Determine whether time travel can counteract the second law of thermodynamics

Ascertain whether time travel—such as travel along closed timelike curves—can counteract the second law of thermodynamics, for example by enabling entropy reduction or avoidance of heat death, thereby testing the assumption used in the model that time travel does not affect thermodynamic irreversibility and the associated finiteness of available cosmic time for constructing time machines.

Background

In developing the model’s dynamics, the paper assumes a maximum possible construction number for time machines, motivated in part by a finite available temporal horizon due to the heat death of the universe. This relies on the second law of thermodynamics as an underpinning assumption about the directionality of entropy and the finiteness of usable time.

The author explicitly notes uncertainty regarding whether time travel might be able to counteract the second law. If time travel could reduce or reverse entropy, the assumption of a finite temporal horizon (and therefore the bound on the construction number) would require reevaluation. The quoted sentence highlights this unresolved issue.