Bouncing universe of entropy-corrected Friedmann equations

Salehi, Amin; Mahmoudi-Fard, Mojtaba

doi:10.1140/epjc/s10052-018-5727-y

Cited by 15 publications

(12 citation statements)

References 113 publications

(146 reference statements)

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“…Investigating relation (1) in different cosmological contexts can provide an accurate estimation to the true values of α and β on the cosmological scale. Depending on the values of α and β, The existence of bouncing solutions of the system (2) and (3) has been discussed in details in [51]. The modified Friedmann equations derived from the corrected entropy-area relation without the last β term have been derived in ( [50]) where some possible analytical solutions have been discussed depending on the values of α.…”

Section: Cosmological Equations and Solutionsmentioning

confidence: 99%

A stable flat entropy-corrected FRW universe

Ahmed

Alamri

2019

Int. J. Geom. Methods Mod. Phys.

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In this paper, a general entropy-corrected FRW cosmological model has been presented in which a deceleration-to-acceleration transition occurs according to recent observations. We found that the case for the flat universe (k = 0), supported by observations, is the most stable one where it successfully passes all stability tests. The stability of the model has been studied through testing the sound speed, the classical and the new nonlinear energy conditions. The model predicts a positive pressure during the early-time decelerating epoch, and a negative pressure during the late-time accelerating epoch in a good agreement with cosmic history and dark energy assumption. We have investigated all possible values of the prefactors α and β in the corrected entropy-area relation to find the best values required for a stable flat universe. We have also made use of the evolution of the equation of state parameters ω(t) in predicting the correct values of α and β. The jerk and density parameters have been calculated where a good agreement with observations and ΛCDM model has been obtained. Two dark energy proposals have been investigated in this model, the entropy-corrected holographic dark energy and the modified holographic Ricci dark energy. : 98.80.-k, 95.36.+x, 65.40.gd Keywords: Cosmology, entropy-corrected universe, dark energy. PACSHawking radiation [37] is a quantum phenomenon in which the black hole's entropy S is proportional to its horizon area A, the discovery of this phenomenon indicated a deep connection 1

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Section: Cosmological Equations and Solutionsmentioning

confidence: 99%

A stable flat entropy-corrected FRW universe

Ahmed

Alamri

2019

Int. J. Geom. Methods Mod. Phys.

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“…There is an extensive research literature on various types of bouncing solutions, constructed in different models and using various assumptions [25,26,27,28,29,30,31]. Recently, a model-independent and general approach for studying the bouncing and cyclic solutions was proposed in [32] and [33].…”

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confidence: 99%

Cosmological bounce and the cosmological constant problem

Pavlović¹,

Sossich²

2021

Preprint

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We demonstrate that the famous cosmological constant problem of the standard cosmology naturally vanishes in the suitable model-independent effective approach towards quantum gravity, while also studying the effect of quantum space-time fluctuations on the cosmological evolution. We start from the general list of assumptions required for a consistent and complete model of the Universe, which replaces the big bang singularity with a bounce, and thus invokes a modification of the classical field equations for gravity. We first concentrate on the case of the classical FRWL spacetime and show that in a bouncing cosmology, where the modification of the Einstein-Hilbert action can be represented by some general continuous function of time, S(t), the cosmological constant problem is absent if this function at late cosmological times approaches a sufficiently large value. Motivated by the recent studies of cosmological constant problem in the context of quantum vacuum and spacetime fluctuations in the standard cosmology, we then generalize our study to incorporate the effects of quantum spacetime fluctuations. We show that some problems of the earlier proposals, like singularities and negative values of the scale factor, are also naturally resolved in the approach proposed here.

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“…where the second and higher orders of 1/(4π G M 2 ) of the logarithm expansion were neglected since the most popular values of the pre-factors are small values around unity [43]. Besides, since the equipartition law is an average value of energy, we can also use an approximate value for the energy of the logarithmically corrected-entropy.…”

Section: Barrow Logarithm Corrected-entropymentioning

confidence: 99%

“…where α and β are dimensionless constant pre-factors and their values are being discussed and not yet confirmed even within loop quantum gravity [43]. Several formulations concerning BH entropy provided the logarithmic correction yielding α = −1/2 or −3/2 as standard values for this coefficient [44,45].…”

Section: Introductionmentioning

confidence: 99%

Thermal features of Barrow corrected-entropy black hole formulation

Abreu

Neto

2020

Eur. Phys. J. C

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Through the last years, it was demonstrated that quantum corrections of entropy, represented by logarithmic and power law corrections terms, constituted an association between semi-classical entropic areas and the curvature correction in Einstein–Hilbert’s Lagrangian and vice-versa. Loop quantum gravity approach provided the logarithmic corrections, which arises from quantum and thermal equilibrium fluctuations. On the other hand, Barrow’s entropy was introduced from the fact that the black hole surface can be modified due to quantum gravitational effects. The new exponent $$\Delta $$Δ that appears in Barrow’s entropy is a measure of this perturbation. In this letter we have analyzed the thermodynamical effects of the quantum fluctuations upon the geometry of a Barrow’s black hole. We demonstrated that new formulations of the equipartition law, which corresponds to the horizon energy, can be constructed from both entropic formalisms. Besides, we have calculated the heat capacity for both formulations and we discussed their thermal viability. We have also establish a condition on one of the constant pre-factors of the logarithmic correction.

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Bouncing universe of entropy-corrected Friedmann equations

Cited by 15 publications

References 113 publications

A stable flat entropy-corrected FRW universe

A stable flat entropy-corrected FRW universe

Cosmological bounce and the cosmological constant problem

Thermal features of Barrow corrected-entropy black hole formulation

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