I Copenhagen Interpretation vs Pilot Waves

[lukephysics]

I was unsatisfied with the measurement problem so I was looking at pilot wave (PW)

Sabine says one downside of pilot wave is there is no QFT version for pilot wave yet. And a significant problem in replacing the QFT is that PW is non-local, and that copenhagen very much depends on being local. But i was confused by this. The copenhagen wavefunction collapses in two places instantaneously. doesnt this make it non-local as well?

so then why did Sabine say locality is important for Copenhagen and the standard QFT? (it was from this video )

has anyone done work on producing a new QFT based on pilot wave? I think it would be fruitful. Pilot wave seems more correct and its a physical deterministic solution rather than the philosophical copenhagen.

 

[Demystifier]

I had several discussions with Sabine on pilot waves, she doesn't really understand it. There is a plenty of work on the QFT version of pilot waves. See e.g. my recent https://arxiv.org/abs/2205.05986

 

[vanhees71]

But in this paper you rather confirm the skepticism, because you admit already in the abstract that your Bohmian verion of relativistic QFT theory is not relativistic, because it "lacks Lorentz covariance". So it's not relativistic.

 

[Lord Jestocost]

Pilot wave seems more correct and its a physical deterministic solution rather than the philosophical copenhagen.

Maybe, a pilot wave theory might be more illustrative for someone. However, how does a pilot wave theory get rid of the irreducible randomness related to Born’s rule?

 

[gentzen]

However, how does a pilot wave theory get rid of the irreducible randomness related to Born’s rule?

Basically just like in chaos theory. Do you know a bit of symbolic dynamics? Basically, all the randomness is encoded in the initial conditions, and it turns out to be an endless supply of randomness which never gets reduced, no matter how many measurments you do.
I have also read somewhere how this plays out more in detail for Bohmian mechanics, but my attempt to find it again just now "on the fly" failed. If it really interests you, I can take the time to find it again.

However, it should be clear that this will not resolve the disagreement between Demystifier and vanhees71.

 

[Lord Jestocost]

Basically, all the randomness is encoded in the initial conditions.....

So what?

Chaos Theory: Because we can never know all the initial conditions of a complex system!

The “in principle knowable unknowns” are grounded in epistemology alone.

 

[Demystifier]

Maybe, a pilot wave theory might be more illustrative for someone. However, how does a pilot wave theory get rid of the irreducible randomness related to Born’s rule?

The Born rule does not say that the randomness is irreducible. It just says that probability should be computed by this rule, but it says nothing about irreducibility. Copenhagen-like interpretations assume that it's irreducible, but there is no formal proof that it must be irreducible.

Anyway, according to the Bohmian interpretation, the randomness is reducible. For a thorough analysis see https://arxiv.org/abs/quant-ph/0308039

 

[Demystifier]

But in this paper you rather confirm the skepticism, because you admit already in the abstract that your Bohmian verion of relativistic QFT theory is not relativistic, because it "lacks Lorentz covariance". So it's not relativistic.

https://www.physicsforums.com/threa...sed-opportunities.1054134/page-2#post-6916115

 

[Demystifier]

However, it should be clear that this will not resolve the disagreement between Demystifier and vanhees71.

As I said elsewhere, our disagreements would be easily resolved if he could make some decisions and stick to them.
https://www.physicsforums.com/threa...sed-opportunities.1054134/page-2#post-6916115

 

[vanhees71]

Should I really address this gibberish? I don't see, what merit it has to introduce superfluous mathematical elements, which do not even help in calculation techniques to get to the observable predictions of the theory. For me Bohmian mechanics doesn't add anything to Q(F)T as a physical theory. Is that clear enough?

 

[Demystifier]

For me Bohmian mechanics doesn't add anything to Q(F)T as a physical theory. Is that clear enough?

It is not clear enough. Since you are very active on this subforum, it is clear enough that you actually care a lot about interpretations and philosophy, even when it is not relevant to physics.

 

[vanhees71]

I care about to give the scientific point of view in addition to all these confusing philosophical statements. That's all.

 

[lukephysics]

I care about to give the scientific point of view in addition to all these confusing philosophical statements. That's all.

Boemian is less philosophical and more ontic than Copenhagen so you should be in to that right? The whole thing is physical! Coming from the top of a different field and in to physics with fresh eyes, Copenhagen seems lost in metaphysics for no reason when here is a better alternative.

 

[Demystifier]

I care about to give the scientific point of view in addition to all these confusing philosophical statements. That's all.

So tell us from the scientific point of view, does Bohmian QFT make the same measurable predictions as standard QFT? Yes or no? That's all what matters from the scientific point of view.

 

[vanhees71]

Bohmian trajectories are not physical since they are unobservable. Whether a theory is ontic or epistemic doesn't matter for a physical theory. All it should do is to describe observations in nature (within its realm of applicability, i.e., for QT as far as we know everything except the gravitational interaction).

 

[vanhees71]

So tell us from the scientific point of view, does Bohmian QFT make the same measurable predictions as standard QFT? Yes or no? That's all what matters from the scientific point of view.

I don't know. If it's not Poincare invariant, it seems to make different predictions than standard QFT.

 

[Demystifier]

I don't know. If it's not Poincare invariant, it seems to make different predictions than standard QFT.

If you don't know, then leave the talk about it to those who know.

 

[Demystifier]

Whether a theory is ontic or epistemic doesn't matter for a physical theory. All it should do is to describe observations in nature

To paraphrase Bohr: Stop telling the physical theory what it should do!

 

[vanhees71]

To paraphrase Bohr: Stop telling the physical theory what it should do!

If a theory doesn't describe anything observable, it's not a physical theory. Bohr did a lot to confuse QT with his philosophy. I never understood, why he had such a high reputation.

 

[Demystifier]

If a theory doesn't describe anything observable, it's not a physical theory.

It's one thing to say that a theory should describe something observable (nobody here denies it), but completely another to say that that's all it should do. Many physicists think that that's not all, that it should do this and something more.

This whole subforum is made for those who think that it should do something more. Those who disagree waste their time by even reading it, let alone writing in it.

 

[PeterDonis]

If a theory doesn't describe anything observable

Bohmian mechanics does describe observable things--the same ones that "basic" QM describes.

Bohmian mechanics also includes unobservable things--the particle trajectories and the pilot wave. But so does "basic" QM: the wave function is unobservable. In fact, every physical theory includes things that are unobservable. So I fail to see what distinction you are drawing here.

 

[vanhees71]

I fail to see the merit of the Bohmian trajectories. They are not needed at all to calculate the observable facts, QT predicts and which can be compared to experiments. So why should one calculate them? It's different with the wave function. E.g., solving the time-independent Schrödinger equation for, e.g., an electron interacting with a proton through the Coulomb interaction, it provides me with the energy levels of the hydrogen atom and scattering eigenmodes leading to the Rutherford cross section. So calculating the wave function, though not directly observable, is a way to get the predictions for observable (e.g., the spectrum of the H atom).

Of course, rigged Hilbert spaces + operator theory + observable-algebras/representation theory of symmetry groups, and all that, are not observable elements of the theory either, but they define the theory! Bohmian trajectories are not needed for the abstract formulation nor add them anything observable. So they are simply superfluous.

My argument against BM is just Occam's razor: Why should one introduce theoretical balast, which doesn't add anything to the physics content of the theory.

 

[PeterDonis]

I fail to see the merit of the Bohmian trajectories.

Yes, we know this because you have stated it repeatedly. That means that at this point you have nothing useful to add to a thread that is specifically about Bohmian trajectories. The best policy to follow for someone who does not see the merit of a particular intepretation is to refrain from posting in threads in this subforum that are about that specific interpretation.

My argument against BM is just Occam's razor: Why should one introduce theoretical balast, which doesn't add anything to the physics content of the theory.

You could make the same argument against any QM interpretation. And my statement about the best policy to follow for threads in this subforum would apply the same for all of them.

 

[vanhees71]

Yes, we know this because you have stated it repeatedly. That means that at this point you have nothing useful to add to a thread that is specifically about Bohmian trajectories. The best policy to follow for someone who does not see the merit of a particular intepretation is to refrain from posting in threads in this subforum that are about that specific interpretation.

So you define, what's useful? Why aren't objections against an interpretation useful? Is it not allowed to post scientific arguments against a specific interpretation anymore? What is then the interpretation subforum good for at all? Shouldn't one then strictly restrict the entire forum to the scientific content of QT (which is the minimal statistical interpretation) and forbid any discussions about interpretations?

You could make the same argument against any QM interpretation. And my statement about the best policy to follow for threads in this subforum would apply the same for all of them.

Yes, this statement is valid against any interpretation that goes beyond the minimal statistical interpretation. So?

 

[Demystifier]

Why aren't objections against an interpretation useful?

Your objections in particular are not useful because they do not help to understand any particular interpretation. We all know that all interpretations, except the minimal one, add something additional that is not directly observable, so it doesn't help us when you remind us that it is so. We want to understand this additional thing, you don't want to understand it (but only want to know whether it makes new predictions, which it usually doesn't), so your contribution is not useful.

 

[PeterDonis]

So you define, what's useful?

No, I am just reminding you what the interpretations subforum is for and what it is not for. It is not for claiming that any interpretation is either right or wrong. You are basically claming that a particular interpretation is wrong. That is off limits in this subforum by the PF rules.

Why aren't objections against an interpretation useful? Is it not allowed to post scientific arguments against a specific interpretation anymore?

Stating that certain objections are made in the literature to a certain interpretation is fine. But, as the guidelines to this forum note, arguments of this kind cannot be resolved here because there is no experimental way to distinguish between QM interpretations. So continuing to state the same objections in thread after thread is not fine; it's just hijacking the threads with your personal opinions for no useful purpose.

What is then the interpretation subforum good for at all? Shouldn't one then strictly restrict the entire forum to the scientific content of QT (which is the minimal statistical interpretation) and forbid any discussions about interpretations?

This discussion was had some time ago in the SA forum, before the intepretations subforum was spun off. It is off topic here. If you really want to make a case for the interpretations subforum being shut down, please do so in a thread in the SA forum.

 

[apostolosdt]

I had several discussions with Sabine on pilot waves, she doesn't really understand it. There is a plenty of work on the QFT version of pilot waves. See e.g. my recent https://arxiv.org/abs/2205.05986

I went through that paper of yours; I found Section 4.3 a bit daring. In just thirty lines, you manage to reject relativity as one fundamental pillar of contemporary physics and suggest that some nonrelativistist QM theory underlying QFT predicts BSM-like particles to be discovered in the future at CERN. Really?

 

[vanhees71]

No, I am just reminding you what the interpretations subforum is for and what it is not for. It is not for claiming that any interpretation is either right or wrong. You are basically claming that a particular interpretation is wrong. That is off limits in this subforum by the PF rules.Stating that certain objections are made in the literature to a certain interpretation is fine. But, as the guidelines to this forum note, arguments of this kind cannot be resolved here because there is no experimental way to distinguish between QM interpretations. So continuing to state the same objections in thread after thread is not fine; it's just hijacking the threads with your personal opinions for no useful purpose.This discussion was had some time ago in the SA forum, before the intepretations subforum was spun off. It is off topic here. If you really want to make a case for the interpretations subforum being shut down, please do so in a thread in the SA forum.

No, I don't want to propose that at all. To the contrary, it was split off as a subforum to be able to discuss freely about metaphysical implications and keeping the scientific QT forum free from it. I only wondreed that you now wanted to imply the stricter rules of the latter also in here.

 

[PeterDonis]

I don't understand the purpose of this subforum at all.

We had a detailed discussion on this before the subforum was added. Please go look it up. Also look at the sticky threads at the top of the subforum, which will give you the forum guidelines.

If you really can't grok the purpose of this subforum after reading all that, then the very least you can do is to stop posting in it, in order to not ruin the discussion for others who do see reasons for it and who post here in order to have substantive discussions.

 

[PeterDonis]

I only wondreed that you now wanted to imply the stricter rules of the latter also in here.

I have no idea what you're talking about. The only guidelines I have discussed at all in this thread are the guidelines for this forum.