Query: Einstein Relativity theory

Relevant passages:
Absolute time and space <=SEP=> Originally introduced by Sir Isaac Newton in Philosophiæ Naturalis Principia Mathematica, the concepts of absolute time and space provided a theoretical foundation that facilitated Newtonian mechanics.

Aether drag hypothesis <=SEP=> In the 19th century, the theory of the luminiferous aether as the hypothetical medium for the propagation of light was widely discussed. An important part of this discussion was the question concerning the state of motion of Earth with respect to this medium. The aether drag hypothesis dealt with the question whether the luminiferous aether is dragged by or entrained within moving matter.

Albert Einstein <=SEP=> Albert Einstein (/ˈaɪnstaɪn/; German: [ˈalbɐrt ˈaɪnʃtaɪn]; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist. He developed the general theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics). Einstein's work is also known for its influence on the philosophy of science. Einstein is best known in popular culture for his mass–energy equivalence formula E = mc2 (which has been dubbed "the world's most famous equation").

Alternatives to general relativity <=SEP=> Alternatives to general relativity are physical theories that attempt to describe the phenomena 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: Straightforward alternatives to general relativity (GR), such as the Cartan, Brans–Dicke and Rosen bimetric theories.

Annus Mirabilis papers <=SEP=> The Annus mirabilis papers (from Latin annus mīrābilis, "extraordinary year") are the papers of Albert Einstein published in the Annalen der Physik scientific journal in 1905. These four articles contributed substantially to the foundation of modern physics and changed views on space, time, mass, and energy. The annus mirabilis is often called the "miracle year" in English or Wunderjahr in German.

Classical field theory <=SEP=> A classical field theory is a physical theory that describes the study of how one or more physical fields interact with matter. The word 'classical' is used in contrast to those field theories that incorporate quantum mechanics (quantum field theories).A physical field can be thought of as the assignment of a physical quantity at each point of space and time.

Classical unified field theories <=SEP=> Since the 19th century, some physicists have attempted to develop a single theoretical framework that can account for the fundamental forces of nature – a unified field theory. Classical unified field theories are attempts to create a unified field theory based on classical physics. In particular, unification of gravitation and electromagnetism was actively pursued by several physicists and mathematicians in the years between World War I and World War II.

Cosmological constant <=SEP=> 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. It was originally introduced by Albert Einstein in 1917 as an addition to his theory of general relativity to "hold back gravity" and achieve a static universe, which was the accepted view at the time.

Criticism of the theory of relativity <=SEP=> 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.

Dante Tessieri <=SEP=> Dante Tessieri was an Argentine scientist born in the late nineteenth century.Between many of the today unknown geniuses on history, we can not avoid watching Dante, a man who excelled on the fields of physics, electricity and mathematics.

Dark star (Newtonian mechanics) <=SEP=> A dark star is a theoretical object compatible with Newtonian mechanics that, due to its large mass, has a surface escape velocity that equals or exceeds the speed of light.  Whether light is affected by gravity under Newtonian mechanics is questionable but if it were accelerated the same way as projectiles, any light emitted at the surface of a dark star would be trapped by the star's gravity, rendering it dark, hence the name.

Einstein Prize (APS) <=SEP=> Since 2003, the Einstein Prize is a biennial prize awarded by the American Physical Society. The recipients are chosen for their outstanding accomplishments in the field of gravitational physics. The prize is named after Albert Einstein (1879-1955), who authored the theories of special and general relativity. The prize was established by the Topical Group on Gravitation at the beginning of 1999. As of 2013, the prize is valued at $10,000.

Einstein Symposium <=SEP=> In the centennial of "Annus Mirabilis" of 1905 (the miracle year during which Einstein published his five major papers on the special theory of relativity, Brownian motion and the quantum theory; which earned him the 1921 Nobel Prize in Physics), the UNESCO designated year 2005 to be the World Year of Physics (WYP).Bibliotheca Alexandrina, the newly revived Library of Alexandria in Egypt, then organized a symposium with participation from several noted Nobel laureates, to commemorate this worldwide recognition of WYP, which has had three main events: Public forum Scientific symposium ExhibitionIn the year of the 150th anniversary of ETH Zurich, the swiss university was home to an Einstein Symposium, which was jointly organized with the University of Zurich. @en <http://en.wikipedia.org/wiki/Einstein_Symposium?oldid=541630926> .
<http://dbpedia.org/resource/Masonry_dam> <http://www.w3.org/2000/01/rdf-schema#comment> Masonry dams are dams made out of masonry — mainly stone and brick, sometimes joined with mortar. They are either the gravity or the arch-gravity type. One of the largest masonry dam in Asia is Nagarjunasagar Dam in India.

Einstein Tower <=SEP=> The Einstein Tower (German: Einsteinturm) is an astrophysical observatory in the Albert Einstein Science Park in Potsdam, Germany built by Erich Mendelsohn.  It was built on the summit of the Potsdam Telegraphenberg to house a solar telescope designed by the astronomer Erwin Finlay-Freundlich.  The telescope supports experiments and observations to validate (or disprove) Albert Einstein's relativity theory.

Einstein aether theory <=SEP=> In physics the Einstein æther theory, also called æ-theory, is a generally covariant modification of general relativity which describes a spacetime endowed with both a metric and a unit timelike vector field named the æther.  The theory has a preferred reference frame and hence violates Lorentz invariance.

Einstein notation <=SEP=> In mathematics, especially in applications of linear algebra to physics, the Einstein notation or Einstein summation convention is a notational convention that implies summation over a set of indexed terms in a formula, thus achieving notational brevity. As part of mathematics it is a notational subset of Ricci calculus; however, it is often used in applications in physics that do not distinguish between tangent and cotangent spaces. It was introduced to physics by Albert Einstein in 1916.

Einstein synchronisation <=SEP=> Einstein synchronisation (or Poincaré–Einstein synchronisation) is a convention  for synchronising clocks at different places by means of signal exchanges. This synchronisation method was used already by telegraphers in the middle 19th century, but was popularized by Henri Poincaré and Albert Einstein who applied it to light signals and recognized its fundamental role in relativity theory.  Its principal value is for clocks within a single inertial frame.

Einstein–Cartan theory <=SEP=> In theoretical physics, the Einstein–Cartan theory, also known as the Einstein–Cartan–Sciama–Kibble theory, is a classical theory of gravitation similar to general relativity but relaxing the assumption that the affine connection has vanishing antisymmetric part (torsion tensor), so that the torsion can be coupled to the intrinsic angular momentum (spin) of matter, much in the same way in which the curvature is coupled to the energy and momentum of matter.

Einstein–Maxwell–Dirac equations <=SEP=> Einstein–Maxwell–Dirac equations (EMD) are related to quantum field theory.  The current Big Bang Model is a quantum field theory in a curved spacetime. Unfortunately, no such theory is mathematically well-defined; in spite of this, theoreticians claim to extract information from this hypothetical theory. On the other hand, the super-classical limit of the not mathematically well-defined QED in a curved spacetime is the mathematically well-defined Einstein–Maxwell–Dirac system.

Erich Kretschmann <=SEP=> Erich Justus Kretschmann (July 14, 1887 in Berlin – 1973) was a German physicist.He obtained his D.Phil. at Berlin University in 1914 with his dissertation entitled "Eine Theorie der Schwerkraft im Rahmen der ursprünglichen Einsteinschen Relativitätstheorie (A theory of gravity in the framework of the original Einstein theory of relativity)". His advisors were Max Planck and Heinrich Rubens.

Espen Gaarder Haug <=SEP=> Espen Gaarder Haug is an author,  quantitative trader and arbitrageur specializing in options and other derivatives.  He is best known for his book The Complete Guide to Option Pricing Formulas, and is a regular columnist for Wilmott Magazine. He has worked as a trader for J.P. Morgan Chase in New York City, Chemical Banking, Paloma Partners, Tempus Financial Engineering, and Den norske Bank.

Experimentum crucis <=SEP=> In the sciences, an experimentum crucis (English: crucial experiment or critical experiment) is an experiment capable of decisively determining whether or not a particular hypothesis or theory is superior to all other hypotheses or theories whose acceptance is currently widespread in the scientific community.

Extended theories of gravity <=SEP=> Extended theories of gravity are alternative theories of gravity developed from the exact starting points investigated first by Einstein and Hilbert. These are theories describing gravity, which are metric theory, "a linear connection" or related affine theories, or metric-affine gravitation theory.

Four-dimensional space <=SEP=> In mathematics, four-dimensional space "\4D") is a geometric space with four dimensions. It typically is more specifically four-dimensional Euclidean space, generalizing the rules of three-dimensional Euclidean space.

Frank Watson Dyson <=SEP=> Sir Frank Watson Dyson, KBE, FRS (8 January 1868 – 25 May 1939) was an English astronomer and Astronomer Royal who is remembered today largely for introducing time signals "\pips") from Greenwich, England, and for the role he played in proving Einstein's theory of general relativity.

Gauge theory gravity <=SEP=> Gauge theory gravity (GTG) is a theory of gravitation cast in the mathematical language of geometric algebra.  To those familiar with general relativity, it is highly reminiscent of the tetrad formalism although there are significant conceptual differences.  Most notably, the background in GTG is flat, Minkowski spacetime.  The equivalence principle is not assumed, but instead follows from the fact that the gauge covariant derivative is minimally coupled.

Goldberg–Sachs theorem <=SEP=> The Goldberg–Sachs theorem is a result in Einstein's theory of general relativity about vacuum solutions of the Einstein field equations relating the existence of a certain type of congruence with algebraic properties of the Weyl tensor.

Gravitational constant <=SEP=> The gravitational constant, approximately 6989667400000000000♠6.674×10−11 N⋅m2/kg2 and denoted by letter G, is an empirical physical constant involved in the calculation(s) of gravitational force between two bodies. It usually appears in Sir Isaac Newton's law of universal gravitation, and in Albert Einstein's general theory of relativity. It is also known as the universal gravitational constant, Newton's constant, and colloquially as Big G.

Gravitational time dilation <=SEP=> Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass. The stronger the gravitational potential (the closer the clock is to the source of gravitation), the slower time passes.

Gravity <=SEP=> Gravity or gravitation is a natural phenomenon by which all things with mass are brought towards (or 'gravitate' towards) one another including stars, planets, galaxies and even light and sub-atomic particles. Gravity is responsible for the complexity in the universe, by creating spheres of hydrogen, igniting them under pressure to form stars and grouping them into galaxies.

Higher-dimensional Einstein gravity <=SEP=> Higher-dimensional Einstein gravity is any of various physical theories that attempt to generalise to higher dimensions various results of the well established theory of standard (four-dimensional) Einstein gravity, that is, general relativity. This attempt at generalisation has been strongly influenced in recent decades by string theory.At present, this work can probably be most fairly described as extended theoretical speculation.

History of loop quantum gravity <=SEP=> 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.

History of special relativity <=SEP=> The history of special relativity consists of many theoretical results and empirical findings obtained by Albert A. Michelson, Hendrik Lorentz, Henri Poincaré and others. It culminated in the theory of special relativity proposed by Albert Einstein and subsequent work of Max Planck, Hermann Minkowski and others.

Hole argument <=SEP=> In general relativity, the hole argument is an apparent paradox that much troubled Albert Einstein while developing his famous field equation.Some philosophers of physics take the argument to raise a problem for manifold substantialism, a doctrine that the manifold of events in spacetime is a "substance" which exists independently of the matter within it.

Introduction to the mathematics of general relativity <=SEP=> The mathematics of general relativity are complex. In Newton's theories of motion, an object's length and the rate at which time passes remain constant while the object accelerates, meaning that many problems in Newtonian mechanics may be solved by algebra alone. In relativity, however, an object's length and the rate at which time passes both change appreciably as the object's speed approaches the speed of light, meaning that more variables and more complicated mathematics are required to calculate the object's motion. As a result, relativity requires the use of concepts such as vectors, tensors, pseudotensors and curvilinear coordinates.

Jürgen Ehlers <=SEP=> Jürgen Ehlers (German: [ˈjʏʁɡŋ̩ ˈeːlɐs]; December 29, 1929 – May 20, 2008) was a German physicist who contributed to the understanding of Albert Einstein's theory of general relativity. From graduate and postgraduate work in Pascual Jordan's relativity research group at Hamburg University, he held various posts as a lecturer and, later, as a professor before joining the Max Planck Institute for Astrophysics in Munich as a director.

Kaluza–Klein theory <=SEP=> In physics, Kaluza–Klein theory (KK theory) is a unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the usual four of space and time.  It is considered to be an important precursor to string theory.The five-dimensional theory was developed in three steps. The original hypothesis came from Theodor Kaluza, who sent his results to Einstein in 1919, and published them in 1921.

Laws of science <=SEP=> The laws of science or scientific laws are statements that describe or predict a range of phenomena behave as they appear to in nature. The term "law" has diverse usage in many cases: approximate, accurate, broad or narrow theories, in all natural scientific disciplines (physics, chemistry, biology, geology, astronomy etc.).

Light <=SEP=> Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 6993400000000000000♠400×10−9 m to 6993700000000000000♠700×10−9 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

List of scientific publications by Albert Einstein <=SEP=> Albert Einstein (1879–1955) was a renowned theoretical physicist of the 20th century, best known for his theories of special relativity and general relativity.  He also made important contributions to statistical mechanics, especially his treatment of Brownian motion, his resolution of the paradox of specific heats, and his connection of fluctuations and dissipation.

Lorentz ether theory <=SEP=> What is now often called Lorentz ether theory (LET) has its roots in Hendrik Lorentz's "theory of electrons", which was the final point in the development of the classical aether theories at the end of the 19th and at the beginning of the 20th century.Lorentz's initial theory created in 1892 and 1895 was based on a completely motionless aether.

Lorentz transformation <=SEP=> In physics, the Lorentz transformation (or transformations) is named after the Dutch physicist Hendrik Lorentz. It was the result of attempts by Lorentz and others to explain how the speed of light was observed to be independent of the reference frame, and to understand the symmetries of the laws of electromagnetism.

Lovelock theory of gravity <=SEP=> 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. It is the most general metric theory of gravity yielding conserved second order equations of motion in arbitrary number of spacetime dimensions D. In this sense, Lovelock's theory is the natural generalization of Einstein's General Relativity to higher dimensions.

Luminiferous aether <=SEP=> In the late 19th century, luminiferous aether, æther or ether, meaning light-bearing aether, was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do.The concept was the topic of considerable debate throughout its history, as it required the existence of an invisible and infinite material with no interaction with physical objects.

Magnetism <=SEP=> Magnetism is a class of physical phenomena that are mediated by magnetic fields.  Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. Every material is influenced to some extent by a magnetic field. The most familiar effect is on permanent magnets, which have persistent magnetic moments caused by ferromagnetism. Most materials do not have permanent moments.

Mass in special relativity <=SEP=> Mass in special relativity incorporates the general understandings from the concept of mass–energy equivalence.

Max Planck Institute for Gravitational Physics <=SEP=> The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) is a Max Planck Institute whose research is aimed at investigating Einstein’s theory of relativity and beyond: Mathematics, quantum gravity, astrophysical relativity, and gravitational wave astronomy.

Michelson–Morley experiment <=SEP=> The Michelson–Morley experiment was performed over the spring and summer of 1887 by Albert A. Michelson and Edward W. Morley at what is now Case Western Reserve University in Cleveland, Ohio, and published in November of the same year. It compared the speed of light in perpendicular directions, in an attempt to detect the relative motion of matter through the stationary luminiferous aether "\aether wind").

Minkowski space <=SEP=> In mathematical physics, Minkowski space or Minkowski spacetime is a combination of Euclidean space and time into a four-dimensional manifold where the spacetime interval between any two events is independent of the inertial frame of reference in which they are recorded.

Nordström's theory of gravitation <=SEP=> In theoretical physics, Nordström's theory of gravitation was a predecessor of general relativity.  Strictly speaking, there were actually two distinct theories proposed by the Finnish theoretical physicist Gunnar Nordström, in 1912 and 1913 respectively.

Null dust solution <=SEP=> In mathematical physics, a null dust solution (sometimes called a null fluid) is a Lorentzian manifold in which the Einstein tensor is null.  Such a spacetime can be interpreted as an exact solution of Einstein's field equation, in which the only mass-energy present in the spacetime is due to some kind of massless radiation.

Numerical relativity <=SEP=> Numerical relativity is one of the branches of general relativity that uses numerical methods and algorithms to solve and analyze problems. To this end, supercomputers are often employed to study black holes, gravitational waves, neutron stars and many other phenomena governed by Einstein's Theory of General Relativity. A currently active field of research in numerical relativity is the simulation of relativistic binaries and their associated gravitational waves. Other branches are also active.

Observer (special relativity) <=SEP=> In special relativity, an observer is a frame of reference from which a set of objects or events are being measured. Usually this is an inertial reference frame or "inertial observer". Less often an observer may be an arbitrary non-inertial reference frame such as a Rindler frame which may be called an "accelerating observer".  The special relativity usage differs significantly from the ordinary English meaning of "observer".

Outline of physics <=SEP=> The following outline is provided as an overview of and topical guide to physics:Physics – natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

Pantur Silaban <=SEP=> Pantur Silaban is one of the foremost physicists in Indonesia, especially in the field of theoretical physics.  He is also one of the earliest physicists from ASEAN countries who studied Einstein's general relativity theories in depth.

Petr Beckmann <=SEP=> Petr Beckmann (November 13, 1924 in Prague, Czechoslovakia – August 3, 1993 in Boulder, Colorado) was a professor of electrical engineering who became a well-known advocate of libertarianism and nuclear power. Later in his life he challenged Albert Einstein's theory of relativity and other accepted theories in modern physics.

Philosophy of space and time <=SEP=> Philosophy of space and time is the branch of philosophy concerned with the issues surrounding the ontology, epistemology, and character of space and time. While such ideas have been central to philosophy from its inception, the philosophy of space and time was both an inspiration for and a central aspect of early analytic philosophy.

Photoelectric effect <=SEP=> The photoelectric effect is the observation that many metals emit electrons when light shines upon them. Electrons emitted in this manner can be called photoelectrons. The phenomenon is commonly studied in electronic physics, as well as in fields of chemistry, such as quantum chemistry or electrochemistry.According to classical electromagnetic theory, this effect can be attributed to the transfer of energy from the light to an electron in the metal.

Photon <=SEP=> A photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation. It is the force carrier for the electromagnetic force, even when static via virtual photons. The effects of this force are easily observable at the microscopic and at the macroscopic level, because the photon has zero rest mass; this allows long distance interactions.

Photon polarization <=SEP=> Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. Individual photon eigenstates have either right or left circular polarization.

Physical theories modified by general relativity <=SEP=> This article will use the Einstein summation convention.The theory of general relativity required the adaptation of existing theories of physical, electromagnetic, and quantum effects to account for non-Euclidean geometries. These physical theories modified by general relativity are described below.

Postulates of special relativity <=SEP=> See also: Special relativity

Principle of relativity <=SEP=> 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.

Quantum cosmology <=SEP=> Quantum cosmology is the attempt in theoretical physics to develop a quantum theory of the Universe. This approach attempts to answer open questions of classical cosmology, particularly those related to the first phases of the universe.The classical cosmology is based on Albert Einstein's General Theory of Relativity (GTR). It describes the evolution of the universe very well, as long as you do not approach the Big Bang.

Quantum gravity <=SEP=> Quantum gravity (QG) is a field of theoretical physics that seeks to describe the force of gravity according to the principles of quantum mechanics.The current understanding of gravity is based on Albert Einstein's general theory of relativity, which is formulated within the framework of classical physics. On the other hand, the nongravitational forces are described within the framework of quantum mechanics, a radically different formalism for describing physical phenomena based on probability.

Relational theory <=SEP=> In physics and philosophy, a relational theory is a framework to understand reality or a physical system in such a way that the positions and other properties of objects are only meaningful relative to other objects. In a relational spacetime theory, space does not exist unless there are objects in it; nor does time exist without events. The relational view proposes that space is contained in objects and that an object represents within itself relationships to other objects.

Relativity: The Special and the General Theory <=SEP=> 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:. . . an exact insight into the theory of relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics.It was first published in German in 1916 and later translated into English in 1920.

Relativity of simultaneity <=SEP=> In physics, the relativity of simultaneity is the concept that distant simultaneity – whether two spatially separated events occur at the same time – is not absolute, but depends on the observer's reference frame.

Relativity priority dispute <=SEP=> Albert Einstein presented the theories of Special Relativity and General Relativity in groundbreaking publications that either contained no formal references to previous literature, or referred only to a small number of his predecessors for fundamental results on which he based his theories, most notably to the work of Hendrik Lorentz for special relativity, and to the work of Gauss, Riemann, and Mach for general relativity.

Ricci curvature <=SEP=> In differential geometry, the Ricci curvature tensor, named after Gregorio Ricci-Curbastro, represents the amount by which the volume of a geodesic ball in a curved Riemannian manifold deviates from that of the standard ball in Euclidean space.  As such, it provides one way of measuring the degree to which the geometry determined by a given Riemannian metric might differ from that of ordinary Euclidean n-space.

Satyendra Nath Bose <=SEP=> Satyendra Nath Bose, FRS (Bengali: সত্যেন্দ্র নাথ বসু Shottendronath Boshū, IPA: [ʃot̪ːend̪ronat̪ʰ boʃu]; 1 January 1894 – 4 February 1974) was an Indian Bengali physicist specialising in mathematical physics.  He is best known for his work on quantum mechanics in the early 1920s, providing the foundation for Bose–Einstein statistics and the theory of the Bose–Einstein condensate.

Scalar field solution <=SEP=> In general relativity, a scalar field solution is an exact solution of the Einstein field equation in which the gravitational field is due entirely to the field energy and momentum of a scalar field.  Such a field may or may not be massless, and it may be taken to have minimal curvature coupling, or some other choice, such as conformal coupling.

Scientific theory <=SEP=> A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation.

Sobral, Ceará <=SEP=> Sobral is a municipality in the state of Ceará, Brazil.Sobral is the fifth largest municipality of Ceará, after Fortaleza. Its economy is based on agriculture, services and some manufacturing industries.

Space <=SEP=> Space is the boundless three-dimensional extent in which objects and events have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe.

Spacetime <=SEP=> In physics, spacetime (also space–time, space time or space–time continuum) is any mathematical model that combines space and time into a single interwoven continuum. The spacetime of our universe is usually interpreted from a Euclidean space perspective, which regards space as consisting of three dimensions, and time as consisting of one dimension, the "fourth dimension".

Special relativity <=SEP=> In physics, special relativity (SR, also known as the special theory of relativity or STR) is the generally accepted physical theory regarding the relationship between space and time. It is based on two postulates: (1) that the laws of physics are invariant (i.e. identical) in all inertial systems (non-accelerating frames of reference); and (2) that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source.

Special relativity (alternative formulations) <=SEP=> As formulated by Albert Einstein in 1905, the theory of special relativity was based on two main postulates: The principle of relativity — The form of a physical law is the same in any inertial frame. The speed of light is constant — In all inertial frames, the speed of light c is the same whether the light is emitted from a source at rest or in motion. (Note this does not apply in non-inertial frames, indeed between accelerating frames the speed of light cannot be constant.

Speed of gravity <=SEP=> In classical theories of gravitation, the speed of gravity is the speed at which changes in a gravitational field propagate. This is the speed at which a change in the distribution of energy and momentum of matter results in subsequent alteration, at a distance, of the gravitational field which it produces. In a more physically correct sense, the "speed of gravity" refers to the speed of a gravitational wave, which in turn is the same speed as the speed of light (c).

Static universe <=SEP=> A static universe, also referred to as a "stationary" or "infinite" or "static infinite" universe, is a cosmological model in which the universe is both spatially infinite and temporally infinite, and space is neither expanding nor contracting. Such a universe does not have spatial curvature; that is to say that it is 'flat'.

Test theories of special relativity <=SEP=> Test theories of special relativity give a mathematical framework for analyzing results of experiments to verify special relativity.An experiment to test the theory of relativity cannot assume the theory is true, and therefore needs some other framework of assumptions that are wider than those of relativity. For example, a test theory may have a different postulate about light concerning one-way speed of light vs.

Tests of special relativity <=SEP=> Special relativity is a physical theory that plays a fundamental role in the description of all physical phenomena, as long as gravitation is not significant. Many experiments played (and still play) an important role in its development and justification. The strength of the theory lies in its unique ability to correctly predict to high precision the outcome of an extremely diverse range of experiments.

The Einstein Theory of Relativity <=SEP=> The Einstein Theory of Relativity (1923) is a silent film directed by Max and 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.

The Evolution of Physics <=SEP=> The Evolution of Physics: The Growth of Ideas From Early Concepts to Relativity and Quanta is a science book for the lay reader, by Albert Einstein and Leopold Infeld, tracing the development of ideas in physics. It was originally published in 1938 by Cambridge University Press. It was a popular success, and was featured in a Time magazine cover story.

Theoretical physics <=SEP=> Theoretical physics is a branch of physics which 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 depends in general on the interplay between experimental studies and theory.

Theory of everything <=SEP=> A theory of everything (ToE) or final theory, ultimate theory, or master theory is a hypothetical single, all-encompassing, coherent theoretical framework of physics that fully explains and links together all physical aspects of the universe. Finding a ToE is one of the major unsolved problems in physics. Over the past few centuries, two theoretical frameworks have been developed that, as a whole, most closely resemble a ToE.

Theory of relativity <=SEP=> The theory of relativity, or simply relativity in physics,  usually encompasses two theories by Albert Einstein: special relativity and general relativity.Concepts introduced by the theories of relativity include:Measurements of various quantities are relative to the velocities of observers. In particular, space contracts and time dilates.Spacetime: space and time should be considered together and in relation to each other.

Time dilation <=SEP=> In the theory of relativity, time dilation is a difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from a gravitational mass or masses.An accurate clock at rest with respect to one observer may be measured to tick at a different rate when compared to a second observer's own equally accurate clocks.

Timeline of black hole physics <=SEP=> Timeline of black hole physics 1640 — Ismaël Bullialdus suggests an inverse-square gravitational force law 1676 — Ole Rømer proves that light has a finite speed 1684 — Isaac Newton writes down his inverse-square Law of universal gravitation 1758 — Rudjer Josip Boscovich develops his Theory of forces, where gravity can be repulsive on small distances.

Twin paradox <=SEP=> In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, according to an incorrect naive application of time dilation and the principle of relativity, each should paradoxically find the other to have aged more slowly.

Unified field theory <=SEP=> In physics, a unified field theory (UFT), occasionally referred to as a uniform field theory, is a type of field theory that allows all that is usually thought of as fundamental forces and elementary particles to be written in terms of a single field.  There is no accepted unified field theory, and thus it remains an open line of research.  The term was coined by Einstein, who attempted to unify the general theory of relativity with electromagnetism.

Variable speed of light <=SEP=> Variable speed of light (VSL) is a hypothesis that states that the speed of light, usually denoted by c, may be  a function of space and time. Variable speed of light  occurs in some situations of classical physics as equivalent formulations of accepted theories, but also in various alternative theories of gravitation and cosmology, many of them non-mainstream. In classical physics, the refractive index describes how light slows down when traveling through a medium.

Variational methods in general relativity <=SEP=> 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.

Yilmaz theory of gravitation <=SEP=> 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 his proposed field equation is ill-defined, event horizons can occur in weak field situations according to the general theory of relativity, in the case of a supermassive black hole.

Zero-point energy <=SEP=> Zero-point energy, also called quantum vacuum zero-point energy, is the lowest possible energy that a quantum mechanical physical system may have; it is the energy of its ground state.All quantum mechanical systems undergo fluctuations even in their ground state and have an associated zero-point energy, a consequence of their wave-like nature. The uncertainty principle requires every physical system to have a zero-point energy greater than the minimum of its classical potential well.