum gravity. In September 1905, Albert Einstein published his theory of special relativity, which reconciles Newton's laws of motion with electrodynamics (the interaction between objects with electric charge). Special relativity introduced a new framework for all of physics by proposing new concepts of space and time. Some then-accepted physical theories were inconsistent with that framework; a key example was Newton's theory of gravity, which describes the mutual attraction experienced by bodies due to their mass. Several physicists, including Einstein, searched for a theory that would reconcile Newton's law of

neg: Theory of relativity and gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. With relativity, cosmology and astrophysics predicted extraordinary astronomical phenomena such as neutron stars, black holes, and gravitational waves. Albert Einstein published the theory of special relativity in 1905, building on many theoretical results and empirical findings obtained by Albert A. Michelson, Hendrik Lorentz, Henri Poincaré and others. Max Planck, Hermann Minkowski and others did subsequent work. Einstein developed general relativity between 1907 and 1915, with contributions by many others after

neg: Numerical relativity solutions. Numerical relativity research is distinct from work on classical field theories as many techniques implemented in these areas are inapplicable in relativity. Many facets are however shared with large scale problems in other computational sciences like computational fluid dynamics, electromagnetics, and solid mechanics. Numerical relativists often work with applied mathematicians and draw insight from numerical analysis, scientific computation, partial differential equations, and geometry among other mathematical areas of specialization. Albert Einstein published his theory of general relativity in 1915. It, like his earlier theory of special relativity, described space and time as a unified spacetime subject to what are

neg: Ludwik Silberstein Ludwik Silberstein Ludwik Silberstein (1872 – 1948) was a Polish-American physicist who helped make special relativity and general relativity staples of university coursework. His textbook "The Theory of Relativity" was published by Macmillan in 1914 with a second edition, expanded to include general relativity, in 1924. Silberstein was born May 17, 1872 in Warsaw to Samuel Silberstein and Emily Steinkalk. He was educated in Cracow, Heidelberg, and Berlin. To teach he went to Bologna, Italy from 1899 to 1904. Then he took a position at Sapienza University of Rome. In 1907 Silberstein described a bivector approach to the fundamental electromagnetic

neg: History of general relativity Big Bang model of cosmology. As Einstein later said, the reason for the development of general relativity was the preference of inertial motion within special relativity, while a theory which from the outset prefers no state of motion appeared more satisfactory to him. So, while still working at the patent office in 1907, Einstein had what he would call his "happiest thought". He realized that the principle of relativity could be extended to gravitational fields. Consequently, in 1907 he wrote an article (published 1908) on acceleration under special relativity. In that article, he argued that free fall is really inertial

neg: Criticism of the theory of relativity general relativity). In addition, in the theoretical field there is continuing research intended to unite general relativity and quantum theory. The most promising models are string theory and loop quantum gravity. Some variations of those models also predict violations of Lorentz invariance on a very small scale. Criticism of the theory of relativity Criticism of the theory of relativity of Albert Einstein was mainly expressed in the early years after its publication in the early twentieth century, on scientific, pseudoscientific, philosophical, or ideological bases. Though some of these criticisms had the support of reputable scientists, Einstein's theory of relativity is

neg: Friedwardt Winterberg constant at the Planck length to be computed, and this value remarkably agrees with the empirical value. He has published extensively on many aspects of physics from the 1950s through the present. In 2008, Winterberg criticized string theory and pointed out the shortcomings of Einstein's general theory of relativity because of its inability to be reconciled with quantum mechanics at the Physical Interpretations of Relativity Theory conference and published his findings in "Physics Essays".<ref name="doi:10.4006/1.3176669"></ref> Winterberg has published a series of articles treating Quantum Gravity on viXra, the most recent in 2018. In a 1955 paper Winterberg proposed a test

neg: Ludwik Silberstein structures ("struts", "ropes", or "membranes") that are responsible for holding masses against the attractive force of gravity in a static configuration. According to Martin Claussen, Ludwik Silberstein initiated a line of thought involving eddy currents in the atmosphere, or fluids generally. He says that Silberstein anticipated foundational work by Vilhelm Bjerknes (1862 – 1951). Ludwik Silberstein Ludwik Silberstein (1872 – 1948) was a Polish-American physicist who helped make special relativity and general relativity staples of university coursework. His textbook "The Theory of Relativity" was published by Macmillan in 1914 with a second edition, expanded to include general relativity, in 1924.

neg: Woodward effect of gravity, a Machian version of Einstein's general relativity. Fred Hoyle and Jayant Narlikar originally developed their cosmological model as a quasi steady state model of the universe, adding a "Creation field" generating matter out of empty space, an hypothesis contradicted by recent observations. When the C-field is not used, ignoring the parts regarding mass creation, the theory is no longer steady state and becomes a Machian extension of general relativity. This modern development is known as the "Gravitational Absorber Theory". As the gravitational absorber theory reduces to general relativity in the limit of a smooth fluid model of particle

neg: Theory of relativity relativity is the replacement of the Galilean transformations of classical mechanics by the Lorentz transformations. (See Maxwell's equations of electromagnetism). General relativity is a theory of gravitation developed by Einstein in the years 1907–1915. The development of general relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example, when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion: an object in free fall is falling because that is how objects move when there is no

neg: Mathematics of general relativity Mathematics of general relativity The mathematics of general relativity refers to various mathematical structures and techniques that are used in studying and formulating Albert Einstein's theory of general relativity. The main tools used in this geometrical theory of gravitation are tensor fields defined on a Lorentzian manifold representing spacetime. This article is a general description of the mathematics of general relativity. The principle of general covariance states that the laws of physics should take the same mathematical form in all reference frames and was one of the central principles in the development of general relativity. The term 'general covariance' was

neg: Mach's principle such as the Brans–Dicke theory and the Hoyle–Narlikar theory of gravity, but most physicists argue that none have been fully successful. At an exit poll of experts, held in Tübingen in 1993, when asked the question "Is general relativity perfectly Machian?", 3 respondents replied "yes", and 22 replied "no". To the question "Is general relativity with appropriate boundary conditions of closure of some kind very Machian?" the result was 14 "yes" and 7 "no". However, Einstein was convinced that a valid theory of gravity would necessarily have to include the relativity of inertia: The broad notion that "mass there influences

neg: Project-706 Fayyazuddin, Ishfaq Ahmad, and Masud Ahmad, had begun research on theoretical and quantum physics. Faheem Hussain became the first physicist at IP to published research analysis on string theory. Later on, the Relativity Group under Fayyazuddin carried out work on the Bethe-Bloch theory. In 1969, Raziuddin Siddiqui established Einstein's Physics Group (EPG) and carried out experiments on general relativity and quantum mechanics. In March 1970, the general elections were held in Pakistan under the Military government of General Yahya Khan. The electoral results triggered the Bangladesh Liberation War in East Pakistan. Meanwhile, the political situation in West Pakistan was further

neg: Theory of relativity Theory of relativity The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity. Special relativity applies to elementary particles and their interactions, describing all their physical phenomena except gravity. General relativity explains the law of gravitation and its relation to other forces of nature. It applies to the cosmological and astrophysical realm, including astronomy. The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic

neg: Walk of Ideas the most well-known equation in physics: E=mc². It belongs to the revolutionizing papers of Albert Einstein concerning the Theory of Relativity. In 1905, his paper “Zur Elektrodynamik bewegter Körper” (“The electrodynamics of objects in motion”) established the Special Theory of Relativity, which revolutionized the understanding of space and time. In 1915, he published the General Theory of Relativity, in which the curvature of spacetime brings about gravity. Nowadays, Albert Einstein is seen by many as the epitome of a scientist and a genius. He also used his fame outside of the scientific community in his efforts to further international understanding

neg: Theory of relativity work if relativistic considerations were omitted. Theory of relativity The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity. Special relativity applies to elementary particles and their interactions, describing all their physical phenomena except gravity. General relativity explains the law of gravitation and its relation to other forces of nature. It applies to the cosmological and astrophysical realm, including astronomy. The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space

neg: Criticism of the theory of relativity completing the field equations of general relativity (see Relativity priority dispute). A collection of various criticisms can be found in the book "Hundert Autoren gegen Einstein" ("A Hundred Authors Against Einstein"), published in 1931. It contains very short texts from 28 authors, and excerpts from the publications of another 19 authors. The rest consists of a list that also includes people who only for some time were opposed to relativity. Besides philosophic objections (mostly based on Kantianism), also some alleged elementary failures of the theory were included; however, as some commented, those failures were due to the authors' misunderstanding of

neg: Albert Einstein in physics at the time—was superfluous. In his paper on mass–energy equivalence, Einstein produced "E" = "mc" as a consequence of his special relativity equations. Einstein's 1905 work on relativity remained controversial for many years, but was accepted by leading physicists, starting with Max Planck. Einstein originally framed special relativity in terms of kinematics (the study of moving bodies). In 1908, Hermann Minkowski reinterpreted special relativity in geometric terms as a theory of spacetime. Einstein adopted Minkowski's formalism in his 1915 general theory of relativity. General relativity (GR) is a theory of gravitation that was developed by Einstein between 1907

neg: Scientific theory theories are approximations; the potential unification of these is sometimes called the Theory of Everything. In 1905, Albert Einstein published the principle of special relativity, which soon became a theory. Special relativity predicted the alignment of the Newtonian principle of Galilean invariance, also termed "Galilean relativity", with the electromagnetic field. By omitting from special relativity the luminiferous aether, Einstein stated that time dilation and length contraction measured in an object in relative motion is inertial—that is, the object exhibits constant velocity, which is speed with direction, when measured by its observer. He thereby duplicated the Lorentz transformation and the Lorentz

neg: Edwin F. Taylor text on special relativity, which began with Wheeler's relativity lectures to an honors physics freshman class, which Taylor transcribed, and evolved into an intense collaboration that resulted in the book "Spacetime Physics", published in 1965. Taylor and Wheeler later resumed their collaboration to produce an introduction to general relativity, published in 2000 as "Exploring Black Holes". The book presents fundamental ideas from the theory, using no more than basic differential and integral calculus. Specific aspects of relativity are explored in "project" chapters interspersed throughout the main text. Together with the British physicist and physics educator Anthony French, Taylor wrote the

neg: Tropical year an electromagnetic computer, the IBM Selective Sequence Electronic Calculator was used since 1948. When modern computers became available, it was possible to compute ephemerides using numerical integration rather than general theories; numerical integration came into use in 1984 for the joint US-UK almanacs . Einstein's General Theory of Relativity provided a more accurate theory, but the accuracy of theories and observations did not require the refinement provided by this theory (except for the advance of the perihelion of Mercury) until 1984. Time scales incorporated general relativity beginning in the 1970s . A key development in understanding the tropical year over

neg: Willem Jacob van Stockum Stockum became an early enthusiast of the then new theory of gravitation, general relativity. In 1937, he published a paper which contains one of the first exact solutions in general relativity which modeled the gravitational field produced by a configuration of "rotating" matter, the van Stockum dust, which remains an important example noted for its unusual simplicity. In this paper, van Stockum was apparently the first to notice the possibility of closed timelike curves, one of the strangest and most disconcerting phenomena in general relativity. Van Stockum left for the United States in hope of studying under Albert Einstein, eventually

neg: Arthur W. Conway quaternions. De Valera warmed to the subject and engaged in research of this novelty of abstract algebra. Later, when de Valera became Taoiseach (he was also subsequently President of Ireland), he called upon Conway while forming the Dublin Institute for Advanced Studies. Conway's earliest publications, dating back to 1903, were on the electromagnetic theory. He is remembered for his application of biquaternion algebra to the special theory of relativity, and in 1915 published a 43-page tract "Relativity" in Edinburgh. He published an article in 1911, and in 1912 asserted priority over Ludwik Silberstein, who also applied biquaternions to relativity. This

neg: Bose–Einstein statistics from English into German (Bose had earlier translated Einstein's article on the theory of General Relativity from German to English), and saw to it that it was published. Bose's theory achieved respect when Einstein sent his own paper in support of Bose's to "Zeitschrift für Physik", asking that they be published together. The paper came out in 1924. The reason Bose produced accurate results was that since photons are indistinguishable from each other, one cannot treat any two photons having equal energy as being two distinct identifiable photons. By analogy, if in an alternate universe coins were to behave like

neg: Theodor Kaluza in 1899). He spent his youth in Königsberg, where his father, Max Kaluza, was a professor of the English language. He entered the University of Königsberg to study mathematics and gained his doctorate with a thesis on Tschirnhaus transformations. Kaluza was primarily a mathematician but began studying relativity. In April 1919 Kaluza noticed that when he solved Albert Einstein's equations for general relativity using five dimensions, then Maxwellian equations for electromagnetism emerged spontaneously. Kaluza wrote to Einstein who, in turn, encouraged him to publish. Kaluza's theory was published in 1921 in a paper, "Zum Unitätsproblem der Physik" with Einstein's support

neg: Yuri Yappa in the 1970s–1990s he continued at the Chair of the Theory of Nucleus and Elementary Particles (nowadays the Chair of High Energy and Elementary Particle Physics). Yuri Yappa was a senior research scientist () since 1956 and an assistant professor () since 1968. He published over 40 papers on quantum field theory, General Relativity, mathematics, and philosophy of science. Yuri Yappa led a number of theoretical courses in the Leningrad/St.-Petersburg University, including his well-known courses of General Relativity, which was passed to him by Vladimir Fock in 1958, and of classical electrodynamics, which served the base of his graduate book

neg: Tests of general relativity principle could occur in a theory of gravitation, but do not occur in general relativity. Other important theoretical developments included the inception of alternative theories to general relativity, in particular, scalar-tensor theories such as the Brans–Dicke theory; the parameterized post-Newtonian formalism in which deviations from general relativity can be quantified; and the framework of the equivalence principle. Experimentally, new developments in space exploration, electronics and condensed matter physics have made additional precise experiments possible, such as the Pound–Rebka experiment, laser interferometry and lunar rangefinding. Early tests of general relativity were hampered by the lack of viable competitors to the theory:

neg: History of general relativity which it can differ from general relativity has been severely constrained by these observations. In addition, general relativity is inconsistent with quantum mechanics, the physical theory that describes the wave–particle duality of matter, and quantum mechanics does not currently describe gravitational attraction at relevant (microscopic) scales. There is a great deal of speculation in the physics community as to the modifications that might be needed to both general relativity and quantum mechanics in order to unite them consistently. The speculative theory that unites general relativity and quantum mechanics is usually called quantum gravity, prominent examples of which include String Theory

neg: Force however no such planet could be found. When Albert Einstein formulated his theory of general relativity (GR) he turned his attention to the problem of Mercury's orbit and found that his theory added a correction, which could account for the discrepancy. This was the first time that Newton's Theory of Gravity had been shown to be inexact. Since then, general relativity has been acknowledged as the theory that best explains gravity. In GR, gravitation is not viewed as a force, but rather, objects moving freely in gravitational fields travel under their own inertia in straight lines through curved space-time –

neg: Wolfgang Pauli deist and a mystic. Pauli attended the Döblinger-Gymnasium in Vienna, graduating with distinction in 1918. Only two months after graduation, he published his first paper, on Albert Einstein's theory of general relativity. He attended the Ludwig-Maximilians University in Munich, working under Arnold Sommerfeld, where he received his PhD in July 1921 for his thesis on the quantum theory of ionized diatomic hydrogen (). Sommerfeld asked Pauli to review the theory of relativity for the "Encyklopädie der mathematischen Wissenschaften" ("Encyclopedia of Mathematical Sciences"). Two months after receiving his doctorate, Pauli completed the article, which came to 237 pages. It was praised

neg: Brans–Dicke theory individual terms vanish. 6 further terms combine when manipulated using Stokes' theorem to provide the desired formula_44. For comparison, the Lagrangian defining general relativity is Varying the gravitational term with respect to formula_38 gives the vacuum Einstein field equation. In both theories, the full field equations can be obtained by variations of the full Lagrangian. 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. It is a competitor of Einstein's theory of general relativity. It is an example of a scalar–tensor theory, a gravitational theory in which

neg: History of special relativity electrodynamics of Minkowski as overly complicated "learned superfluousness" and published a "more elementary", non-four-dimensional derivation of the basic-equations for moving bodies. But it was Minkowski's geometric model that (a) showed that the special relativity is a complete and internally self-consistent theory, (b) added the Lorentz invariant proper time interval (which accounts for the actual readings shown by moving clocks), and (c) served as a basis for further development of relativity. Eventually, Einstein (1912) recognized the importance of Minkowski's geometric spacetime model and used it as the basis for his work on the foundations of general relativity. Today special relativity is

neg: Theory of everything called a theory of everything. In the late 1920s, the new quantum mechanics showed that the chemical bonds between atoms were examples of (quantum) electrical forces, justifying Dirac's boast that "the underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known". After 1915, when Albert Einstein published the theory of gravity (general relativity), the search for a unified field theory combining gravity with electromagnetism began with a renewed interest. In Einstein's day, the strong and the weak forces had not yet been discovered, yet, he found the

neg: Lorentz ether theory law. The attempts of Lorentz and Poincaré (and other attempts like those of Abraham and Gunnar Nordström) to formulate a theory of gravitation were superseded by Einstein's theory of general relativity. This theory is based on principles like the equivalence principle, the general principle of relativity, the principle of general covariance, geodesic motion, local Lorentz covariance (the laws of special relativity apply locally for all inertial observers), and that spacetime curvature is created by stress-energy within the spacetime. In 1920 Einstein compared Lorentz's ether with the "gravitational ether" of general relativity. He said that immobility is the only mechanical property

neg: History of general relativity of a Binary black hole of black holes. There have been various attempts to find modifications to general relativity. The most famous of these are the Brans–Dicke theory (also known as scalar-tensor theory), and Rosen's bimetric theory. Both of these theories proposed changes to the field equations of general relativity, and both suffer from these changes permitting the presence of bipolar gravitational radiation. As a result, Rosen's original theory has been refuted by observations of binary pulsars. As for Brans–Dicke (which has a tunable parameter "ω" such that "ω = ∞" is the same as general relativity), the amount by

neg: Gunnar Nordström theory of gravitation, was for a long time considered as a competitor to Einstein's theory of general relativity which was published in 1915, after Nordström's theory. In 1914 Nordström introduced an additional space dimension to his theory, which provided coupling to electromagnetism. This was the first of the extra dimensional theories, which later came to be known as Kaluza–Klein theory. Kaluza and Klein, whose names are commonly used today for the theory, did not publish their work until the 1920s. Some speculations as to why Nordström's contribution fell into oblivion are that his theory was partly published in Swedish and

neg: History of general relativity History of general relativity General relativity (GR) is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915, with contributions by many others after 1915. According to general relativity, the observed gravitational attraction between masses results from the warping of space and time by those masses. Before the advent of general relativity, Newton's law of universal gravitation had been accepted for more than two hundred years as a valid description of the gravitational force between masses, even though Newton himself did not regard the theory as the final word on the nature of gravity. Within a

neg: Principle of relativity gravitation as an effect of the geometry of spacetime. Einstein based this new theory on the general principle of relativity, and he named the theory after the underlying principle. See the special relativity references and the general relativity references. Principle of relativity In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference. For example, in the framework of special relativity the Maxwell equations have the same form in all inertial frames of reference. In the framework of general relativity the Maxwell equations or

neg: Gravitational wave to 10 Hz. The possibility of gravitational waves was discussed in 1893 by Oliver Heaviside using the analogy between the inverse-square law in gravitation and electricity. In 1905, Henri Poincaré proposed gravitational waves ("ondes gravifiques"), emanating from a body and propagating at the speed of light, as being required by the Lorentz transformations and suggested that, in analogy to an accelerating electrical charge producing electromagnetic waves, accelerated masses in a relativistic field theory of gravity should produce gravitational waves. When Einstein published his general theory of relativity in 1915, he was skeptical of Poincaré's idea since the theory implied there

neg: M-theory problems in modern physics is the problem of quantum gravity. The current understanding of gravity is based on Albert Einstein's general theory of relativity, which is formulated within the framework of classical physics. However, nongravitational forces are described within the framework of quantum mechanics, a radically different formalism for describing physical phenomena based on probability. A quantum theory of gravity is needed in order to reconcile general relativity with the principles of quantum mechanics, but difficulties arise when one attempts to apply the usual prescriptions of quantum theory to the force of gravity. String theory is a theoretical framework that

neg: Wolfgang Rindler for Advanced Studies, later called University of Texas at Dallas, where he is Professor Emeritus. He was visiting scholar at King's College London (1961/62), at the University La Sapienza in Rome (1968/69), In 1969 Springer published the first edition of his "Essential Relativity: Special, General, and Cosmological". The undergraduate textbook was lauded as a "refreshingly modern approach to the critical problem of "teaching" relativity theory." Another reviewer said it is "simply the best introduction" and is "filled with fabulous insights." When the second edition appeared in 1977 a reviewer noted its treatment "reminiscent of Mach's celebrated examination of the foundations

neg: Introduction to the mathematics of general relativity of energy and momentum in spacetime, generalizing the stress tensor of Newtonian physics. It is an attribute of matter, radiation, and non-gravitational force fields. The stress–energy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity. The Einstein field equations (EFE) or Einstein's equations are a set of 10 equations in Albert Einstein's general theory of relativity which describe the fundamental interaction of gravitation as a result of spacetime being curved by matter and energy. First published by Einstein in

neg: Tests of general relativity it was not clear what sorts of tests would distinguish it from its competitors. General relativity was the only known relativistic theory of gravity compatible with special relativity and observations. Moreover, it is an extremely simple and elegant theory. This changed with the introduction of Brans–Dicke theory in 1960. This theory is arguably simpler, as it contains no dimensionful constants, and is compatible with a version of Mach's principle and Dirac's large numbers hypothesis, two philosophical ideas which have been influential in the history of relativity. Ultimately, this led to the development of the parametrized post-Newtonian formalism by Nordtvedt and

neg: Edward Fomalont Edward Fomalont Edward Fomalont (born May 14, 1940) is an American scientist working at the National Radio Astronomy Observatory. He specializes in radio galaxies, X-ray binary systems, astrometry, and general relativity. He has published more than 330 papers in peer-reviewed journals and proceedings of scientific conferences. In 1975, Fomalont and Richard Sramek made a first radio-interferometric occultation experiment to test the theory of general relativity by measuring the bending of microwave radiation in the gravitational field of the Sun. Fomalont and colleagues made the most precise VLBI test of general relativity in 2005 that had reached precision of few parts

neg: Foundations of Physics Foundations of Physics Foundations of Physics is a monthly journal "devoted to the conceptual bases and fundamental theories of modern physics and cosmology, emphasizing the logical, methodological, and philosophical premises of modern physical theories and procedures". The journal publishes results and observations based on fundamental questions from all fields of physics, including: quantum mechanics, quantum field theory, special relativity, general relativity, string theory, M-theory, cosmology, thermodynamics, statistical physics, and quantum gravity "Foundations of Physics" has been published since 1970. Its founding editors were Henry Margenau and Wolfgang Yourgrau. The 1999 Nobel laureate Gerard 't Hooft was editor-in-chief from January 2007.

neg: History of loop quantum gravity History of loop quantum gravity The history of loop quantum gravity spans more than three decades of intense research. General relativity is the theory of gravitation published by Albert Einstein in 1915. According to it, the force of gravity is a manifestation of the local geometry of spacetime. Mathematically, the theory is modelled after Bernhard Riemann's metric geometry, but the Lorentz group of spacetime symmetries (an essential ingredient of Einstein's own theory of special relativity) replaces the group of rotational symmetries of space. (Later, loop quantum gravity inherited this geometric interpretation of gravity, and posits that a quantum theory of

neg: Hans Reichenbach as "Privatdozent". In the same year, he published his first book on the philosophical implications of the theory of relativity, "The Theory of Relativity and A Priori Knowledge", which criticized the Kantian notion of synthetic "a priori". He subsequently published "Axiomatization of the Theory of Relativity" (1924), "From Copernicus to Einstein" (1927) and "The Philosophy of Space and Time" (1928), the last stating the logical positivist view on the theory of relativity. In 1926, with the help of Albert Einstein, Max Planck and Max von Laue, Reichenbach became assistant professor in the physics department of Humboldt University of Berlin. He

neg: Raman Research Institute its attractive universality, its long range and the fact that matter on the large scale is essentially neutral. The correct theory of gravitation is now believed to be Einstein's General Theory of Relativity. One of the fundamental predictions of General Theory of Relativity is that of gravitational waves — waves of distortion of spacetime itself - propagating at a finite speed of light. This replaces the Newtonian gravitations forces which was instantaneous. Such waves are expected to be emitted when, for example, two massive inspiralling stars tend to coalesce under their mutual gravitations attraction. Accurate calculation of this gravitational radiation

neg: Gunnar Nordström physics for his theory of relativity. Einstein never received the Nobel prize for the theory, as the first experimental evidence presented in 1919 could at the time still be disputed and there was not yet a consensus or even general understanding in the scientific community of the complex mathematical models that Einstein, Nordström and others had developed. Nordström's scalar theory is today mainly used as a pedagogical tool when learning general relativity. Today there is a limited public knowledge of Nordström's contributions to science even in Finland. However, after his death a number of Finnish physicists and mathematicians devoted their

neg: Variational methods in general relativity Variational methods in general relativity Variational methods in general relativity refers to various mathematical techniques that employ the use of variational calculus in Einstein's theory of general relativity. The most commonly used tools are Lagrangians and Hamiltonians and are used to derive the Einstein field equations. The equations of motion in physical theories can often be derived from an object called the Lagrangian. In classical mechanics, this object is usually of the form, 'kinetic energy − potential energy'. In general, the Lagrangian is that function which when integrated over produces the Action functional. David Hilbert gave an early and classic

neg: Scale relativity Scale relativity Scale relativity is a geometrical and fractal space-time physical theory. Relativity theories (special relativity and general relativity) are based on the notion that position, orientation, movement and acceleration cannot be defined in an absolute way, but only relative to a system of reference. The scale relativity theory proposes to extend the concept of relativity to physical scales (time, length, energy, or momentum scales), by introducing an explicit "state of scale" in coordinate systems. This extension of the relativity principle was originally introduced by Laurent Nottale, based on the idea of a fractal space-time theory first introduced by Garnet

neg: Criticism of the theory of relativity confirmation of general relativity, but may also be explained by the Stokes-Planck theory of complete aether drag. However, such models are in contradiction with the aberration of light and other experiments (see "Alternative theories"). In 1935, Silberstein claimed to have found a contradiction in the Two-body problem in general relativity. However, also this claim was refuted by Einstein and Rosen (1935). The consequences of relativity, such as the change of ordinary concepts of space and time, as well as the introduction of non-Euclidean geometry in general relativity, were criticized by some philosophers of different philosophical schools. It was characteristic for

neg: Scale relativity to be opposed. Indeed, Castro suggested to combine string theory with the principle of scale relativity: It was emphasized by Nottale in his book that a full motion plus scale relativity including all spacetime components, angles and rotations remains to be constructed. In particular the general theory of scale relativity. Our aim is to show that string theory provides an important step in that direction and vice versa: the scale relativity principle must be operating in string theory. Scale relativity is based on a geometrical approach, and thereby recovers the quantum laws, instead of assuming them. This distinguishes it from

neg: Clive W. Kilmister of King's College in 1950. The entirety of his academic career was spent at King's. In 1954, Kilmister founded the King's Gravitational Theory Group, in concert with Hermann Bondi and Felix Pirani, which focused on Einstein's theory of general relativity. At retirement, Kilmister was both a Professor of Mathematics and Head of the King's College Mathematics Department. Clive W. Kilmister Clive W. Kilmister (1924 – May 2, 2010) was a British Mathematician who specialised in the mathematical foundations of Physics, especially Quantum Mechanics and Relativity and published widely in these fields (see References). He was one of the discoverers of

neg: Tests of general relativity May 29, 1919, when the stars near the Sun (at that time in the constellation Taurus) could be observed. Observations were made simultaneously in the cities of Sobral, Ceará, Brazil and in São Tomé and Príncipe on the west coast of Africa. The result was considered spectacular news and made the front page of most major newspapers. It made Einstein and his theory of general relativity world-famous. When asked by his assistant what his reaction would have been if general relativity had not been confirmed by Eddington and Dyson in 1919, Einstein famously made the quip: "Then I would feel

neg: William Kingdon Clifford his independent development. The book continues with a chapter "On the bending of space", the substance of general relativity. Clifford also discussed his views in "" in 1876. In 1910 William Barrett Frankland quoted the "Space-Theory of Matter" in his book on parallelism. He wrote: Years later, after general relativity had been advanced by Albert Einstein, various authors noted that Clifford had anticipated Einstein: In 1923 Hermann Weyl mentioned Clifford as one of those who, like Bernhard Riemann, anticipated the geometric ideas of relativity. In 1940 Eric Temple Bell published his "The Development of Mathematics". There on pages 359 and

neg: Charles Lane Poor Charles Lane Poor Charles Lane Poor (January 18, 1866 – September 27, 1951) was an American astronomy professor, noted for his opposition to Einstein's theory of relativity. He was born on January 18, 1866 in Hackensack, New Jersey to Edward Erie Poor. He graduated from the City College of New York and received a Ph.D. in 1892 from Johns Hopkins University. Poor became an astronomer and professor of celestial mechanics at Columbia University from 1903 to 1944, when he was named Professor Emeritus. He published several works disputing the evidence for Einstein's theory of relativity during the 1920s. Poor published

neg: Alternatives to general relativity 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. There have been many different attempts at constructing an ideal theory of gravity. These attempts can be split into four broad categories: This article deals only with straightforward alternatives to GR. For quantized gravity theories, see the article quantum gravity. For the unification of gravity and other forces, see the article classical unified field theories. For those theories that attempt to do several at once, see the article theory of everything. Motivations for

neg: History of special relativity published his original paper on special relativity in which, again based on the relativity principle, he independently derived and radically reinterpreted the Lorentz transformations by changing the fundamental definitions of space and time intervals, while abandoning the absolute simultaneity of Galilean kinematics, thus avoiding the need for any reference to a luminiferous aether in classical electrodynamics. Subsequent work of Hermann Minkowski, in which he introduced a 4-dimensional geometric "spacetime" model for Einstein's version of special relativity, paved the way for Einstein's later development of his general theory of relativity and laid the foundations of relativistic field theories. Following the work

neg: Gunnar Nordström from 1913 regarding the measurement of the "radioactive emancipation power" of different springs and ground waters in Finland. During Nordström's career he published 34 articles and research papers in languages including German, Dutch, Finnish, and his mother-tongue Swedish. Nordström is probably the first person to write about the theory of relativity in the languages of Finland. Gunnar Nordström Gunnar Nordström (12 March 1881 – 24 December 1923) was a Finnish theoretical physicist best remembered for his theory of gravitation, which was an early competitor of general relativity. Nordström is often designated by modern writers as "The Einstein of Finland" due

neg: Terrell rotation "explained" effects that the theory did not actually predict – while these papers did not change the "actual" mathematical structure of special relativity in any way, they did correct a misconception regarding the theory's predictions. Terrell rotation Terrell rotation or Terrell effect is the visual distortion that a passing object would appear to undergo, according to the special theory of relativity if it were travelling a significant fraction of the speed of light. This behaviour was described independently by both James Terrell and Roger Penrose in pieces published in 1959, though the general phenomenon was noted already in 1924 by

neg: Mathematics of general relativity holes and neutron stars. The nonlinearity of the Einstein field equations often leads one to consider approximation methods in solving them. For example, an important approach is to linearise the field equations. Techniques from perturbation theory find ample application in such areas. <div id=note_1> The defining feature (central physical idea) of general relativity is that matter and energy cause the surrounding spacetime geometry to be curved. Mathematics of general relativity The mathematics of general relativity refers to various mathematical structures and techniques that are used in studying and formulating Albert Einstein's theory of general relativity. The main tools used in

neg: Initial value formulation (general relativity) evaluate, for instance, perturbations representing gravitational waves) and the occurrence of singularities (which, when they are allowed to occur within the simulated portion of spacetime, lead to arbitrarily large numbers that would have to be represented in the computer model). Initial value formulation (general relativity) 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. Each solution of the Einstein field equations encompasses the whole history of a universe – it is not just some snapshot of how things are, but a whole spacetime: a statement

neg: Mathematics of general relativity performed in a relatively small region of spacetime and this is one reason for studying the local structure of spacetime in general relativity, whereas determining the global spacetime structure is important, especially in cosmological problems. An important problem in general relativity is to tell when two spacetimes are 'the same', at least locally. This problem has its roots in manifold theory where determining if two Riemannian manifolds of the same dimension are locally isometric ('locally the same'). This latter problem has been solved and its adaptation for general relativity is called the Cartan–Karlhede algorithm. One of the profound consequences of

neg: Einstein–Cartan–Evans theory Einstein–Cartan–Evans theory Einstein–Cartan–Evans theory or ECE theory was an attempted unified theory of physics proposed by the Welsh chemist and physicist Myron Wyn Evans (born May 26, 1950), which claimed to unify general relativity, quantum mechanics and electromagnetism. The hypothesis was largely published in the journal "Foundations of Physics Letters" between 2003 and 2005. Several of Evans' central claims were later shown to be mathematically incorrect and, in 2008, the new editor of "Foundations of Physics", Nobel laureate Gerard 't Hooft, published an editorial note effectively retracting the journal's support for the hypothesis. Earlier versions of the theory were called

neg: General covariance that has such a formulation. Albert Einstein proposed this principle for his special theory of relativity; however, that theory was limited to space-time coordinate systems related to each other by uniform "inertial" motion. Einstein recognized that the general principle of relativity should also apply to accelerated relative motions, and he used the newly developed tool of tensor calculus to extend the special theory's global Lorentz covariance (applying only to inertial frames) to the more general local Lorentz covariance (which applies to all frames), eventually producing his general theory of relativity. The local reduction of the metric tensor to the Minkowski

neg: Introduction to general relativity checked by experiment. Newton's law of gravity was accepted because it accounted for the motion of planets and moons in the Solar System with considerable accuracy. As the precision of experimental measurements gradually improved, some discrepancies with Newton's predictions were observed, and these were accounted for in the general theory of relativity. Similarly, the predictions of general relativity must also be checked with experiment, and Einstein himself devised three tests now known as the classical tests of the theory: Of these tests, only the perihelion advance of Mercury was known prior to Einstein's final publication of general relativity in 1916.

neg: Brans–Dicke theory the Standard Model. Brans–Dicke theory is "less stringent" than general relativity in another sense: it admits more solutions. In particular, exact vacuum solutions to the Einstein field equation of general relativity, augmented by the trivial scalar field formula_6, become exact vacuum solutions in Brans–Dicke theory, but some spacetimes which are "not" vacuum solutions to the Einstein field equation become, with the appropriate choice of scalar field, vacuum solutions of Brans–Dicke theory. Similarly, an important class of spacetimes, the pp-wave metrics, are also exact null dust solutions of both general relativity and Brans–Dicke theory, but here too, Brans–Dicke theory allows additional

neg: Criticism of the theory of relativity the general covariance of his 1915 theory of gravity ensured implementation of a generalized relativity principle. This view was challenged by Erich Kretschmann (1917), who argued that every theory of space and time (even including Newtonian dynamics) can be formulated in a covariant way, if additional parameters are included, and thus general covariance of a theory would in itself be insufficient to implement a generalized relativity principle. Although Einstein (1918) agreed with that argument, he also countered that Newtonian mechanics in general covariant form would be too complicated for practical uses. Although it is now understood that Einstein's response to

neg: General relativity black holes, respectively. The bending of light by gravity can lead to the phenomenon of gravitational lensing, in which multiple images of the same distant astronomical object are visible in the sky. General relativity also predicts the existence of gravitational waves, which have since been observed directly by the physics collaboration LIGO. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe. Widely acknowledged as a theory of extraordinary beauty, general relativity has often been described as "the" most beautiful of all existing physical theories. Soon after publishing the special theory of relativity in

neg: History of physics of Einstein's General Theory of Relativity in 1915 although it did not enter the scientific mainstream until the period known as the "Golden age of general relativity". About a decade later, in the midst of what was dubbed the "Great Debate", Hubble and Slipher discovered the expansion of universe in the 1920s measuring the redshifts of Doppler spectra from galactic nebulae. Using Einstein's general relativity, Lemaître and Gamow formulated what would become known as the big bang theory. A rival, called the steady state theory was devised by Hoyle, Gold, Narlikar and Bondi. Cosmic background radiation was verified in the

neg: Classical physics refers to post-1900 physics which incorporates elements of quantum mechanics and relativity. Classical theory has at least two distinct meanings in physics. In the context of quantum mechanics, classical theory refers to theories of physics that do not use the quantisation paradigm, which includes classical mechanics and relativity. Likewise, classical field theories, such as general relativity and classical electromagnetism, are those that do not use quantum mechanics. In the context of general and special relativity, classical theories are those that obey Galilean relativity. Depending on point of view, among the branches of theory sometimes included in classical physics are variably:

neg: Pervez Hoodbhoy re-published the work of Jens Lyng Peterson the Maldacena conjecture (a conjectured equivalence between a string theory and gravity defined on one space, and a quantum field theory without gravity defined by one or less dimension) where he contributed mathematically to the theory. In the same year, he re-published the work of Edward Witten on Anti-de Sitter space and its extension to the field of Holography. While the paper was published experimentally in 1998 by Witten, Hoodbhoy provided the brief mathematical proofs and description to understand, logically, the subject of Sitter space— a scalar curvature in general theory of relativity.

neg: Alexander I. Poltorak was born in 1957 in Krasnodar, Russia, the former Soviet Union. He earned a graduate degree in Theoretical Physics – the equivalent of a Ph.D. in the United States – at Kuban State University (Kubanski Gosudarstvennyi Universitet). He devoted his academic studies to Einstein’s theory of relativity and gravitation. Poltorak published several research papers in this field and wrote his doctoral thesis on a solution to a long-standing “energy problem” in "The Theory of General Relativity". He left for the United States, and served as an assistant professor of biomathematics at Cornell University Medical College, where he conducted research on

neg: Branches of physics and time into the frame-dependent concept of spacetime. General relativity is the geometrical theory of gravitation published by Albert Einstein in 1915/16. It unifies special relativity, Newton's law of universal gravitation, and the insight that gravitation can be described by the curvature of space and time. In general relativity, the curvature of spacetime is produced by the energy of matter and radiation. Quantum mechanics is the branch of physics treating atomic and subatomic systems and their interaction with radiation. It is based on the observation that all forms of energy are released in discrete units or bundles called "quanta". Remarkably,

neg: Fundamental interaction at the same rate. Isaac Newton's law of Universal Gravitation (1687) was a good approximation of the behaviour of gravitation. Our present-day understanding of gravitation stems from Einstein's General Theory of Relativity of 1915, a more accurate (especially for cosmological masses and distances) description of gravitation in terms of the geometry of spacetime. Merging general relativity and quantum mechanics (or quantum field theory) into a more general theory of quantum gravity is an area of active research. It is hypothesized that gravitation is mediated by a massless spin-2 particle called the graviton. Although general relativity has been experimentally confirmed (at

neg: An Experiment with Time the moments like yesterday, today and tomorrow, or was it the travelling between them that we experience as the present moment? Any answer was beyond her, but the observation formed the basis of Serialism. Within the fixed spacetime landscape described by the recently-published theory of general relativity, an observer travels along a timeline running in the direction of physical time, "t". Quantum mechanics was also a newly-emerging science, though in a less-developed state. Neither relativity nor quantum mechanics offered any explanation of the observer's place in spacetime, but both required it in order to develop the physical theory around it.

neg: Cosmological perturbation theory techniques, such as N-body simulations, must be used. Because of the gauge invariance of general relativity, the correct formulation of cosmological perturbation theory is subtle. There are currently two distinct approaches to perturbation theory in classical general relativity: The gauge-invariant perturbation theory is based on developments by Bardeen (1980), Kodama and Sasaki (1984) building on the work of Lifshitz (1946). This is the standard approach to perturbation theory of general relativity for cosmology. This approach is widely used for the computation of anisotropies in the cosmic microwave background radiation as part of the physical cosmology program and focuses on predictions

neg: Yilmaz theory of gravitation some have tested competitors of general relativity; see . Yilmaz theory of gravitation The Yilmaz theory of gravitation is an attempt by Huseyin Yilmaz (1924-2013) (Turkish: "Hüseyin Yılmaz") and his coworkers to formulate a classical field theory of gravitation which is similar to general relativity in weak-field conditions, but in which event horizons cannot appear. Yilmaz's work has been criticized on the grounds that It is well known that attempts to quantize general relativity along the same lines which lead from Maxwell's classical field theory of electromagnetism to quantum electrodynamics fail, and that it has proven very difficult to construct

neg: Edward Arthur Milne Arthur Eddington. From the early 1930s, Milne's interests focused increasingly on relativity theory and cosmology. From 1932 he worked on the problem of the "expanding universe" and in "Relativity, Gravitation, and World-Structure" (1935), proposed an alternative to Albert Einstein's general relativity theory. With McCrea (1934) he also showed that the 3 models which form the foundations of modern cosmology first proposed by Friedmann (1922) using the general theory of relativity, can also be derived using only Newtonian mechanics. The main difference between the Milne model of an expanding universe, and the current (Einstein's) model of an expanding universe was that

neg: Lorentz ether theory it necessary to invoke the principle of relativity itself in order to make the theory match all the available empirical data. By this point, most vestiges of a substantial ether had been eliminated from Lorentz's "ether" theory, and it became both empirically and deductively equivalent to special relativity. The main difference was the metaphysical postulate of a unique absolute rest frame, which was empirically undetectable and played no role in the physical predictions of the theory, as Lorentz wrote in 1909, 1910 (published 1913), 1913 (published 1914), or in 1912 (published 1922). As a result, the term "Lorentz ether theory"

neg: Criticism of the theory of relativity the electromagnetic worldview had to be given up. Eventually, Albert Einstein published in September 1905 what is now called special relativity, which was based on a radical new application of the relativity principle in connection with the constancy of the speed of light. In special relativity, the space and time coordinates depend on the inertial observer's frame of reference, and the luminiferous aether plays no role in the physics. Although this theory was founded on a very different kinematical model, it was experimentally indistinguishable from the aether theory of Lorentz and Poincaré, since both theories satisfy the relativity principle of

neg: Mendel Sachs for the "International Journal of Theoretical Physics". On his retirement in 1997 he was given the title Professor of Physics Emeritus. A symposium was held in Sachs honour to mark his retirement, the event was attended by Nobel laureates Willis E. Lamb and Herbert A. Hauptman and a subsequent festschrift was published. Sachs published 13 books and over 200 journal articles during his life. Sachs progressed towards completing Albert Einstein's unified field theory, i.e. unifying the fields in general relativity, from which quantum mechanics emerges under certain conditions. His theory rests on three axioms. The general idea is (1) to

neg: Equivalence principle enough that tidal effects can be neglected. Although the equivalence principle guided the development of general relativity, it is not a founding principle of relativity but rather a simple consequence of the "geometrical" nature of the theory. In general relativity, objects in free-fall follow geodesics of spacetime, and what we perceive as the force of gravity is instead a result of our being unable to follow those geodesics of spacetime, because the mechanical resistance of matter prevents us from doing so. Since Einstein developed general relativity, there was a need to develop a framework to test the theory against other

neg: A Brief History of Time origin of these laws was left in God's domain. In the twentieth century, quantum theory introduced the uncertainty principle, which set limits to the predictive accuracy of laws to be discovered. The big bang implied by the general theory of relativity indicates that a creator of the universe or God has the freedom to choose the origin and the laws of the universe. When one combines theory of relativity with quantum mechanics, however, a unified and completely self-contained theory may emerge, in which God has little or no role to play. So the search of a unified theory may shed

neg: History of special relativity a consequence, the notion of a complete "special relativistic" theory of gravitation had to be given up, as in general relativity the constancy of light speed (and Lorentz covariance) is only locally valid. The decision between those models was brought about by Einstein, when he was able to exactly derive the perihelion precession of Mercury, while the other theories gave erroneous results. In addition, only Einstein's theory gave the correct value for the deflection of light near the sun. The need to put together relativity and quantum mechanics was one of the major motivations in the development of quantum field