It makes a lot of sense to me to imagine a cannonball flying through space as not so much experiencing a macroscopic non-conservative drag force, but as pushing a bunch of air molecules and giving away its momentum and energy to them, thereby losing speed. I'd also imagine that if one took a snapshot of the cannonball in mid-flight, replicated the system exactly down to each molecule (assuming this is possible), and then reversed all of the velocities and angular velocities, and pressed 'play', the cannonball would end up flying back to where it was launched. Is this right?
Drag, therefore, is simply an emergent phenomenon that is a result of our simplification of the entire system, isn't it? And is really the result of kinematic principles and classical mechanics.
In thinking about this I noticed that if we think of drag on mechanical terms, conservation of mechanical energy is held -- and in the result, time-reversal symmetry (right?). So conservation of mechanical energy is therefore "linked" to time-reversal symmetry -- would this be related to how mechanical energy is the conserved quantity associated with time translation symmetry, as well?
What about something like a sugar cube dissolving in tea? If I dropped a sugar cube into tea, and then watched it dissolve, froze that system and recreated it while swapping all velocities of all of the molecules, would the sugar cube re-gather and then pop out of the cup?