Time-dependent 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>G</mml:mi></mml:math>
 in Einstein’s equations as an alternative to the cosmological constant

Hanımeli, Ekim Taylan; Lamine, Brahim; Tutusaus, I.; Blanchard, Alain

doi:10.1103/physrevd.101.063513

Cited by 16 publications

(9 citation statements)

References 35 publications

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“…Higher order terms for G do not improve the fit, as they are less relevant for a close to one. The χ 2 values and best-fit values obtained for all parameters can be found in Equations ( 10)- (12). As Equation (10) shows, the present varying G model is consistent with cosmological data in a similar way to ΛCDM:…”

Section: Analysis and Resultssupporting

confidence: 68%

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Can Dark Energy Emerge from a Varying G and Spacetime Geometry?

et al. 2022

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The accelerated expansion of the universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown. We will discuss an alternative gravity model in which this dark energy contribution emerges naturally, as a result of allowing for a time-dependence on the gravitational constant, G, in Einstein’s field equations. With this modification, Bianchi’s identities require an additional tensor field to be introduced so that the usual conservation equation for matter and radiation is satisfied. The equation of state of this tensor field is obtained using additional constraints, coming from the assumption that this tensor field represents the space-time response to the variation of G. We will also present the predictions of this model for the late-universe data, and show that the energy contribution of this new tensor is able to explain the accelerated expansion of the universe without the addition of a cosmological constant. Unlike many other alternative gravities with varying gravitational strength, the predicted G evolution is also consistent with local observations and therefore this model does not require screening. We will finish by discussing possible other implications this approach might have for cosmology and some future prospects.

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Section: Analysis and Resultssupporting

confidence: 68%

“…The discussion and results presented in the following are based on Ref. [12] by the present authors, and we refer the reader to this reference for further details.…”

Section: Introductionmentioning

confidence: 99%

Can Dark Energy Emerge from a Varying G and Spacetime Geometry?

et al. 2022

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“…The dynamics of VSL models have been investigated in theoretical as well as empirical aspects [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50].…”

Section: Previous Vslmentioning

confidence: 99%

“…Also, the VSL theory provides a solution to the cosmological constant problem. The dynamics of VSL have been investigated in both theoretical and empirical aspects [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

The minimally extended Varying Speed of Light (meVSL)

Lee

2020

Preprint

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Even though there have been the various varying speed of light (VSL) cosmology models, they remain out of the mainstream because of their possible violation of physics laws built into fundamental physics. In order to be the VSL as a viable theory, it should inherit the success of special relativity including Maxwell equations and thermodynamics at least. Thus, we adopt that the speed of light, c varies for the cosmic time not for the local time, i.e., c[z] where z is the cosmological redshift.When one describes the background FLRW universe, one can define the constanttime hypersurface by using physical quantities such as temperature, density, and c.It is because they evolve in time, and the homogeneity of the Universe demands that they must equal at the equal cosmic time. The variation of c accompanies the joint variations of all related physical constants in order to satisfy the Lorentz invariance, thermodynamics, and Bianchi identity. We call this VSL model as a "minimally extended VSL (meVSL)". We derive cosmological observables of meVSL and obtain the constraints on the variation of c by using the current observations. Interestingly, z and all geometrical distances except the luminosity distance of meVSL are the same as those of general relativity. However, the Hubble parameter of meVSL is rescaled as H = (1 + z) −b/4 H (GR) which might be used as a solution for the tension of the Hubble parameter measurements. In this manuscript, we provide the main effects of meVSL on various cosmological observations including BBN, CMB, SZE, BAO, SNe, GWs, H, SL, and ∆α.

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“…We will then conclude with a discussion of the results, and what other impacts this model might have for cosmology. The discussion and results presented in the following are based on Ref [7] by the present authors, and we refer the reader to this reference for further details.…”

Section: Introductionmentioning

confidence: 99%

Can Dark Energy Emerge from a Varying $G$ and Spacetime Geometry?

Hanımeli,

Tutusaus,

Lamine

et al. 2022

Preprint

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The accelerated expansion of the Universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown. We will discuss an alternative gravity model in which this dark energy contribution emerges naturally, as a result of allowing for a time-dependence on the gravitational constant, G, in Einstein's Field Equations. With this modification, Bianchi's identities require an additional tensor field to be introduced so that the usual conservation equation for matter and radiation is satisfied. The equation of state of this tensor field is obtained using additional constraints, coming from the assumption that this tensor field represents the space-time response to the variation of G. We will also present the predictions of this model for the late-Universe data, and show that the energy contribution of this new tensor is able to explain the accelerated expansion of the Universe without the addition of a cosmological constant. Unlike many other alternative gravities with varying gravitational strength, the predicted G evolution is also consistent with local observations and therefore this model does not require screening. We will finish by discussing possible other implications this approach might have for cosmology and some future prospects.

show abstract

Time-dependent G in Einstein’s equations as an alternative to the cosmological constant

Cited by 16 publications

References 35 publications

Can Dark Energy Emerge from a Varying G and Spacetime Geometry?

Can Dark Energy Emerge from a Varying G and Spacetime Geometry?

The minimally extended Varying Speed of Light (meVSL)

Can Dark Energy Emerge from a Varying $G$ and Spacetime Geometry?

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