What is free will? By Manuel Lozano Leyva

This post is also available in: Spanish

I don’t see free will can fit into the law of gravity. Science, and Physics in particular, is much more modest than Philosophy or Theology. We want to test things experimentally and that restricts us a lot, theoretically. Because if we don’t experiment that’s not Science, so it has nothing to do with me, free will or anything else. I can have my free will to do an experiment or not, but if I do, it means a great restriction. But when Science says something or concludes something, that’s forever. And I mean it: it’s forever. Many people say that Science reaches some conclusions and then, later, they change them. No. That’s denying the steam engine ever existed. And steam-powered trains existed and worked perfectly. What happens is that later more advanced ones came. But steam worked fine. Newton’s mechanical theory is exact, rigorous, perfect, what happens is it cannot be applied to atoms. If you apply it to atoms, it fails. Why? Because it’s applied where it shouldn’t. And that’s Physics. Free will doesn’t have a place in it, nor do beliefs. So there’s a 99% of Philosophy, of the human constructions that doesn’t have a place in it. We are modest, what happens is later we place satellites in orbit and the GPS tells you exactly where you are. And GPS is based in Relativity. GPS devices have to be adjusted according to Einstein’s theory of General Relativity. And a plane flies, whatever your opinion is and however stubborn you may get.

But, in a world where all the particles’ movements are determined…

No, no. Not only does Quantum Mechanics question the causality principle, but it is also not fully deterministic. Precisely because of the indeterminacy principle. When classical mechanics is applied to the normal world, it is rigorously exact. What does “deterministic” mean to Physics? It means you have some particle at a given instant and, with the equations of movement, you can predict exactly where and when it’s going to be at a later time. And that is determined by Newton’s equations. However, when you apply that to a subatomic particle, using quantum equations, you cannot speak about positions at instants, but about probability. A probability distribution means you measure the position or the instant and you do not get certainty about whether the particle is there or not at that time. You get a probability of finding it there when you make a measurement. Probability is a concept which is not deterministic. I teach Quantum Mechanics and I always give my students the following example: imagine a map of Spain on December the 22nd, made like this: every lottery ticket (before the day of the results) on every person is a little red dot. The more money you bet that day, the brighter the dot is. If you only see the map like that, it looks pretty much like a normal road map, because of the population densities and so forth. When the result is finally made public, all the lights go off and only one remains shining in some remote little village. That’s what Quantum Mechanics does. It doesn’t predict where the prize is going to appear, only the possibility of its appearing at some place. And it does that in an exact and rigorous way. What it gives with precision is the probability. Not the exact determination of the position of an object, a system or whatever. Despite all that, the reality that both maps reflect -the one with lights and the geographical one- are very much alike. But Quantum Mechanics doesn’t aspire to so much.

Maybe this randomness gives us room for choice. But to what extent does a die have free will?

Einstein’s doubts when he said God doesn’t play dice were profound. Einstein didn’t get Quantum Mechanics much, though. After discovering the photoelectric effect and much more he helped build the pillars of the discipline, but he never believed it and ended his days still not understanding it. He said, and he was partially right, that the sentence “God doesn’t play dice” mean the following: Quantum Mechanics says that, if the die is perfect, you throw it and you have one in six chances for any of the faces coming up, and that’s exact. That’s the prediction from Quantum Mechanics. Einstein said that cannot be so, the world cannot be described in terms of probabilities. What happens is that if I knew the die’s mass, its irregularities and the weight of the number six face relative to the number one face, the angle between my hand and the table, friction, etc., it would be deterministic. And I would know exactly which face I’m going to get if I throw it a certain way. The problem is that, since it’s impossible to control all that, there’s a huge amount of what we call “hidden variables”. These hidden variables, which we cannot reach, make up the indeterminacy. Quantum Mechanics is a tremendous restriction and it uses probabilities because it can’t do anything else. But that’s all false. There are no hidden variables. That’s simply an objection Einstein raised. Just look at our technology: it is calculated that nowadays 40% or our technology, including trucks, is based on Quantum Mechanics. Quantum Mechanics works perfectly with these probability distributions. Is there anything hidden we’re not using? No. What happens is Science is still not finished, there’s no unification, there are lots of things we still we don’ know. Every time someone thinks Science, with unified theories, M theories, has practically reached its limit, it reminds me of a dialog between Schroedinger and some other guy, at the end of the XIXth century: Science is almost over, Physics especially, they said, it’s reached its limit, electricity and magnetism is are perfectly formulated. We’re talking about the end of the XIXth century. So, this physicist wrote to Schroedinger saying he was sad about getting to the end of his life and seeing Physics was over: “except for some details, we’ve done our job.” Then, Schroedinger answered with a funny letter, almost completely blank. He had drawn a frame and, inside, a crude drawing with just some lines. And he said below: “except for some details, I paint like Titian.” Every time someone tells me M theories unify everything and we’re only left with details, I think about that.

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