Fractional Action Cosmology: Emergent, Logamediate, Intermediate, Power law Scenarios of the Universe and Generalized Second Law of Thermodynamics

TL;DR

This paper investigates the validity of the generalized second law of thermodynamics within Fractional Action Cosmology across various universe expansion scenarios and cosmic horizons, revealing conditions under which the law holds or breaks down.

Contribution

It systematically analyzes the GSL in FAC for different scale factors and horizons, considering cases with and without the first law, providing new insights into thermodynamic behavior in cosmological models.

Findings

GSL holds for emergent and logamediate expansions across multiple horizons.

GSL is valid for intermediate scenarios with certain horizons, with some exceptions.

Power law expansion shows conditional validity of GSL depending on specific cases.

Abstract

In the framework of Fractional Action Cosmology (FAC), we study the generalized second law of thermodynamics for the Friedmann Universe enclosed by a boundary. We use the four well-known cosmic horizons as boundaries namely, apparent horizon, future event horizon, Hubble horizon and particle horizon. We construct the generalized second law (GSL) using and without using the first law of thermodynamics. To check the validity of GSL, we express the law in the form of four different scale factors namely emergent, logamediate, intermediate and power law. For Hubble, apparent and particle horizons, the GSL holds for emergent and logamediate expansions of the universe when we apply with and without using first law. For intermediate scenario, the GSL is valid for Hubble, apparent, particle horizons when we apply with and without first law. Also for intermediate scenario, the GSL is valid for event horizon when we apply first law but it breaks down without using first law. But for power law expansion, the GSL may be valid for some cases and breaks down otherwise.