A Would this experiment disprove Bohmian mechanics?

[bolbteppa]

May I ask why do you think so?

I think it's a good attempt, I think his thinking in the first few pages is interesting, I think it's interesting to try to frame QM as analogous to statistical mechanics as a way to explain why experiments indicate paths do not exist as a way to save the idea of paths existing as though they were analogous to the microscopic variables underlying statistical mechanics - but then to go off and literally just steal equations and concepts like wave functions out of thin air and use them blindly (because he wants to recover normal QM theory) is actually so egregious it can't be taken seriously...

By the way, many misunderstandings of Bohmian mechanics (BM) stem from reading only the first and not the second Bohm's paper. The true essence of BM can only be found in the second paper, which explains what happens during the measurement and why BM makes the same measurable predictions as standard QM. About 99% of "disproofs" of BM arise from ignoring the Bohm's crucial insight about the measurement process in the second paper.

The second paper does even less to address the fundamental issues with paths not existing and his use of concepts derived explicitly on the assumption of no paths as a way to end up with a theory allowing paths to exist.

(I have written it in my younger days when I still thought that Lorentz invariance should be fundamental.)

I must say any claims that Galilean relativity rules the world and in any way underlies relativity let alone the standard model is probably even more egregious than the notion of paths existing, it's not only denying quantum theory (since we are only trying to fit the square peg of Galilean relativity into the round hole of relativistic quantum theory in order to try to save Bohmian mechanics) it's also denying Einsteinian relativity, I don't know how people take this seriously - quantum field theory is fascinating and hard enough without trying to recover this stuff from a starting point which denies the very thing (lack of determinism) leading to all this stuff in the first place, but to also deny relativity as being fundamental, this is actually unbelievable.

 

[bobob]

The problem with trying to falsify bohmian mechanics is that the folks who see bohmian mechanics as an explanation will never make use of its ontology to make a prediction that differs from standard quantum mechanics, even though there is physics in the difference between interpretations. Standard quantum mechanics is telling you that the amount of information that exists about something is lmited by the uncertainty relations and that since nature follows tyhe same laws of physics that everything else (including us) must follow, even nature has no more information about those quantities. On the other hand, bohmian mechanics is telling you that information is there and used by nature, but for whatever reason (the quantum equilibrium hypothesis), we cannot access it. That should lead to different ways of figuring entropies. However, the point of bohmian mechanics seems to be to make certain that it doesn't get different answers from quantum mechanics, so no matter what the ontology might imply, it will be disregarded if it actually implies anything physical.

 

[Mentz114]

[]
So the main reason for changing my opinion was the derivation of the "quantum equilibrium conjecture" from BM. It's not ad hoc as it occurs in everything I've read so far about BM but it simply follows from the usual continuity equation of probabilities,
$$\dot{\rho} + \vec{\nabla} \cdot \vec{j}=0,$$
where
$$\rho=|\psi|^2, \quad \vec{j}=\frac{-\mathrm{i}}{2m} [\psi^* \vec{\nabla} \psi -(\vec{\nabla} \psi^*)\psi].$$
Given that the BM trajectories are defined through the stream lines of the velocity field $\vec{v}$ which obeys $\vec{j}=\rho \vec{v}$ makes this consistent.
[]

I recently read ( and finally grasped) the derivations of the Schrodinger equation and a classical wave equation in Schleich et. al.
It is impressive that one can write a (non-linear) wave equation for classical mechanics that reproduces the evolution of density in standard statistical mechanics.
But the way one derives the linear Schrodinger equation from the same ancestor I found illuminating. It requires two assumptions different from the classical case namely a different continuity equation and that the quantum dynamics be governed by the BM quantum potential. The second assumption removes the non-linear term from the classical equation.

This suggests that the Schrodinger equation silently assumes the BM equation of motion. I think I might get Duerr and Teufel (2009).

 

[Boing3000]

The problem with trying to falsify bohmian mechanics is that the folks who see bohmian mechanics as an explanation will never make use of its ontology to make a prediction that differs from standard quantum mechanics, even though there is physics in the difference between interpretations.

My understanding is that depends entirely on the existence of "non-equilibrium" configuration. That may or may-not exist. The fact that it may, and that is a feature uniquely understandble through BM, makes it a very interesting topic.

Standard quantum mechanics is telling you that the amount of information that exists about something is lmited by the uncertainty relations and that since nature follows the same laws of physics that everything else (including us) must follow, even nature has no more information about those quantities.

Nature certainly has enough information to frustrate physicists about information availability. I don't think the converse is true.

On the other hand, bohmian mechanics is telling you that information is there and used by nature, but for whatever reason (the quantum equilibrium hypothesis), we cannot access it. That should lead to different ways of figuring entropies.

And that's what actually make me appreciate BM. The quantum equilibrium, and especially its connection with non locality (as explained in the last paragraph here)

However, the point of bohmian mechanics seems to be to make certain that it doesn't get different answers from quantum mechanics, so no matter what the ontology might imply, it will be disregarded if it actually implies anything physical.

Not quite. The point of BM if the same point as QM (and the converse is true). It's quite a tautology, as BM is QM. The only valid reason why it is disregarded, is that it is not as powerful as QFT.

 

[bolbteppa]

The problem with trying to falsify bohmian mechanics is that the folks who see bohmian mechanics as an explanation will never make use of its ontology to make a prediction that differs from standard quantum mechanics, even though there is physics in the difference between interpretations.

The start of Bohm's paper makes very clear one should not only find new results, one should actually improve on standard QM in the realms where (he claims/at the time) it had issues

"...our alternative interpretation permits modifications of the mathematical formulation which could not even be described in terms of the usual interpretation. Moreover, the modifications can quite easily be formulated in such a way that their effects are insignificant in the atomic domain, where the present quantum theory is in such good agreement with experiment, but of crucial importance in the domain of dimensions of the order of 10cm, where, as we have seen, the present theory is totally inadequate. It is thus entirely possible that some of the modifications describable in terms of our suggested alternative interpretation, but not in terms of the usual interpretation, may be needed for a more thorough understanding of phenomena associated with very small distances"
- A Suggested Interpretation of the Quantum Theory in Terms of "Hidden" Variables. I. P166-167

e.g. especially in the domain where relativity kicks in, but let's just ignore that Bohm's theory by his own most basic reasoning should actually explain quantum field theory/RQM even better than the usual theory (the reality as we have seen in this thread is that one is likely to end up questioning special, special!, relativity as being fundamental) for no reason. This is another reason why it is simply so galling for him to go off and use the non-relativistic Schrodinger equation 2-3 pages later.

I recently read ( and finally grasped) the derivations of the Schrodinger equation and a classical wave equation in Schleich et. al.

Another Bohmian mechanics-like paper that begins with strawmen ('The reason given is that “it works”') that illustrates a serious lack of knowledge of the authors of basic standard QM ("This approach is unfortunate. Many of us recall feeling dissatisfied with this recipe.") and that magically introduces quantum concepts for no justifiable reason and calls them classical ("It is interesting that ħ appears in the nonlinear wave equation despite the fact that it is of classical nature"), this is unfortunately typical - every introduction of spin I have seen so far is even more hilarious, e.g. using the relativistic Dirac equation or spinor wave functions out of thin air but never a word about group representation theory or simple connectivity or why those concepts should even arise...

This suggests that the Schrodinger equation silently assumes the BM equation of motion. I think I might get Duerr and Teufel (2009).

Yes, Bohm derived everything from the Schrodinger equation, of course one can take PDE's like the Schrodinger equation and end up calling things velocity fields or paths or whatever you want, one needs to justify why one can even do this.

 

[Demystifier]

but then to go off and literally just steal equations and concepts like wave functions out of thin air and use them blindly (because he wants to recover normal QM theory) is actually so egregious it can't be taken seriously...

I don't understand. What's wrong with stealing results from other theories that are known to work? The point of Bohmian mechanics is not to replace QM with another theory. The point is to improve or refine QM to make it even better.

 

[bolbteppa]

I don't understand. What's wrong with stealing results from other theories that are known to work? The point of Bohmian mechanics is not to replace QM with another theory. The point is to improve or refine QM to make it even better.

It's very simple - one can't just steal equations (especially extremely complicated equations, and even worse extremely complicated equations obeying one symmetry group [Galilean] but not another [Lorentz], this is how one spots plagiarism in any other context) that were derived on the assumption of no paths, call them axioms and then use them to claim paths exist (in any sense) and expect to be taken seriously.

Doubly worse is calling this an improvement, refinement or an equivalent when one has literally torn to shreds the basis (no paths) which led to the equation they stole and then used those equations to derive the complete opposite (paths exist) of the claims (no paths) on which the entire theory rests.

 

[Mentz114]

[]
Yes, Bohm derived everything from the Schrodinger equation, of course one can take PDE's like the Schrodinger equation and end up calling things velocity fields or paths or whatever you want, one needs to justify why one can even do this.

This is your answer to speculation I made, which you clearly misunderstand. Most of your objections to BM seem to based on personal taste and have no discursive value.

 

[vanhees71]

For a long time I couldn't accept BM for the very reasons you state, but that's just that I've read not the best expositions of the theory. The point is that BM does not give the usual probabilistic meaning to the wave function but takes it as a "pilot wave", and the theory is a non-local deterministic theory of particle trajectories in configuration space.

Using this concept the probabilistic interpretation (Born's rule) is derived for effective wave functions describing "microscopic" subsystems in interaction with "macroscopic" measurement devices in an analogous way as you derive the probabilistic description of phase-space distribution functions from the Liouville equation.

All the ballast with making BM look like classical Hamilton-Jacobi descriptions and the ominous "quantum potential" (which is not a potential as in classical physics at all but brings in the non-locality).

It's also a feature of the theory that it leads to the same probabilistic predictions for measurements of microscopic objects with macroscopic measurement devices as QM in the standard minimal representation since QM is the best empirically verified theory ever. Whether you need (or even can afford) deviations from this standard core of QM is of course not clear, as long as alternative theories with such ingredients like spontaneous-collapse theories a la GRW aren't empirically tested with the necessary accuracy. In this sense BM is the most conservative interpretative extension of standard QM and as such pretty attractive.

 

[Boing3000]

It's very simple - one can't just steal equations

So QFT did not "steal" the equation of SR by using Lorentz covariance ?

that were derived on the assumption of no paths,

Can you point to a reference when that assumption is made ? Because not being based on "path" is not the same as proving they don't exist...

and expect to be taken seriously.

Actually reality has already proven you wrong on that point. So how can such a sentence be taken seriously ?

Doubly worse is calling this an improvement, refinement or an equivalent when one has literally torn to shreds the basis (no paths)

Actually, BM improve QM noticeably by getting rid of the measurement postulate (also known as the "measurement problem"), by not "tearing it to shred" whatever you think that may means.

which led to the equation they stole

Equations do not sit a a vault so that nobody can "steal" them

 

[Demystifier]

one can't just steal equations ... this is how one spots plagiarism

It's not plagiarism if you don't say (as Bohm didn't) that you invented those equations.

that were derived on the assumption of no paths,

The Schrodinger equation is not derived from the assumption of no paths. It is guessed from the analogy with Hamilton-Jacobi equation, which does involve paths. Moreover, the first wave equation for quantum mechanics was proposed by de Broglie, who explicitly introduced trajectories. For that reason, Bohmian theory is also called de Broglie-Bohm theory.

call them axioms and then use them to claim paths exist (in any sense) and expect to be taken seriously.

As you can see, many have taken Bohm seriously. That proves that he was right in expecting to be taken seriously.

the claims (no paths) on which the entire theory rests.

As I already said, the theory does not rest on the claim of no paths. Read about history of quantum mechanics.

 

[bolbteppa]

The Schrodinger equation is not derived from the assumption of no paths. It is guessed from the analogy with Hamilton-Jacobi equation, which does involve paths. Moreover, the first wave equation for quantum mechanics was proposed by de Broglie, who explicitly introduced trajectories. For that reason, Bohmian theory is also called de Broglie-Bohm theory... As I already said, the theory does not rest on the claim of no paths. Read about history of quantum mechanics.

This is such a fundamental misunderstanding of the most basic claims of quantum mechanics - the Schrodinger equation is absolutely derived on the assumption of no paths, please carefully (it's a hard but cool book) read secton 1 (this alone for the basic claim of no paths, but to then get the general Schrodinger equation read), 2, 3, 6, 7, 8 and then 17 (to see how specialized the non-relativistic form of the Schrodinger equation is) of Landau vol. 3 and be ready to compare to ch. 1 of vol. 1.

I should not even need to point out the flaws with going by historical derivations or the first/early attempts at making sense of QM.

This is unfortunately very typical of all of the proponents of BM I have seen so far, for example the earlier paper quoted, or discussions of spin - start from a misunderstanding of QM and then end up contradicting literally the most basic claims of the theory without realizing it, even worse when it leads to questioning special, special!, relativity - again, how is this taken seriously.

 

[bolbteppa]

For a long time I couldn't accept BM for the very reasons you state, but that's just that I've read not the best expositions of the theory. The point is that BM does not give the usual probabilistic meaning to the wave function but takes it as a "pilot wave", and the theory is a non-local deterministic theory of particle trajectories in configuration space.

I would be very open to it if you could actually explain how it makes even a hint of theoretical sense to use things like wave functions let alone insanely complicated and specialized things like the non-relativistic (my god) Schrodinger equation without fundamentally contradicting either the most basic principles of either mathematics or classical mechanics, or without fundamentally contradicting the most basic claim of QM that paths don't exist.

I was really disappointed with the leaps Bohm made after his initial setup in his paper (which also has it's issues, but we could go with it for arguments sake), it's amazing that even recent books on BM take these things as postulates...

 

[Demystifier]

and then end up contradicting literally the most basic claims of the theory without realizing it

It's OK as long as one doesn't contradict any existing experiments. And Bohm's theory doesn't.

 

[vanhees71]

Well, for a very good reason one uses non-relativistic quantum theory where it is applicable. It's just simpler to solve certain problems, e.g., the bound-state problem. Also there is indeed tension between BM and relativistic QFT. I've not yet seen a convincing concept to extend the pilot-wave ideas to relativistic QFT, but I've also not read about a clear proof that such a formulation is not possible. With Bohm's original papers I've also never been happy, but with the exposition of the theory by Dürr et al in their papers and textbooks I got convinced that de Broglie and Bohm have had a point, but weren't able to explain it clearly enough to convince the Copenhagen believers, which formed the strongest group for decades concerning the interpretation of QT (and they are the main culprits to make QM as weird as some people think it is; even without BM there's nothing weird as soon as you accept the minimal interpretation, which is FAPP all you ever need to describe real-world observations).

Einstein has been convinced for a short time after Bohm's theory came out, but very quickly he realized the "non-locality" which he (and many other physicists) couldn't accept at the time. This non-locality, however is inherent in standard QT without BM. The point of course is that (a) there was the work by Bell who made this metaphysical quibbles of Einstein's a physically testable issue, and as has been proven by zillions of experiments since the 1980ies when Aspect pioneered the field, the "non-locality" of QT is precisely what's realized in Nature.

However, and even this is denied by some proponents of Copenhagen who follow the collapse hypothesis, there's no tension with Einstein causality, because relativistic QFT is by construction microcausal and thus the S-matrix obeys the linked-cluster principle. In other words, the interactions in realtivistic QFT are strictly local by construction, while the "non-local" correlations (I prefer to say "long-range correlations" between far-distantly observed parts of a single quantum system) described by entanglement are of course still there as it must be for any QT and in accordance with all the very precise Bell experiments.

The merit of BM is that, at least for non-relativistic QT, shows that there is a consistent non-local deterministic theory which let's you derive the probabilistic interpretation (Born's rule) for microscopic systems as measured by macroscopic systems (measurement devices). On top there's no quantum-classical cut to be assumed within BM. In my opinion, however, that's also not the case in conventionally minimally interpreted QT as soon as one uses the appropriate coarse-graining procedures of many-body quantum statistics to describe the macroscopic measurement devices necessary to make observations on the microscopic systems.

 

[bolbteppa]

It's OK as long as one doesn't contradict any existing experiments. And Bohm's theory doesn't.

This is why it is absolutely shocking BM is taken seriously - just ignore all the egregious issues and inherent contradictions (coupled with basic misunderstandings of QM in actual published literature for good measure) and claim it's all OK, we are a step away from justifying intelligent design by this logic...

 

[bolbteppa]

but with the exposition of the theory by Dürr et al in their papers and textbooks I got convinced that de Broglie and Bohm have had a point, but weren't able to explain it clearly enough to convince the Copenhagen believers,

https://arxiv.org/pdf/quant-ph/9503013.pdf

https://arxiv.org/pdf/quant-ph/9504010.pdf

https://arxiv.org/pdf/quant-ph/9512031.pdf

https://arxiv.org/pdf/0903.2601.pdfThere's a bunch of papers by Duerr that all blindly use wave functions and Schrodinger equations out of thin air, just as the Quantum Physics Without Philosophy book also does - how is this convincing in the slightest?

It's basically no different to Bohm's paper starting from wave functions and the Schrodinger equation (and the craziness of using concepts derived/needed explicitly on the assumption of no paths, otherwise it'd be crazy to even use these concepts, to end up with paths existing, [again Landau vol. 3 sec 1]).

 

[Demystifier]

This is why it is absolutely shocking BM is taken seriously - just ignore all the egregious issues and inherent contradictions (coupled with basic misunderstandings of QM in actual published literature for good measure) and claim it's all OK, we are a step away from justifying intelligent design by this logic...

It's actually good for BM to have opponents like you, because then the other former opponents of BM tend to turn into supporters.

 

[bolbteppa]

It's actually good for BM to have opponents like you, because then the other former opponents of BM tend to turn into supporters.

Thank you

I'm open to being convinced, indeed that's obviously why I read into this stuff, it really is just very very unlikely given how confused the basic claims are and how they have to hide behind stealing equations and calling them axioms, I was expecting better than this - I similarly encourage you to read the references I have mentioned and to think about how seriously BM conflicts with the most basic claims of QM.

 

[Demystifier]

This non-locality, however is inherent in standard QT without BM.

Are you now fine with calling it non-locality? Recently, before you turned into a BM sympathizer, you insisted that it should be called non-separability.

 

[Demystifier]

It's basically no different to Bohm's paper starting from wave functions and the Schrodinger equation (and the craziness of using concepts derived/needed explicitly on the assumption of no paths, otherwise it'd be crazy to even use these concepts, to end up with paths existing, [again Landau vol. 3 sec 1]).

Even from a strictly logical point of view, if there was a theorem saying

no paths $\Rightarrow$ Schrodinger equation

it would not logically follow that

Schrodinger equation $\Rightarrow$ no paths

 

[bolbteppa]

Even from a strictly logical point, if there was a theorem saying

no paths $\Rightarrow$ Schrodinger equation

it would not logically follow that

Schrodinger equation $\Rightarrow$ no paths

Indeed, I said the same thing a few posts ago:

Yes, Bohm derived everything from the Schrodinger equation, of course one can take PDE's like the Schrodinger equation and end up calling things velocity fields or paths or whatever you want, one needs to justify why one can even do this.

that's why it's so insane to take the Schrodinger equation as an axiom, and hilarious to take the special case of the non-relativistic one...

 

[Demystifier]

Indeed, I said the same thing a few posts ago:

So do you agree that Schrodinger equation is compatible with the possibility that paths might exist?

 

[bolbteppa]

So do you agree that Schrodinger equation is compatible with the possibility that paths might exist?

Just so we're clear - you're asking me if one can take a PDE and then end up calling some curve/characteristic on the surface satisfying this PDE a path? Absolutely, and this is exactly why one would expect the Hamilton-Jacobi formalism to be the most likely to end up approximately similar to QM in some cases...

 

[Demystifier]

Just so we're clear - you're asking me if one can take a PDE and then end up calling some curve/characteristic on the surface satisfying this PDE a path? Absolutely, and this is exactly why one would expect the Hamilton-Jacobi formalism to be the most likely to end up approximately similar to QM in some cases...

So let me try to explain your objection against BM in my own words. You like the idea that the theory is based on paths. You just don't like the idea that a theory that is based on paths takes the Schrodinger equation as one its postulates. You would be more happy if Schrodinger equation was somehow derived, perhaps as some kind of approximation resulting from a more fundamental theory based on paths. Would that be right?

If that's your objection, then I can agree with you that such theory would be much better than BM. And some people are trying to do something like that. Nevertheless, such attempts have not been very successful, so BM seems to be the best we can do at the moment. Perhaps we should not take BM too seriously as the final theory, but I believe that at least it can serve as an inspiration in a search for a better theory.

 

[vanhees71]

https://arxiv.org/pdf/quant-ph/9503013.pdf

https://arxiv.org/pdf/quant-ph/9504010.pdf

https://arxiv.org/pdf/quant-ph/9512031.pdf

https://arxiv.org/pdf/0903.2601.pdfThere's a bunch of papers by Duerr that all blindly use wave functions and Schrodinger equations out of thin air, just as the Quantum Physics Without Philosophy book also does - how is this convincing in the slightest?

It's basically no different to Bohm's paper starting from wave functions and the Schrodinger equation (and the craziness of using concepts derived/needed explicitly on the assumption of no paths, otherwise it'd be crazy to even use these concepts, to end up with paths existing, [again Landau vol. 3 sec 1]).

Why out of thin air? The Schrödinger equation is 92 years old. You cannot say it comes out of thin air at all. There is no "assumption of no path" anywhere. You cannot derive QT logically from anything else since it's the most fundamental theory we have today. It's always a creative act to get it somehow by intuition. In Schrödinger's case it was based on de Broglie's assumption of "wave-particle duality" also for particles from the idea of "wave-particle duality" for light. Then he used the analogy to go from wave optics to ray optics by using the eikonal approximation (singular perturbation theory) backwards to derive his equation as the wave equation whose eikonal approximation leads to the Hamilton-Jacobi partial differential equation. For Heisenberg it were transition probabilities as the "observable quantities" which he derived on the island Helgoland on the example of the harmonic oscillator, and for Dirac it was the idea of "q-numbers" obeying commutation relations as given through the Poisson brackets in classical Hamiltonian mechanics.

What de Broglie and later Bohm did was to use the Schrödinger equation and the resulting wave function but they reinterpreted the physical meaning of this wave function completely compared to the mainstream Copenhagen interpretation, which indeed has more problems than it pretends to solve, because it's merely philosophical with ad-hoc assumptions that are untenable like the naive collapse used in some flavors and the quantum-classical cut, which cannot be empirically verified at all (to the contrary the more refined our engineering gets the larger objects we can prepare in "non-classical" states), and then Bohr came around murmaring mystifyingly about "the principle of complementarity". Bohm just reinterpreted the wave function as pilot wave which guides the particles on their trajectories.

 

[vanhees71]

Are you now fine with calling it non-locality? Recently, before you turned into a BM sympathizer, you insisted that it should be called non-separability.

No, as I wrote, one should not use the same word for different things. E.g., relativistic local QFT is, as its name says, local in the sense that interactions are local, but as any QT it necessarily leads to entanglement of observables of far-distant parts of quantum systems (e.g., the polarization entangled state of photon pairs from parametric down-conversion). Also Einstein carefully called this inseparability rather than non-locality. Note that Einstein was not particularly happy with one of his most famous papers, i.e., the EPR paper, and he wrote a single-authored paper later in 1948 (however in German), where he makes this particular point very clear. I guess that's also the main reason for Einstein to dislike BM, because it didn't get rid with this unseparability. Nowadays we know of course that this is a feature rather than a bug for any theory, because as the empirical results concerning Bell's inequality and all that shows that this inseparability is as Nature really behaves, and thus it's a feature not a bug of QM or BM. I think Bell is a hero from bringing QM towards "physics without philosophy/Bohrian esoterics".

 

[vanhees71]

Just so we're clear - you're asking me if one can take a PDE and then end up calling some curve/characteristic on the surface satisfying this PDE a path? Absolutely, and this is exactly why one would expect the Hamilton-Jacobi formalism to be the most likely to end up approximately similar to QM in some cases...

Obviously you haven't read the very few pages needed to understand what BM is all about. So please check, e.g., the first few pages of the 2nd paper you quoted above yourself.

 

[Demystifier]

No, as I wrote, one should not use the same word for different things.

My question is this. If we accept the terminology according to which Bell theorem shows that QM is non-separable, and if we accept the QFT-textbook terminology according to which relativistic QFT interactions are local, then what is the correct word to describe BM? Is BM non-local, or is it just non-separable?

Another important point. To understand locality of interactions in quantum theory, you don't need to deal with QFT. Ordinary non-relativistic QM has local interactions if the potential in the $n$-body Schrodinger equation has the form
$$V({\bf x}_1,\ldots, {\bf x}_n)=V_1({\bf x}_1)+\cdots +V_n({\bf x}_n)$$
BM works perfectly for such local interactions in non-relativistic QM and again leads to characteristic Bohmian "non-locality" in entangled states. Again, would you call it non-locality of BM or non-separability of BM?

Or perhaps we need a third word to charactrize BM?

 

[Boing3000]

This is such a fundamental misunderstanding of the most basic claims of quantum mechanics - the Schrodinger equation is absolutely derived on the assumption of no paths, please carefully (it's a hard but cool book) read secton 1

Indeed you have a very fundamental misunderstanding of what Landau writes.

In quantum mechanics there is no such concept as the path of a particle. This forms the content of what is called the uncertainty principle, one of the fundamental principles of quantum mechanics, discovered by W. HEISENBERG in 1927.t In that it rejects the ordinary ideas of classical mechanics, the uncertainty principle might be said to be negative in content. Of course, this principle in itself does not suffice as a basis on which to construct a new mechanics of particles. Such a theory must naturally be founded on some positive assertions, which we shall discuss below (§2).

The emphasis is mine. I am under the impression that you cannot make the difference between those two propositions:
-QM is not based on path
-QM is based on no path.

It must also be said that the uncertainty principle is not something special within QM, and that it also apply to classical mechanics (which if I understood Landau correctly, is not refuted, contains path, and is a special case of QM.

I should not even need to point out the flaws with going by historical derivations or the first/early attempts at making sense of QM.

That's true, historian's fallacy will not help at all. That's why it is fine that "silly" QFT was kept alive in the 30th even though it was not mathematically sound, plaged with infinities, and I am quite sure many people name-call it "shameful laughable unjustifiable plagiarism".
Anyway, all those theories are confirmed by experiments (in their regime) and that's why they are called "scientific".

even worse when it leads to questioning special, special!, relativity - again, how is this taken seriously.

How can QFT can be taken seriously then ? It leads to question general, general!, relativity. It is unjustifiable shameful laughable to take seriously a theory that refute that apples fall