A Matter Of Free Will

Heisenberg Rides Again

Slashdot links to this article by Julie Rehmeyer with a very intriguing lead – Do subatomic particles have free will?

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.

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2 Comments on “A Matter Of Free Will”

  1. An intertubes user Says:

    Well, technically this paper did not prove that free will exists.

    It just proved that “if people have free will, so do subatomic particles”

    Apologies if I am misreading your post but I don’t believe it proves what you seem to seem to imply it proves in this post, which is: particles seem to exhibit free will, so it must have free will.

    This is not proven by the paper.

    It is perfectly possible that neither we nor subatomic particles have free will, without breaking this proff.

    Also I am not completely sure why information cannot be passed between infinite distances instantaneously. This seems to be a necessary assumption of this proof’s validity. However, I’m not a physics guy so maybe this is not an issue.

  2. joe Says:

    Hummm… A couple of things, Intertubes.

    I think you’re right, in that I haven’t shown anything to be proven here. But then again, I couldn’t do that with a synopsis of a report of a paper. I certainly couldn’t replicate their arguments here, and to be honest, I wouldn’t understand them if I could!

    But what this experiment shows, apparently, is that it’s much more difficult to construct a physics that is self-consistent and deterministic than we thought. It seems that you always have to stick in “uncertainty”, just like Heisenberg does, or it doesn’t work. The only other choice you have is to say that you have no choice, no free will, when you do anything. It’s not you that decides to turn on a light switch (or not) – the universe made the decision for you, and you could do nothing about it. There’s lots of reasons for not buying that one! That’s why I quoted ‘t Hooft saying “If you believe in determinism, you have to believe it all the way.”

    So you’re exactly right when you say “It is perfectly possible that neither we nor subatomic particles have free will, without breaking this proff.”, but that’s just not a popular position.

    For me, I’m a little surprised to read that many physicists are still insisting on “hidden variables” and other ways of making their physics deterministic. I really thought that that effort died in the ’70s.

    Thanks for reading!


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