On the time arrows, and randomness in cosmological signals

TL;DR

This paper explores the origins of the arrow of time across various domains, proposing that limited observability and dark sector interactions influence the thermodynamical arrow and cosmological signals.

Contribution

It introduces a framework linking the arrow of time to initial conditions, non-unitary dynamics, and dark sector effects, offering a unified perspective on temporal asymmetry in the universe.

Findings

Limited observability explains thermodynamical arrow emergence.

Dark sector acts as a bath influencing cosmic time direction.

Void-induced hyperbolicity affects cosmological observations.

Abstract

Arrows of time - thermodynamical, cosmological, electromagnetic, quantum mechanical, psychological - are basic properties of Nature. For a quantum system-bath closed system the de-correlated initial conditions and no-memory (Markovian) dynamics are outlined as necessary conditions for the appearance of the thermodynamical arrow. The emergence of the arrow for the system evolving according to non-unitary dynamics due to the presence of the bath, then, is a result of limited observability, and we conjecture the arrow in the observable Universe as determined by the dark sector acting as a bath. The voids in the large scale matter distribution induce hyperbolicity of the null geodesics, with possible observational consequences.