scholarly journals A Topological Magueijo-Smolin Varying Speed of Light Theory, the Accelerated Cosmic Expansion and the Dark Energy of Pure Gravity

2014 ◽  
Vol 05 (12) ◽  
pp. 1780-1790 ◽  
Author(s):  
Mohamed Salah El Naschie ◽  
Leila Marek-Crnjac ◽  
Mohamed Atef Helal ◽  
Ji-Huan He
Keyword(s):  
Dark Energy ◽  
Speed Of Light ◽  
Cosmic Expansion ◽  
Pure Gravity ◽  
Light Theory

Ghost dark energy in Rastall theory

2021 ◽  
pp. 2150090
Author(s):  
E. E. Kangal ◽  
M. Salti ◽  
O. Aydogdu
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Text Analysis ◽  
Functional Form ◽  
Expansion Rate ◽  
Dark Energy Density ◽  
Cosmic Expansion ◽  
Astrophysical Data ◽  
Ghost Dark Energy ◽  
History Of

Making use of the generalized form of the Ghost dark energy density, which has the functional form [Formula: see text] where [Formula: see text] represents the Hubble expanding rate, the present accelerated enlargement behavior of the cosmos is investigated from the Rastall theory perspective. After finding a relation for the Hubble cosmic expansion rate, we consider recent cosmology-independent measurements calculated for the expansion history of the cosmos to fit the model via the [Formula: see text]-analysis. Moreover, we discuss the cosmographic properties of the model with the help of some cosmological quantities. We show that our model is stable and consistent with the recent astrophysical data. Also, for our model, we investigate cosmological interpretations of thermodynamics.

scholarly journals Can a negative-mass cosmology explain dark matter and dark energy?

2019 ◽  
Vol 626 ◽  
pp. A5 ◽  
Author(s):  
H. Socas-Navarro
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Large Scale ◽  
Dark Matter Halos ◽  
Challenging Problem ◽  
Speed Of Light ◽  
Negative Mass ◽  
Galactic Dark Matter

A recent study by Farnes (2018, A&A, 620, A92) proposed an alternative cosmological model in which both dark matter and dark energy are replaced with a single fluid of negative mass. This paper presents a critical review of that model. A number of problems and discrepancies with observations are identified. For instance, the predicted shape and density of galactic dark matter halos are incorrect. Also, halos would need to be less massive than the baryonic component, otherwise they would become gravitationally unstable. Perhaps the most challenging problem in this theory is the presence of a large-scale version of the “runaway effect”, which would result in all galaxies moving in random directions at nearly the speed of light. Other more general issues regarding negative mass in general relativity are discussed, such as the possibility of time-travel paradoxes.

MAXWELL BRANE COSMOLOGY WITH HIGHER-ORDER STRING CURVATURE CORRECTIONS, A NONMINIMALLY COUPLED SCALAR FIELD, DARK MATTER–DARK ENERGY INTERACTION AND A VARYING SPEED OF LIGHT

2009 ◽  
Vol 18 (02) ◽  
pp. 289-318 ◽  
Author(s):  
R. A. EL-NABULSI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Friedmann Equation ◽  
Building Blocks ◽  
Higher Order ◽  
Alternative Theory ◽  
Speed Of Light ◽  
Energy Interaction ◽  
Curvature Term

We investigate the cosmological effects of an alternative theory of gravity on the four-dimensional Randall–Sundrum braneworld of type II with a higher-order string curvature term added to the action. We discuss the possibility of a varying speed of light, which has recently attracted considerable attention, in the presence a Maxwell field and of a dynamically evolving bulk scalar field nonminimally coupled to scalar curvature in a quadratic form, together with a dark matter–dark energy interaction term. After deriving the modified Friedmann equation on the brane, as well as the scalar field equations, we then analyze the dynamical equations obtained so far. Special attention is paid to scaling solutions which could be important building blocks in constructing the models of dark energy. The constructed model exhibits several features of cosmological and astrophysical interest for both the early and the late universe, consistent with recent observations, in particular the ones concerned with celerity of light, four and five gravitational constants, black hole masses and entropies.

scholarly journals Thermodynamics in Variable Speed of Light Theories

2009 ◽  
Vol 5 (H15) ◽  
pp. 301-301
Author(s):  
Juan Racker ◽  
Paolo Sisterna ◽  
Hector Vucetich
Keyword(s):  
Scalar Field ◽  
Newtonian Limit ◽  
Variable Speed ◽  
Speed Of Light ◽  
Light Theory

Variable speed of light theories (VSL) are interesting because they could solve several cosmological puzzles. In this work we study the thermodynamics and Newtonian limit of the varying speed of light theory developed by J. Magueijo (Magueijo 2000). In the covariant and locally Lorentz invariant VSL proposed by Magueijo c is a dimensionless dynamical scalar field c=c0eψ, where c0 is a constant. The matter and gravitational lagrangians are multiplied by the factors ebψ and eaψ respectively.

THE IMPRINT OF DARK ENERGY

2004 ◽  
Vol 19 (13n16) ◽  
pp. 1063-1070 ◽  
Author(s):  
ROBERT CALDWELL
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmic Microwave Background ◽  
Cosmological Constant ◽  
Negative Pressure ◽  
Inhomogeneous Field ◽  
Time Varying ◽  
Microwave Background ◽  
Cosmic Expansion ◽  
Cosmological Observations

Diverse cosmological observations indicate the existence of dark energy, comprising ~ 70% of the total cosmic energy density and driving the accelerated cosmic expansion. Possible explanations for the dark energy include a cosmological constant and quintessence — a time-varying, inhomogeneous field with negative pressure. In this article we summarize how the dark energy imprints features on the cosmic microwave background. Observation of these features could be useful in discriminating amongst various theories, and could reveal clues as to the nature of the dark energy.

scholarly journals The WiggleZ Dark Energy Survey: measuring the cosmic expansion history using the Alcock-Paczynski test and distant supernovae

2011 ◽  
Vol 418 (3) ◽  
pp. 1725-1735 ◽  
Author(s):  
Chris Blake ◽  
Karl Glazebrook ◽  
Tamara M. Davis ◽  
Sarah Brough ◽  
Matthew Colless ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cosmic Expansion ◽  
Dark Energy Survey ◽  
Energy Survey ◽  
Cosmic Expansion History

scholarly journals The Fundamental Discussion between Newton and Einstein

2021 ◽  
Author(s):  
Wim Vegt
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Gravitational Field ◽  
Energy Density ◽  
Speed Of Sound ◽  
Gravitational Energy ◽  
Quantum Mechanical ◽  
Quantum Field ◽  
Speed Of Light ◽  
Light Theory

Isaac Newton and Albert Einstein lived in fundamentally different time frames. An interesting question would be: “Who would win the fundamental discussion about the interaction between gravity and light”? Einstein or Newton? Einstein with the fundamental concept of a “curved space-time continuum” within a gravitational field. Or Newton with the fundamental “3rd law of equilibrium between the forces (force-densities)”. It is still the question who was right? Einstein or Newton? Einstein assumes a deformation of the space-time continuum because of a gravitational field. But in general a deformation of any medium will be caused by the change of the energy density within the medium. Like the speed of sound will increase/ decrease when we change the air pressure. However, the speed of sound (which became higher or lower) will still be the same in any direction. The change of the speed of sound will be omni-directional.A gravitational field contains a gravitational energy-density. For that reason the change in the speed of light will be omni-directional within a gravitational field (with a omni-directional gravitational energy density). Einstein however assumes a one-directional change in the speed of light, (only in the direction of the gravitational field). When the change of the speed of light was omni-directional, a beam of light would never be deflected by a gravitational field which is in contradiction with what we measure. Only the absolute value of the speed of light would change omni-directional.The theory of Newton however results in the theory of a 2-directional inertia of photons. The inertia of photons equals zero only in the direction of propagation. Perpendicular to the direction of propagation the mass density of photons is according Einstein’s E = m c^2).The inertia of photons in the direction of propagation will not change within a gravitational field. Gravity can only interact with mass (inertia). Because the mass of the photons in the direction of propagation equals zero, there will ne no interaction with the gravitational field and the photon in the direction of propagation. The speed of light in the direction of propagation will remain unaltered. But according Newton, the photon will have inertia (mass) in the directions perpendicular to the direction of propagation and for that reason the photon will interact with the gravitational field and the photon will be deflected, only in the direction of the gravitational field.And that leads to the consequence that photons will be deflected within a gravitational field when the direction of the gravitational field is perpendicular to the direction of propagation of the photons.To find fundamental mathematical evidence for this concept, we have to make use of Quantum Light Theory. Quantum Light Theory (QLT) is the development in Quantum Field Theory (QFT). In Quantum Field Theory, the fundamental interaction fields are replacing the concept of elementary particles in Classical Quantum Mechanics. In Quantum Light Theory the fundamental interaction fields are being replaced by One Single Field. The Electromagnetic Field, generally well known as Light. To realize this theoretical concept, the fundamental theory has to go back in time 300 years, the time of Isaac Newton to follow a different path in development. Nowadays experiments question more and more the fundamental concepts in Quantum Field Theory and Classical Quantum Mechanics. The publication “Operational Resource Theory of Imaginarity“ in “Physical Review Letters” in 2021 (Ref. [2]) presenting the first experimental evidence for the measurability of “Quantum Mechanical Imaginarity” directly leads to the fundamental question in this experiment: How is it possible to measure the imaginary part of “Quantum Physical Probability Waves”? This publication provides an unambiguously answer to this fundamental question in Physics, based on the fundamental “Gravitational Electromagnetic Interaction” force densities. The “Quantum Light Theory” presents a new “Gravitational-Electromagnetic Equation” describing Electromagnetic Field Configurations which are simultaneously the Mathematical Solutions for the Quantum Mechanical “Schrodinger Wave Equation” and more exactly the Mathematical Solutions for the “Relativistic Quantum Mechanical Dirac Equation”. The Mathematical Solutions for the “Gravitational-Electromagnetic Equation” carry Mass, Electric Charge and Magnetic Spin at discrete values.

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