200 relations: Abhay Ashtekar, Acceleration, Albert Einstein, Alexander Friedmann, Amanda Weltman, Andrei Sakharov, Angular momentum, Anti-gravity, Apocrypha, Aristotelian physics, Aristotle, Arthur Eddington, Artificial gravity, Astronomical object, Astronomical unit, Big Bang, Binary black hole, Birkeland current, Black hole, Brans–Dicke theory, Bulge (astronomy), Carlo Rovelli, Chameleon particle, Circular symmetry, Classical limit, Classical mechanics, Conformal gravity, Contact force, Cosmic microwave background, Cosmological constant, Curvature, Dark energy, Dark flow, Dark matter, Differential equation, Distance, Drag (physics), Earth, Earth tide, Edwin Hubble, Einstein field equations, Einstein–Infeld–Hoffmann equations, Electromagnetism, Energy, Entropic gravity, Equivalence principle, Escape velocity, Event horizon, Expansion of the universe, F(R) gravity, ..., False vacuum, Field equation, Flyby anomaly, Force, Formation and evolution of the Solar System, Frame-dragging, Friedmann–Lemaître–Robertson–Walker metric, Fundamental interaction, G-force, Galaxy formation and evolution, Galaxy groups and clusters, Galaxy rotation curve, Galileo Galilei, Gauge gravitation theory, Gauss's law for gravity, General relativity, Geodesics in general relativity, Geometrized unit system, Georges Lemaître, Georges-Louis Le Sage, Gravitational binding energy, Gravitational constant, Gravitational field, Gravitational lens, Gravitational potential, Gravitational redshift, Gravitational singularity, Gravitational time dilation, Gravitational wave, Gravitational wave background, Gravity assist, Gravity gradiometry, Gravity Probe B, Gravity Recovery and Climate Experiment, Gravity Research Foundation, Gravity well, Hafele–Keating experiment, Horndeski's theory, Hulse–Taylor binary, Inclined plane, Induced gravity, International Bureau of Weights and Measures, International System of Units, Inverse-square law, Irwin I. Shapiro, Isaac Newton, Ismaël Bullialdus, Jacob Bekenstein, Johann Gottfried Galle, John Couch Adams, John Moffat (physicist), Jovian–Plutonian gravitational effect, Kaluza–Klein theory, Kepler's laws of planetary motion, Kerr metric, Kerr–Newman metric, Lagrangian point, Le Sage's theory of gravitation, Leaning Tower of Pisa, Lee Smolin, LIGO, List of natural phenomena, Loop quantum gravity, Loránd Eötvös, Lyman-alpha forest, Macroscopic scale, Mass, Max Born, Mercury (planet), Metric tensor (general relativity), Micro-g environment, Mixmaster universe, Modified Newtonian dynamics, Moon, Mordehai Milgrom, N-body problem, Neptune, Neutron star, Newton (unit), Newton's law of universal gravitation, Newton's laws of motion, Nonlinear system, Nonsymmetric gravitational theory, Nordström's theory of gravitation, Orbit, Philosophiæ Naturalis Principia Mathematica, Philosophical Transactions of the Royal Society A, Photon, Photon energy, Physical cosmology, Pioneer anomaly, Planck length, Planck time, Planck units, Potential energy, Pound–Rebka experiment, Pressuron, Proportionality (mathematics), Pulsar, Quantum field theory, Quantum gravity, Quantum mechanics, Quasar, Quasiparticle, Reissner–Nordström metric, Ritz ballistic theory, Rotation, Rutherford Appleton Laboratory, Scalar theories of gravitation, Schwarzschild metric, Schwarzschild radius, Science Bulletin, Shapiro time delay, Solar eclipse of May 29, 1919, Solar System, Space, Spacetime, Speed of gravity, Square (algebra), Standard gravitational parameter, Standard gravity, Star formation, Stellar evolution, STEP (satellite), String theory, Strong interaction, Supercluster, Superfluid vacuum theory, Superfluidity, Supergravity, System of equations, Tensor–vector–scalar gravity, Tests of general relativity, Theory of everything, Theory of relativity, Tide, Time, Trajectory, Two New Sciences, Universe, University of Oregon, Uranus, Urbain Le Verrier, Vacuum state, Virgo interferometer, Virtual particle, Weak interaction, Weight, Weightlessness, Whitehead's theory of gravitation. Expand index (150 more) » « Shrink index
Abhay Vasant Ashtekar (born July 5, 1949) is an Indian theoretical physicist.
In physics, acceleration is the rate of change of velocity of an object with respect to time.
Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics).
Alexander Alexandrovich Friedmann (also spelled Friedman or Fridman; Алекса́ндр Алекса́ндрович Фри́дман) (June 16, 1888 – September 16, 1925) was a Russian and Soviet physicist and mathematician.
Amanda Weltman (born 1979) is a South African theoretical physicist.
Andrei Dmitrievich Sakharov (p; 21 May 192114 December 1989) was a Russian nuclear physicist, dissident, and activist for disarmament, peace and human rights.
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational equivalent of linear momentum.
Anti-gravity (also known as non-gravitational field) is an idea of creating a place or object that is free from the force of gravity.
Apocrypha are works, usually written, of unknown authorship or of doubtful origin.
Aristotelian physics is a form of natural science described in the works of the Greek philosopher Aristotle (384–).
Aristotle (Ἀριστοτέλης Aristotélēs,; 384–322 BC) was an ancient Greek philosopher and scientist born in the city of Stagira, Chalkidiki, in the north of Classical Greece.
Sir Arthur Stanley Eddington (28 December 1882 – 22 November 1944) was an English astronomer, physicist, and mathematician of the early 20th century who did his greatest work in astrophysics.
Artificial gravity (sometimes referred to as pseudogravity) is the creation of an inertial force that mimics the effects of a gravitational force, usually by rotation.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun.
The Big Bang theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution.
A binary black hole (BBH) is a system consisting of two black holes in close orbit around each other.
A Birkeland current is a set of currents that flow along geomagnetic field lines connecting the Earth’s magnetosphere to the Earth's high latitude ionosphere.
A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.
In theoretical physics, the Brans–Dicke theory of gravitation (sometimes called the Jordan–Brans–Dicke theory) is a theoretical framework to explain gravitation.
In astronomy, a bulge is a tightly packed group of stars within a larger formation.
Carlo Rovelli (born 3 May 1956) is an Italian theoretical physicist, philosopher and writer who has worked in Italy, the United States and since 2000, in France.
The chameleon is a hypothetical scalar particle that couples to matter more weakly than gravity, postulated as a dark energy candidate.
In geometry, circular symmetry is a type of continuous symmetry for a planar object that can be rotated by any arbitrary angle and map onto itself.
The classical limit or correspondence limit is the ability of a physical theory to approximate or "recover" classical mechanics when considered over special values of its parameters.
Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars and galaxies.
Conformal gravity are gravity theories that are invariant under conformal transformations in the Riemannian geometry sense; more accurately, they are invariant under Weyl transformations g_\rightarrow\Omega^2(x)g_ where g_ is the metric tensor and \Omega(x) is a function on spacetime.
A contact force is any force that requires contact to occur.
The cosmic microwave background (CMB, CMBR) is electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology.
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.
In mathematics, curvature is any of a number of loosely related concepts in different areas of geometry.
In physical cosmology and astronomy, dark energy is an unknown form of energy which is hypothesized to permeate all of space, tending to accelerate the expansion of the universe.
In astrophysics, dark flow is a possible non-random component of the peculiar velocity of galaxy clusters.
Dark matter is a theorized form of matter that is thought to account for approximately 80% of the matter in the universe, and about a quarter of its total energy density.
A differential equation is a mathematical equation that relates some function with its derivatives.
Distance is a numerical measurement of how far apart objects are.
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.
Earth is the third planet from the Sun and the only astronomical object known to harbor life.
Earth tide (also known as solid Earth tide, crustal tide, body tide, bodily tide or land tide) is the displacement of the solid earth's surface caused by the gravity of the Moon and Sun.
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer.
The Einstein field equations (EFE; also known as Einstein's equations) comprise the set of 10 equations in Albert Einstein's general theory of relativity that describe the fundamental interaction of gravitation as a result of spacetime being curved by mass and energy.
The Einstein–Infeld–Hoffmann equations of motion, jointly derived by Albert Einstein, Leopold Infeld and Banesh Hoffmann, are the differential equations of motion describing the approximate dynamics of a system of point-like masses due to their mutual gravitational interactions, including general relativistic effects.
Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles.
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
Entropic gravity, also known as emergent gravity, is a theory in modern physics that describes gravity as an entropic force—a force with macro-scale homogeneity but which is subject to quantum-level disorder—and not a fundamental interaction.
In the theory of general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass, and to Albert Einstein's observation that the gravitational "force" as experienced locally while standing on a massive body (such as the Earth) is the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference.
In physics, escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a massive body.
In general relativity, an event horizon is a region in spacetime beyond which events cannot affect an outside observer.
The expansion of the universe is the increase of the distance between two distant parts of the universe with time.
f(R) gravity is a type of modified gravity theory which generalizes Einstein's general relativity.
In quantum field theory, a false vacuum is a hypothetical vacuum that is somewhat, but not entirely, stable.
In theoretical physics and applied mathematics, a field equation is a partial differential equation which determines the dynamics of a physical field, specifically the time evolution and spatial distribution of the field.
The flyby anomaly is a discrepancy between current scientific models and the actual increase in speed (i.e. increase in kinetic energy) observed during a planetary flyby by a spacecraft.
In physics, a force is any interaction that, when unopposed, will change the motion of an object.
The formation and evolution of the Solar System began 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud.
Frame-dragging is an effect on spacetime, predicted by Einstein's general theory of relativity, that is due to non-static stationary distributions of mass–energy.
The Friedmann–Lemaître–Robertson–Walker (FLRW) metric is an exact solution of Einstein's field equations of general relativity; it describes a homogeneous, isotropic, expanding or contracting universe that is path connected, but not necessarily simply connected.
In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic interactions.
The gravitational force, or more commonly, g-force, is a measurement of the type of acceleration that causes a perception of weight.
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies.
Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation.
The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre.
Galileo Galilei (15 February 1564Drake (1978, p. 1). The date of Galileo's birth is given according to the Julian calendar, which was then in force throughout Christendom. In 1582 it was replaced in Italy and several other Catholic countries with the Gregorian calendar. Unless otherwise indicated, dates in this article are given according to the Gregorian calendar. – 8 January 1642) was an Italian polymath.
In quantum field theory, gauge gravitation theory is the effort to extend Yang–Mills theory, which provides a universal description of the fundamental interactions, to describe gravity.
In physics, Gauss's law for gravity, also known as Gauss's flux theorem for gravity, is a law of physics that is essentially equivalent to Newton's law of universal gravitation.
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.
In general relativity, a geodesic generalizes the notion of a "straight line" to curved spacetime.
A geometrized unit system or geometric unit system is a system of natural units in which the base physical units are chosen so that the speed of light in vacuum, c, and the gravitational constant, G, are set equal to unity.
Georges Henri Joseph Édouard Lemaître, RAS Associate (17 July 1894 – 20 June 1966) was a Belgian Catholic Priest, astronomer and professor of physics at the Catholic University of Leuven.
Georges-Louis Le Sage (13 June 1724 – 9 November 1803) was a Genevan physicist and is most known for his theory of gravitation, for his invention of an electric telegraph and his anticipation of the kinetic theory of gases.
A gravitational binding energy is the minimum energy that must be added to a system for the system to cease being in a gravitationally bound state.
The gravitational constant (also known as the "universal gravitational constant", the "Newtonian constant of gravitation", or the "Cavendish gravitational constant"), denoted by the letter, is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general theory of relativity.
In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer.
In classical mechanics, the gravitational potential at a location is equal to the work (energy transferred) per unit mass that would be needed to move the object from a fixed reference location to the location of the object.
In astrophysics, gravitational redshift or Einstein shift is the process by which electromagnetic radiation originating from a source that is in a gravitational field is reduced in frequency, or redshifted, when observed in a region at a higher gravitational potential.
A gravitational singularity or spacetime singularity is a location in spacetime where the gravitational field of a celestial body becomes infinite in a way that does not depend on the coordinate system.
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.
Gravitational waves are the disturbance in the fabric ("curvature") of spacetime generated by accelerated masses and propagate as waves outward from their source at the speed of light.
The gravitational wave background (also GWB and stochastic background) is a random gravitational wave signal produced by a large number of weak, independent, and unresolved sources.
In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter the path and speed of a spacecraft, typically to save propellant and reduce expense.
Gravity gradiometry is the study and measurement of variations in the acceleration due to gravity.
Gravity Probe B (GP-B) was a satellite-based mission which launched on 20 April 2004 on a Delta II rocket.
The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center.
The Gravity Research Foundation is an organization established in 1948 by businessman Roger Babson (founder of Babson College) to find ways to implement gravitational shielding.
A gravity well or gravitational well is a conceptual model of the gravitational field surrounding a body in space – the more massive the body, the deeper and more extensive the gravity well associated with it.
The Hafele–Keating experiment was a test of the theory of relativity.
Horndeski's theory is the most general theory of gravity in four dimensions whose Lagrangian is constructed out of the metric tensor and a scalar field and leads to second order equations of motion.
PSR B1913+16 (also known as PSR J1915+1606, PSR 1913+16, and the Hulse–Taylor binary after its discoverers) is a pulsar (a radiating neutron star) which together with another neutron star is in orbit around a common center of mass, thus forming a binary star system.
An inclined plane, also known as a ramp, is a flat supporting surface tilted at an angle, with one end higher than the other, used as an aid for raising or lowering a load.
Induced gravity (or emergent gravity) is an idea in quantum gravity that space-time curvature and its dynamics emerge as a mean field approximation of underlying microscopic degrees of freedom, similar to the fluid mechanics approximation of Bose–Einstein condensates.
The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
The inverse-square law, in physics, is any physical law stating that a specified physical quantity or intensity is inversely proportional to the square of the distance from the source of that physical quantity.
Irwin Ira Shapiro (born October 10, 1929 in New York City) is an American astrophysicist and Timken University Professor at Harvard University.
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, astronomer, theologian, author and physicist (described in his own day as a "natural philosopher") who is widely recognised as one of the most influential scientists of all time, and a key figure in the scientific revolution.
Ismaël Bullialdus (born Ismaël Boulliau,; 28 September 1605 – 25 November 1694) was a 17th-century French astronomer and mathematician who was also interested in history, theology, classical studies, and philology.
Jacob David Bekenstein (יעקב בקנשטיין; May 1, 1947 – August 16, 2015) was a Mexican-born Israeli-American theoretical physicist who made fundamental contributions to the foundation of black hole thermodynamics and to other aspects of the connections between information and gravitation.
Johann Gottfried Galle, 1880 Galle's signature Memorial plaque in Wittenberg Johann Gottfried Galle (9 June 1812 – 10 July 1910) was a German astronomer from Radis, Germany, at the Berlin Observatory who, on 23 September 1846, with the assistance of student Heinrich Louis d'Arrest, was the first person to view the planet Neptune and know what he was looking at.
John Couch Adams (5 June 1819 – 21 January 1892) was a British mathematician and astronomer.
John W. Moffat (born 24 May 1932) is a Danish-born British-Canadian physicist.
The Jovian–Plutonian gravitational effect was a hoax phenomenon purported to cause a noticeable short-term reduction in gravity on Earth that was invented for April Fools' Day by the English astronomer Patrick Moore and broadcast on BBC Radio 2 on 1 April 1976.
In physics, Kaluza–Klein theory (KK theory) is a classical unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the usual four of space and time and considered an important precursor to string theory.
In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.
The Kerr metric or Kerr geometry describes the geometry of empty spacetime around a rotating uncharged axially-symmetric black hole with a spherical event horizon.
The Kerr–Newman metric is a solution of the Einstein–Maxwell equations in general relativity that describes the spacetime geometry in the region surrounding a charged, rotating mass.
In celestial mechanics, the Lagrangian points (also Lagrange points, L-points, or libration points) are positions in an orbital configuration of two large bodies, wherein a small object, affected only by the gravitational forces from the two larger objects, will maintain its position relative to them.
Le Sage's theory of gravitation is a kinetic theory of gravity originally proposed by Nicolas Fatio de Duillier in 1690 and later by Georges-Louis Le Sage in 1748.
The Leaning Tower of Pisa (Torre pendente di Pisa) or simply the Tower of Pisa (Torre di Pisa) is the campanile, or freestanding bell tower, of the cathedral of the Italian city of Pisa, known worldwide for its unintended tilt.
Lee Smolin (born June 6, 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the philosophy department at the University of Toronto.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool.
Types of natural phenomena include, but are not limited to, the following: Weather, fog, thunder, tornadoes; biological processes, decomposition, germination; physical processes, wave propagation, erosion; tidal flow, and natural disasters such as electromagnetic pulses, volcanic eruptions, and earthquakes.
Loop quantum gravity (LQG) is a theory of quantum gravity, merging quantum mechanics and general relativity.
Baron Loránd Eötvös de Vásárosnamény (vásárosnaményi báró Eötvös Loránd Ágoston or Loránd Eötvös,; 27 July 1848 – 8 April 1919), more commonly called Baron Roland von Eötvös in English literature, was an Austro-Hungarian physicist of ethnic Hungarian origin.
In astronomical spectroscopy, the Lyman-alpha forest is a series of absorption lines in the spectra of distant galaxies and quasars arising from the Lyman-alpha electron transition of the neutral hydrogen atom.
The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible almost practically with the naked eye, without magnifying optical instruments.
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.
Max Born (11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics.
Mercury is the smallest and innermost planet in the Solar System.
In general relativity, the metric tensor (in this context often abbreviated to simply the metric) is the fundamental object of study.
The term micro-g environment (also µg, often referred to by the term microgravity) is more or less a synonym for weightlessness and zero-g, but indicates that g-forces are not quite zero—just very small.
The Mixmaster universe (named after Sunbeam Mixmaster, a brand of Sunbeam Products electric kitchen mixer) is a solution to Einstein field equations of general relativity studied by Charles Misner in an effort to better understand the dynamics of the early universe.
Modified Newtonian dynamics (MOND) is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies.
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite.
Mordehai "Moti" Milgrom is an Israeli physicist and professor in the department of Particle Physics and Astrophysics at the Weizmann Institute in Rehovot, Israel.
In physics, the -body problem is the problem of predicting the individual motions of a group of celestial objects interacting with each other gravitationally.
Neptune is the eighth and farthest known planet from the Sun in the Solar System.
A neutron star is the collapsed core of a large star which before collapse had a total of between 10 and 29 solar masses.
The newton (symbol: N) is the International System of Units (SI) derived unit of force.
Newton's law of universal gravitation states that a particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Newton's laws of motion are three physical laws that, together, laid the foundation for classical mechanics.
In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input.
In theoretical physics, the nonsymmetric gravitational theory (NGT) of John Moffat is a classical theory of gravitation that tries to explain the observation of the flat rotation curves of galaxies.
In theoretical physics, Nordström's theory of gravitation was a predecessor of general relativity.
In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.
Philosophiæ Naturalis Principia Mathematica (Latin for Mathematical Principles of Natural Philosophy), often referred to as simply the Principia, is a work in three books by Isaac Newton, in Latin, first published 5 July 1687.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences is a fortnightly peer-reviewed scientific journal published by the Royal Society.
The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).
Photon energy is the energy carried by a single photon.
Physical cosmology is the study of the largest-scale structures and dynamics of the Universe and is concerned with fundamental questions about its origin, structure, evolution, and ultimate fate.
The Pioneer anomaly or Pioneer effect was the observed deviation from predicted accelerations of the Pioneer 10 and Pioneer 11 spacecraft after they passed about on their trajectories out of the Solar System.
In physics, the Planck length, denoted, is a unit of length, equal to metres.
In quantum mechanics, the Planck time is the unit of time in the system of natural units known as Planck units.
In particle physics and physical cosmology, Planck units are a set of units of measurement defined exclusively in terms of five universal physical constants, in such a manner that these five physical constants take on the numerical value of 1 when expressed in terms of these units.
In physics, potential energy is the energy possessed by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors.
The Pound–Rebka experiment is a well known experiment to test Albert Einstein's theory of general relativity.
The pressuron is a hypothetical scalar particle which couples to both gravity and matter theorised in 2013.
In mathematics, two variables are proportional if there is always a constant ratio between them.
A pulsar (from pulse and -ar as in quasar) is a highly magnetized rotating neutron star or white dwarf that emits a beam of electromagnetic radiation.
In theoretical physics, quantum field theory (QFT) is the theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics.
Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics, and where quantum effects cannot be ignored, such as near compact astrophysical objects where the effects of gravity are strong.
Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.
A quasar (also known as a QSO or quasi-stellar object) is an extremely luminous active galactic nucleus (AGN).
In physics, quasiparticles and collective excitations (which are closely related) are emergent phenomena that occur when a microscopically complicated system such as a solid behaves as if it contained different weakly interacting particles in free space.
In physics and astronomy, the Reissner–Nordström metric is a static solution to the Einstein-Maxwell field equations, which corresponds to the gravitational field of a charged, non-rotating, spherically symmetric body of mass M. The metric was discovered by Hans Reissner, Hermann Weyl, Gunnar Nordström and G. B. Jeffery.
Ritz ballistic theory is a theory in physics, first published in 1908 by Swiss physicist Walther Ritz.
A rotation is a circular movement of an object around a center (or point) of rotation.
The Rutherford Appleton Laboratory (RAL) is one of the national scientific research laboratories in the UK operated by the Science and Technology Facilities Council (STFC).
Scalar theories of gravitation are field theories of gravitation in which the gravitational field is described using a scalar field, which is required to satisfy some field equation.
In Einstein's theory of general relativity, the Schwarzschild metric (also known as the Schwarzschild vacuum or Schwarzschild solution) is the solution to the Einstein field equations that describes the gravitational field outside a spherical mass, on the assumption that the electric charge of the mass, angular momentum of the mass, and universal cosmological constant are all zero.
The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is a physical parameter that shows up in the Schwarzschild solution to Einstein's field equations, corresponding to the radius defining the event horizon of a Schwarzschild black hole.
Science Bulletin is a multidisciplinary scientific journal co-sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China.
The Shapiro time delay effect, or gravitational time delay effect, is one of the four classic solar-system tests of general relativity.
A total solar eclipse occurred on May 29, 1919.
The Solar SystemCapitalization of the name varies.
Space is the boundless three-dimensional extent in which objects and events have relative position and direction.
In physics, spacetime is any mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum.
In classical theories of gravitation, the changes in a gravitational field propagate.
In mathematics, a square is the result of multiplying a number by itself.
In celestial mechanics, the standard gravitational parameter μ of a celestial body is the product of the gravitational constant G and the mass M of the body.
The standard acceleration due to gravity (or standard acceleration of free fall), sometimes abbreviated as standard gravity, usually denoted by or, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth.
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars.
Stellar evolution is the process by which a star changes over the course of time.
The Satellite Test of the Equivalence Principle (STEP) is a proposed space science experiment to test the equivalence principle of general relativity.
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings.
In particle physics, the strong interaction is the mechanism responsible for the strong nuclear force (also called the strong force or nuclear strong force), and is one of the four known fundamental interactions, with the others being electromagnetism, the weak interaction, and gravitation.
A supercluster is a large group of smaller galaxy clusters or galaxy groups; it is among the largest-known structures of the cosmos.
Superfluid vacuum theory (SVT), sometimes known as the BEC vacuum theory, is an approach in theoretical physics and quantum mechanics where the fundamental physical vacuum (non-removable background) is viewed as superfluid or as a Bose–Einstein condensate (BEC).
Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without loss of kinetic energy.
In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity where supersymmetry obeys locality; in contrast to non-gravitational supersymmetric theories such as the Minimal Supersymmetric Standard Model.
In mathematics, a set of simultaneous equations, also known as a system of equations or an equation system, is a finite set of equations for which common solutions are sought.
Tensor–vector–scalar gravity (TeVeS), developed by Jacob Bekenstein in 2004, is a relativistic generalization of Mordehai Milgrom's Modified Newtonian dynamics (MOND) paradigm.
Tests of general relativity serve to establish observational evidence for the theory of general relativity.
A theory of everything (ToE), 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.
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity.
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of Earth.
Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.
A trajectory or flight path is the path that a massive object in motion follows through space as a function of time.
The Discourses and Mathematical Demonstrations Relating to Two New Sciences (Discorsi e Dimostrazioni Matematiche Intorno a Due Nuove Scienze), published in 1638 was Galileo's final book and a scientific testament covering much of his work in physics over the preceding thirty years.
The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
The University of Oregon (also referred to as UO, U of O or Oregon) is a public flagship research university in Eugene, Oregon.
Uranus is the seventh planet from the Sun.
Urbain Jean Joseph Le Verrier (11 March 1811 – 23 September 1877) was a French mathematician who specialized in celestial mechanics and is best known for predicting the existence and position of Neptune using only mathematics.
In quantum field theory, the quantum vacuum state (also called the quantum vacuum or vacuum state) is the quantum state with the lowest possible energy.
The Virgo interferometer is a large interferometer designed to detect gravitational waves predicted by the general theory of relativity.
In physics, a virtual particle is a transient fluctuation that exhibits some of the characteristics of an ordinary particle, but whose existence is limited by the uncertainty principle.
In particle physics, the weak interaction (the weak force or weak nuclear force) is the mechanism of interaction between sub-atomic particles that causes radioactive decay and thus plays an essential role in nuclear fission.
In science and engineering, the weight of an object is related to the amount of force acting on the object, either due to gravity or to a reaction force that holds it in place.
Weightlessness, or an absence of weight, is an absence of stress and strain resulting from externally applied mechanical contact-forces, typically normal forces (from floors, seats, beds, scales, etc.). Counterintuitively, a uniform gravitational field does not by itself cause stress or strain, and a body in free fall in such an environment experiences no g-force acceleration and feels weightless.
In theoretical physics, Whitehead's theory of gravitation was introduced by the mathematician and philosopher Alfred North Whitehead in 1922.
Acceleration of gravity, Apparent gravity, Fg (physics), Force of gravity, Formulae of gravity, Gravitaiton, Gravitation, Gravitation (astronomy), Gravitational, Gravitational attraction, Gravitational force, Gravitational interaction, Gravitational motion, Gravitational physics, Gravitational pull, Gravitational theory, Gravitationally, Gravity (astronomy), Gravity (old version), Gravity and motion, Gravity force, Law of Gravity, Law of gravity, Laws of Gravity, Laws of gravity, Newtonian theory of gravitation, Physics/Gravity, Theories of gravitation, Theory of Gravitation, Theory of Gravity, Theory of gravitation, Theory of gravity, Vertical Circular Motion.