Let me go back to the coffee sipping event from the section on how now works.  In this sip event, the state changes include the active kind, involving departures from Nature’s preferred state as expressed by maximal aging or the psi-function. My hand moved.  The cup was raised.  Liquid flowed.  Let’s try to isolate the first state change in the sipping event.  Was it the first perceptible change, in the hand’s approach to the cup?  Probably a chain of state changes preceded any perceptible motion, including the state changes in my brain that made up my decision to take the sip.

Perhaps the decision to sip was precipitated by the state changes in the olfactory sensors in my nose, which resulted from the state change in the liquid in the cup to a vapor.  And so on and so forth until the idea of an isolated event, like the sip of coffee, slips from our grasp.

From the time of the Big Bang, my sip of coffee at this particular spacetime location has been included in a possible future of the universe.  Its probability just lay there close to zero for somewhere around 13.7 thousand million years.  During all that time, as now rolled up the t-axis trimming away possible events, it never broke the chain of events that enabled the possibility of that sip of coffee.

Does that mean that the coffee sipping event was preordained from the time of the Big Bang, what with one thing leading to another over the last 13.7 thousand million years or so.  I seriously doubt it.  The possibility of the event has existed since the Big Bang but there are an infinite variety of ways that the probability might have remained vanishingly low. 

In recent history events conspired to raise the sip event probability.  I was born, I was exposed to coffee, and so on.  Also events may have reduced the probability.  The price of coffee went up, I learned to like tea as well, and so on.  Even as late as a few minutes ago the phone might have rung, causing that particular sip of coffee to land on now’s scrap heap of events that never happened. 

Throughout that entire chain of events back to the Big Bang there were very likely instances where the most probable event was not the one realized by quantum state reduction.  The sip of coffee event may even have benefited from that.  It was only with the passage of now that the event became a certainty and immediately passed into history.  The probability of any future possible event is influenced by the realization of current possible events, just as the probability of current events was influenced by the realization of past events.

Those readers inclined to philosophy may ask if I had any choice in taking the sip of coffee.  I think all can agree that after the fact there is no choice, what is done is done, but I have the impression that I could have decided to forego the sip or interrupt it anytime before its completion.  In another context (the role of an attractor in chaotic systems) I have observed that the universe runs on rules, not rails.  In the language of this topic, Nature operates through preferred paths, not rigid regulation.  There seems to me to be enough slack in the working of Nature’s laws, with their element of chance at the quantum level and tolerance for redefining the preferred path at the macroscopic level, taking a realized state as initial conditions for future development, to allow for a considerable degree of free will.

Suppose I had decided to sip the coffee by levitating the cup to my lips by willpower alone.  I just tried it and nothing happened.  Free will has its limits, imposed by an objective reality that governs the workings of the universe.  Still it appears that living organisms have the ability to redirect the stream of events.  The stack of events that leads from the Big Bang to now at this place and time has not been shaped entirely by chance. Animal intent has redirected the flow of history, in ways both trivial and profound.

Those of you familiar with the notion from system dynamics of sensitivity to initial conditions will recognize that it may take only the tiniest nudge to, in a short time, result in a profound change in the state of a system from what would have existed in the absence of that touch. Operating at the most subtle level in the brain might be a principle that makes a bear turn left rather than right and destroy my garbage can rather than that of my neighbor.