Examining the Myth of Decoherence & the Measurement Problem

[Hurkyl]

I don't like or believe in the Bohmian mechanics either.

The funny thing is, neither do I.

 

[humanino]

This clearly indicates an intelligence behind the creation of the universe.

Considering Einstein has never such a statement, it would be best if you refrain from now on to put words into his mouth/hand, especially when it bears relevance to current issues he could not have been aware of, such as the "ID" controversy. Please use some caution considering other people can read your posts and draw their own conclusion. It has been seen before...

 

[Hurkyl]

What I have a problem understanding is why there was ever any need for a Determinst quantum intepretation.

Intellectual achievement is enough. Also, it thoroughly refutes the assertion that quantum mechanics is fundamentally nondeterminstic. Furthermore, nondeterminism is a much trickier philosophical position than determinism, so there are advantages to deterministic interpretations of quantum mechanics.

The Bohm interpretation also refutes the assertion that quantum mechanics disproves the old classical-particle and classical-field approach to physics. And amongst all interpretations I know, the connection between its ontological primitives and experimental observation seems to be the most 'obvious', and demands the least explanation.

Someone who actually studies the Bohm interpretation can probably add a lot more than I have added.

I was under the impression that science is about taking observables, or lack of observables, at face value; without having to concoct a theory which in its final result contradicts the apparent indeterminsim of a quantum state. To me it just seems completely counter-intuitive.

As a practical matter, the more ways you have of approaching a subject, the better you will understand the subject. And there's also the question of what parts you take at face value -- the whole interpretation problem with quantum mechanics stems from the fact the collection of things we would like to take at face value are logically inconsistent. Different interpretations arise from giving up different things but keeping others. Bohm, for example, gives up locality as a fundamental notion, but retains the particles we're used to looking at.

Letting the theory guide the interpretation, as you seem to be suggesting, leads directly to the many worlds interpretation (and similar) -- but as I recall, the very reason you started this thread was because you wanted to complain about that...

I don't want to argue anymore, but If you are not a Determinist i would appreciate if you explained what else is it about BM that makes you think its correct?

I know you're not talking to be, but I will assume you would have asked me a similar question -- my response would be "where did you get the idea that I think it's correct?" I, personally, think the question of "correctness" of an interpretation is an effectively meaningless question. However, interpretations are important for understanding the theory -- and equally important to expose the mental blocks and personal biases that people have that impair their ability to understand the theory.

 

[Coldcall]

Hurkyl,

"Intellectual achievement is enough. Also, it thoroughly refutes the assertion that quantum mechanics is fundamentally nondeterminstic. Furthermore, nondeterminism is a much trickier philosophical position than determinism, so there are advantages to deterministic interpretations of quantum mechanics."

What's so intellectual about claiming Determinism? The way I see it; the whole Determinist angst appears to require that our universe is 100% predictable. I don't agree that there is any nuance in the various degrees of Determinism vs Indeterminism. If there is one iota of indeterminsim the whole system as a whole becomes non-deterministic. Yes, certain sub systems in isolation can remain deterministic but the non-deterministic whole remains non-deterministic.

"Bohm, for example, gives up locality as a fundamental notion, but retains the particles we're used to looking at."

Yes but if I'm not mistaken Bohmian mechanics changed from insisting on maintianing locality to a non-local theory only after Bell's tests falsified locality. Is this not a case of re-interpetating a falsified local theory into one which is compatible with empirical evidence?

The part you mention about retaining particles is where i have the most difficulty because i don't know of any other theories in any scientific specialism which proposes that we accept defined values or properties, without having objectively observed it to be a truth; or provided any empirical evidence to support such unseen axioms. We are being asked to "believe" something through faith, much like religions depend on faith.

"Letting the theory guide the interpretation, as you seem to be suggesting, leads directly to the many worlds interpretation (and similar) -- but as I recall, the very reason you started this thread was because you wanted to complain about that..."

I don't think quantum theory naturally leads to a many-worlds intepretation; however it does make a bit more sense than BM. Still if I had to choose between BM and MWI; I'd regrettably settle for MWI. Though you've not given me much of a choice

"I know you're not talking to be, but I will assume you would have asked me a similar question -- my response would be "where did you get the idea that I think it's correct?" I, personally, think the question of "correctness" of an interpretation is an effectively meaningless question. However, interpretations are important for understanding the theory -- and equally important to expose the mental blocks and personal biases that people have that impair their ability to understand the theory."

Can all the interpretations be correct/genuine? If that was the case then it would make quantum mechanics even weirder; and even more of a non-realistic theory because that would suggest it becomes whatever we want it to in our minds. I'm all for non-realism at the quantum level but hey even i would not go that far.

The amazing plurality of QM intepretations does allow a very healthy debate but I would argue that it is people's biases, ideologies or philosophical considerations at the heart of the various theories. I think the objective scientific aspect of Quantum mechanics lay only in the observables or non-observables of the basic tenets of QM.

But what is amazing about this impasse regarding inepretation of quantum mechanics is how this controversy has been raging since the Copenhagen intepretation was founded almost a century ago. We appear to be no closer to an intepretation everyone can agree on.

 

[Hurkyl]

What's so intellectual about claiming Determinism?

Once upon a time, we thought that QM (if complete) required nondeterminism. Now we know better. Thus, intellectual achievement.

The way I see it; the whole Determinist angst

I shall refer you to the millenia of discourse on determinism versus nondeterminism.

Yes but if I'm not mistaken Bohmian mechanics changed from insisting on maintianing locality to a non-local theory only after Bell's tests falsified locality. Is this not a case of re-interpetating a falsified local theory into one which is compatible with empirical evidence?

I'm not knowledgeable about the history of Bohmian mechanics, but it wouldn't surprise me -- revising theories upon gathering new data is one of the most basic processes in science. But it sounds like you're implying that's a bad thing?

The part you mention about retaining particles is where i have the most difficulty because i don't know of any other theories in any scientific specialism which proposes that we accept defined values or properties, without having objectively observed it to be a truth; or provided any empirical evidence to support such unseen axioms. We are being asked to "believe" something through faith, much like religions depend on faith.

How does one observe a truth? (And you seem to want to have us "believe" that the Bohm intertation is wrong -- wouldn't that require just as much faith? )

Anyways, I would like to remind you that I do not care for discussions about the "true" nature of "reality" -- in my experience, they simply serve as an excuse for people to take their preconceived biases about how they think the universe ought to work and try to shove it down others' throats.

I should also like to remind you that you are responding to a paragraph talking about the benefits of understanding a subject from many viewpoints; there is no "belief" involved.

I don't think quantum theory naturally leads to a many-worlds intepretation;

Well, as I've said before, MWI is the only interpretation I know which deals with the unitary evolution of the wavefunction and nothing else. Every other interpretation (that I know) requires some sort of addition or change to the formalism of quantum mechanics. Sure, there is room for new analytical methods, or different choices of terminology, but as long as you're simply studying unitary evolution of quantum states, you're using the MWI.

Can all the interpretations be correct/genuine?

I'm not sure what "genuine" would mean here, and I don't think "correct" is a meaningful adjective in this context.

I think the objective scientific aspect of Quantum mechanics lay only in the observables or non-observables of the basic tenets of QM.

An interesting thing is that the role of "observables" isn't quite as obvious as they seem at first glance once you start 'internalizing' experiments into the formalism of QM.

We appear to be no closer to an intepretation everyone can agree on.

This is generally a good thing. In other mathematical subjects, progress often comes by reinterpreting problems in different ways, so as to make use of the vast amounts of mathematical machinery available in various mathematical subjects.

 

[Maaneli]

Coldcall,

Yes but if I'm not mistaken Bohmian mechanics changed from insisting on maintianing locality to a non-local theory only after Bell's tests falsified locality. Is this not a case of re-interpetating a falsified local theory into one which is compatible with empirical evidence?

Quickly, you are mistaken. The pilot wave theory of de Broglie and Bohm was always a nonlocal theory. Bohm never ever insisted on keeping locality. In fact it was the nonlocality in deBB theory that motivated Bell to think up his theorem in the first place!

 

[Coldcall]

Hurkyl,

"Once upon a time, we thought that QM (if complete) required nondeterminism. Now we know better. Thus, intellectual achievement"

All we know is its possible to concoct an imaginary determinism into the observables. Is that really such a grand achievement?

"Anyways, I would like to remind you that I do not care for discussions about the "true" nature of "reality" -- in my experience, they simply serve as an excuse for people to take their preconceived biases about how they think the universe ought to work and try to shove it down others' throats."

Yes i agree, though i consider BM to be very much in that category regarding pre-conceived biases. For instance CI, is pretty non-descript in delving into the philosophical side of things. It's microscopic/classical measurement boundary leaves it at that, and gets on with the science as observed, it does not include extra parameters of unobserved/imagined certainty.

 

[Hurkyl]

All we know is its possible to concoct an imaginary determinism into the observables. Is that really such a grand achievement?

I'm pretty sure the discovery of a deterministic interpretation of QM was a grand achievement. I could see how you might think otherwise, since it threatens the a priori decision you have apparently made about how the universe behaves.

 

[Maaneli]

Hurkyl,

"Once upon a time, we thought that QM (if complete) required nondeterminism. Now we know better. Thus, intellectual achievement"

All we know is its possible to concoct an imaginary determinism into the observables. Is that really such a grand achievement?

"Anyways, I would like to remind you that I do not care for discussions about the "true" nature of "reality" -- in my experience, they simply serve as an excuse for people to take their preconceived biases about how they think the universe ought to work and try to shove it down others' throats."

Yes i agree, though i consider BM to be very much in that category regarding pre-conceived biases. For instance CI, is pretty non-descript in delving into the philosophical side of things. It's microscopic/classical measurement boundary leaves it at that, and gets on with the science as observed, it does not include extra parameters of unobserved/imagined certainty.

You still don't seem to get that even in CI, the Schroedinger evolution is deterministic. So determinism is an indispensable part of any unitary wavefunction formulation of QM.

 

[Maaneli]

Coldcall,


My dear Professor Maaneli,

I never labelled you as religious per se. However i did label you as a Determinist, and I noted the "religious" or "evangelical" fervour of Bohmians in general. However i would not claim to know what goes on in peoples minds when it comes to spirituality etc..


You did call me a religious Bohmian and determinist. And why would you even call me a determinist when I repeatedly mentioned my interest and support of stochastic deBB theories, and the stochastic GRW collapse theories?


What I have a problem understanding is why there was ever any need for a Determinst quantum intepretation. I was under the impression that science is about taking observables, or lack of observables, at face value; without having to concoct a theory which in its final result contradicts the apparent indeterminsim of a quantum state. To me it just seems completely counter-intuitive.


No, the purpose of science (or even physics in particular) was never a priori to just take observables at "face value". That was a belief imposed by the CI interpretation of Heisenberg and Born with the advent of standard QM. Before that, with classical mechanics, electrodynamics, fluid mechanics, and statistical mechanics, it was always the goal of physics to understand how those observables evolve dynamically in spacetime before we humans interact with them in an experiment.

In the case of deBB theory, it just happens to solve the measurement problems in a mathematically very simple way (arguably the simplest of all QM formulations), and it turns out that the simplest deBB solution to the measurement problems is a deterministic one. You do know what the measurement problems are don't you? I recall I pointed you early on exactly to the references which clearly discuss how deBB theory solves the measurement problems. It also turns out that the deterministic deBB approach to QM also does the best job so far of all the formulations of QM in accounting for quantum chaos, and all manifestations of the quantum-classical limit. It also provides considerable practical computational advantages in a number of different nonrelativistic and relativistic QM phenomena.


If so, it seems a whole set of intepretations have been created with the sole purpose of re-intepreting the non-detrminstic results of quantum measurements, in order to placate a philosophical or theological preference.


As Hurkly has alread explained, a deterministic view of QM is certainly much more conceptually palatable to human intuition than an instrinsically probabilistic one. And as long as it is logically possible and plausible, it is not unreasonable to look for deterministic ones and then compare them to an intrinsically probabilistic one, and see what the merits and demerits are of each.


I don't want to argue anymore, but If you are not a Determinist i would appreciate if you explained what else is it about BM that makes you think its correct?


Hopefully what I've said above is enough for you to understand, even if you still happen to disagree.

 

[Maaneli]

You gave up Coldcall?

 

[Evo]

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