Dynamical Horizon Entropy Bound Conjecture in Loop Quantum Cosmology

TL;DR

This paper investigates the dynamical horizon entropy bound conjecture within loop quantum cosmology, demonstrating that quantum geometry effects uphold the conjecture near the big bang, where classical theories fail.

Contribution

It extends the dynamical horizon entropy bound conjecture to loop quantum cosmology, showing quantum effects preserve the conjecture near the big bang.

Findings

Quantum geometry effects protect the entropy bound near the big bang.

The conjecture holds for photon gas in loop quantum cosmology.

Classical breakdown of the conjecture is prevented by quantum effects.

Abstract

The covariant entropy bound conjecture is an important hint for the quantum gravity, with several versions available in the literature. For cosmology, Ashtekar and Wilson-Ewing ever show the consistence between the loop gravity theory and one version of this conjecture. Recently, S. He and H. Zhang proposed a version for the dynamical horizon of the universe, which validates the entropy bound conjecture for the cosmology filled with perfect fluid in the classical scenario when the universe is far away from the big bang singularity. However, their conjecture breaks down near big bang region. We examine this conjecture in the context of the loop quantum cosmology. With the example of photon gas, this conjecture is protected by the quantum geometry effects as expected.