A quantum solution to the arrow-of-time dilemma

TL;DR

This paper proposes a quantum mechanical explanation for the arrow of time, suggesting that only processes with non-decreasing entropy leave observable information, making entropy decrease processes fundamentally unobservable.

Contribution

It introduces a quantum framework that explains the arrow of time by linking observable phenomena to entropy increase or constancy, reducing the second law to a tautology.

Findings

Processes with decreasing entropy leave no observable information.

The second law of thermodynamics is a tautology within this framework.

Observable phenomena are those where entropy does not decrease.

Abstract

The arrow of time dilemma: the laws of physics are invariant for time inversion, whereas the familiar phenomena we see everyday are not (i.e. entropy increases). I show that, within a quantum mechanical framework, all phenomena which leave a trail of information behind (and hence can be studied by physics) are those where entropy necessarily increases or remains constant. All phenomena where the entropy decreases must not leave any information of their having happened. This situation is completely indistinguishable from their not having happened at all. In the light of this observation, the second law of thermodynamics is reduced to a mere tautology: physics cannot study those processes where entropy has decreased, even if they were commonplace.