Cosmological constraints and cosmic growth factor for ghost dark energy models in varying G $G$ theories

Malekjani, M.; Lu, Jianbo; Nazari-Pooya, N.; Xu, Lixin; Jassur, D. M. Z.; Honari-Jafarpour, M.

doi:10.1007/s10509-015-2534-x

Cited by 9 publications

(3 citation statements)

References 55 publications

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“…Dirac, in 1937, argued that variations in G of about 5 parts in 10 11 per annum could explain the relatively small strength of the gravitational force compared to other fundamental forces of nature. In order to unify gravitation and elementary particle physics, Einstein's theory with time-varying G is already in the literature [50,[54][55][56][57][58][59][60][61][62][63][64][65]. Singh [57] has presented a cosmological model with G ∼ a 2/α , where a is the scale factor of the universe and α a constant.…”

Section: Introductionmentioning

confidence: 99%

Cosmology with Variable G and Nonlinear Electrodynamics

Joseph

Овгун

2021

Preprint

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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.

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Section: Introductionmentioning

confidence: 99%

Cosmology with Variable G and Nonlinear Electrodynamics

Joseph

Овгун

2021

Preprint

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“…It is noted that there are significant evidence that gravitational constant G can be varying in a time [48]. Spurred by the discovery of occurrence of large numbers Weyl and Dirac proposed the theory of variable G. In other to unify gravitation and elementary particle Physics, Einstein's theory with time varying G is already in the literature [46,[49][50][51][52][53][54][55][56][57][58][59].…”

Section: Introductionmentioning

confidence: 99%

Cosmology with Variable G and Nonlinear Electrodynamics

Joseph¹,

Овгун²

2020

Preprint

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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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“…Spurred by the discovery huge inconsistency between distance scales in force field, Dirac had proposed the time dependent cosmological model. In other to unify gravitation and elementary particle Physics, Einstein's theory with time varying G is already in the literature [46,[50][51][52][53][55][56][57][58][59][60][61]. Singh [53] has presented a cosmological model with G ∼ a 2/α , where a is the scale factor of the universe and α a constant.…”

Section: Introductionmentioning

confidence: 99%