Recent astronomical tests of general relativity
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This history of experimentation relevant to general relativity covers the time post-1928. Classes of investigation are the weak equivalence principle (equivalence of inertial and gravitational mass and gravitational redshift), orbital precession of a body in gravitational fields (the relativistic perihelion advance of the planets, the relativistic periastron advance of binary pulsars, geodetic precession and Lense-Thirring effect), light propagation in gravitational fields (gravitational optical light deflection, gravitational radio deflection due to the Sun, gravitational lensing, time dilation and atomic clocks) and strong gravity implications (Nordtved effect and potential gravitational waves). The results of experiments are analysed to conclude to what extent they support general relativity. A number of questions are then answered: (a) how much evidence exists to support general relativity, (b) is it a reasonable way of thinking and (c) what is the niche it may occupy? Key words: general relativity, equivalence principle, orbital precession, gravitational fields.Keywords:
Gravity Probe A
Equivalence principle (geometric)
Gravitational time dilation
Speed of gravity
Abstract The article contains sections titled: Introduction General Relativity and Relativistic Gravity Gravitation Theory: An Overview Relativistic Gravity in Physics Where Relativistic Gravity Is Important Fundamental Ideas and New Concepts of General Relativity The Incorporation of Newtonian Gravity Basic Ingredients of General Relativity General Relativity: Gravity as Geometry Sources of Gravity: How Matter Creates the Geometry Other Theories of Gravity A Cosmological Term in E instein's Equations Some Consequences of Einstein's Field Equations Momentum and Stress Also Make Gravity Gravitomagnetism Gravitational Collapse Black‐Hole Theory Black Holes in the Eighteenth Century Black Holes in General Relativity Singularities Inside the Hole Black Holes Have No Hair Black‐Hole Thermodynamics Wormholes Gravitational Waves The Necessity of Gravitational Waves The Interaction of Gravitational Waves with Matter Wave Emission: The Quadrupole Formula Applications of General Relativity Relativistic Stars (Pulsars) and Gravitational Collapse Black Holes in X ‐Ray Binaries and in Galactic Centers Gravitational Lensing Solar System and Stellar Orbits Cosmology, Inflation, and the Origins of the Universe Tests of Gravitational Theories and Their Technological Demands Tests of the E instein Equivalence Principle Tests of Special Relativity The E ötvös Experiment, the Weak Equivalence Principle, and the Fifth Force Gravitational Redshift Solar‐System Tests of General Relativity The Deflection and Retardation of Light M ercury's Perihelion Advance Test of the Strong Equivalence Principle The Binary Pulsar: An Astronomical Relativity Laboratory Future Work in Experimental Gravitation Search for Gravitomagnetic Effects Tests of the E instein Equivalence Principle Further Fifth‐Force Searches Gravitational‐wave Detection: A Technological Frontier Likely Sources of Detectable Waves Supernovae Coalescing Binaries Pulsars Ordinary Binaries Cosmological Background Unexpected Sources Detectors Bar‐Type Detectors Laser‐Interferometric Detectors Space‐Based Detectors
Equivalence principle (geometric)
Black hole (networking)
Gravitational time dilation
Speed of gravity
Gravity Probe A
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Gravitational field is a kind of vector field,and the description of general relativity to gravitational force problem is very effective.This paper deals with the equivalence principle and the principle of general covariance in general relativity,discusses Einstein’s gravitational field equations,researches on the principle of relativity,time dilation,contraction of length in gravitational field.
Gravitational time dilation
Equivalence principle (geometric)
General Covariance
Gravity Probe A
Speed of gravity
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A proper discussion of the various philosophical views of the nature of time and gravitational field and the different issues related to time as such would take us far beyond the scope of this article. For our purposes, time and gravitational field are related somehow. In any case, especially due to Einstein’s relativity theory, there is a very close relationship between time the gravitational field and vice versa. The aim of this publication is to work out the interior logic between gravitational field and time. As we will see, the gravitational field is equivalent to time and vice versa, both are equivalent or identical.
Gravity Probe A
Gravitational time dilation
Speed of gravity
Equivalence principle (geometric)
Gravitational constant
Versa
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Einstein’s theory of general relativity, which has been experimentally proved to be a true theory of gravity does not need gravitational potential energy to predict the trajectory of particles in space. This is because general relativity is a purely geometric theory. Objects move along the geodesics in the curved space–time. The energy–momentum tensor that warps space–time as per Einstein’s field equations takes into account only the energy–momentum of matter and radiation. Thus, gravitational potential energy does not come into the picture in Einstein’s theory of gravity and its role is taken over by the curvature of space–time. However, a general relativistically correct expression for gravitational potential energy is required for energy conservation and some energy-based approaches in physics. Conventionally, the correct form of gravitational potential energy is derived by using the full mathematical formality of general relativity. In this paper, we derive the same general relativistic expression for gravitational potential energy simply by using the principle of equivalence and gravitational time dilation.
Equivalence principle (geometric)
Gravitational time dilation
Gravity Probe A
Speed of gravity
Linearized gravity
Gravitational binding energy
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This history of experimentation relevant to general relativity covers the time post-1928. Classes of investigation are the weak equivalence principle (equivalence of inertial and gravitational mass and gravitational redshift), orbital precession of a body in gravitational fields (the relativistic perihelion advance of the planets, the relativistic periastron advance of binary pulsars, geodetic precession and Lense-Thirring effect), light propagation in gravitational fields (gravitational optical light deflection, gravitational radio deflection due to the Sun, gravitational lensing, time dilation and atomic clocks) and strong gravity implications (Nordtved effect and potential gravitational waves). The results of experiments are analysed to conclude to what extent they support general relativity. A number of questions are then answered: (a) how much evidence exists to support general relativity, (b) is it a reasonable way of thinking and (c) what is the niche it may occupy? Key words: general relativity, equivalence principle, orbital precession, gravitational fields.
Gravity Probe A
Equivalence principle (geometric)
Gravitational time dilation
Speed of gravity
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A simple general relativity theory for objects moving in gravitational fields is developed based on studying the behavior of an atom in a gravitational field. The theory is applied to calculate the satellite time dilation, light deflection by the sun, and Mercury's precession with an error of less than 1%. The approach to the new theory introduced here is radically different from the geometric approach used by Einstein's general relativity. The theory is field based where the potential energy of a system of masses can be easily calculated and the force can be found as the gradient of the potential field in analogy to the Newtonian mechanics. The resulting field equations become the traditional Newton's equations when week gravitational effects are present. The theory complies with all the known experimental results such as the gravitational time dilation and faster light speeds higher in the gravitational field. The special relativity theory of an object moving without experiencing gravitational fields can be derived directly from the gravitational field equations introduced here. The theory introduced here has crucial differences to Einstein's general relativity theory. For example, the gravitational field cannot accelerate an object to higher than the speed of light and the event horizon of a black hole (where light cannot escape) has to be of zero radius, essentially meaning that light can escape any object unless the object has infinite density. Another primary consequence of this study is that the principle of equivalence of gravitational and inertial mass has only limited validity and a new definition of gravitational mass is given here.
Gravitational time dilation
Gravity Probe A
Speed of gravity
Equivalence principle (geometric)
Linearized gravity
Gravitational binding energy
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Equivalence principle (geometric)
Speed of gravity
Gravitational time dilation
Gravity Probe A
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Equivalence principle (geometric)
Gravitational time dilation
Gravity Probe A
Speed of gravity
Relativistic mechanics
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Gravitational time dilation directly reflects the difference between gravitational potentials at different altitudes in the gravitational field. At the same time this phenomenon is expected to obey the Einstein’s equivalence principle, one of two pillars (apart from general covariance) of general relativity. The experiments aimed at detecting the gravitational time dilation are therefore described as the tests of general relativity or, alternatively, the tests of equivalence principle. When applied to the exterior of a solid sphere, these two interpretations are fully compatible both theoretically and experimentally. However, when applied to the interior of a solid sphere (e.g., to the interior of Earth), they seem to contradict each other. Namely, a strict dependence of the gravitational time dilation on the gravitational potential inside the sphere proves to be at odds with the equivalence principle. This paper reveals this problem and provides solution to it. As a consequence, it is concluded that, contrary to the current belief, the Earth’s center is older, not younger, than the Earth’s surface. Since all the previous experiments have been performed either on or above the Earth’s surface, an experiment performed below the Earth’s surface is proposed.
Gravitational time dilation
Equivalence principle (geometric)
Gravity Probe A
General Covariance
Gravitational potential
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Time and space are important for relativity study in physics. In matter space exists a gravitational field, owning to which time is varied, space is bent, and light trace is changed.It discusses theory of relativity featuring the characteristics of time and space, the principles of equivalence and general covariance in general relativity, gravitational field equations, the principle of relativity, time dilation, contraction of length, and gravitational waves in gravitational field.
Gravitational time dilation
Gravity Probe A
Equivalence principle (geometric)
General Covariance
Speed of gravity
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