Pre-bangian origin of our entropy and time arrow

TL;DR

This paper proposes that classical and quantum effects in string cosmology naturally produce the observed entropy and time arrow, aligning with holographic bounds and suggesting a critical transition in the early universe.

Contribution

It introduces a mechanism where entropy and the arrow of time emerge from string cosmology effects, linking holographic bounds to a crucial branch change and phase transition.

Findings

Entropy saturates holographic bounds at radiation exit

A critical branch change triggers the end of the string phase

Effective Planck mass reaches a critical value during transition

Abstract

I argue that, in the chaotic version of string cosmology proposed recently, classical and quantum effects generate, at the time of exit to radiation, the correct amount of entropy to saturate a Hubble (or holography) entropy bound (HEB) and to identify, within our own Universe, the arrow of time. Demanding that the HEB be fulfilled at all times forces a crucial "branch change" to occur, and the so-called string phase to end at a critical value of the effective Planck mass, in agreement with previous conjectures.