Quantum Mechanics and Free Will

Speaking in Many Tongues

It’s rather stunning, sometimes, when the language used by physicists to describe what they know becomes, well, metaphysical.  What does it mean when you say that quantum particles have free will?

On the basis of three physical axioms, we prove that if the choice of a particular type of spin 1 experiment is not a function of the information accessible to the experimenters, then its outcome is equally not a function of the information accessible to the particles. We show that this result is robust, and deduce that neither hidden variable theories nor mechanisms of the GRW type for wave function collapse can be made relativistic. We also establish the consistency of our axioms and discuss the philosophical implications.

Near gobblelygook.  Except it isn’t.  That abstract will give you this link to the full article (in PDF format), which says, in essence, that if you have free will, then so does every particle in nature.  If you have the ability to make a decision that is not constrained by your past history (and all of past history), but freely chosen and spontaneous, then so do electrons (and every thing else).  Gotta be, or the universe isn’t self-consistent and can’t exist.

But wait.  What kind of decisions can an electron make, anyway?

Lemme explain.  Imagine two identical twins; we’ll call them Sally and Katherine.   Let’s move Katherine to Alpha Centauri, and proceed to ask them both a set of questions. To do this, we need two questioners, and a list of questions to be asked.  As soon as the question is asked, then the answers are reported back to the lab, examined, and then (and only then) is the next question asked.  Oh, you also have to know that the questioners can ask any question on the list in any order, and have no idea what question is being asked by the other in this round.

When the questions have to do with their common, identical past (i.e. how tall were you at age 20; what hair color at age 25, etc. – remember, their identical!), we expect agreement.  When the questions are asked in random order, then we expect a certain set of statistics that reflect this.  If they were not identical twins, then we’d expect a different set of statistics.

Some of you may recognize this as the beginning of the famous Einstein, Rosen, Podolsky thought experiment.  I’m going to take the opportunity to name-drop here, and tell you that I was a student of the late Prof. Okalowski (one of my favorite professors, ever!), who was a student of Rosen.

So far, this may all seem very mundane.

The experiment becomes interesting, though, when you begin to ask Sally and Katherine questions when only one could know the answer.  Ask Sally in Dec. of 2012 who the next president of the U.S. is, and she might very well say “Sarah Palin”, while Katherine might be expected to say “Barack Obama”.

But what if they both consistently answer the same, statistically speaking, to these kinds of questions?  Only one of them should know the answer.  We put Katherine an Alpha Centauri to make sure of that, after all, and it would be weird (indeed, physically impossible) for her to know who won before the televised results of the 2012 election even got to Alpha Centauri.

But the universe is weird.  If you use electrons that are created together (so that the quantum-mechanical spin polarization for both is related), separated far enough so that you know a signal can’t travel between them fast enough and ask the right question (Are you polarized in this direction right now?), and check the results statistically, it turns out that the electrons answer just as if they’ve talked to each other.  That experiment was done in the ’80s, so we know.  They can’t have communicated, but they must have, faster than light.  It’s very weird, and physics now considers the quantum mechanical states of these two particles to be “entangled”.

So what has this to do with free will?  If the quantum-mechanical wave function of one of those particles collapses to a definite state when the experiment is done (that is the decision about a particles spin is determined only when someone looks at it, and not a moment sooner), then we have to ask if the state of the other, quantum-mechanically entangled particle is determined by the choice made by the first particle.  That second particle may have no choice in the matter.  And in the aggregate, you have no choice in anything, either.  Everyone of your actions has been pre-determined by something else, and by history.

In their heart of hearts, nobody finds that easy to believe.  John Conway, Simon Kochen demonstrate rigorously that you’ll free will depends upon the ability of quantum mechanical particles to choose their state independent of their history.

I find it sort of neat that physics is capable of saying anything at all, wrong or right, about the topic of free will. You wouldn’t think that it could.

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