On the Statistical Arrow of Time
Andreas Henriksson
Abstract
What is the physical origin of the arrow of time? It is a commonly held belief in the physics community that it relates to the increase of disorder, or entropy, as it appears in the statistical interpretation of the second law of thermodynamics. In this article, it is argued that the philosophical point of view that the arrow of time is a fundamental property of Nature is incompatible with the subjective information-theoretical interpretation of probability and entropy in statistical mechanics, where they arise due to the ignorance of the observer. This conclusion, however, relies on the premise that time's arrow has a statistical mechanical origin. If this assumption is abandoned, then there is no conflict between the belief in the fundamental character of time's arrow and the belief in the subjective information-theoretical interpretation.