Tag Archives: free will

The Physics of Free Will

bluePillRedPillThe French mathematician and physicist Pierre-Simon Laplace famously boasted that if he knew the exact position and velocity of every particle in the universe at a given instant in time, he could predict with perfect precision the state of the universe at any time in the future (and, presumably, the past as well). Such was his faith in the universality, immutability, and sovereignty of the classical laws of motion, that he believed no particle, out to the very farthest reaches of space and back to the earliest moment in time, could escape the path predetermined for it by all of the interactions it was destined to have with the rest of the universe since creation. It is a nice-sounding boast, as it paints a picture of an unshakable, perfectly ordered world; and yet, it is terribly disturbing, as it utterly disallows any concept of free will whatsoever.

In Laplace’s world, the innermost workings of the human mind, down to our apparent ability to make decisions and move according to our will, are in fact governed by the laws of motion as they apply to the tiny particles that make up our brains and the physical processes that constitute thoughts — enormously complex to be sure, but entirely predictable with the right amount of knowledge. If true, Laplace’s boast would seem to be an end not just to free will, but to much of the meaning we find in life. After all, what significance is there in a work of art if the artist’s hands were merely being moved by the inevitable firings of neurons determined by the laws of physics since the beginning of time? Creativity would be only an illusion. There would be no spontaneity of thought or expression, no hope of controlling one’s own fate.

The performance of a symphony, with the musicians playing in harmony under the direction of a conductor and to the enjoyment of their audience, would in fact be nothing more than a fully predetermined combination of motions. The composition itself could no longer be truly ascribed to the composer, as he was predetermined from the beginning of time to write down precisely the notes of the piece being performed; and the husband who falls asleep in the audience could not be faulted for his inattentiveness, because that’s just how things had to play out. Even the guy whose cell phone rings during the adagio would be blameless.

But twentieth century physics has shown Laplace’s view to be wrong. We now know that pure chance plays a fundamental role in the outcome of any process. Quantum mechanics has shown irrefutably that particles actually don’t even have precise locations — it’s not just that we can’t measure them precisely enough to know where they are exactly, but rather there is no exact value to be measured. Nor do they have precise velocities. The highly celebrated but oft-misinterpreted uncertainty principle of Heisenberg describes not just limitations in our knowledge about the position and momentum of a particle, but the fuzziness of the particle’s actual being.

This is a huge leap in thinking that most physics students have trouble making, but it is at the heart of quantum mechanics. And not only are every particle’s actual position and momentum fuzzy in a fundamental way, but there is a very real element of pure chance involved in the particle’s behavior. An electron can disappear from one region of space and reappear in another region without crossing the space in between; and just where it reappears is a matter of chance that even the particle itself cannot know ahead of time. Einstein hated these revelations of quantum mechanics, but he recognized their truth. And so now we know on the basis of science alone — even if our bodies and souls are nothing more than extremely complex physical systems — that our fates are not entirely predetermined by the laws of physics. Certain outcomes are highly likely, to be sure, but never certain beyond all doubt (unless, of course, the “many worlds interpretation” of quantum mechanics is correct, in which case every possibility will, with certainty, come to pass in some universe).

So what does this new understanding of our world imply? Does it restore the free will and meaning that Laplace would have robbed from us? At first, it would seem that the answer must be no. The random events described by quantum mechanics cannot directly result in free will, for if they did, there must be a means for an agent of will to tell electrons (for example) where they should appear and interact with other particles (which is essentially the main physical process in our brains that is relevant to thought); but if this were the case, then the electrons would no longer be obeying the laws of chance that they have, in fact, been shown to obey. So it seems that random processes alone cannot account for free will.

However, our universe is governed not by chance alone, but by a most intriguing combination of deterministic rules and random processes — a continuum that fades from pure randomness at the infinitesimally small scale to pure determinism at the infinitely large scale. Could it be that the combination of these two components allows for the construction of something that amounts to more than the sum of its parts? In plane geometry, a straightedge limits its user to the construction of line segments, and a compass limits its user to the construction of arcs; but when the two tools are used in tandem, a whole new level of complexity becomes possible, allowing the geometer to draw impressive figures. Perhaps the classical, deterministic laws of motion and the more recently discovered quantum mechanical laws of chance are, respectively, the straightedge and compass that, when used together, allow for the construction of high-level phenomena such as consciousness and free will, which would otherwise be inaccessible under classical laws or the laws of chance alone.

If so, we would expect such phenomena to emerge in systems that exist at the boundary between the macroscopic scale, where deterministic laws prevail, and the microscopic scale, where quantum mechanics prevails. And it so happens that the human brain (and any mammalian brain, for that matter) is just such a system. The brain as a whole is a macroscopic system composed of networks that are just at the boundary between macroscopic and microscopic, which are further composed of individual neurons that belong to the microscopic realm. Could there be a more suitable system for emergent phenomena such as consciousness and free will to develop? (Some might suggest that the answer to this question is yes: a computer.)

The point of these speculations is not to demean humanity by reducing the soul to a mere physical construct — the above meanderings certainly prove nothing of the kind, nor are they intended to do so — but to suggest that there might be hidden potential in the physical substance of our universe. Matter, space, and time, together with the rules that govern their interaction, may contain some life and magic that we haven’t yet imagined. In Genesis 1:24, God says, “Let the land produce living creatures” [emphasis mine]. Is it possible that the land itself — the material substance of the universe — has, buried deep within it, the very components not only of life and consciousness, but free will as well?