"So the arrow of time isn’t just about simple mechanical processes; it’s a necessary feature of the existence of life itself. But it’s also responsible for a deep feature of what it means to be a conscious person: the fact that we remember the past, but not the future. According to the fundamental laws of physics, the past and future are treated on an equal footing; but when it comes to how we perceive the world, they couldn’t be more different. We carry in our heads representations of the past, in the form of memories. Concerning the future, we can make predictions, but those predictions have nowhere near the reliability of our memories of the past. Ultimately, the reason we can form a reliable memory of the past is that the entropy was lower then."

The formation of a trace is the formation of a subsystem of temporarily lower entropy than that of its surroundings... A footprint in the sand is a temporarily highly ordered state of the sand; this orderliness is brought about at the expense of an increased disorderliness (metabolic depletion) of the pedestrian who made it... On investigation it will be seen that all sorts of traces, whether footprints in the sand, photographs, fossil bones, or the like can be understood as traces in this sense. Indeed, so are written records. The close connection between information and entropy is brought out in modern information theory, the mathematics of which is much the same as that of statistical mechanics.

Cited in Earman article on pp 41-2