scholarly journals An exact solution of the five-dimensional Einstein equations with four-dimensional de Sitter-like expansion

2005 ◽  
Vol 46 (6) ◽  
pp. 062504 ◽  
Author(s):  
Tomáš Liko ◽  
Paul S. Wesson
Keyword(s):  
Exact Solution ◽  
Einstein Equations ◽  
De Sitter

scholarly journals Vacuum solutions of Einstein equations that depend on one coordinate

2020 ◽  
pp. 10-11
Author(s):  
S. Parnovsky
Keyword(s):  
Exact Solution ◽  
General Theory ◽  
Cosmological Constant ◽  
Gravitational Wave ◽  
Einstein Equations ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Vacuum Metrics ◽  
Vacuum Solutions ◽  
Zero Frequency

In the famous textbook written by Landau and Lifshitz all the vacuum metrics of the general theory of relativity are derived, which depend on one coordinate in the absence of a cosmological constant. Unfortunately, when considering these solutions the authors missed some of the possible solutions discussed in this article. An exact solution is demonstrated, which is absent in the book by Landau and Lifshitz. It describes space-time with a gravitational wave of zero frequency. It is shown that there are no other solutions of this type than listed above and Minkowski’s metrics. The list of vacuum metrics that depend on one coordinate is not complete without solution provided in this paper.

scholarly journals Cosmological model favored by the holographic principle

2016 ◽  
Vol 41 ◽  
pp. 1660127
Author(s):  
Irina Dymnikova ◽  
Anna Dobosz ◽  
Bożena Sołtysek
Keyword(s):  
Cosmological Model ◽  
Cosmological Constant ◽  
Space Time ◽  
Holographic Principle ◽  
Einstein Equations ◽  
Energy Tensor ◽  
De Sitter ◽  
Quantum Evaporation ◽  
Stress Energy ◽  
De Sitter Vacua

We present a regular spherically symmetric cosmological model of the Lemaitre class distinguished by the holographic principle as the thermodynamically stable end-point of quantum evaporation of the cosmological horizon. A source term in the Einstein equations connects smoothly two de Sitter vacua with different values of cosmological constant and corresponds to anisotropic vacuum dark fluid defined by symmetry of its stress-energy tensor which is invariant under the radial boosts. Global structure of space-time is the same as for the de Sitter space-time. Cosmological evolution goes from a big initial value of the cosmological constant towards its presently observed value.

DE SITTER-SCHWARZSCHILD BLACK HOLE: ITS PARTICLELIKE CORE AND THERMODYNAMICAL PROPERTIES

1996 ◽  
Vol 05 (05) ◽  
pp. 529-540 ◽  
Author(s):  
I.G. DYMNIKOVA
Keyword(s):  
Black Hole ◽  
Lower Limit ◽  
Mass Parameter ◽  
Hawking Temperature ◽  
Einstein Equations ◽  
Black Hole Mass ◽  
De Sitter ◽  
Schwarzschild Black Hole ◽  
Schwarzschild Solution ◽  
Second Order Phase Transition

We analyze the globally regular solution of the Einstein equations describing a black hole whose singularity is replaced by the de Sitter core. The de Sitter—Schwarzschild black hole (SSBH) has two horizons. Inside of it there exists a particlelike structure hidden under the external horizon. The critical value of mass parameter M cr1 exists corresponding to the degenerate horizon. It represents the lower limit for a black-hole mass. Below M cr1 there is no black hole, and the de Sitter-Schwarzschild solution describes a recovered particlelike structure. We calculate the Hawking temperature of SSBH and show that specific heat is broken and changes its sign at the value of mass M cr 2>M cr 1 which means that a second-order phase transition occurs at that point. We show that the Hawking temperature drops to zero when a mass approaches the lower limit M cr1 .

scholarly journals QUANTUM KALB–RAMOND FIELD IN D-DIMENSIONAL DE SITTER SPACE–TIMES

2013 ◽  
Vol 28 (05n06) ◽  
pp. 1350011
Author(s):  
G. ALENCAR ◽  
I. GUEDES ◽  
R. R. LANDIM ◽  
R. N. COSTA FILHO
Keyword(s):  
Exact Solution ◽  
Wave Function ◽  
Quantum Theory ◽  
De Sitter Space ◽  
Equation Of Motion ◽  
Time Dependent ◽  
De Sitter ◽  
Sitter Background ◽  
Dynamic Invariant ◽  
Math Phys

In this work, we investigate the quantum theory of the Kalb–Ramond fields propagating in D-dimensional de Sitter space–times using the dynamic invariant method developed by Lewis and Riesenfeld [J. Math. Phys.10, 1458 (1969)] to obtain the solution of the time-dependent Schrödinger equation. The wave function is written in terms of a c-number quantity satisfying the Milne–Pinney equation, whose solution can be expressed in terms of two independent solutions of the respective equation of motion. We obtain the exact solution for the quantum Kalb–Ramond field in the de Sitter background and discuss its relation with the Cremmer–Scherk–Kalb–Ramond model.

scholarly journals Comparative Analysis of Standard ΛCDM and ΛCS Models

2021 ◽  
Vol 57 (11) ◽  
pp. 1169
Author(s):  
V.E. Kuzmichev ◽  
V.V. Kuzmichev
Keyword(s):  
Cosmological Constant ◽  
Semiclassical Approximation ◽  
Cosmic Strings ◽  
Cosmological Parameters ◽  
Einstein Equations ◽  
Scale Transformation ◽  
De Sitter ◽  
Field Equations ◽  
Low Velocity ◽  
Sitter Model

We draw a comparison of time-dependent cosmological parameters calculated in the standard ΛCDM model with those of the model of a homogeneous and isotropic Universe with non-zero cosmological constant filled with a perfect gas of low-velocity cosmic strings (ΛCS model). It is shown that pressure-free matter can obtain the properties of a gas of low-velocity cosmic strings in the epoch, when the global geometry and the total amount of matter in the Universe as a whole obey an additional constraint. This constraint follows from the quantum geometrodynamical approach in the semiclassical approximation. In terms of general relativity, its effective contribution to the field equations can be linked to the time evolution of the equation of state of matter caused by the processes of redistribution of the energy between matter components. In the present article, the exact solutions of the Einstein equations for the ΛCS model are found. It is demonstrated that this model is equivalent to the open de Sitter model. After the scale transformation of the time variable of the ΛCS model, the standard ΛCDM and ΛCS models provide the equivalent descriptions of cosmological parameters as functions of time at equal values of the cosmological constant. The exception is the behavior of the deceleration parameter in the early Universe.

Geometry of Black Holes

2020 ◽  
Author(s):  
Piotr T. Chruściel
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Einstein Equations ◽  
De Sitter ◽  
Black Hole Spacetimes ◽  
Local Coordinates ◽  
The Subject ◽  
Basic Facts ◽  
Kaluza Klein

There exists a large scientific literature on black holes, including many excellent textbooks of various levels of difficulty. However, most of these prefer physical intuition to mathematical rigour. The object of this book is to fill this gap and present a detailed, mathematically oriented, extended introduction to the subject. The first part of the book starts with a presentation, in Chapter 1, of some basic facts about Lorentzian manifolds. Chapter 2 develops those elements of Lorentzian causality theory which are key to the understanding of black-hole spacetimes. We present some applications of the causality theory in Chapter 3, as relevant for the study of black holes. Chapter 4, which opens the second part of the book, constitutes an introduction to the theory of black holes, including a review of experimental evidence, a presentation of the basic notions, and a study of the flagship black holes: the Schwarzschild, Reissner–Nordström, Kerr, and Majumdar–Papapetrou solutions of the Einstein, or Einstein–Maxwell, equations. Chapter 5 presents some further important solutions: the Kerr–Newman–(anti-)de Sitter black holes, the Emperan–Reall black rings, the Kaluza–Klein solutions of Rasheed, and the Birmingham family of metrics. Chapters 6 and 7 present the construction of conformal and projective diagrams, which play a key role in understanding the global structure of spacetimes obtained by piecing together metrics which, initially, are expressed in local coordinates. Chapter 8 presents an overview of known dynamical black-hole solutions of the vacuum Einstein equations.

scholarly journals THE NATURE OF Λ AND THE MASS OF THE GRAVITON: A CRITICAL VIEW

2011 ◽  
Vol 03 ◽  
pp. 3-26 ◽  
Author(s):  
J.-P. GAZEAU ◽  
M. NOVELLO
Keyword(s):  
Cosmological Constant ◽  
Einstein Equation ◽  
Universal Constant ◽  
Einstein Equations ◽  
Theoretical Interpretation ◽  
De Sitter ◽  
Current Estimate ◽  
Left Hand ◽  
Fundamental State ◽  
The Right

The observational evidence of a cosmological constant Λ raises natural questions. Is Λ a universal constant fixing the geometry of an empty universe, as fundamental as the Planck constant or the speed of light in the vacuum? Its natural place is then on the left-hand side of the Einstein equation. Is it instead something emerging from a perturbation calculation performed on the metric gμν solution of the Einstein equation and to which it might be given a material status of (dark or bright) "energy"? It should then be part of the content of the right-hand side of the Einstein equations. The purpose of this paper is to analyze some of the arguments in favor of each one of these interpretations of the cosmological constant. Recent estimates based on observational data give a bound on the graviton mass to be about 100 Mpc-1. If this value and the current estimate on the cosmological constant Λ are put into perspective, one faces the interesting coincidence that between the Compton wavelength of the graviton and the cosmological constant there exists the relation [Formula: see text]. Since a physical quantity like mass originates in a minkowskian conservation law, we proceed with a group theoretical interpretation of this relation in terms of the two possible Λ-deformations of the Poincaré group, namely the de Sitter and anti de Sitter groups. We use a very suitable formula, the so-called Garidi mass, and the typically dS/AdS dimensionless parameter ℏH/mc2 in order to make clear the asymptotic relations between minkowskian masses m and their possible dS/AdS counterparts. We conclude that if the fundamental state of the geometry of space-time is minkowskian, then the square of the mass of the graviton is proportional to Λ; otherwise, if the fundamental state is de Sitter, then the graviton is massless in the deSitterian sense.

The First Solutions and the Challenge of Their Interpretation

2017 ◽  
Author(s):  
Hanoch Gutfreund ◽  
Jürgen Renn
Keyword(s):  
Exact Solution ◽  
Approximate Solution ◽  
Gravitational Field ◽  
Exact Solutions ◽  
De Sitter ◽  
Field Equations ◽  
Gravitational Field Equations ◽  
Nonlinear Character ◽  
Georges Lemaître

This chapter discusses the first wave of the exploration of exact solutions to Einstein's gravitational field equations. When Einstein published the final form of the field equations in 1915, only an approximate solution was known. Given the complicated nonlinear character of the field equations, he did not expect that exact solutions could easily be found. He was all the more surprised when the astronomer Karl Schwarzschild presented him with just such an exact solution. Thus, this chapter presents a series of these solutions, beginning with the work of Karl Schwarzschild, Johannes Droste, Willem de Sitter, Alexander Friedmann, Hans Reissner, Gunnar Nordström, and finally, Georges Lemaître.

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