A Matter Of Free Will
Heisenberg Rides Again
Human free will might seem like the squishiest of philosophical subjects, way beyond the realm of mathematical demonstration. But two highly regarded Princeton mathematicians, John Conway and Simon Kochen, claim to have proven that if humans have even the tiniest amount of free will, then atoms themselves must also behave unpredictably.
That’s interesting, because sub-atomic particles do behave unpredictably. The well-known, quantum mechanical Heisenberg Uncertainty Principle is an oft misunderstood, but rock solid part of our understanding of – everything. Einstein, and quite a number of other physicists, didn’t like it however and still don’t, because it implies that there are intrinsic, naturally imposed limits to our knowledge. We can know exactly where a particle is, or we can know exactly how fast it’s moving (more precisely, we can know to any arbitrarily great level of precision). But not at the same time.
The pair of observables, time and energy, are like that too. A particle can spontaneously pop into existence with any amount of energy, so long as it disappears again fast enough (usually too fast for us to detect it, btw…). The universe, and everything in it, is intrinsically non-deterministic. Physicists don’t like being told it’s a “crap-shoot”.
But physicists all the way back to Einstein have been unhappy with this idea. Einstein famously grumped, “God does not play dice.” And indeed, ever since the birth of quantum mechanics, some physicists have offered alternate interpretations of its equations that aim to get rid of this indeterminism. The most famous alternative is attributed to the physicist David Bohm, who argued in the 1950s that the behavior of subatomic particles is entirely determined by “hidden variables” that cannot be observed.
Two physicists, Kochen and Specker, have devised and executed an interesting experiment that forces subatomic particles to select a “spin” axis that causes a very peculiar thing to happen.
Conway compares the situation to the game “Twenty Questions.” If you play the game fairly, you decide upfront on a single object and honestly answer each of the questions, hoping your opponent won’t deduce what you chose. But a clever player could also cheat, changing the object partway through. In that case, his answers aren’t determined in advance. The particle, Kochen and Specker showed, is like a cheating player. They found it out by showing that no single object satisfies all the “questions” (or all 33 axes) at once.
That’s the interesting part. What they’ve done is force nature into a paradox.
Kochen and Conway say the best way out of this paradox is to accept that the particle’s spin doesn’t exist until it’s measured. But there’s one way to escape their noose: Suppose for a moment that Alice and Bob’s choice of axis to measure is not a free choice. Then Nature could be conspiring to prevent them from choosing the axes that will reveal the violation of the rule. Kochen and Conway can’t rule that possibility out entirely, but Kochen says, “A man on the street would say, ‘Don’t be ridiculous.’ A natural feeling is, of course, that what we do, we do of our own free will.
In other words, the particles exhibit what we think of as free will, if we accept that we have free will. The inverse, that if particles have free will, then we must also, is also true.
Some pretty high powered names in the world of physics sort of, kind of disagree with the experiment’s interpretation. Nobel Prize winner Gerard ‘t Hooft is one.
“As a determined determinist I would say that yes, you bet, an experimenter’s choice what to measure was fixed from the dawn of time, and so were the properties of the thing he decided to call a photon,” ’t Hooft says. “If you believe in determinism, you have to believe it all the way. No escape possible. Conway and Kochen have shown here in a beautiful way that a half-hearted belief in pseudo-determinism is impossible to sustain.”
It’s rather “Catholic” of me to say that I don’t find Kochen and Conway’s results surprising.