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From an extended relativistic dynamics for a particle moving in a cosmic background field with temperature T, we aim to obtain the speed of light with an explicit dependence on the background temperature of the universe. Although finding…

General Relativity and Quantum Cosmology · Physics 2021-02-04 Cláudio Nassif Cruz , Antônio Carlos Amaro de Faria

An exact inhomogeneous solution of Einstein's field equations is shown to be able to inflate in a non-uniform way in the early universe and explain anomalies in the WMAP power spectrum data. It is also possible for the model to explain the…

Astrophysics · Physics 2007-06-13 J. W. Moffat

The concept of oscillatory Universe appears to be realistic and buried in the dynamic dark energy equation of state. We explore its evolutionary history under the frame work of general relativity. We observe that oscillations do not go…

General Physics · Physics 2013-03-15 Partha Pratim Ghosh , Saibal Ray , A. A. Usmani , Utpal Mukhopadhyay

I present a brief review of astro-ph/0406099, which argues that there is a limit on the number of efolds of inflation which are observable in a universe which undergoes an eternally accelerated expansion in the future. Such an acceleration…

High Energy Physics - Theory · Physics 2007-05-23 Matthew Kleban

Following recent studies of Ford, we suggest -- in the framework of general relativity -- an inflationary cosmological model with the self-interacting spinning matter. A generalization of the standard fluid model is discussed and estimates…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Yuri N. Obukhov

The very basics of cosmological inflation are discussed. We derive the equations of motion for the inflaton field, introduce the slow-roll parameters, and present the computation of the inflationary perturbations and their connection to the…

General Relativity and Quantum Cosmology · Physics 2012-01-31 K. Enqvist

The rotation rate of a star has important implications for the detectability, characterisation and stability of any planets that may be orbiting it. This chapter gives a brief overview of stellar rotation before describing the methods used…

Earth and Planetary Astrophysics · Physics 2018-12-05 P. F. L. Maxted

The theory of cosmological perturbations has become a cornerstone of modern quantitative cosmology since it is the framework which provides the link between the models of the very early Universe such as the inflationary Universe scenario…

High Energy Physics - Theory · Physics 2017-08-23 Robert H. Brandenberger

A brief introduction to the gauge invariant classical and quantum theory of cosmological perturbations is given. The formalism is applied to inflationary Universe models and yields a consistent and unified description of the generation and…

Astrophysics · Physics 2007-05-23 R. Brandenberger , H. Feldman , V. Mukhanov

I present an outline for cosmological evolution in the framework of string theory with emphasis on a phase of dilaton-driven kinetic inflation. It is shown that a typical background of stochastic gravitational radiation is generated, with…

High Energy Physics - Theory · Physics 2007-05-23 Ram Brustein

Conformal geometry is considered within a general relativistic framework. An invariant distant for proper time is defined and a parallel displacement is applied in the distorted space-time, modifying Einstein's equation appropriately. A…

General Relativity and Quantum Cosmology · Physics 2015-06-16 Edmund A. Chadwick , Timothy F. Hodgkinson , Graham S. McDonald

We consider the problem of constructing a non-singular inflationary universe in stringy gravity via branch changing, from a previously superexponentially expanding phase to an FRW-like phase. Our approach is based on the phase space…

High Energy Physics - Theory · Physics 2009-09-15 Nemanja Kaloper , Richard Madden , Keith A. Olive

We consider the fate of the observable universe in the light of the discovery of a dark energy component to the cosmic energy budget. We extend results for a cosmological constant to a general dark energy component and examine the…

Astrophysics · Physics 2009-11-07 Dragan Huterer , Glenn D. Starkman , Mark Trodden

In a previous paper we proposed a new approach to the beginning of inflation -- a lingering universe. The universe begins in a lingering state with a nearly vanishing Hubble parameter. This calls into question the absolute age of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-09 Brandon Melcher , Arnab Pradhan , Scott Watson

A model of cosmological inflation is proposed in which field space is a hyperbolic plane. The inflaton never slow-rolls, and instead orbits the bottom of the potential, buoyed by a centrifugal force. Though initial velocities redshift away…

High Energy Physics - Theory · Physics 2019-01-03 Adam R. Brown

This study reviews the advances made in inflationary theory, especially regarding the seeming disparity between inflation energy and dark energy, and their significance to cosmic evolution as a whole. I attempt to connect the two sources of…

General Relativity and Quantum Cosmology · Physics 2018-12-17 Anantya Bhatnagar

Using Mach's principle, we will show that the observed diurnal and annual motion of the Earth can just as well be accounted as the diurnal rotation and annual revolution of the Universe around the fixed and centered Earth. This can be…

General Physics · Physics 2015-03-17 Luka Popov

We consider an extended scalar-tensor theory of gravity where the action has two interacting scalar fields, a Brans-Dicke field which makes the effective Newtonian constant a function of coordinates and a Higgs field which has derivative…

General Relativity and Quantum Cosmology · Physics 2021-01-13 Soumya Chakrabarti

Using the model based on the Regge-like laws, new analytical formulas are obtained for the moment of inertia, the rotation frequency, and the radius of astronomical non-exotic objects (planets, stars, galaxies, and clusters of galaxies).…

Classical Physics · Physics 2021-05-12 G. G. Adamian , N. V. Antonenko , H. Lenske , V. V. Sargsyan

Barrow, and Barrow and collaborators, have put forward theoretical models with variable fundamental constants including JBD theories. The experimental evidence for an accelerating Universe points out to a deceleration parameter…

General Relativity and Quantum Cosmology · Physics 2009-09-23 Marcelo Samuel Berman , Luis A. Trevisan
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