The generalized second law of thermodynamics in the accelerating universe

TL;DR

This paper investigates the validity of the generalized second law of thermodynamics in an accelerating universe, finding it holds only at the apparent horizon and not at the event horizon, implying the event horizon may not be a physical boundary thermodynamically.

Contribution

It demonstrates the conditions under which the generalized second law holds in an accelerating universe, emphasizing the significance of the apparent horizon over the event horizon.

Findings

The law holds at the apparent horizon.

The law does not hold at the event horizon.

Event horizon may not be a physical thermodynamic boundary.

Abstract

We show that in the accelerating universe the generalized second law of thermodynamics holds only in the case where the enveloping surface is the apparent horizon, but not in the case of the event horizon. The present analysis relies on the most recent SNe Ia events, being model independent. Our study might suggest that event horizon is not a physical boundary from the point of view of thermodynamics.