1. The generalized second law of thermodynamics with Barrow entropy
- Author
-
Spyros Basilakos and Emmanuel N. Saridakis
- Subjects
High Energy Physics - Theory ,Computer Science::Machine Learning ,Surface (mathematics) ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Physics and Astronomy (miscellaneous) ,media_common.quotation_subject ,FOS: Physical sciences ,Second law of thermodynamics ,QC770-798 ,General Relativity and Quantum Cosmology (gr-qc) ,Astrophysics ,Computer Science::Digital Libraries ,01 natural sciences ,General Relativity and Quantum Cosmology ,Statistics::Machine Learning ,Nuclear and particle physics. Atomic energy. Radioactivity ,0103 physical sciences ,010303 astronomy & astrophysics ,Engineering (miscellaneous) ,Entropy (arrow of time) ,Mathematical physics ,media_common ,Physics ,010308 nuclear & particles physics ,Function (mathematics) ,Universe ,QB460-466 ,High Energy Physics - Theory (hep-th) ,Apparent horizon ,Computer Science::Mathematical Software ,Dark energy ,Exponent ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We investigate the validity of the generalized second law of thermodynamics, applying Barrow entropy for the horizon entropy. The former arises from the fact that the black-hole surface may be deformed due to quantum-gravitational effects, quantified by a new exponent $\Delta$. We calculate the entropy time-variation in a universe filled with the matter and dark energy fluids, as well as the corresponding quantity for the apparent horizon. We show that although in the case $\Delta=0$, which corresponds to usual entropy, the sum of the entropy enclosed by the apparent horizon plus the entropy of the horizon itself is always a non-decreasing function of time and thus the generalized second law of thermodynamics is valid, in the case of Barrow entropy this is not true anymore, and the generalized second law of thermodynamics may be violated, depending on the universe evolution. Hence, in order not to have violation, the deformation from standard Bekenstein-Hawking expression should be small as expected., Comment: 6 pages, 2 figures, version published in Eur.Phys.J.C
- Published
- 2021