The above framing raises two issues. At this point it is worth distinguishing the concept of a direction of time from that of an asymmetry of some physical law or process in time. The authors of the paper cited in detail below point out: "In fact philosophical discussions around the question are usually subsumed under the label 'the problem of the direction of time', as if we could find an exclusively physical criterion for singling out the direction of time, identified with what we call 'the future'. But there is nothing in physics that distinguishes, in a non-arbitrary way, between past and future as we conceive them".

We will take this distinction as given in the mapping of the physics of time below. Rather than attempting to find a physical correlate of our understanding of the terms 'past' and 'future', we will be looking for asymmetries of physical processes in time. In the case of the thermodynamic arrow, we can seek a physical asymmetry without being committed to labeling the direction of increased entropy as 'the future'. This approach implies avoiding tensed language in this part of the map.

Acknowledging that the laws of physics per se provide no basis for regarding a particular direction 'the future' does not preclude seeking other objective bases for such labeling - such as the fact the past is encoded in memory and the future is not - this possibility is dealt with elsewhere on the map.