COSMOLOGICAL EFFECTS OF NONLINEAR ELECTRODYNAMICS

2005 ◽  
Vol 20 (11) ◽  
pp. 2421-2430 ◽  
Author(s):  
M. NOVELLO
Keyword(s):  
Nonlinear Electrodynamics ◽  
Global Properties ◽  
The Universe

We present some consequences induced by nonlinear electrodynamics on the global properties of the universe.

scholarly journals CYCLIC MAGNETIC UNIVERSE

2009 ◽  
Vol 24 (30) ◽  
pp. 5639-5658 ◽  
Author(s):  
M. NOVELLO ◽  
ALINE N. ARAUJO ◽  
J. M. SALIM
Keyword(s):  
Magnetic Field ◽  
Present Model ◽  
Nonlinear Electrodynamics ◽  
Acceleration Phase ◽  
Maxwell Theory ◽  
Cosmological Scenario ◽  
One Step ◽  
The Universe ◽  
Friedmann Robertson Walker ◽  
Main Factor

Recent works have shown the important role nonlinear electrodynamics (NLED) can have in two crucial questions of cosmology, concerning particular moments of its evolution for very large and for low-curvature regimes, that is for very condensed phase and at the present period of acceleration. We present here a toy model of a complete cosmological scenario in which the main factor responsible for the geometry is a nonlinear magnetic field which produces a Friedmann–Robertson–Walker homogeneous and isotropic geometry. In this scenario we distinguish four distinct phases: a bouncing period, a radiation era, an acceleration era, and a re-bouncing period. It has already been shown that in NLED a strong magnetic field can overcome the inevitability of a singular region typical of linear Maxwell theory; on the other extreme situation, that is for very weak magnetic field it can accelerate the expansion. The present model goes one step further: after the acceleration phase the universe re-bounces and enters into a collapse era. This behavior is a manifestation of the invariance under the dual map of the scale factor a(t) → 1/a(t), a consequence of the corresponding inverse symmetry of the electromagnetic field (F → 1/F, where F ≡ FμνFμν) of the NLED theory presented here. Such sequence collapse–bouncing–expansion–acceleration–re-bouncing–collapse constitutes a basic unitary element for the structure of the universe that can be repeated indefinitely yielding what we call a cyclic magnetic universe.

scholarly journals Cosmology with Variable G and Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Gabriel W. Joseph ◽  
Ali Övgün
Keyword(s):  
Power Law ◽  
Speed Of Sound ◽  
Gravitational Constant ◽  
Cosmic Time ◽  
Scale Factor ◽  
Fine Tuning ◽  
Nonlinear Electrodynamics ◽  
The Stability ◽  
The Universe ◽  
Constants Of Nature

In a bid to resolve lingering problems in cosmology, more focus is being tilted towards cosmological models in which physical constants of nature are not necessarily real constants, but varying with cosmic time. In this paper we have study cosmology in nonlinear electrodynamics with the Newton's gravitational constant $G$ not a constant but vary in form of power-law of the scale factor of the universe. The evolution of the scale factor $a (t)$ is studied in this model which depends on nonlinear electrodynamics fine tuning term of $\alpha$. Then we check the stability of the model using the speed of sound.

scholarly journals Inflation of universe due to nonlinear electrodynamics

2017 ◽  
Vol 32 (13) ◽  
pp. 1750071 ◽  
Author(s):  
S. I. Kruglov
Keyword(s):  
Minkowski Space ◽  
Electromagnetic Fields ◽  
Spectral Index ◽  
Nonlinear Electrodynamics ◽  
Gravitation Field ◽  
Dimensional Parameter ◽  
Minkowski Space Time ◽  
Wmap Data ◽  
Stochastic Magnetic Fields ◽  
The Universe

A model of nonlinear electrodynamics with a dimensional parameter [Formula: see text] is considered. Electromagnetic fields are the source of the gravitation field and inflation of the universe. We imply that the universe is filled by stochastic magnetic fields. It is demonstrated that after the universe inflation the universe decelerates approaching the Minkowski space–time. We evaluate the spectral index, the tensor-to-scalar ratio, and the running of the spectral index which approximately agree with the Planck and WMAP data.

scholarly journals Global properties of the growth index of matter inhomogeneities in the Universe

2019 ◽  
Vol 100 (8) ◽  
Author(s):  
R. Calderon ◽  
D. Felbacq ◽  
R. Gannouji ◽  
D. Polarski ◽  
A. A. Starobinsky
Keyword(s):  
Growth Index ◽  
Global Properties ◽  
The Universe

scholarly journals Accelerating cosmologies with nonlinear electrodynamics

2018 ◽  
Vol 96 (9) ◽  
pp. 992-998
Author(s):  
G.P. Singh ◽  
N. Hulke ◽  
Ashutosh Singh
Keyword(s):  
Cosmological Model ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Big Bang ◽  
Accelerated Expansion ◽  
Nonlinear Electrodynamics ◽  
Classical Stability ◽  
Initial Anisotropy ◽  
The Big Bang ◽  
The Universe

In this paper, we consider the framework of nonlinear electrodynamics in locally rotationally symmetric (LRS) Bianchi-I universe model composed of magnetic fluid. It has been shown that an accelerated universe expansion takes place if the nonlinear electromagnetic field is a source of gravitational field. In this model, after the big bang, the universe undergoes inflation and the accelerated expansion, dissipates the initial anisotropy of the curvature part without using a selected initial condition. Further validity of generalised second law of thermodynamics in the cosmological model enclosed by apparent horizon is investigated. We also discuss the classical stability of the cosmological model and observational viability of the model.

scholarly journals Probing modified gravity in cosmic filaments

2018 ◽  
Vol 619 ◽  
pp. A122 ◽  
Author(s):  
Alex Ho ◽  
Max Gronke ◽  
Bridget Falck ◽  
David F. Mota
Keyword(s):  
Modified Gravity ◽  
Gravity Models ◽  
Accelerated Expansion ◽  
Radial Density ◽  
Post Process ◽  
Global Properties ◽  
Modified Gravity Theories ◽  
Expansion Of The Universe ◽  
Gravity Theories ◽  
The Universe

Multiple modifications of general relativity (GR) have been proposed in the literature in order to understand the nature of the accelerated expansion of the Universe. However, thus far all the predictions of GR have been confirmed with constantly increasing accuracy. In this work, we study the imprints of a particular class of models – “screened” modified gravity theories – on cosmic filaments. We have utilized the N-body code ISIS/RAMSES to simulate the symmetron model and the Hu–Sawicky f(R) model, and we post-process the output with DisPerSE to identify the filaments of the cosmic web. We investigated how the global properties of the filaments – such as their lengths, masses, and thicknesses – as well as their radial density and speed profiles change under different gravity theories. We find that filaments are, on average, shorter and denser in modified gravity models compared to in ΛCDM. We also find that the speed profiles of the filaments are enhanced, consistent with theoretical expectations. Overall, our results suggest that cosmic filaments can be an effective complementary probe of screened modified gravity theories on Mpc scales.

scholarly journals Rational nonlinear electrodynamics causes the inflation of the universe

2020 ◽  
Vol 35 (26) ◽  
pp. 2050168
Author(s):  
S. I. Kruglov
Keyword(s):  
Magnetic Fields ◽  
Electric Field ◽  
Electromagnetic Fields ◽  
Ricci Tensor ◽  
De Sitter Space ◽  
Nonlinear Electrodynamics ◽  
De Sitter ◽  
Number Formula ◽  
Stochastic Magnetic Fields ◽  
The Universe

The source of the universe inflation is electromagnetic fields obeying rational nonlinear electrodynamics proposed earlier. Within this model the singularities of the electric field at the center of charges, the Ricci scalar, the Ricci tensor squared and the Kretschmann scalar are absent. We consider the universe which is filled by stochastic magnetic fields. It is demonstrated that the inflation lasts approximately [Formula: see text] s with the reasonable [Formula: see text]-folding number [Formula: see text]. The inflation starts from de Sitter space–time and after the universe inflation end it decelerates approaching the radiation era.

scholarly journals CORRESPONDENCE BETWEEN ELECTROMAGNETIC FIELD AND OTHER DARK ENERGIES IN NONLINEAR ELECTRODYNAMICS

2011 ◽  
Vol 20 (12) ◽  
pp. 2337-2350 ◽  
Author(s):  
SAYANI MAITY ◽  
SHUVENDU CHAKRABORTY ◽  
UJJAL DEBNATH
Keyword(s):  
Electromagnetic Field ◽  
Dark Energy ◽  
Scalar Fields ◽  
Chaplygin Gas ◽  
The Other ◽  
Nonlinear Electrodynamics ◽  
Tachyonic Field ◽  
Frw Model ◽  
Nonlinear Form ◽  
The Universe

In this work, we have considered the flat FRW model of the universe filled with electromagnetic field. First, the Maxwell's electromagnetic field in linear form has been discussed and after that the modified Lagrangian in nonlinear form for accelerated universe has been considered. The corresponding energy density and pressure for nonlinear electromagnetic field have been calculated. We have found the condition such that the electromagnetic field generates dark energy. The correspondence between the electromagnetic field and the other dark energy candidates namely tachyonic field, DBI-essence, Chaplygin gas, hessence dark energy, k-essence and dilaton dark energy have been investigated. We have also reconstructed the potential functions and the scalar fields in this scenario.

scholarly journals Cosmology with Variable G and Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Gabriel W. Joseph ◽  
Ali Övgün
Keyword(s):  
Gravitational Constant ◽  
Magnetic Monopole ◽  
Cosmic Time ◽  
Scale Factor ◽  
Cosmological Models ◽  
Nonlinear Electrodynamics ◽  
Physical Constants ◽  
The Stability ◽  
The Universe ◽  
Constants Of Nature

In a bid to resolve lingering problems in cosmology, more focus is being tilted towards cosmological models in which physical constants of nature are not necessarily real constants, but varying with cosmic time. In this paper we study cosmology in nonlinear electrodynamics with the Newton's gravitational constant $G$ not a constant but varies with the scale factor of the universe. The evolution of the scale factor $a(t)$ in this model depends on $\alpha$, which gives an steady universe when $\alpha=0.5$. As $\alpha$ increases to $\alpha=1.0, 1.5, 2.0, 3.0$ the universe enter into inflation scenario after that the magnetic monopole field decayed and is converted to radiation. We checked the stability of the model and obtained that it is classically stable with the best condition for the stability at $5/2\geq \alpha >7/4$ .

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