Spatial Curvature and Thermodynamics

TL;DR

The paper shows that the apparent horizon's area increases in our universe regardless of spatial curvature, aligning with thermodynamic principles and suggesting the second law holds universally.

Contribution

It demonstrates that the second law of thermodynamics applies to the apparent horizon across different spatial curvatures using current Hubble data.

Findings

Horizon area increases regardless of curvature sign

Data smoothing confirms thermodynamic consistency

Second law holds in open, flat, and closed universes

Abstract

Reasonable parametrizations of the current Hubble data set of the expansion rate of our homogeneous and isotropic universe, after suitable smoothing of these data, strongly suggests that the area of the apparent horizon increases irrespective of whether the spatial curvature of the metric is open, flat or closed. Put in another way, any sign of the spatial curvature appears consistent with the second law of thermodynamics.