Memory and Entropy

Round 1

Reviewer 1 Report

This is a quite profound paper that deserves to be published without delay. It makes a significant contribution to understanding of temporal asymmetries. I have a couple of recommendations:

(i) the paper might benefit from discussion of more complex examples of traces that shows how they can be assimilated to the simple model provided, going through a couple of his own examples (e.g. photos, impact craters, and memory in computers) would illustrate the power of the simple model. 

(ii)  a bit more articulation in the vocabulary, might be helpful. The author treats 'memory' and 'trace' interchangeably, but the notion of memory we use in everyday life is something like a psychological state representing past events. Conflating 'memory' and 'trace' leaves little room for a substantive account of how 'memory' in the psychological sense relates to traces in the sense that are understood here. (Memories in the psychological sense aren't simply traces in the brain (p. 1)). The author need not provide such an account, but there is a gap that needs to be acknowledged. By using 'memory' to mean 'trace' the author might seem to be promising more than he delivers in the title of the paper. 

(iii) the notion of available information in the claim that the mechanism described transforms low entropy into available information might bear a little more scrutiny. Available to whom? or for what?  is there any implicitly relativization to particular classes of information consumers or users? 

These are minor and marginal suggestions, to be followed at the authors discretion, on a quite wonderful paper. 

Author Response

Thank you very much for the very kind report and the three very useful suggestions. I have implemented all three of them: 

(i) I have added a short section with physical examples.

(ii) I have added a paragraph in the introduction making clear the sense in which "memory" is used in the paper and clearly stating what the paper does not address.

(iii) I have added a paragraph in the last section, with a few more details about the kind of information I am talking about.

Reviewer 2 Report

see attachment.

Comments for author File: Comments.pdf

Author Response

I sincerely thanks the referee for his/her report.