Multiscalar field models: Interaction potentials, wave functions and cosmological solutions

2020 ◽  
Vol 29 (07) ◽  
pp. 2050046
Author(s):  
Sameerah Jamal
Keyword(s):  
Wave Function ◽  
Wave Functions ◽  
Scalar Interaction ◽  
Coordinate Transformations ◽  
Spatial Curvature ◽  
Field Equations ◽  
Interaction Potentials ◽  
Cosmological Solutions ◽  
The Universe ◽  
Friedmann Robertson Walker

We consider a multiscalar tensor cosmology model described by Friedmann–Robertson–Walker (FRW) spacetime with zero spatial curvature. Three specific scalar interaction potentials that characterize the model are analyzed under a set of coordinate transformations. By implication, we solve for the wave function of the universe, reduce the dimension of the underlying Hamiltonian system and consequently, establish analytical solutions of the multiscalar model’s field equations.

Gravity as the curvature of the wave function of the universe.

2019 ◽  
Author(s):  
Vitaly Kuyukov
Keyword(s):  
Wave Function ◽  
Wave Functions ◽  
Main Task ◽  
Reference Systems ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Principle Of Equivalence ◽  
Relative Wave Function ◽  
New Equation ◽  
The Universe

Modern general theory of relativity considers gravity as the curvature of space-time. The theory is based on the principle of equivalence. All bodies fall with the same acceleration in the gravitational field, which is equivalent to locally accelerated reference systems. In this article, we will affirm the concept of gravity as the curvature of the relative wave function of the Universe. That is, a change in the phase of the universal wave function of the Universe near a massive body leads to a change in all other wave functions of bodies. The main task is to find the form of the relative wave function of the Universe, as well as a new equation of gravity for connecting the curvature of the wave function and the density of matter.

COSMOLOGICAL SOLUTIONS AND THEIR EFFECTIVE PROPERTIES OF MATTER IN KALUZA-KLEIN THEORY

1994 ◽  
Vol 03 (03) ◽  
pp. 627-637 ◽  
Author(s):  
HONGYA LIU ◽  
PAUL S. WESSON
Keyword(s):  
Globular Clusters ◽  
Effective Properties ◽  
Plane Waves ◽  
Big Bang ◽  
Field Equations ◽  
Fifth Dimension ◽  
Cosmological Solutions ◽  
Klein Theory ◽  
The Universe ◽  
Kaluza Klein

We derive a “wave-like” class of exact cosmological solutions of the apparently empty 5D Kaluza-Klein field equations. Here by “wave-like” we mean that the solutions look like plane waves propagating in the fifth dimension. In the interpretation that the fifth dimension in Kaluza-Klein theory may induce matter in four dimensions, we then calculate the effective energy density ρ and pressure p, and study in detail the case for which the equation of state is p=γρ (where γ is an arbitrary constant). We show that for both the matter-dominated (γ=0) and radiation-dominated (γ=1/3) eras of the universe, the 4D spacetime defined by hypersurfaces of the 5D metrics are just the same as those of the standard Friedmann-Robertson-Walker models of general relativity. However, in our models the big bang is like a shock wave propagating along the fifth dimension, and different observers can measure different ages for the universe. This property may be tested using the spread in ages of astrophysical objects such as globular clusters.

A unified picture of cosmological entropy on apparent horizon in F(R, G) gravity

2017 ◽  
Vol 32 (33) ◽  
pp. 1750182 ◽  
Author(s):  
Ali İhsan Keskin ◽  
Irfan Acikgoz
Keyword(s):  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Hawking Temperature ◽  
Second Law ◽  
Field Equations ◽  
Frw Universe ◽  
Generalized Second Law ◽  
History Of ◽  
The Universe ◽  
Friedmann Robertson Walker

In this study, the validity of the generalized second law of thermodynamics (GSLT) has been investigated in F(R, G) gravity. We consider that the boundary of the universe is surrounded by an apparent horizon in the spatially flat Friedmann–Robertson–Walker (FRW) universe, and we take into account the Hawking temperature on the horizons. The unified solutions of the field equations corresponding to gravity theory have been applied to the validity of the GSLT frame, and in this way, both the solutions have been verified and all the expansion history of the universe has been shown in a unified picture.

scholarly journals FREE CURVILINEAR SPACE WITH TORSION

Globus ◽  
2021 ◽  
Vol 7 (6(63)) ◽  
pp. 27-33
Author(s):  
Y.A. Sharin
Keyword(s):  
Field Theory ◽  
Mass Density ◽  
Classical Field Theory ◽  
Classical Field ◽  
Field Equations ◽  
Curved Space ◽  
Astronomical Observations ◽  
Average Mass ◽  
Cosmological Solutions ◽  
The Universe

Under the classical field theory, a variant unification of gravity and electromagnetism on the basis of four-dimensional curved space with torsion is proposed. The connection between electromagnetic field and torsion of space is discovered, a physical interpretation of the space scalar curvature as the density of matter mass is proposed. The solution for the eigenstate of a curved space with torsion, corresponding to the electron is obtained. The identification of the field equations as the Schrodinger equation for the hydrogen atom is shown. Cosmological solutions for the expanding Universe are found, the average mass density in the Universe is estimated, and the results corresponding to the data of astronomical observations are obtained.

FRW universe in f(R,T) gravity

2021 ◽  
pp. 2150104
Author(s):  
R. K. Tiwari ◽  
D. Sofuoğlu ◽  
A. Beesham
Keyword(s):  
Phase Transition ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Field Equations ◽  
Frw Universe ◽  
Expansion Phase ◽  
Age Of The Universe ◽  
The Universe ◽  
Modified Theory ◽  
Friedmann Robertson Walker

In this study, Friedmann–Robertson–Walker space-time filled with a perfect fluid in [Formula: see text] modified theory, where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of the energy–momentum tensor of matter, has been considered. The investigation of the phase transition of the universe from the decelerating expansion phase to the accelerating one has been made by adopting a special form of the varying deceleration parameter that is inversely proportional to the Hubble parameter. The exact solution of the field equations has been derived. The kinematic and dynamical quantities of the model have been obtained and their evolutions have been discussed by means of their graphs. The statefinder diagnostic has been used and the age of the universe has been computed for testing the validity of the model. It has been shown that the dominant energy of the model is ordinary matter which behaves as the SCDM model at the beginning and it is a quintessence like fluid which behaves as the [Formula: see text]CDM model at late times.

scholarly journals THE WAVE FUNCTION OF THE UNIVERSE BY THE NEW EUCLIDEAN PATH-INTEGRAL APPROACH IN QUANTUM COSMOLOGY

1993 ◽  
Vol 02 (02) ◽  
pp. 249-256 ◽  
Author(s):  
ATUSHI ISHIKAWA ◽  
HARUHIKO UEDA
Keyword(s):  
Wave Function ◽  
Path Integral ◽  
Regularization Method ◽  
Positive Definite ◽  
Integral Approach ◽  
Type I ◽  
Path Integral Approach ◽  
The Universe ◽  
Friedmann Robertson Walker ◽  
Hilbert Action

The wave function of the universe is evaluated by using the Euclidean path integral approach. As is well known, the real Euclidean path integral diverges because the Einstein-Hilbert action is not positive definite. In order to obtain a finite wave function, we propose a new regularization method and calculate the wave function of the Friedmann-Robertson-Walker type minisuperspace model. We then consider a homogeneous but anisotropic type minisuperspace model, which is known as the Bianch type I model. The physical meaning of the wave function by this new regularization method is also examined.

Inhomogeneous solutions in cosmology

1990 ◽  
Vol 68 (9) ◽  
pp. 824-826
Author(s):  
Paul S. Wesson
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
General Relativity ◽  
Particle Physics ◽  
Quantum Field ◽  
Einstein’S Equations ◽  
Einstein's Equations ◽  
Cosmological Solutions ◽  
The Universe ◽  
Friedmann Robertson Walker

The standard cosmological solutions of Einstein's equations of general relativity describe a fluid that is homogeneous and isotropic in density and pressure. These solutions, often called the Friedmann–Robertson–Walker solutions, are believed to be good descriptions of the universe at the present time. But early on, processes connected with particle physics and quantum field theory may have caused localized inhomogeneities, and recently some new kinds of solution of Einstein's equations have been found, which may describe such regions. In one solution being studied by Wesson and Ponce de Leon (Phys. Rev. D: Part. Fields, 39, 420 (1989)), the density is still uniform but the pressure is nonuniform about a centre. The mass is given by a relation that looks like the familiar Newtonian relation m = (4/3)πR3ρ. However, the solution has other properties that are quite strange (e.g. a region of negative pressure and a kind of dipolar geometry). It is not known if solutions like this are merely mathematical curiosities or imply something about the behaviour of real matter in extreme situations.

scholarly journals THE VALUE OF THE COSMOLOGICAL CONSTANT

2011 ◽  
Vol 20 (14) ◽  
pp. 2875-2880 ◽  
Author(s):  
JOHN D. BARROW ◽  
DOUGLAS J. SHAW
Keyword(s):  
Wave Function ◽  
Cosmological Constant ◽  
Classical Limit ◽  
Constraint Equation ◽  
Einstein Equations ◽  
Spatial Curvature ◽  
Self Consistent ◽  
Curvature Parameter ◽  
The Universe ◽  
Planck Satellite

We make the cosmological constant, Λ, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts the solutions of the standard Einstein equations and is the requirement that the cosmological wave function possess a classical limit. When applied to the Friedmann metric it requires that the cosmological constant measured today, tU, be [Formula: see text], as observed. This is the classical value of Λ that dominates the wave function of the universe. Our new field equation determines Λ in terms of other astronomically measurable quantities. Specifically, it predicts that the spatial curvature parameter of the universe is [Formula: see text], which will be tested by Planck Satellite data. Our theory also creates a new picture of self-consistent quantum cosmological history.

Kantowski–Sachs cosmological solutions in the generalized teleparallel gravity via Noether symmetry

2016 ◽  
Vol 31 (15) ◽  
pp. 1650095 ◽  
Author(s):  
H. Motavalli ◽  
A. Rezaei Akbarieh ◽  
M. Nasiry
Keyword(s):  
Equation Of State ◽  
Teleparallel Gravity ◽  
Noether Symmetry ◽  
Anisotropic Model ◽  
Eos Parameter ◽  
Scale Factors ◽  
Cosmological Solutions ◽  
Frw Metric ◽  
The Universe ◽  
Friedmann Robertson Walker

We study the f(T) theory as an extension of teleparallel gravity and consider the Noether symmetry of Kantowski–Sachs (KS) anisotropic model for this theory. We specify the explicit teleparallel form of f(T) and find the corresponding exact cosmological solutions under the assumption that the Lagrangian admits the Noether symmetry. It is found that the universe experiences a power law expansion for the scale factors in the context of f(T) theory. By deriving equation of state (EOS) parameter, we show that the universe passes through the phantom and [Formula: see text]CDM theoretical scenarios. In this way, we estimate a lower limit age for the universe in excellent agreement with the value reported from recent observations. When KS model reduces to the flat Friedmann–Robertson–Walker (FRW) metric, our results are properly transformed into the corresponding values.

scholarly journals The simplest possible bouncing quantum cosmological model

2016 ◽  
Vol 31 (21) ◽  
pp. 1640006 ◽  
Author(s):  
Patrick Peter ◽  
Sandro D. P. Vitenti
Keyword(s):  
Wave Function ◽  
Quantum Mechanics ◽  
Cosmological Model ◽  
Functional Form ◽  
Initial Conditions ◽  
Wave Functions ◽  
General Situation ◽  
Spatial Curvature ◽  
Bianchi I ◽  
Contracting Phase

We present and expand the simplest possible quantum cosmological bouncing model already discussed in previous works: the trajectory formulation of quantum mechanics applied to cosmology (through the Wheeler–De Witt equation) in the Friedmann–Lemaître–Robertson–Walker (FLRW) minisuperspace without spatial curvature. The initial conditions that were previously assumed were such that the wave function would not change its functional form but instead provide a dynamics to its parameters. Here, we consider a more general situation, in practice consisting of modified Gaussian wave functions, aiming at obtaining a nonsingular bounce from a contracting phase. Whereas previous works consistently obtain very symmetric bounces, we find that it is possible to produce highly non-symmetric solutions, and even cases for which multiple bounces naturally occur. We also introduce a means of treating the shear in this category of models by quantizing in the Bianchi I minisuperspace.

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