Frame dragging in Einstein and Einstein zero mass scalar cosmologies

1983 ◽  
Vol 61 (8) ◽  
pp. 1198-1204
Author(s):  
K. D. Krori ◽  
J. C. Sarmah ◽  
D. Goswami
Keyword(s):  
Angular Velocity ◽  
Cosmological Model ◽  
Inertial Frame ◽  
Frame Dragging ◽  
Evolution Of The Universe ◽  
Zero Mass ◽  
Isotropic Cosmological Model ◽  
Scalar Theories ◽  
Rotating Shell ◽  
The Universe

We investigate in this paper the perturbations caused by a spherical rotating shell in a closed homogeneous and isotropic cosmological model in Einstein and Einstein zero mass scalar theories. It is found from our solutions that in both theories the inertial frame at the origin is dragged with the angular velocity of the rotating shell during only a certain interval in the evolution of the universe when the shell covers the whole universe.

scholarly journals AN OPEN INFLATIONARY MODEL FOR DIMENSIONAL REDUCTION AND ITS EFFECTS ON THE OBSERVABLE PARAMETERS OF THE UNIVERSE

2005 ◽  
Vol 20 (11) ◽  
pp. 2449-2453
Author(s):  
KORAY KARACA ◽  
SELÇUK BAYIN
Keyword(s):  
Phase Transition ◽  
Cosmological Model ◽  
Boundary Conditions ◽  
Dimensional Reduction ◽  
Higher Dimensions ◽  
Inflationary Model ◽  
Early Stages ◽  
Isotropic Cosmological Model ◽  
Spatially Homogeneous ◽  
The Universe

Assuming that higher dimensions existed in the early stages of the universe where the evolution was inflationary, we construct an open, singularity-free, spatially homogeneous and isotropic cosmological model to study the effects of dimensional reduction that may have taken place during the early stages of the universe. We consider dimensional reduction to take place in a stepwise manner and interpret each step as a phase transition. By imposing suitable boundary conditions we trace their effects on the present day parameters of the universe.

scholarly journals Noether symmetry approach in f (T, B) teleparallel gravity with a fermionic field

2021 ◽  
Vol 2090 (1) ◽  
pp. 012058
Author(s):  
Yerlan Myrzakulov ◽  
Sabit Bekov ◽  
Kairat Myrzakulov
Keyword(s):  
Cosmological Model ◽  
Teleparallel Gravity ◽  
Noether Symmetry ◽  
Accelerated Expansion ◽  
Late Time ◽  
Fermionic Field ◽  
Symmetry Approach ◽  
Expansion Of The Universe ◽  
Isotropic Cosmological Model ◽  
The Universe

Abstract In this work, we consider a homogeneous and isotropic cosmological model of the universe in f (T, B) gravity with non-minimally coupled fermionic field. In order to find the form of the coupling function F(Ψ), the potential function V (Ψ) of the fermionic field and the function f (T, B), we found through the Noether symmetry approach. The results obtain are coincide with the observational data that describe the late-time accelerated expansion of the universe.

scholarly journals EFEK SERETAN KERANGKA INERSIAL DI DALAM MEDAN BINTANG NEUTRON YANG BEROTASI DAN STASIONER

2020 ◽  
Vol 5 (2) ◽  
pp. 48-53
Author(s):  
Tika Restianingsih ◽  
Muhammad Farchani Rosyid
Keyword(s):  
Neutron Star ◽  
Angular Velocity ◽  
General Theory ◽  
Inertial Frame ◽  
Space Time ◽  
Compact Stars ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Frame Dragging ◽  
Stationary Frame

The inertial frame dragging effect of rotating neutron star has been studied. Inertial frame dragging effect, also well known as Lense Thirring effect, has been predicted using general theory of relativity in 1918. When the neutron star rotates very quickly, the space time around it will be dragged to the direction of the rotation. The Lense Thirring effect is small enough for small objects so it will be clearly seen for massive objects like compact stars, especially neutron star. Later, we derive the equation of frame dragging rate () inside the rotating neutron star, which is axisymmetrik and stationary. Frame dragging rate is decreasing from the center to the surface of stars. It is also noted that  is proportional to the angular velocity of star.

scholarly journals THE COSMOLOGICAL DYNAMICS OF INTERACTING HOLOGRAPHIC DARK ENERGY MODEL

2009 ◽  
Vol 18 (01) ◽  
pp. 147-157 ◽  
Author(s):  
M. R. SETARE ◽  
ELIAS C. VAGENAS
Keyword(s):  
Dark Energy ◽  
Cosmological Model ◽  
Critical Points ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Cosmic Acceleration ◽  
Holographic Dark Energy Model ◽  
Evolution Of The Universe ◽  
Energy Scenario ◽  
The Universe

Motivated by the recent observations for cosmic acceleration and the suitable evolution of the universe provided an interaction (decay of dark energy to matter) is incorporated in a cosmological model, we study the cosmological evolution of the interacting holographic dark energy scenario. Critical points are derived and their corresponding cosmological models are presented. The dynamical character of these models is revealed.

Rotational perturbations of Friedmann universes in Einstein zero mass scalar theory

1983 ◽  
Vol 61 (5) ◽  
pp. 744-747 ◽  
Author(s):  
K. D. Krori ◽  
J. C. Sarmah ◽  
D. Goswami
Keyword(s):  
Scalar Field ◽  
Recent Work ◽  
Scalar Boson ◽  
Scalar Theory ◽  
Evolution Of The Universe ◽  
Damping Effect ◽  
Zero Mass ◽  
Pseudo Scalar ◽  
The Universe

In an extension of a recent work by Bayin and Cooperstock, we investigate in this paper rotational perturbations of Friedmann universes in Einstein zero mass scalar theory. We find that except in the case of "perfect dragging", the zero mass scalar field has a damping effect on the rotation of matter. One of the three cases studied here shows that the scalar field may exist only during a certain interval in the course of the evolution of the universe. The zero mass scalar field has acquired particular importance recently because of a suggestion by Weinberg and Wilczek that there should exist a pseudo-scalar boson, the so-called axion, of negligible mass. The work of Peccei and Quinn has lent further support to the idea of axions.

scholarly journals Constraining the anisotropy of the universe from supernovae and gamma-ray bursts

2014 ◽  
Vol 29 (15) ◽  
pp. 1450067 ◽  
Author(s):  
Zhe Chang ◽  
Xin Li ◽  
Hai-Nan Lin ◽  
Sai Wang
Keyword(s):  
Cosmological Model ◽  
Coordinate System ◽  
Gamma Ray ◽  
Line Element ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Anisotropic Cosmological Model ◽  
Isotropic Cosmological Model ◽  
The Universe ◽  
Friedmann Robertson Walker

Recently, an anisotropic cosmological model was proposed. An arbitrary one-form, which picks out a privileged axis in the universe, was added to the Friedmann–Robertson–Walker (FRW) line element. The distance-redshift relation was modified such that it is direction-dependent. In this paper, we use the Union2 dataset and 59 high-redshift gamma-ray bursts (GRBs) to give constraints on the anisotropy of the universe. The results show that the magnitude of anisotropy is about D = -0.044±0.018, and the privileged axis points toward the direction (l0, b0) = (306.1°±18.7°, -18.2°±11.2°) in the galactic coordinate system. The anisotropy is small and the isotropic cosmological model is an excellent approximation.

Cosmological spacetimes

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Cosmological Model ◽  
Large Scale ◽  
Cosmic Time ◽  
De Sitter ◽  
Matter Distribution ◽  
Observable Universe ◽  
Cosmological Principle ◽  
Riemannian Spacetime ◽  
The Universe ◽  
Copernican Principle

This chapter provides a few examples of representations of the universe on a large scale—a first step in constructing a cosmological model. It first discusses the Copernican principle, which is an approximation/hypothesis about the matter distribution in the observable universe. The chapter then turns to the cosmological principle—a hypothesis about the geometry of the Riemannian spacetime representing the universe, which is assumed to be foliated by 3-spaces labeled by a cosmic time t which are homogeneous and isotropic, that is, ‘maximally symmetric’. After a discussion on maximally symmetric space, this chapter considers spacetimes with homogenous and isotropic sections. Finally, this chapter discusses Milne and de Sitter spacetimes.

scholarly journals Mixed fluid cosmological model in f(R, T) gravity

2020 ◽  
Vol 98 (11) ◽  
pp. 1015-1022 ◽  
Author(s):  
Parbati Sahoo ◽  
Barkha Taori ◽  
K.L. Mahanta
Keyword(s):  
Cosmological Model ◽  
Bianchi Type ◽  
Type I ◽  
Time Varying ◽  
Eos Parameter ◽  
Barotropic Fluid ◽  
Rotationally Symmetric ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Mixed Fluid

We construct a locally rotationally symmetric (LRS) Bianchi type-I cosmological model in f(R, T) theory of gravity when the source of gravitation is a mixture of barotropic fluid and dark energy (DE) by employing a time-varying deceleration parameter. We observe through the behavior of the state finder parameters (r, s) that our model begins from the Einstein static era and goes to ΛCDM era. The equation of state (EOS) parameter (ωd) for DE varies from the phantom (ω < –1) phase to quintessence (ω > –1) phase, which is consistent with observational results. It is found that the discussed model can reproduce the current accelerating phase of the expansion of the universe.

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