Cosmology with Varying Constants from a Thermodynamic Viewpoint

Gohar, Hussain

doi:10.3390/universe3010026

Cited by 6 publications

(9 citation statements)

References 47 publications

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“…We believe most of the negative findings on the variation of physical constants are possibly due to the variation of a constant being considered in isolation rather than holistically for all the constants involved. We have established that the physical constants not only vary but also how much they vary: H/H = −0.6 H. In addition, from the null results on the variation of the fine structure constant [14,15], we have shown that . h/h = 1.8H.…”

Section: Discussionmentioning

confidence: 67%

“…The orbit of Earth around the sun is Keplerian and thus is governed by Equation (15). A radiometric measurement will therefore yield a null result in our approach using evolutionary G and c. However, the eccentricity evolution is equally valid for the moon and Earth.…”

Section: Astronomical Unit (Au) Anomalymentioning

confidence: 99%

“…α/α = (−1.6 ± 2.3) × 10 −17 yr −1 derived from the constancy of the ratio of aluminum and mercury single-ion optical clock frequencies. More recently Gohar [15], using his entropic model of the universe and data on supernovae 1a, baryon acoustic oscillations, and cosmic microwave background, has established even more stringent constraint on the variation of α. Additionally, he states that in his model G and c should be increasing with the evolution of the universe, which corroborates our findings in this work. Similar constraints on α were shown by Songaila and Cowie [16] from the observation of narrow quasar absorption lines at redshift z > 1.5.…”

Section: Introductionmentioning

confidence: 99%

“…c/c almost cancel each other except for a small residual. This may be compared with the case of using Kepler's Equation (15) when the two contributions cancel out entirely.…”

mentioning

confidence: 99%

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Varying Physical Constants, Astrometric Anomalies, Redshift and Hubble Units

Gupta¹

2019

Galaxies

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We have developed a cosmological model by allowing the speed of light c, gravitational constant G and cosmological constant Λ in the Einstein filed equation to vary in time, and solved them for Robertson-Walker metric. Assuming the universe is flat and matter dominant at present, we obtain a simple model that can fit the supernovae 1a data with a single parameter almost as well as the standard ΛCDM model with two parameters, and which has the predictive capability superior to the latter. The model, together with the null results for the variation of G from the analysis of lunar laser ranging data determines that at the current time G and c both increase as dG/dt = 5.4GH0 and dc/dt = 1.8cH0 with H0 as the Hubble constant, and Λ decreases as dΛ/dt = −1.2ΛH0. This variation of G and c is all what is needed to account for the Pioneer anomaly, the anomalous secular increase of the moon eccentricity, and the anomalous secular increase of the astronomical unit. We also show that the Planck’s constant ħ increases as dħ/dt = 1.8ħH0 and the ratio D of any Hubble unit to the corresponding Planck unit increases as dD/dt = 1.5DH0. We have shown that it is essential to consider the variation of all the physical constants that may be involved directly or indirectly in a measurement rather than only the one whose variation is of interest.

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Section: Discussionmentioning

confidence: 67%

Section: Astronomical Unit (Au) Anomalymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…c/c almost cancel each other except for a small residual. This may be compared with the case of using Kepler's Equation (15) when the two contributions cancel out entirely.…”

mentioning

confidence: 99%

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Varying Physical Constants, Astrometric Anomalies, Redshift and Hubble Units

Gupta¹

2019

Galaxies

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“…Rosenband et al [14] have put a constraint on the ̇/ = (−1.6 ± 2.3) × 10 −17 yr −1 derived from the constancy of the ratio of aluminum and mercury single-ion optical clock frequencies. More recently Gohar [15], using his entropic model of the universe and data on supernovae 1a, baryon acoustic oscillations, and cosmic microwave background, has established even more stringent constraint on the variation of . Additionally, he states that in his model and should be increasing with the evolution of the universe, which corroborates our findings in this work.…”

Section: Introductionmentioning

confidence: 99%

Varying Physical Constants, Astrometric Anomalies, Redshift and Hubble Units

Gupta¹

2019

Preprint

View full text Add to dashboard Cite

We have developed a cosmological model by allowing the speed of light c, gravitational constant G and cosmological constant Λ in the Einstein filed equation to vary in time, and solved them for Robertson-Walker metric. Assuming the universe is flat and matter dominant at present, we obtain a simple model that can fit the supernovae 1a data with a single parameter almost as well as the standard ΛCDM model with two parameters, and has the predictive capability superior to the latter. The model, together with the null results for the variation of G from the analysis of lunar laser ranging data determines that at the current time G and c both increase as dG/dt = 5.4GH0 and dc/dt = 1.8cH0 with H0 as the Hubble constant, and Λ decreases as dΛ/dt = -1.2ΛH0. This variation of G and c is all what is needed to account for the Pioneer anomaly, the anomalous secular increase of the Moon eccentricity, and the anomalous secular increase of the astronomical unit. We also show that the Planck’s constant ħ increases as dħ/dt = 1.8ħH0 and the ratio D of any Hubble unit to the corresponding Planck units increases as dD/dt = 1.5DH0. We have shown that it is essential to consider the variation of all the physical constants that may be involved directly or indirectly in a measurement rather than only the one whose variation is being considered.

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Cosmological constraints on entropic cosmology with matter creation

Gohar

Salzano

2021

Eur. Phys. J. C

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We investigate entropic force cosmological models with the possibility of matter creation and energy exchange between the bulk and the horizon of a homogeneous and isotropic flat Universe. We consider three different kinds of entropy, Bekenstein’s, the non-extensive Tsallis–Cirto’s, and the quartic entropy, plus some phenomenological functional forms for matter creation rate to model different entropic force models and put the observational constraints on them. We show that while most of them are indistinguishable from a standard $$\Lambda $$ Λ CDM scenario, the Bekenstein entropic force model with a matter creation rate proportional to the Hubble parameter is statistically highly favored over $$\Lambda $$ Λ CDM. As a general result, we also find that both the Hawking temperature parameter $$\gamma $$ γ , which relates the energy exchange between the bulk and the boundary of the Universe, and the matter creation rate $$\Gamma (t)$$ Γ ( t ) , must be very small to reproduce observational data.

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Cosmology with Varying Constants from a Thermodynamic Viewpoint

Cited by 6 publications

References 47 publications

Varying Physical Constants, Astrometric Anomalies, Redshift and Hubble Units

Varying Physical Constants, Astrometric Anomalies, Redshift and Hubble Units

Varying Physical Constants, Astrometric Anomalies, Redshift and Hubble Units

Cosmological constraints on entropic cosmology with matter creation

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