European satellite to test Einstein's gravitational theory

Physics Today ◽  
2012 ◽  
Keyword(s):  
Gravitational Theory ◽  
European Satellite

scholarly journals Entanglement entropy in cubic gravitational theories

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Elena Cáceres ◽  
Rodrigo Castillo Vásquez ◽  
Alejandro Vilar López
Keyword(s):  
Entanglement Entropy ◽  
Gravitational Theory ◽  
Riemann Tensor ◽  
Holographic Entanglement Entropy ◽  
Gravitational Theories ◽  
Entropy Functional ◽  
Wide Range ◽  
Splitting Problem ◽  
Range Of Values

Abstract We derive the holographic entanglement entropy functional for a generic gravitational theory whose action contains terms up to cubic order in the Riemann tensor, and in any dimension. This is the simplest case for which the so-called splitting problem manifests itself, and we explicitly show that the two common splittings present in the literature — minimal and non-minimal — produce different functionals. We apply our results to the particular examples of a boundary disk and a boundary strip in a state dual to 4- dimensional Poincaré AdS in Einsteinian Cubic Gravity, obtaining the bulk entanglement surface for both functionals and finding that causal wedge inclusion is respected for both splittings and a wide range of values of the cubic coupling.

Orbit simulation and perturbations analysis for the European satellite GOCE

2008 ◽  
Author(s):  
Zhicai Luo ◽  
Bo Zhong ◽  
Jinsheng Ning ◽  
Qiong Li
Keyword(s):  
European Satellite

THE GRAVITATIONAL ORIGIN OF THE DISTINCTION BETWEEN SPACE AND TIME

2009 ◽  
Vol 18 (14) ◽  
pp. 2155-2158 ◽  
Author(s):  
ASHER YAHALOM
Keyword(s):  
General Relativity ◽  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Flat Space ◽  
Gravitational Theory ◽  
Clear Distinction ◽  
Temporal Dimension ◽  
Spatial Dimensions ◽  
Standard Presentation

To the ordinary human it is obvious that there is a clear distinction between the spatial dimensions, in which one can go either way, and the temporal dimension, in which one seems only to move forward. But the uniqueness of time is also rooted in the standard presentation of general relativity, in which the metric of space–time is locally Lorentzian, i.e. ημν = diag (1, -1, -1, -1). This is presented as an independent axiom of the theory, which cannot be deduced. In this essay I will claim otherwise. I will show that the existence of time should not be enforced on the gravitational theory of general relativity but rather should be deduced from it. The method of choice is linear stability analysis of flat space–times.

The Field Equations of Metric-Affine Gravitational Theories

1978 ◽  
Vol 33 (4) ◽  
pp. 398-401 ◽  
Author(s):  
S. J. Aldersley
Keyword(s):  
Vector Potential ◽  
Gravitational Theory ◽  
Field Equations ◽  
Gravitational Theories ◽  
Special Case ◽  
Potential Conditions

The notions of conservation of charge and dimensional consistency are used to obtain conditions which uniquely characterize the field equations of electromagnetism and gravitation in a metric-affine gravitational framework with a vector potential. Conditions for the uniqueness of the choice of field equations of a metric-affine gravitational theory (in the absence of electromagnetism) follow as a special case. Some consequences are discussed.

scholarly journals A MAXWELL-LIKE FORMULATION OF GRAVITATIONAL THEORY IN MINKOWSKI SPACE–TIME

2007 ◽  
Vol 16 (06) ◽  
pp. 1027-1041 ◽  
Author(s):  
EDUARDO A. NOTTE-CUELLO ◽  
WALDYR A. RODRIGUES
Keyword(s):  
Gravitational Field ◽  
Minkowski Space ◽  
Gravitational Theory ◽  
Space Time ◽  
Lorentzian Geometry ◽  
Field Equations ◽  
Yang Mills ◽  
Minkowski Space Time ◽  
Clifford Bundle ◽  
Gauge Fixing

Using the Clifford bundle formalism, a Lagrangian theory of the Yang–Mills type (with a gauge fixing term and an auto interacting term) for the gravitational field in Minkowski space–time is presented. It is shown how two simple hypotheses permit the interpretation of the formalism in terms of effective Lorentzian or teleparallel geometries. In the case of a Lorentzian geometry interpretation of the theory, the field equations are shown to be equivalent to Einstein's equations.

Black Holes and Gravitational Theory

Nature ◽  
1972 ◽  
Vol 236 (5347) ◽  
pp. 377-380 ◽  
Author(s):  
ROGER PENROSE
Keyword(s):  
Black Holes ◽  
Gravitational Theory

General form of the analytic function f(T) in diverse dimension for a static planar spacetime

2019 ◽  
Vol 28 (12) ◽  
pp. 1950158 ◽  
Author(s):  
Gamal Nashed
Keyword(s):  
Black Hole ◽  
Analytic Function ◽  
Black Hole Solution ◽  
Static Solution ◽  
Gravitational Theory ◽  
Interesting Property ◽  
Constant Function ◽  
Field Equations ◽  
Adm Mass ◽  
Laws Of Thermodynamics

We derive an exact static solution in diverse dimension, without any constraints, to the field equations of [Formula: see text] gravitational theory using a planar spacetime with two unknown functions, i.e. [Formula: see text] and [Formula: see text]. The black hole solution is characterized by two constants, [Formula: see text] and [Formula: see text], one is related to the mass of the black hole, [Formula: see text], and the other is responsible to make the solution deviate from the teleparallel equivalent of general relativity (TEGR). We show that the analytic function [Formula: see text] depends on the constant [Formula: see text] and becomes constant function when [Formula: see text] which corresponds to the TEGR case. The interesting property of this solution is the fact that it makes the singularity of the Kretschmann invariant much softer than the TEGR case. We calculate the energy of this black hole and show that it is equivalent to ADM mass. Applying a coordinate transformation, we derive a rotating black hole with nontrivial values of the torsion scalar and [Formula: see text]. Finally, we examine the physical properties of this black hole solution using the laws of thermodynamics and show that it has thermodynamical stability.

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