Volume 143, Number 5, September 2023
|Number of page(s)||7|
|Section||Gravitation, cosmology and astrophysics|
|Published online||31 August 2023|
Modified Friedmann equations from fractional entropy
1 Department of Physics, Faculty of Science, Istanbul University - Istanbul, 34134, Türkiye
2 Theoretical and Computational Physics Research Laboratory, Istanbul University - Istanbul, Türkiye
Received: 7 May 2023
Accepted: 17 August 2023
Based on the fractional black-hole entropy (Jalalzadeh S. et al., Eur. Phys. J. C, 81 (2021) 632), we derive the modified Friedmann equations from two different frameworks. First, we consider the modifications of Friedmann equations from the first law of thermodynamics at the apparent horizon. We show that the generalized second law (GSL) of thermodynamics always holds in a region bounded by the apparent horizon. Then, we obtain Friedmann equations from Verlinde's entropic gravity framework. We also compute the fractional corrections to the deceleration parameter q in the flat case k = 0 for both frameworks. Furthermore, we consider the time to reach the initial singularity for the two frameworks. The results indicate that the initial singularity is accessible for both frameworks. However, fractional effects may provide a constraint on the equation-of-state parameter in the entropic gravity scenario since the time is imaginary for .
© 2023 The author(s)
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