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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.


Papers
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Journal ArticleDOI
TL;DR: The quantization of spherically symmetric gravitational systems using the Dirac formalism and the WKB approximation is developed for the nucleation of false-vacuum bubbles, which may have been the origin of the inflationary universe and matter.
Abstract: We develop the quantization of spherically symmetric gravitational systems using the Dirac formalism and the WKB approximation. The particular application is the nucleation of false-vacuum bubbles, which may have been the origin of the inflationary universe and matter. Consistency between our results and those obtained by the Euclidean method requires that the latter include metrics with degeneracies. Our work also raises several other questions of principle, including the meaning of the wave function and the necessity of topology change. A tentative application of this work to quantum cosmology indicates that the "Hartle-Hawking wave function" is inconsistent.

162 citations

Journal ArticleDOI
TL;DR: It is shown that there is remarkable agreement between static supergravity solutions and extrema of a field theory potential for essentially any function V(alpha) there are boundary conditions in anti-de Sitter space so that gravitational solitons exist precisely at the extrems of V and have masses given by the value of V at these extremas.
Abstract: Motivated by the anti-de Sitter conformal field theory correspondence, we show that there is remarkable agreement between static supergravity solutions and extrema of a field theory potential. For essentially any function V(alpha) there are boundary conditions in anti-de Sitter space so that gravitational solitons exist precisely at the extrema of V and have masses given by the value of V at these extrema. Based on this, we propose new positive energy conjectures. On the field theory side, each function V can be interpreted as the effective potential for a certain operator in the dual field theory.

162 citations

Journal ArticleDOI
TL;DR: In this paper, it has been shown that the geometrical framework of Riemannian geometry that un- derlies general relativity can be obtained from a procedure known as gauging the Poincare algebra, which when made dynamical gives rise to Hoyrava-Lifshitz gravity.
Abstract: It is well known that the geometrical framework of Riemannian geometry that un- derlies general relativity and its torsionful extension to Riemann-Cartan geometry can be obtained from a procedure known as gauging the Poincare algebra. Recently it has been shown that gauging the centrally extended Galilei algebra, known as the Bargmann algebra, leads to a geometrical framework that when made dynamical gives rise to Hoyrava-Lifshitz gravity. Here we consider the case where we contract the Poincare al- gebra by sending the speed of light to zero leading to the Carroll algebra. We show how this algebra can be gauged and we construct the most general affine connection leading to the geometry of so-called Carrollian space-times. Carrollian space-times appear for example as the geometry on null hypersurfaces in a Lorentzian space-time of one di- mension higher. We also construct theories of ultra-relativistic (Carrollian) gravity in 2+1 dimensions with dynamical exponent z < 1 including cases that have anisotropic Weyl invariance for z = 0.

162 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show that the strong energy condition (SEC) is violated at some time between the epoch of galaxy formation and the present, which implies that no possible combination of {ital {open_quotes}normal{close-quotes}} matter is capable of fitting the observational data.
Abstract: The energy conditions of Einstein gravity (classical general relativity) are designed to extract as much information as possible from classical general relativity without enforcing a particular equation of state for the stress energy. This systematic avoidance of the need to specify a particular equation of state is particularly useful in a cosmological setting {emdash} since the equation of state for the cosmological fluid in a Friedmann-Robertson-Walker-type universe is extremely uncertain. I shall show that the energy conditions provide simple and robust bounds on the behavior of both the density and look-back time as a function of redshift. I shall show that current observations {ital suggest} that the so-called {ital strong energy condition} (SEC) is violated at some time between the epoch of galaxy formation and the present. This implies that no possible combination of {ital {open_quotes}normal{close_quotes}} matter is capable of fitting the observational data. {copyright} {ital 1997} {ital The American Physical Society}

162 citations

Book
30 Jun 2003
TL;DR: In this paper, the authors discuss the relationship between the Earth's interior and its upper atmosphere, and the two-body problem and the three-body Problem, as well as the dynamical evolution of the solar system.
Abstract: 1. Dynamical Principles.- 2. The Gravitational Field of an Isolated Body.- 3. Planetary Rotation.- 4. Gravitational Torques and Tides.- 5. The Interior of the Earth.- 6. Planetary Magnetism.- 7. Atmospheres.- 8. Upper Atmospheres.- 9. The Sun and the Solar Wind.- 10. Magnetospheres.- 11. The Two-Body Problem.- 12. Perturbation Theory.- 13. The Three-Body Problem.- 14. The Planetary System.- 15. Dynamical Evolution of the Solar System.- 16. Origin of the Solar System.- 17. Relativistic Effects in the Solar System.- 18. Artificial Satellites.- 19. Telecommunications.- 20. Precise Measurements in Space.

162 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023745
20221,538
20211,353
20201,587
20191,566
20181,592