Heisenburg Uncertainty Principle

[Gunner B]

Some people suggest that free will is proven by the Heisenberg uncertainty principle, which states that you can not predict the outcome of a quantum event. Does this mean that humans can some how consciously tell every electron in their body how to act in order for their desires to be fulfilled by their so-called free will? I think not. I believe that the big bang (first cause) created electrons and the uncertainty principle (effect). Though it may be impossible to predict with complete certainty a future event, it is possible to understand that the future event was caused by a past event, which can not be changed. I don't understand why people don't realize this when talking about the uncertainty principle. It seems that every event is governed by the laws of physics AND, in a sense, hidden by the laws of physics. Am I missing anything here? By the way, this question was caused by Michio Kaku's video blog where he answered a question about free will and used the Heisenberg uncertainty principle to prove that humans have free will.

 

[SpectraCat]

Kaku's point is can be summed up as follows:

1) the HUP shows that nature is fundamentally unpredictable on a microscopic scale

2) human thought processes happen on that microscopic scale (electrical impulses in the brain)

Thus it is fundamentally impossible for an external observer to predict in advance with certain what choice an individual will make in a given set of circumstances. Kaku argues that this is empirically indistinguishable from free-will.

The question of consciousness doesn't arise in his analysis at all. Of course, the same argument can be made for any entity that ever reaches a decision point of any kind, including dogs and bugs, and even computer programs are subject to the same "unpredictability" if you take the possibility of errors due to random electronic noise into account. So, I would take Kaku's analysis not as a complete proof of human free-will, but rather a refutation of Newtonian determinism, which is a necessary but not sufficient condition for what we normally think of as "free-will".

 

[nnnm4]

Right on, determinism and free-will are two different philosophical questions. I've run into people who say the same thing about quantum mechanics and it's relation to free-will and I just say if one was to write down the Hamiltonian for the entire universe, as quantum mechanics allows you to do in principle, the state's which were solutions to the Schrödinger equation and the physical states of the universe would, according to QM, evolve in a unitary fashion, completely determined.

 

[Rap]

Kaku's point is can be summed up as follows:

1) the HUP shows that nature is fundamentally unpredictable on a microscopic scale

2) human thought processes happen on that microscopic scale (electrical impulses in the brain)

Thus it is fundamentally impossible for an external observer to predict in advance with certain what choice an individual will make in a given set of circumstances. Kaku argues that this is empirically indistinguishable from free-will.

The question of consciousness doesn't arise in his analysis at all. Of course, the same argument can be made for any entity that ever reaches a decision point of any kind, including dogs and bugs, and even computer programs are subject to the same "unpredictability" if you take the possibility of errors due to random electronic noise into account. So, I would take Kaku's analysis not as a complete proof of human free-will, but rather a refutation of Newtonian determinism, which is a necessary but not sufficient condition for what we normally think of as "free-will".

Just for fun, we can throw in the fact that Bell type experiments can be explained by the lack of "counterfactual definiteness". ( http://en.wikipedia.org/wiki/Counterfactual_definiteness ). In other words, since a single Bell-type experiment violates no physical law, but rather the statistics of many such experiments give inconsistent results when you use the words "what if", if we say there is no "what if", then there is no problem. That means the future is fully determined, there is no free will.

 

[SpectraCat]

Just for fun, we can throw in the fact that Bell type experiments can be explained by the lack of "counterfactual definiteness". ( http://en.wikipedia.org/wiki/Counterfactual_definiteness ). In other words, since a single Bell-type experiment violates no physical law, but rather the statistics of many such experiments give inconsistent results when you use the words "what if", if we say there is no "what if", then there is no problem. That means the future is fully determined, there is no free will.

Um .. that's quite a leap there. How do you get from lack of CFD to no free will? Lack of free will means everything is determined .. lack of CFD is going in the other direction .. it means there are things that you cannot know, not that everything is determined.

 

[Rap]

Um .. that's quite a leap there. How do you get from lack of CFD to no free will? Lack of free will means everything is determined .. lack of CFD is going in the other direction .. it means there are things that you cannot know, not that everything is determined.

Well, maybe I am pushing the envelope here. I interpret CFD by considering the canonical example - If I measure position, I cannot know the momentum. CFD is stronger - it says that if you suppose that you had in fact measured momentum, then you may arrive at conclusions that are logically inconsistent with the results you obtained when you measured the position. I don't think its a problem in this particular case, its just a way of stating CFD.

It is in fact the case with the Bell inequalities. They rely on results which are based on supposition, not on actual measurements. If you have two spin detectors oriented on the same axis, they will always measure opposite spins for an entangled pair. If you assume CFD, then you assume that if one detector measures a particular string of spin directions, then the other detector, not oriented in the same direction, would have measured the same string of opposite spin directions if it had been oriented in the same direction. You can choose non-locality to explain Bell, but you can also choose lack of CFD.

I'm not a fanatic supporter of this - it just makes me wonder if CFD is another prejudice of our classical brains that might not be justified in the quantum realm and is in fact the resolution of the Bell paradox. I guess it does not imply lack of free will, just that lack of free will would imply lack of CFD. Or does it imply lack of free will? I don't know, it's just a puzzle that bothers me. See http://en.wikipedia.org/wiki/Counterfactual_definiteness

People give me a hard time for harping on the idea that we should not use language which makes implicit classical assumptions when discussing QM, using concepts which are untestable in principle, or statements which do not refer ultimately to measurements. Just about every quantum paradox violates this rule, but not Bell. I'm starting to check every statement I make not only for untestable concepts, but for CFD as well, just to see where it goes.

 

[Demystifier]

Thus it is fundamentally impossible for an external observer to predict in advance with certain what choice an individual will make in a given set of circumstances. Kaku argues that this is empirically indistinguishable from free-will.

A deterministic chaotic system is also empirically indistinguishable from free will. Of course, deterministic laws are incompatible with a FUNDAMENTAL free will, but so are the probabilistic laws.

 

[SpectraCat]

A deterministic chaotic system is also empirically indistinguishable from free will. Of course, deterministic laws are incompatible with a FUNDAMENTAL free will, but so are the probabilistic laws.

Hmm .. I don't think I agree with the first part of that, at least not unless a qualifier of "sufficiently complex that not all interactions can be accounted for" is added. If you can account for all of the interactions, then trajectories can always be predicted, right?

The second part is interesting .. can you elaborate a bit? Are you saying that, for the probabilistic case, just because we can't predict outcomes with certainty doesn't mean that free-will would give us any control over which outcome is obtained? Are you saying that free-will would amount to a local hidden variables explanation, which we know is forbidden by Bell's Theorem?

 

[Demystifier]

Hmm .. I don't think I agree with the first part of that, at least not unless a qualifier of "sufficiently complex that not all interactions can be accounted for" is added. If you can account for all of the interactions, then trajectories can always be predicted, right?

Right.

The second part is interesting .. can you elaborate a bit? Are you saying that, for the probabilistic case, just because we can't predict outcomes with certainty doesn't mean that free-will would give us any control over which outcome is obtained? Are you saying that free-will would amount to a local hidden variables explanation, which we know is forbidden by Bell's Theorem?

No, I meant something completely different: If nature obeys purely probabilistic laws, then free will does not exist.

It is easy to explain why. If something has free will, than it can decide to behave in a regular, non-random fashion. On the other hand, if something behaves in a regular, non-random fashion, then it is NOT governed by purely stochastic (i.e., probabilistic) laws.

For example, an electron with a free will could decide to be in spin up WHENEVER the wave function before the measurement is a 50:50 superposition of spin up and spin down. No matter how many times you repeat the measurement, you ALWAYS get spin up. Such a regular behavior of the electron would contradict the quantum probabilistic law according to which the probability for being in spin up is only 50%.

 

[Rap]

Thus it is fundamentally impossible for an external observer to predict in advance with certain what choice an individual will make in a given set of circumstances. Kaku argues that this is empirically indistinguishable from free-will.

The question of consciousness doesn't arise in his analysis at all. Of course, the same argument can be made for any entity that ever reaches a decision point of any kind, including dogs and bugs, and even computer programs are subject to the same "unpredictability" if you take the possibility of errors due to random electronic noise into account. So, I would take Kaku's analysis not as a complete proof of human free-will, but rather a refutation of Newtonian determinism, which is a necessary but not sufficient condition for what we normally think of as "free-will".

I agree. Your questions have gotten me to think about it. I want to look at free will as a scientific concept. That means there must be a test for free will. I cannot think of any such test, when applied by myself to another macro or micro object, including another human being. It follows that I cannot think of any test that another machine or object could apply to me to determine if I have free will. So I think that free will is not a scientific concept, not worthy of scientific inquiry, unless someone can come up with such a test. As I said, I agree that Kaku's test is not a test of free will.

 

[Gunner B]

Has neuroscience found the science behind consciousness? If so, then that may be a starting point. I still believe that every conscious decision must have an influence, going back to the big bang. That to me is not free-will. Maybe neuroscience will help make it possible to put mathematics behind this potential theory.

 

[computerphys]

if one was to write down the Hamiltonian for the entire universe the state's which were solutions to the Schrödinger equation and the physical states of the universe would, according to QM, evolve in a unitary fashion, completely determined.

Uncertainity (HUP) and collapse have consequences (causality) as in Schrödinger's cat. A wavefunction that let's the cat being alive or dead could also be a wavefunction that would make possible any future events conditioned to our choice (free will).

Wavefunction determinism is not in contradiction with free-will indeterminism.

 

[nnnm4]

Uncertainity (HUP) and collapse have consequences (causality) as in Schrödinger's cat. A wavefunction that let's the cat being alive or dead could also be a wavefunction that would make possible any future events conditioned to our choice (free will).

Wavefunction determinism is not in contradiction with free-will indeterminism.

Show me an isolated quantum mechanical system (i.e. the universe in the context of my post) that exhibits "wave-function collapse" and does not evolve in a unitary fashion according to the laws of quantum mechanics.

 

[edpell]

What is free will? A system that makes decision not based on its past physical history (both internal and external)? If so, that sounds like making decision randomly. Not an interesting nor useful thing but maybe possible.

 

[Mannix99]

What is free will? A system that makes decision not based on its past physical history (both internal and external)? If so, that sounds like making decision randomly. Not an interesting nor useful thing but maybe possible.

Or a system that make decision according to it's past physical history AND input from some things outside our physical Universe.

 

[mikeph]

...I just say if one was to write down the Hamiltonian for the entire universe, as quantum mechanics allows you to do in principle, the state's which were solutions to the Schrödinger equation and the physical states of the universe would, according to QM, evolve in a unitary fashion, completely determined.

This post blew my mind and I "feel" it is wrong, but I cannot come up with any kind or argument against it.

Hmm .. I don't think I agree with the first part of that, at least not unless a qualifier of "sufficiently complex that not all interactions can be accounted for" is added. If you can account for all of the interactions, then trajectories can always be predicted, right?

Can I ask why? I thought it was a fundamental mathematical feature that you couldn't predict trajectories, even with perfect information.

 

[edpell]

Heisenberg in his book "The Physical Principles of the Quantum Theory" (1949) on page 25 writes

"The simplest and most fundamental method of measuring velocity depends on the determination of position at two different times. If the time interval elapsing between the position measurements is sufficiently large, it is possible to determine the velocity before the second was made with any desired accuracy, but it is the velocity after this measurement which alone is of importance to the physicist, and this cannot be determined with exactness."

It is interesting that one can retroactively know things with any desired accuracy.