Gerard 't Hooft on the incompleteness of quantum mechanics

[javisot]

Although true, what is the point being made here? This seems to be pointing out an issue with the frequentist view of probability.

No Bell test has ever produced an infinite number of samples. No experiment has ever produced an infinite-sigma result.

All I wanted to say is that the coin example doesn't seem like the best example.

 

[PeterDonis]

it implies that every decision we have ever made, from what pie you ate a year ago to which shoe to tie first on your birthday next year, was determined before our Grandparents were born.

You're ignoring the key point: what determines these things?

For you to have any kind of meaningful free will, the world needs to be deterministic enough that you can predict what will happen if you choose one thing or another. Free will does not require that your "choice" has any fundamental randomness. All it requires is that your choices, meaning the processes in your brain that take as input what you perceive, what you know, what you believe, and what you want, and output what you choose to do, determine (note the word) what you do--as opposed to something else other than your choice determining what you do. Whether the fundamental physics is completely deterministic at bottom, or only "deterministic enough", is irrelevant to that.

 

[Matterwave]

All I wanted to say is that the coin example doesn't seem like the best example.

I see.

I believe @Demystifier was making a rhetorical point (an analogy, which he enjoys) in response to post #11.

The idea is that there is apparent randomness in the coin example even if it is symmetric between heads or tails. There, the indeterminism comes from small variations in initial conditions which is quite similar to where indeterminism comes from in Bohmian mechanics (via the quantum equilibrium condition). So it is one way randomness comes into a deterministic theory.

 

[PeterDonis]

no existing coin offers a 50%-50% split with infinite precision

Neither does any existing photon in the experimental setup that was described in the post @Demystifier was responding to.

 

[Demystifier]

Where could the asymmetric result in a spatial symmetric 1 photon double-slit experiment come from, without real randomness?

If the measurement is cause of the apparent randomness, then an obvious place to look for asymmetry is in the fine details of the measuring apparatus.

 

[Demystifier]

But random processes can also be described eith a deterministic time-evolution so I don't think the fact Schrodinger evolution is deterministic necessarily indicates anything.

By random, do you mean pseudo-random?

 

[Demystifier]

No, no existing coin offers a 50%-50% split with infinite precision.

If you’re talking about a theoretical coin, then yes. But even then, you would have to flip the coin an infinite number of times to confirm that it landed on heads 50% of the time and on tails 50% of the time, in accordance with the law of large numbers.

And how is that different from quantum mechanics?

 

[javisot]

And how is that different from quantum mechanics?

In the coin example, the randomness is only apparent due to lack of information. In quantum mechanics, is the randomness only apparent to you?

 

[Demystifier]

In the coin example, the randomness is only apparent. In quantum mechanics, is the randomness only apparent to you?

No, it's apparent to anyone who cannot observe and compute all fine details of the huge number of degrees of freedom of the macroscopic measuring apparatus.

 

[javisot]

No, it's apparent to anyone who cannot observe and compute all fine details of the huge number of degrees of freedom of the macroscopic measuring apparatus.

We are not using the term "apparent" in the same way. In the case of a coin toss, the randomness is apparent (not real), due to the lack of information that exists. In quantum mechanics, the randomness is not apparent; it is fundamental.

 

[PeroK]

He believes that everything we do, in fact everything that happens anywhere, has been determined by the past.

Bell's Theorem is violated in tests that get random inputs (he would argue they are not random) from star systems many lightyears apart. I find it hard to believe that random sequences from opposite sides of the galaxy are correlated in a devious way. And I think that either source is a sequence without strong time correlations.
If that is his strongest argument, I am not convinced.

It's worse than that! Superdeterminism demands that the correlations are such as to always appear to support QM! It's not just any correlations - but correlations that lead us astray into thinking that QM is a correct description of nature. See Scott Aaronson's blog, who says it better than I can:

https://scottaaronson.blog/?p=6215

 

[Demystifier]

In quantum mechanics, the randomness is not apparent; it is fundamental.

We don't know that. That's an assumption, which may be true, or may be wrong.

 

[martinbn]

We don't know that. That's an assumption, which may be true, or may be wrong.

He said in quantum mechanis. In reality we don't know, but in QM we do.

 

[javisot]

We don't know that. That's an assumption, which may be true, or may be wrong.

Let’s reach an agreement, because I am confused: an interpretation of QM that includes randomness in some sense cannot fully correspond to a version that does not include randomness in any sense.

An interpretation of QM that does not include randomness in any sense fails to account for the UP; therefore, it is not an interpretation of QM.

 

[Demystifier]

Let’s reach an agreement, because I am confused: an interpretation of QM that includes randomness in some sense cannot fully correspond to a version that does not include randomness in any sense.

An interpretation of QM that does not include randomness in any sense fails to account for the UP; therefore, it is not an interpretation of QM.

Fine, but there are interpretations of QM that include randomness in an apparent sense, not in a fundamental sense. Examples are Bohmian mechanics and many world interpretation.

 

[PeterDonis]

He said in quantum mechanis. In reality we don't know, but in QM we do.

No, we don't, because there are interpretations of QM in which the randomness is only apparent, not fundamental.

 

[javisot]

No, we don't, because there are interpretations of QM in which the randomness is only apparent, not fundamental.

I see that we all agree that an interpretation of QM without randomness (neither apparent nor fundamental) cannot reproduce all the results, then it cannot be an interpretation of QM. Therefore, we all agree that every interpretation of QM contains randomness, whether fundamental or apparent.

To me, that is sufficient to say that, in QM, randomness is fundamental, in the sense that it is not something that can simply be eliminated. We cannot discard the UP and still explain the same results.

Returning to Gerard 't Hooft’s perspective: his take on Bell is interesting, but I’m not clear on his view regarding the UP when he makes all those assertions.

 

[gen x]

Where is the evidence for determinism in the real world? There is none.

Did you try email Gerard 't Hooft and explain him why he is wrong?

My two cents:
The insistence that nothing is random is purely because we are not used to that in our macro-existance. But it implies that every decision we have ever made, from what pie you ate a year ago to which shoe to tie first on your birthday next year, was determined before our Grandparents were born.
Personally, I find that less acceptable than believing some subparticle behavior might be random.
Given the practical success of QM, it is a heavy lift to convince me otherwise.

You don't have free will either way: if nature is deterministic, everything is predetermined by the laws of cause and effect; if nature is random, you still can't decide anything because every 'neuron' in your brain fires randomly, in pure chaos.

Some geniuses about determinism:

 

[PeterDonis]

an interpretation of QM without randomness (neither apparent nor fundamental)

As far as I know, does not even exist. If you define such an interpretation as "an interpretation of QM without the UP", then as I've already said, it cannot exist, since the UP is part of the basic math of QM that all interpretations share.

we all agree that every interpretation of QM contains randomness, whether fundamental or apparent.

I think that's true.

To me, that is sufficient to say that, in QM, randomness is fundamental

In other words, you're now disagreeing with what you just said we all agree on.

in the sense that it is not something that can simply be eliminated. We cannot discard the UP and still explain the same results.

Now you're redefining "fundamental" to mean what suits your argument, instead of what it's meant up to this point in the discussion: that the randomness is not apparent, i.e., it does not emerge from something else. Please stop quibbling over the definitions of words.

 

[PeterDonis]

You don't have free will either way

Of course if you define "free will" so it can't possibly exist, then that kind of free will doesn't exist.

But your definition is irrelevant to the kind of free will that is actually worth caring about, the kind where it's your own brain processes that determine your choices, which in turn determine what you do, instead of something else. As I've already pointed out, that kind of free will is perfectly compatible with either a completely deterministic universe, or a universe that is only "deterministic enough" (see further comments below).

if nature is random, you still can't decide anything because every 'neuron' in your brain fires randomly, in pure chaos.

This is false. "Random" is not the same as "chaotic". Processes that are random on small scales can still produce predictable results on larger scales, so things can still be "deterministic enough" at the level of our brains and bodies to allow us to have the kind of free will I described above.

And on the other side, completely deterministic dynamics can still produce chaos, i.e., unpredictability. All you need is nonlinear dynamics with a sufficiently large Lyapunov exponent. So your implicit claim of equivalency here is wrong both ways.

 

[PeterDonis]

Some geniuses about determinism

Arguments from authority carry no weight here.

 

[javisot]

Now you're redefining "fundamental" to mean what suits your argument, instead of what it's meant up to this point in the discussion: that the randomness is not apparent, i.e., it does not emerge from something else. Please stop quibbling over the definitions of words.

I simply used the dictionary definition:
"The word fundamental means serving as a basic, central, or essential foundation upon wich other things develop os depend"

In this sense, no interpretation is free from randomness in its formalism.

 

[gen x]

Arguments from authority carry no weight here.

You mean, we member of physics forum, know better then today Nobel price physicists?
What is our credibility?

 

[PeterDonis]

I simply used the dictionary definition:
"The word fundamental means serving as a basic, central, or essential foundation upon wich other things develop os depend"

And by that definition, in, for example, the Bohmian interpretation of QM, randomness is not fundamental. The "basic, central, or essential foundation upon which other things develop or depend" in BM is deterministic. The randomness emerges from our ignorance of precise initial conditions, just as it does in classical physics.

 

[PeterDonis]

You mean, we member of physics forum, know better then today Nobel price physicists?

No, I mean that just quoting the opinions of someone, with no supporting argument, no data, no theoretical basis, just them making statements, is an argument from authority and carries no weight here, no matter who you are quoting or how smart you think they are.

 

[PeterDonis]

we member of physics forum, know better then today Nobel price physicists?
What is our credibility?

If you are asking for references for the statements I've made about free will, a good start would be the two books on the subject by Daniel Dennett, Elbow Room and Freedom Evolves. Both contain extensive references to other literature on the topic.

 

[PeterDonis]

no interpretation is free from randomness in its formalism.

Wrong. Bohmian mechanics has no randomness "in its formalism". As I said, the randomness arises from ignorance of precise initial conditions, just as in classical physics. Indeed, the BM guiding equation for a particle is the same in form as the corresponding classical equation for a particle in a potential; the only difference in BM is that the potential has an extra term in it that comes from the pilot wave.

 

[pines-demon]

You mean, we member of physics forum, know better then today Nobel price physicists?
What is our credibility?

We avoid fallacy of appealing to authority?

Edit: you have not answered what you wanted to discuss here

 

[gen x]

We avoid fallacy of appealing to authority?

I explain why I think free will is just illusion.
Quotes from Einstein, Spinoza, Schopenhauer, Penrose,Hawkings, Green, Sapolsky
etc etc I just use as example that I am not alone.

I respect members' different opinions. It's completely normal to have different viewpoints on a topic that can't be proven today. I hope that one day we will be able to do that.

Edit: you have not answered what you wanted to discuss here

I want to listen to people opinion why Gerard is right or wrong..

 

[javisot]

Wrong. Bohmian mechanics has no randomness "in its formalism". As I said, the randomness arises from ignorance of precise initial conditions, just as in classical physics. Indeed, the BM guiding equation for a particle is the same in form as the corresponding classical equation for a particle in a potential; the only difference in BM is that the potential has an extra term in it that comes from the pilot wave.

we all agree that every interpretation of QM contains randomness, whether fundamental or apparent.

You seemed to agree with this statement.

In this sense, no interpretation is free from randomness in its formalism.

But you seem to disagree with this other one, and the curious thing is that both statements say the same thing.