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Gravitation
About: Gravitation is a research topic. Over the lifetime, 29306 publications have been published within this topic receiving 821510 citations.
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TL;DR: In this article, the corrections to the Schwarzschild metric necessary to reproduce the Hawking temperature derived from a generalized uncertainty principle (GUP), so that the GUP deformation parameter is directly linked to the deformation of the metric, are presented.
Abstract: We compute the corrections to the Schwarzschild metric necessary to reproduce the Hawking temperature derived from a generalized uncertainty principle (GUP), so that the GUP deformation parameter is directly linked to the deformation of the metric. Using this modified Schwarzschild metric, we compute corrections to the standard general relativistic predictions for the light deflection and perihelion precession, both for planets in the solar system and for binary pulsars. This analysis allows us to set bounds for the GUP deformation parameter from well-known astronomical measurements.
201 citations
TL;DR: In this article, the authors consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is T^3 \times \Re$ and show that two-loop processes act to slow the rate of expansion.
Abstract: We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is $T^3 \times \Re$. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-perturbatively large at late times. By exploiting Feynman's tree theorem we show that all higher loops act in the same sense.
200 citations
TL;DR: In this article, the authors considered the general situation of a compact relativistic body with anisotropic pressures in the presence of the electromagnetic field and provided exact solutions to the Einstein-Maxwell system.
Abstract: We consider the general situation of a compact relativistic body with anisotropic pressures in the presence of the electromagnetic field The equation of state for the matter distribution is linear and may be applied to strange stars with quark matter Three classes of new exact solutions are found to the Einstein–Maxwell system This is achieved by specifying a particular form for one of the gravitational potentials and the electric field intensity We can regain anisotropic and isotropic models from our general class of solutions A physical analysis indicates that the charged solutions describe realistic compact spheres with anisotropic matter distribution The equation of state is consistent with dark energy stars and charged quark matter distributions The masses and central densities correspond to realistic stellar objects in the general case when anisotropy and charge are present
199 citations
TL;DR: In this article, the authors report new constraints on extra-dimensional models and other physics beyond the standard model based on measurements of the Casimir force between two dissimilar metals for separations in the range $0.2 -1.2 pN.
Abstract: We report new constraints on extra-dimensional models and other physics beyond the standard model based on measurements of the Casimir force between two dissimilar metals for separations in the range $0.2--1.2\ensuremath{\mu}\mathrm{m}.$ The Casimir force between a Au-coated sphere and a Cu-coated plate of a microelectromechanical torsional oscillator was measured statically with an absolute error of 0.3 pN. In addition, the Casimir pressure between two parallel plates was determined dynamically with an absolute error of $\ensuremath{\approx}0.6\mathrm{mPa}.$ Within the limits of experimental and theoretical errors, the results are in agreement with a theory that takes into account the finite conductivity and roughness of the two metals. The level of agreement between experiment and theory was then used to set limits on the predictions of extra-dimensional physics and thermal quantum field theory. It is shown that two theoretical approaches to the thermal Casimir force which predict effects linear in temperature are ruled out by these experiments. Finally, constraints on Yukawa corrections to Newton's law of gravity are strengthened by more than an order of magnitude in the range 56--330 nm.
199 citations
TL;DR: In this paper, an analysis of 1389 measurements, accumulated between 1970 and 1974 of echo delays of laser signals transmitted from Earth and reflected from cube corners on the Moon show gravitational binding energy to contribute equally to Earth's inertial and passive gravitational masses to within the estimated uncertainty of 1.5%.
Abstract: Analysis of 1389 measurements, accumulated between 1970 and 1974 of echo delays of laser signals transmitted from Earth and reflected from cube corners on the Moon show gravitational binding energy to contribute equally to Earth’s inertial and passive gravitational masses to within the estimated uncertainty of 1.5%. The corresponding restriction on the Eddington-Robertson parameters is 4β - ϒ - 3 = -0.001 ± 0.015. Combination with other results, as if independent, yields β = 1.003 ± 0.005 and ϒ = 1.008 ± 0.008, in accord with general relativity.
199 citations