Paul,
"Any given physically existent state (of an 'it') does not become another, but altered, physically existent state, for no reason."
"But be careful here, because the 'reason' must, of itself, have physical existence (otherwise how does it work?). In which case one has the physically existent state of a 'reason' which affects the physically existent state of an 'it'."
Reason, or no reason?
"So the real question is what are these fundamental properties, how are they physically existent, interract, etc."
Yes, that is the question.
So we have a process of time, that which is constantly going from one unit to the next and then the units we measure. It would seem to me the process, this constantly churning reality of the present, is cause of the units, the regular cycles within that action that we measure.