Conformal evolution of phantom dominated final stages of the universe in higher dimensions

2020 ◽  
pp. 1-9 ◽  
Author(s):  
S. Natarajan ◽  
R. Chandramohan
Keyword(s):  
Loop Quantum Gravity ◽  
Dimensional Space ◽  
Friedmann Equation ◽  
Higher Dimensions ◽  
Higher Dimensional ◽  
Loop Quantization ◽  
The Universe ◽  
Modified Equation ◽  
Work Loop ◽  
Kaluza Klein

Friedmann solutions and higher-dimensional 5D Kaluza–Klein solutions using mathematical packages such as Sagemath and Cadabra are calculated. A modified Friedmann equation powered by loop quantum gravity in higher dimensions is calculated in this work. Loop quantization in extra-dimensional space is predicted. Modified equation of state for non-interacting dark matter and dark energy are calculated. It has been predicted that the higher curvature due to phantom density would be a local kind of quantized curvature. The modified Friedmann solutions with Kaluza–Klein interpretation are found. To achieve a conformal exit, the non-interacting solutions are discussed in this work. The obtained results are compared with the ΛCDM and quintessence models. The results support conformal cyclic cosmology, which predicts the conformal evolution of the universe without facing any singularity as the result of topological effects.

scholarly journals The Quest for a Realistic Four-dimensional Cosmology

2011 ◽  
Vol 1 ◽  
pp. 18-24
Author(s):  
Ishwaree P Neupane
Keyword(s):  
Cosmological Constant ◽  
Vacuum Energy ◽  
Dimensional Space ◽  
De Sitter ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
Gravitational Vacuum ◽  
Theories Of Gravity ◽  
The Universe ◽  
Kaluza Klein

The existence of a small and positive cosmological constant attributed to gravitational vacuum energy (or dark energy) in the present-day universe appears to be the most pressing obstacle as well as opportunity to significantly improving the models of four-dimensional cosmology from fundamental theories of gravity, including string theory and modern Kaluza-Klein theories. In seeking to resolve this problem, one naturally wonders if the real world can somehow be interpreted as an inflating de Sitter "brane" embedded in a five or even higher-dimensional space-time described by warped or non-factorizable geometry. In this scenario, the four-dimensional cosmological constant may well be determined in terms of two length scales: one is a scale associated with the size of extra dimensions and the other is a scale associated with the expansion rate of the universe, which is also related to the warping of extra spaces.Key words: CosmologyThe Himalayan Physics Vol.1, No.1, May, 2010Page: 18-24Uploaded Date: 28 July, 2011

scholarly journals Dimensions of Space

2020 ◽  
Vol 3 (11) ◽  
pp. 74-79
Author(s):  
Kedar Pansare ◽  
Meghraj Parab ◽  
Vrushabh Parmar ◽  
Yashwantrao Mitnasala ◽  
Rajni Bahuguna
Keyword(s):  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Higher Dimensions ◽  
Superstring Theory ◽  
Unified Theories ◽  
Spatial Dimensions ◽  
The Universe ◽  
Dimensions Of Space

The existence and the mysteries of the universe could not be explained by using just 3 spatial dimensions. There was a need to think of higher dimensions as a tool to explain the phenomena happening in our universe. Therefore, unified theories such as Loop Quantum Gravity and Superstring Theory were proposed. We will be taking an overview of these theories in order to get some idea about each.

NATURE OF THE SINGULARITIES IN HIGHER-DIMENSIONAL HUSAIN SPACE–TIME

2006 ◽  
Vol 15 (09) ◽  
pp. 1359-1371 ◽  
Author(s):  
K. D. PATIL ◽  
S. S. ZADE
Keyword(s):  
Gravitational Collapse ◽  
Dimensional Space ◽  
Higher Dimensions ◽  
Cosmic Censorship ◽  
Space Time ◽  
Spherically Symmetric ◽  
Naked Singularities ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
Cosmic Censorship Hypothesis

We generalize the earlier studies on the spherically symmetric gravitational collapse in four-dimensional space–time to higher dimensions. It is found that the central singularities may be naked in higher dimensions but depend sensitively on the choices of the parameters. These naked singularities are found to be gravitationally strong that violate the cosmic censorship hypothesis.

scholarly journals THE WARPING OF EXTRA SPACES ACCELERATES THE EXPANSION OF THE UNIVERSE

2010 ◽  
Vol 19 (14) ◽  
pp. 2281-2287 ◽  
Author(s):  
ISHWAREE P. NEUPANE
Keyword(s):  
Dimensional Space ◽  
Space Time ◽  
De Sitter ◽  
Four Dimensions ◽  
Accelerating Expansion ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
Expansion Of The Universe ◽  
Theories Of Gravity ◽  
The Universe

Generic cosmological models derived from higher-dimensional theories with warped extra-dimensions have a nonzero cosmological constant-like term induced on the 3 + 1 space–time, or a physical three-brane. In the scenario where this 3 + 1 space–time is an inflating de Sitter "bran" embedded in a higher-dimensional space–time, described by warped geometry, the four-dimensional cosmological term is determined in terms of two length scales: one is a scale associated with the size of extra-dimension(s) and the other is a scale associated with the warping of extra-space(s). The existence of this term in four dimensions provides a tantalizing possibility of explaining the observed accelerating expansion of the universe from fundamental theories of gravity, e.g. string theory.

scholarly journals Tensor perturbations and thick branes in higher-dimensional f(R) gravity

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Zheng-Quan Cui ◽  
Zi-Chao Lin ◽  
Jun-Jie Wan ◽  
Yu-Xiao Liu ◽  
Li Zhao
Keyword(s):  
Effective Potential ◽  
Higher Dimensions ◽  
Brane Worlds ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
Six Dimensions ◽  
Tensor Perturbations ◽  
Thick Branes ◽  
Kaluza Klein

Abstract We study brane worlds in an anisotropic higher-dimensional spacetime within the context of f(R) gravity. Firstly, we demonstrate that this spacetime with a concrete metric ansatz is stable against linear tensor perturbations under certain conditions. Moreover, the Kaluza-Klein modes of the graviton are analyzed. Secondly, we investigate thick brane solutions in six dimensions and their properties. We further exhibit two sets of solutions for thick branes. At last, the effective potential of the Kaluza-Klein modes of the graviton is discussed for the two solved f(R) models in higher dimensions.

scholarly journals REINVENTING SPACETIME ON A DYNAMICAL HYPERSURFACE

2006 ◽  
Vol 21 (12) ◽  
pp. 947-959 ◽  
Author(s):  
J. PONCE DE LEON
Keyword(s):  
Extra Dimension ◽  
New Physics ◽  
Accelerated Expansion ◽  
Effective Equation ◽  
Higher Dimensional ◽  
Internal Contradiction ◽  
Frw Model ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Kaluza Klein

In braneworld models, Spacetime-Matter and other Kaluza–Klein theories, our spacetime is devised as a four-dimensional hypersurface orthogonal to the extra dimension in a five-dimensional bulk. We show that the FRW line element can be "reinvented" on a dynamical four-dimensional hypersurface, which is not orthogonal to the extra dimension, without any internal contradiction. This hypersurface is selected by the requirement of continuity of the metric and depends explicitly on the evolution of the extra dimension. The main difference between the "conventional" FRW, on an orthogonal hypersurface, and the new one is that the latter contains higher-dimensional modifications to the regular matter density and pressure in 4D. We compare the evolution of the spacetime in these two interpretations and find that a wealth of "new" physics can be derived from a five-dimensional metric if it is interpreted on a dynamical (non-orthogonal) 4D hypersurface. In particular, in the context of a well-known cosmological metric in 5D, we construct a FRW model which is consistent with the late accelerated expansion of the universe, while fitting simultaneously the observational data for the deceleration parameter. The model predicts an effective equation of state for the universe, which is consistent with observations.

scholarly journals Kaluza–Klein reduction and Bergmann–Wagoner bi-scalar general action of scalar–tensor gravity

2015 ◽  
Vol 12 (10) ◽  
pp. 1550106 ◽  
Author(s):  
Kazuharu Bamba ◽  
Davood Momeni ◽  
Ratbay Myrzakulov
Keyword(s):  
Dimensional Reduction ◽  
Dimensional Space ◽  
Space Time ◽  
De Sitter ◽  
Higher Dimensional Space Time ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
General Action ◽  
The Stability ◽  
Kaluza Klein

We examine the Kaluza–Klein (KK) dimensional reduction from higher dimensional space-time and the properties of the resultant Bergmann–Wagoner general action of scalar–tensor theories. With the analysis of the perturbations, we also investigate the stability of the anti-de Sitter (AdS) space-time in the (D ∈ 𝒩)-dimensional Einstein gravity with the negative cosmological constant. Furthermore, we derive the conditions for the dimensional reduction to successfully be executed and present the KK compactification mechanism.

RELATIVISTIC STAR SOLUTIONS IN HIGHER DIMENSIONS

2004 ◽  
Vol 13 (02) ◽  
pp. 229-238 ◽  
Author(s):  
B. C. PAUL
Keyword(s):  
Dimensional Space ◽  
Compact Star ◽  
Compact Object ◽  
Higher Dimensions ◽  
Space Time ◽  
Matter Content ◽  
Dimensional Euclidean Space ◽  
Higher Dimensional Space Time ◽  
Higher Dimensional ◽  
Dimensional Space Time

A class of relativistic solutions of compact star which is in hydrostatic equilibrium is obtained in higher dimensions assuming a spherically symmetric space–time. The space–time geometry is assumed to be a (D-1)-spheroid immersed in a D-dimensional Euclidean space. It is noted that the parameter a which is the measure of spheroidicity of the space–time plays here an important role in determining the equation of state of the matter content in such a star. One obtains a realistic solution when the parameter a picks up values [Formula: see text] for D<9 and [Formula: see text] for space–time dimensions D≥9. It is also observed that the higher dimensional space–time accommodates a more massive compact object for a given size compared to that in the usual four dimensional space–times.

MODIFIED BRANEWORLD COSMOLOGIES IN THE PRESENCE OF STRINGY CORRECTIONS COUPLED TO A CANONICAL SCALAR FIELD

2009 ◽  
Vol 18 (05) ◽  
pp. 691-715 ◽  
Author(s):  
R. A. EL-NABULSI
Keyword(s):  
Scalar Field ◽  
Dimensional Space ◽  
High Energy ◽  
Cosmic Acceleration ◽  
Dimensional Model ◽  
Acceleration Of The Universe ◽  
The Universe ◽  
Matter Fields ◽  
Kaluza Klein ◽  
Canonical Scalar Field

The purpose of this paper is to study braneworld cosmologies in the presence of stringy corrections coupled to a canonical scalar field. Two independent models are explored which in their own right provide cosmologies exhibiting the present cosmic acceleration of the universe. The evolution of the cosmological scale factor is studied in four and ten-dimensional space–times. The four-dimensional model is preformed in the context of the nonminimal Maxwell–Gauss–Bonnet gravity while the ten-dimensional model is constructed from the implications of Kaluza–Klein cosmology together with the Gauss–Bonnet Lagrangian in the action with matter fields nonminimally coupled to gravity. Both the low energy and high energy limits are discussed for the two models and many interesting features are described in some detail.

HIGHER DIMENSIONAL SPACE–TIME MODEL FOR A DUST-FILLED UNIVERSE WITH A COSMOLOGICAL CONSTANT

2003 ◽  
Vol 12 (05) ◽  
pp. 905-911 ◽  
Author(s):  
NABAJIT CHAKRAVARTY ◽  
BATUL CHANDRA SANTRA ◽  
SUBENOY CHAKRABORTY
Keyword(s):  
Cosmological Constant ◽  
Vacuum Energy ◽  
Dimensional Space ◽  
Matter Field ◽  
Vacuum Energy Density ◽  
Time Model ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
Space Time Model ◽  
The Universe

In recent years it is generally believed that we should consider positive vacuum energy density or cosmological constant. Also as higher dimensional theory is important at the early stages of the Universe, so it will be interesting to study classical tests of cosmology in a higher dimensional generalized Kantowski–Sachs model. For matter field, we consider dust and a cosmological constant and examine which are physically permissible.

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