  In a previous paper [1] we considered the question, "What underlying property
of nature is responsible for the second law?" A simple answer can be stated in
terms of information: The fundamental loss of information gives rise to the
second law. This line of thinking highlights the existence of two independent
but coupled sets of laws: Information dynamics and energy dynamics. The
distinction helps shed light on certain foundational questions in statistical
mechanics. For example, the confusion surrounding previous "derivations" of the
second law from energy dynamics can be resolved by noting that such derivations
incorporate one or more assumptions that correspond to the loss of information.
In this paper we further develop and explore the perspective in which the
second law is fundamentally a law of information dynamics.
