I A new realistic stochastic interpretation of Quantum Mechanics

[iste]

Does that mean that Barandes is using the MWI? Note that in standard statistical interpretations, such as Ballentine's, measurements do produce results. The quantum state is not interpreted as describing individual systems in these interpretations, only ensembles, so the collapse process in the math doesn't correspond to an actual physical state change on an individual systems. But Barandes, though he talks about statistics, does not appear to be using such a statistical interpretation: he appears to be interpreting the state as describing individual systems, not ensembles. In that context, "measurements don't produce results" seems to me to imply the MWI.

Maybe "don't produce results" is poor choice of words. What I am try to talk about is my belief (at least my impression) that when people think about measurement they automatically think of a model of some event ongoing in time which latches onto one outcome.

But in a stochastic system, statistics could only be realized in ensembles of experimental repetitions - an empirical distribution. The measurement device is also a stochastic system here, so the measurement device is treated in the same way in terms of ensembles of whatever the measurement device reads. From Barandes' dictionary, the quantum state translates to a statistical description using transition matrices; but physically, these statistics are only realizable if you repeat the experiment many many times.

The description of a system evolving in time is then a description of the statistics evolving in time so you will never see a single outcome singled out in the description of the system's time-evolution unless either: 1) you artificially do an exercise in statistical conditioning at your own discretion, 2) the system somehow evolves to a state where only one outcome will occur statistically on repetition due to some other reason unrelated to the act of measuring and seeing an outcome. The evolution of the measurement device is also an evolution of its read-out statistics which may or may not be coupled to the statistics of another system.

 

[PeterDonis]

the quantum state translates to a statistical description using transition matrices; but physically, these statistics are only realizable if you repeat the experiment many many times.

The description of a system evolving in time is then a description of the statistics evolving in time

These two statements contradict each other. The first is something like the standard statistical interpretation as it appears in, say, Ballentine. But it's very important to understand that the statistics described by the quantum state correspond to a specific preparation process. That's how the abstract ensemble that the quantum state describes is defined. (Ballentine discusses all this quite clearly.)

But on that interpretation, there is no such thing as "the statistics evolving in time" in the sense you mean. In order to compare the predictions of your QM model against experiment, you have to run the same experiment many, many times, with the same preparation process each time, and therefore the same underlying statistics each time. If the statistics are "evolving with time", that means your preparation process is changing, and so you're not running the experiment correctly and the data you get is useless for comparing with theory.

 

[iste]

But on that interpretation, there is no such thing as "the statistics evolving in time" in the sense you mean.

You can have an initial preparation, a final measurement, and whatever is going on in the intermediate times. At every point in time the system is described statistically. The statistics then can change over time, but you can only realize this by repeating the experiment over and over again, the particle sampling a definite configuration randomly at every point in time between initial preparation and final measurement.

 

[PeterDonis]

You can have an initial preparation, a final measurement, and whatever is going on in the intermediate times. At every point in time the system is described statistically.

No, this is not correct. Please read Ballentine. The statistical interpretation does not work the way you are thinking.

The statistics then can change over time, but you can only realize this by repeating the experiment over and over again, the particle sampling a definite configuration randomly at every point in time between initial preparation and final measurement.

If you do this, you're not running one experiment. You're running multiple experiments, with different measurements done at different times after the initial preparation, that result in different statistics, and correspond to different statistical ensembles in the theoretical model. Of course the different statistical ensembles are not unrelated; but you are still not testing "how the statistics evolve in time" in the way you are trying to use the term in describing Barandes's approach.

 

[iste]

No, this is not correct. Please read Ballentine. The statistical interpretation does not work the way you are thinking.

I am not talking about the statistical interpretation. I am talking about a stochastic one like Barandes; a stochastic interpretation is necessarily statistical because a stochastic process is just random variables. You cannot observe the statistics of ransom variables, of stochastic processes without realizing their outcomes repeatedly and looking at the empirical distribution, or hypothetically, an infinite ensemble of sample paths. That is just the nature of the stochastic process. If you have a stochastic interpretation of quantum theory then it is going to work in exactly the same way.

If you do this, you're not running one experiment. You're running multiple experiments, with different measurements done at different times after the initial preparation, that result in different statistics, and correspond to different statistical ensembles in the theoretical model. Of course the different statistical ensembles are not unrelated; but you are still not testing "how the statistics evolve in time" in the way you are trying to use the term in describing Barandes's approach.

I don't see the issue. Barandes' formulation will give you statistics for every point in time given an initial time. It then makes perfect sense to be able to talk about how those statistics change as time progresses. At the same time, were you to sample a given time via a measurement, you can't know those statistics for that particular time unless you repeated the experiment over and over again.

Edit:

I do see your point about the different ensembles but ultimately all my original point in that post was about was conveying that the formulation is only about statistics that can only be realized by repeating an experiment. If there is a description of the systems behavior at any point in time, it is a statistical one that can only be realized by repeating an experiment. And naturally you have different statistics at different times even if probing how it got there disturbs the system. If you want to start saying that different measurements are different experiments, I don't see how that really changes my original point or the fact that for any given measurement, you will only know the statistics by repeating that particular experiment.

 

[PeterDonis]

a stochastic interpretation is necessarily statistical because a stochastic process is just random variables. You cannot observe the statistics of random variables, of stochastic processes without realizing their outcomes repeatedly

Yes, which means outcomes have to be realized. Just as in the statistical interpretation of, say, Ballentine, where outcomes have to be realized in order to even do statistics to compare the results of experiments with theory. But you said a few posts ago that outcomes aren't realized in Barandes's interpretation; that's what prompted my question about whether Barandes is using the MWI. So which is it? You can't have it both ways.

Barandes' formulation will give you statistics for every point in time given an initial time. It then makes perfect sense to be able to talk about how those statistics change as time progresses.

Which is just another way of saying, as I said, that you're running different experiments when you sample the statistics at different times.

were you to sample a given time via a measurement, you can't know those statistics for that particular time unless you repeated the experiment over and over again.

Yes--repeat the same preparation process, and then repeat the same measurement the same amount of time after the preparation, multiple times.

So far nothing here is any different from the standard statistical interpretation. And everything only makes sense if outcomes are realized. But you've said that Barandes is not using the standard statistical interpretation, and in his interpretation outcomes are not realized. So I don't understand what you think Barandes's interpretation actually is. Again, you can't have it both ways.

 

[iste]

But you said a few posts ago that outcomes aren't realized in Barandes's interpretation; that's what prompted my question about whether Barandes is using the MWI. So which is it? You can't have it both ways

Yes, and I addressed that in the following posts, and the first thing I said was: "Maybe "don't produce results" is poor choice of words".

And everything only makes sense if outcomes are realized. But you've said that Barandes is not using the standard statistical interpretation, and in his interpretation outcomes are not realized. So I don't understand what you think Barandes's interpretation actually is. Again, you can't have it both ways.

The main difference to a statistical interpretation is that the system you are measuring takes definite configurations even when it isn't measured. A God's eye view would see these definite outcomes, just humans cannot obviously, and Barandes' formulation doesn't give you any statistics for those unmeasured paths. It does this because the unmeasured system is still a stochastic process so it actually does have something a bit more than the statistical interpretation. What I am saying the formulation is is what Barandes says it is. You can see in his interviews he looks at his formulation as an interpretation where particles or whatever other ontology always are in definite configurations when unmeasured.

But I do think that the fact it doesn't tell you about unmeasured stuff is a major criticism of the formulation; in many ways it kind of just looks like a phenomenological model of what happens when you measure a quantum system. Obviously to Barandes it doesn't look that way, but if the formulation or interpretation is agnostic about why quantum behavior occurs or what happens beneath the hood, as they say, then I guess his formulation won't provide him with strong weapons to defend that criticism. Sure, maybe he could say that it shows that quantum theory could plausibly be instantiated in a stochastic system, but because it is so general that can plausibly be used to describe various other things that may be unrelated to physics, he can't as of yet demonstrate exactly how quantum theory would be instantiated in a stochastic process. If you can't do that then I guess people are in their rights to be skeptical about whether his formulation actually is metaphysically plausible, even though it in principle it has the advantages of giving a very straightforward solution to the measurement problem and a relatively conventional, common sense view of reality, at least compared to most other interpretations.

 

[PeterDonis]

The main difference to a statistical interpretation is that the system you are measuring takes definite configurations even when it isn't measured.

In the standard statistical interpretation, individual systems don't have "definite configurations", in the sense of "quantum states", even when they are measured. The quantum state does not describe individual systems at all; it describes abstract ensembles (or, equivalently, preparation processes, as Ballentine makes clear).

If Barandes's "stochastic" interpretation is statistical, as you said it was (though not the "standard" statistical interpretation), then the above property should apply to it as well. But you seem to think that in Barandes's interpretation, individual quantum systems (as opposed to abstract ensembles) do have quantum states. That means Barandes's interpretation can't be statistical. If it's "stochastic", then that must mean something different than "a particular kind of statistical interpretation".

Note that there already is a model in the literature that is "stochastic" in a non-statistical sense--the GRW stochastic collapse model. Which, AFAIK, has been falsified by experiment.

 

[iste]

In the standard statistical interpretation, individual systems don't have "definite configurations", in the sense of "quantum states", even when they are measured. The quantum state does not describe individual systems at all; it describes abstract ensembles (or, equivalently, preparation processes, as Ballentine makes clear).

I mean this description is more-or-less the same as for Barandes' interpretation since the configurations of particles are not the same as the statistics that describe them. What is translated into the quantum state is the statistics. The configurations of particles are therefore not the same as the quantum state and what you have described basically what holds in the Barandes' formulation.

But you seem to think that in Barandes's interpretation, individual quantum systems (as opposed to abstract ensembles) do have quantum states.

There are particles that are in definite configurations at any one time; there are statistics that describe the behavior of those random particles were you to repeat an experiment; those statistics are what get translated into the quantum state, which is therefore not physical insofar that probabilities are not physical objects in the way particles would be.

 

[PeterDonis]

the configurations of particles are not the same as the statistics that describe them. What is translated into the quantum state is the statistics.

If "the configurations of particles" are not the quantum state, which is what you seem to be saying, on what basis are you saying that "the configurations of particles" exist at all? Where are they in the mathematical model? Where are they in the observations?

 

[iste]

If "the configurations of particles" are not the quantum state, which is what you seem to be saying, on what basis are you saying that "the configurations of particles" exist at all? Where are they in the mathematical model? Where are they in the observations?

A stochastic interpretation of quantum theory models quantum theory as a stochastic process. A stochastic process is a set of random variables. Everything I am saying about configurations is just intrinsic to random variables in probability theory.

https://en.wikipedia.org/wiki/Outcome_(probability)
https://en.wikipedia.org/wiki/Realization_(probability)
https://en.wikipedia.org/wiki/Probability_space

"The sample space Ω

is the set of all possible outcomes. An outcome is the result of a single execution of the model. Outcomes may be states of nature, possibilities, experimental results and the like. Every instance of the real-world situation (or run of the experiment) must produce exactly one outcome. If outcomes of different runs of an experiment differ in any way that matters, they are distinct outcomes. Which differences matter depends on the kind of analysis we want to do. This leads to different choices of sample space."

I mean, a random variable doesn't even make sense if there are no definite outcomes.

If you are defining quantum theory in terms of a stochastic process then these things just necessarily follow.

In Barandes' formulation, the dictionary describes the translation of the (unistochastic) transition probabilities into a unitary matrix.

Are the probabilities the same as the outcomes? No, a single realized outcome of a dice roll is clearly not the same as the probabilities that predicts what you would expect if you roll the dice loads of times.

 

[PeterDonis]

A stochastic interpretation of quantum theory models quantum theory as a stochastic process. A stochastic process is a set of random variables

But there are no such things in the standard math of QM. So if this is supposed to be an interpretation of QM, it, um, isn't.

If, OTOH, it's a new theory, which is based on standard QM but adds other elements to it, then it should not be called an interpretation of QM. It should be called a new theory, or a new model. Note that the GRW stochastic collapse model that I referred to earlier did not claim to be an interpretation of QM; it explicitly acknowledged that it was a different theory that made different predictions from standard QM in certain cases.

 

[iste]

But there are no such things in the standard math of QM. So if this is supposed to be an interpretation of QM, it, um, isn't.

So what, different formulatioms of standard QM introduce novel mathematical elements that are not in other formulations. However, they produce the same results. The center of Barandes' formulation is just a dictionary that translates from QM unitary evolution to an indivisible stochastic one. By definition it is saying that they are equivalent (and therefore prosuce the same results). This is perfectly consistent with a formulation of standard quantum theory like any other, and insofar as the indivisible picture implies ontological or metaphysical consequences implied simply by the very definition of random variables, this is perfectly consistent also with an interpretation. Exactly in the same way that Bohmian mechanics can be seen as an interpretation but also has its own mathematical formulation.

And I will mention - just because you bring up the GRW as a kind of model of another stochastic-looking theory / formulation / interpretation / whatever - a genuine stochastic interpretation of QM in the same vein of Barandes has been around for decades that also make the same predictions of QM with a unique mathematical formulation (that is in fact in the same Hamilton-Jacobi family as Bohmian mechanics and Hydrodynamic interpretations and therefore also tell you what particles are doing when they aren't measured, unlike Barandes). The type of interpretation Barandes' espouses is well-established as a bonafide interpretation.

 

[PeterDonis]

a genuine stochastic interpretation of QM in the same vein of Barandes has been around for decades that also make the same predictions of QM with a unique mathematical formulation

Can you give a reference?

 

[Sambuco]

This doesn't happen. It has to be emphasized that in Barandes' formulation, measurements don't produce results. The coupling of the measurement device to a sub-system of an entangled pair is not a one-shot event that causes an outcome, its a statistical description of two statistically coupled systems. So there is then no obligation to change what is going on at the otherside of the now-factorized transition because invoking the measurement device doesn't single out a result. You can invoke statistical conditioning but thats not physical, it is what a statistician does at his desk.

I think your description is not entirely consistent with Barandes' formulation. If a two-particle entangled system (particles A and B) is statistically conditioned by the result of a measurement performed on particle A, the entire transition matrix changes discontinously from a non-factorizable one $\Gamma_{A,B}(t) \neq \Gamma_{A}(t) \otimes \Gamma_{B}(t)$ to a factorizable one $\Gamma_{A,B}(t) = \Gamma_{A}(t) \otimes \Gamma_{B}(t)$. This change is consistent with the collapse of the wavefunction of the entire system upon measurement. I believe we agree on that because this is in the math of QM, so the disagreement is in the interpretation. In $\Psi$-epistemic interpretations (Copenhagen, relational QM, Qbism), the wave function "collapse" is not a physical process, but only statistical conditioning, as you clearly explained in other posts. However, I think that the Barandes's formulation is, in some sense, a kind of nomological interpretation where the transition matrix plays the role of a dynamical law, because the configuration of the particles between measurements is part of the primitive ontology and the transition matrix is what gives the time evolution of this configuration.

Lucas.

 

[Sambuco]

If "the configurations of particles" are not the quantum state, which is what you seem to be saying, on what basis are you saying that "the configurations of particles" exist at all? Where are they in the mathematical model? Where are they in the observations?

In fact, Barandes postulated the existence of "the configuration of particles" in addition to what is usually called the system's state or wave function. which in his formulation is replaced by the transition matrix. This configuration represents the ontology in his interpretation, just as in Bohmian mechanics.

As an example, he explicitly said (regarding the double-slit experiment):
"According to the approach laid out in this paper, the particle really does go through a specific slit in each run of the experiment. The final interference pattern on the detection screen is due to the generic indivisibility of time evolution for quantum systems."

Lucas.

 

[Sambuco]

Note that there already is a model in the literature that is "stochastic" in a non-statistical sense--the GRW stochastic collapse model. Which, AFAIK, has been falsified by experiment.

I share a review about the current status of experimental tests of collapse models: https://www.mdpi.com/1099-4300/25/4/645

Lucas.

 

[PeterDonis]

In fact, Barandes postulated the existence of "the configuration of particles" in addition to what is usually called the system's state or wave function. which in his formulation is replaced by the transition matrix. This configuration represents the ontology in his interpretation, just as in Bohmian mechanics.

Ah, ok. So it is (he claims) equivalent in its predictions to standard QM, but it does add additional elements in the theory that are not present in standard QM, like the particle positions in Bohmian mechanics. That helps.

(Note that in Bohmian mechanics, the wave function is also part of the ontology. It doesn't seem like the stochastic transition matrix in Barandes's formulation is supposed to be part of the ontology.)

 

[iste]

Can you give a reference?

Nelson, 1966 (original paper though he attributes the origin to Fenyes, 1952):
https://scholar.google.co.uk/scholar?cluster=10928480749452078078&hl=en&as_sdt=0,5&as_vis=1
Other Nelson papers and books (including 1985 quantum fluctuations found here: https://web.math.princeton.edu/~nelson/papers.html under sections Review of Stochastic Mechanics, The Mysteries of Stochastic Mechanics, and a directory link at top of page.

Beyer, 2021 (review)
https://scholar.google.co.uk/scholar?cluster=856861870672922375&hl=en&as_sdt=0,5&as_vis=1

Kuipers (2023)
https://scholar.google.co.uk/scholar?cluster=1344814159344840740&hl=en&as_sdt=0,5&as_vis=1
Basically the short version:
https://scholar.google.co.uk/scholar?oi=bibs&hl=en&cluster=10261921445018435117

Carosso, 2024 (Overview of some stochastic quantum field theory with simulations):
https://scholar.google.co.uk/scholar?cluster=14260860180761160032&hl=en&as_sdt=0,5&as_vis=1

Carlen, 1984:
https://scholar.google.co.uk/scholar?cluster=10150740165970720615&hl=en&as_sdt=0,5&as_vis=1

Levy & Krener, 1996:
http://www.math.ucdavis.edu/~krener/ (reference 68 has a PDF link)

Bohm & Hiley's book on Bohmian mechanics, The Undivided Universe (1993):
https://pierre.ag.gerard.web.ulb.be/textbooks/textbooks.html (sections 9.5 - 9.7)

Yang, 2021 (review from which I picked the links afterwards as notable papers):
https://scholar.google.co.uk/scholar?cluster=5106354696323260707&hl=en&as_sdt=0,5&as_vis=1

Yasue, 1981: https://scholar.google.co.uk/scholar?cluster=5030437746717337733&hl=en&as_sdt=0,5&as_vis=1

Guerra & Morato, 1983: https://scholar.google.co.uk/scholar?cluster=12533131275178568694&hl=en&as_sdt=0,5&as_vis=1

Goldstein, 1987 (review):
https://scholar.google.co.uk/scholar?cluster=1903829374888411128&hl=en&as_sdt=0,5&as_vis=1

Pavon (1995): https://scholar.google.co.uk/scholar?cluster=9585205420537686257&hl=en&as_sdt=0,5&as_vis=1

Caticha (2011): https://scholar.google.co.uk/scholar?cluster=10744847120076955847&hl=en&as_sdt=0,5&as_vis=1

Some criticisms of the formulation were the Wallstrom problem regarding a supposedly ad hoc quantization which has been resolved by Kuipers; turns out it was in the theory all along.

There was an issue regarding incorrect multi-time correlations but this is a mistaken criticism. The exact same criticism exists in Bohmian mechanics and is solved in both Bohmian and stochastic mechanics simply by explicitly including measuring devices in the description, as Barandes' formulation also requires. As a bonus, the Kuipers formulation doesn't even have the problem to start with which has a nice explanation I believe related to weak values.

Final major criticism is that the theory has the same breed of non-local influence as Bohmian mechanics due to the quantum potential; but, the Levy & Krener (1996) theory is completely local in precisely the way that Bohmian mechanics is not (as just mentioned). They construct arguably a generalization of stochastic mechanics using reciprocal (Bernstein) stochastic processes which are time-symmetric.
There is a Markovian sub-class of processes which are the same kinds of diffusions as used in regular stochastic mechanics. These do not reproduce the Schrodinger evolution without a correction term which is basically the Bohmian potential.
They also identify a non-Markovian sub-class which has conservation laws identical to the Schrodinger evolution and so do not need correction, hence no Bohmian potential appears and the are completely local in the sense that particle behavior doesn't instantaneously affect distant particles even if their diffusions are non-separable and statistically coupled.
It then appears that the Bohmian non-locality in stochastic mechanics comes from using an artificial Markovian assumption to reconstruct a theory which is inherently non-Markovian, which I guess Barandes' formulation brings to the forefront again explicitly.

 

[Sambuco]

Note that in Bohmian mechanics, the wave function is also part of the ontology

I believe this was true in Bohm's original formulation (https://journals.aps.org/pr/abstract/10.1103/PhysRev.85.166). In contrast, the modern approach to Bohmian mechanics assumes that the wavefunction is not ontic, but plays a nomological role (https://arxiv.org/abs/quant-ph/9512031).

They said:
"(...) the wave function of the universe is not an element of physical reality. We propose that the wave function belongs to an altogether different category of existence than that of substantive physical entities, and that its existence is nomological rather than material. We propose, in other words, that the wave function is a component of physical law rather than of the reality described by the law."

Lucas.

 

[iste]

the entire transition matrix changes discontinously from a non-factorizable one ΓA,B(t)≠ΓA(t)⊗ΓB(t) to a factorizable one ΓA,B(t)=ΓA(t)⊗ΓB(t). This change is consistent with the collapse of the wavefunction of the entire system upon measurement

Change from factorizable to non-factorizable doesn't mean that the measurement has affected the spatially separated subset though or that there is some communication going on between subsets. Factorization more or less indicates correlations due to interactions. You can imagine many reasons why distant systems could become uncorrelated without having to invoke some kind of non-local force between them, including in actual entanglement experiments where extraneous noise can cause entangled systems to lose their correlations. Also, loss of factorization is distinct from collapse; you can see that in something like Many Worlds which makes clear that you don't need collapse in quantum mechanics. Its an additonal postulate.

However, I think that the Barandes's formulation is, in some sense, a kind of nomological interpretation where the transition matrix plays the role of a dynamical law, because the configuration of the particles between measurements is part of the primitive ontology and the transition matrix is what gives the time evolution of this configuration.

Yes, I think he would agree.

 

[bhobba]

Twenty pages of something has been evident to me for quite a while now. Of course, other issues are touched on eg Bell, etc, and on that basis, it has value, but I think reality has been decided.

Ordinary QM (not QFT) approximates a deeper, more exact theory - QFT.

Quantum fields are generally considered real (they have energy, for example). Knowing that I don't quite get why reality is questioned. We have Wienberg's Folk Theorem, which says that at large enough distances, any theory will look like a QFT. To me, I don't understand why quantum physicists question reality. Philosophers can do as they wish, but their musings are off-topic here. Also, in such discussions, I see little mention of QFT.

Thanks
Bill

 

[bhobba]

Yes, photon is a theoretical concept.

I thought it was very real as an excitation in a quantum field. We have all these annihilation and creation operators—exactly what are they creating and annihilating?

What a photon is can only be explained in QFT, which is studied after ordinary QM. What particles are in QFT are subtle, for sure—but just theoretical? Sorry, I don't see it.

Although all are equivalent here is a paper exploring 9 versions of ordinary QM:
https://faculty1.coloradocollege.edu/~dhilt/hilt44211/AJP_Nine formulations of quantum mechanics.pdf.

Interpretation F is much closer to QFT, and, I think, a better starting point for discussing reality. It lacks the antiparticles inherent in QFT, which some think mean ordinary QM, while an approximation of QFT is not a limiting case

https://arxiv.org/abs/1712.06605

Thanks
Bill

 

[iste]

Twenty pages of something has been evident to me for quite a while now. Of course, other issues are touched on eg Bell, etc, and on that basis, it has value, but I think reality has been decided.

Ordinary QM (not QFT) approximates a deeper, more exact theory - QFT.

Quantum fields are generally considered real (they have energy, for example). Knowing that I don't quite get why reality is questioned. We have Wienberg's Folk Theorem, which says that at large enough distances, any theory will look like a QFT. To me, I don't understand why quantum physicists question reality. Philosophers can do as they wish, but their musings are off-topic here. Also, in such discussions, I see little mention of QFT.

Thanks
Bill

And QFT is no less excused from the kind of interpretation in the thread as QM would be.

Interestingly, in the Kuipers links on post #669 you will also find a relativistic single particle stochastic formulation of quantum mechanics

"However, the existence of a stochastic process associated to the Klein-Gordon equation disproves the widespread belief, cf. e.g. Ref. [27], that there does not exist a relativistic quantum theory associated to a single particle." (second Kuipers link)

Edit:

However, the big caveat is that at least for the stochastic formulation used in the Kuiper paper and the Carosso QFT paper, there would be a Bohmian-style non-locality that would obviously be undesirable.
But my optimism is that the Levy & Krener (1996) paper gives a stochastic formulation without the Bohmian-style non-locality. And the Barandes indivisible formulation that is topic of the thread also is another example that doesn't have that non-locality either. So in principle there seems to be optimism there.

 

[Fra]

However, I think that the Barandes's formulation is, in some sense, a kind of nomological interpretation where the transition matrix plays the role of a dynamical law

Yes, this is I think central. It is the "law" of the stochastic evolution.

because the configuration of the particles between measurements is part of the primitive ontology and the transition matrix is what gives the time evolution of this configuration.

The interesting part is the ambiguity that appears when you either

i) divide the whole system; whose stochastic evolution is known, into two parts; what can we logically "know" about an artificial division, when what we reallt know is something about the undivided system?

or reversely

ii) assemble a NEW sytem from two previously "independent" parts; then somehow novel relations must be created, or emerge somehow?

As I see Barandes view, each "part" (I avoid calling it "particle" is it leads to unnecessary preconceptions) has a time evolution that is a guided stochastic, or a "random walk" (in some abstract configuration space). The current configuration is the hidden variables, or the "beables" of this "part". The are part of defining the "part". The guide is given by the time dependent transition matrix.

Apparntly when we SPLIT such as system into TWO; and look at it's "dynamics" from perspective, quantum phenomena appear in Baranders view.

But for me the central things is the construction and update of the time dependent guide - this is not explained by baranders, but could be a possible further work (for example via some sort of predictive autoencoders etc; which means eacn part is volving independently, but still are evolving together with other parts and there is nontrivial emergence - this is why I like Baranders view).

But apart from that, the splitting or merging ot PARTS is central. I don't think Baranders satisfactory solves this, but again, it is not solved in QM either; and as he is providing a correspondence, this is expected!

An improvement that solves this, will most certainly not be equivalent to QM, but qualify as a new theory.

/Fredrik

 

[lodbrok]

As I see Barandes view, each "part" (I avoid calling it "particle" is it leads to unnecessary preconceptions) has a time evolution that is a guided stochastic, or a "random walk" (in some abstract configuration space). The current configuration is the hidden variables, or the "beables" of this "part". The are part of defining the "part". The guide is given by the time dependent transition matrix.

I don't think Barandes will agree with what you call "guide". This is not like Bohmian mechanics at all. As I see it, in Barandes' view, the theory deals only with the evolution of the description, not the evolution of the configuration. Surely you can make inferences back and forth, but the distinction is an important one. Therefore, there is nothing in the theory that guides the configuration. Instead, whatever the configuration is doing (ontology), the time-dependent transition matrix describes it (nomology).

 

[Fra]

What i labeled "guide" is just he transition matrix(the conditional probability).

Why i used the word has nothing todo with bohmian mechanics. Its more inspired by decision making; the "dice" IS the guide. And the transition matrix is the dice; that "guides" the subsystem.

/Fredrik

 

[Fra]

As I see it, in Barandes' view, the theory deals only with the evolution of the description, not the evolution of the configuration.

This is I think also a bit of how you want to "dress" Baranders correspondence. That is IMO a bit open, and the correspondence itself is I think a bit agnostic about this, and it's the part i find missing.

Baranders writes for example like this:
"a given system moves stochastically along a physical trajectory in a classical-looking configuration space
...
At the very least, this approach therefore yields a new formulation of quantum theory, one that is based on a picture of stochastic systems evolving in configuration spaces.
...
Technically speaking, the configurations in this new picture for quantum theory play the role of hidden variables, meaning physical parameters that exist separately from wave functions and density matrices.
...
it will be important to be keep in mind the distinction between deterministic hidden-variables theories and stochastic hidden-variables theories"
-- https://arxiv.org/abs/2302.10778

"At the level of dynamics, the microphysical laws consist of conditional or transition probabilities of the form $\Gamma_{ij}(t) \equiv p(i, t \mid j, 0) \quad \text{for } i, j = 1, \ldots, N$"
-- https://arxiv.org/abs/2402.16935

(edit: I keep forgetting how to get the latex to work on here, that's why i dont like typiing formulas in the thread)
/Fredrik

 

[lodbrok]

What i labeled "guide" is just he transition matrix(the conditional probability).

Why i used the word has nothing todo with bohmian mechanics. Its more inspired by decision making; the "dice" IS the guide. And the transition matrix is the dice; that "guides" the subsystem.

/Fredrik

I see. Sorry, I misread "guide" to mean '... causing it to behave a particular way' as opposed to your intended '... guide our decision making about its behaviour'. That's why I immediately thought of the pilot wave.

 

[Fra]

Now if the dice metaphor is loosely accepted, we could use that to propose a conceptual intuitive understanding of what the indivisibility means; in terms of an "dice rolling" stochastic if we connect it to a system that tries to predict its own experience future and use to for "gamling".

If one system (optional labels particle,agent,inside-observer,etc..) which obviously can never have complete information about the universe not predice the future, put in the optimal way together its "best prediction" of the future - given it's interactionhistory; then this can be consdiered represented by a dice, or a transition matrix.

Now, the only option is throw the dice, or not. There is no such thing as "half-rolling" the dice. But one can ask this: is there a way to take this dice, and decompose it into two smaller dices, that can be thrown in succession? So that the total stochastic process of two rolls, is the same as one roll with the first dice? That is condition for divisibility. And I think it's not hard to realize that, while there are special cases where there is possible - the GENERAL case, is not divisible. The one dice you have is all you have, and to turn it into two dices, you simply need to add more information! And presumably each time you do, the dice needs to be updated (time dependent transition matrix), and this is then not an equivalent process, its different! And then we are stepping outside the whole purpose of predictings based in given imperfect information.

This is why this metahpor is IMO a possible way to get an intuitive hook of WHY a general stochastic case is not markovian and not disivible. Becuase i understnad from the thread that the lack of conceptual and intuitive hook is what prevents us from understanding Baranders papers and seeing the good things.

But there are still issues left to understand i think, but I think the correspondence i nice, even if it does of course not solve all problems at once!

1) For example the rule for updating the dice is should be explained - Barandes does not; and of course neither does QM. It's the "input" via the dynamicla law implicit in hamiltonian etc.

2) The unistochastic constraint on the transition matrix is something left to ponder on for me. it somehow is a constraint on the "predictive model" or its origin, or on the internal structure of the system (particle/agent). I have yet to think about this to find a deeper motivation for this (beyond correspondend), and the link to permutation matrices is indeed deeply interesting as permutation or scrambling is IMO indeed conceptually related to the most basic form of computation or action, scrambling, which is again ocnnecting to black holes as beeing thought of as t he optimal scramblers in nature. I think there is alot of food for thought there to think about, that may or many not lead to deeper progress. So can we understand computation, and emergent laws as somehow origitnating from som fundamental scrambling that gives emergence that looks nothing like scrambling from a macroperspective it will be interesting. This is why i enjoyed the conceptual connection to computing as well in one of the early youtube talks.

/Fredrik

 

[WernerQH]

What a photon is can only be explained in QFT, which is studied after ordinary QM. What particles are in QFT are subtle, for sure—but just theoretical? Sorry, I don't see it.

Photons are surely part of QED, and we have become so accustomed to the term that most physicsts consider them real (apart from those who consider them "mathematical artifacts" of perturbation theory).

I thought it was very real as an excitation in a quantum field. We have all these annihilation and creation operators—exactly what are they creating and annihilating?

I agree with you. Except that the language is deceptive. We are talking of creation and annihilation, and photon "propagators", thinking of quantum "objects" travelling continuously from A to B through spacetime. But this is a metaphysical picture that has been foisted on QED. The theory does not provide definite "paths" connecting an operator $\mathbf a^\dagger(\mathbf x_A,t_A)$ with another operator $\mathbf a(\mathbf x_B,t_B)$. The Feynman rules allow vertices to be connected in different ways, making it meaningless to say that "this" photon interacted with "that" electron. I think what we should consider real are the "creation" and "annihilation" events at A and B, not the "objects" supposedly travelling between them. QFT is a fantastic tool for describing the correlations of events, and has always been a stochastic theory, although not widely recognized as such.

To me, I don't understand why quantum physicists question reality. Philosophers can do as they wish, but their musings are off-topic here. Also, in such discussions, I see little mention of QFT.

Absolutely. Obviously I also sympathise with formulation F of Stryer et al.'s "Nine formulations of quantum mechanics", and I see little need for a tenth formulation that Barandes seems to be proposing.

 

[Lord Jestocost]

To me, I don't understand why quantum physicists question reality.

Which 'reality'? What is commonly subdued under the notion ‘reality’ is a) the ‘agreement reality’ and b) the ‘experiential reality’. Agreement reality is that which we consider to be real because we have been told that it is real and everyone seems to agree. Experiential reality is that which we know from actual direct experience itself.

 

[WernerQH]

Which 'reality'? What is commonly subdued under the notion ‘reality’ is a) the ‘agreement reality’ and b) the ‘experiential reality’. Agreement reality is that which we consider to be real because we have been told that it is real and everyone seems to agree. Experiential reality is that which we know from actual direct experience itself.

I don't think this is a meaningful distinction. Of course we are talking about physical reality -- unless you give up on the idea that physics is concerned with the real world around us. As science evolves, what is considered real can change (caloric, ether, "lines of force", phlogiston, ...). Wasn't seeing the stars for Maxwell "direct experience" of the ether?

 

[physika]

I don't think this is a meaningful distinction.

Obvious, of him.

 

[Sambuco]

Change from factorizable to non-factorizable doesn't mean that the measurement has affected the spatially separated subset though or that there is some communication going on between subsets. Factorization more or less indicates correlations due to interactions. You can imagine many reasons why distant systems could become uncorrelated without having to invoke some kind of non-local force between them, including in actual entanglement experiments where extraneous noise can cause entangled systems to lose their correlations. Also, loss of factorization is distinct from collapse; you can see that in something like Many Worlds which makes clear that you don't need collapse in quantum mechanics. Its an additonal postulate.

I understand your point and it seems to me that what you said perfectly describes how an $\Psi$-epistemic interpretation works. However, I still think that Barandes' formulation/interpretation is different, because it is $\Psi$-nomic. In that sense, a measurement on one of the particles of an entangled system that causes a discontinuous change in the transition matrix has a direct consequence on the dynamics of the other particle, simply because the time evolution of the configuration of the not yet measured particle is (stochastically) "guided" by the transition matrix. Thus, I believe that within Barandes' approach, this "collapse" is, in a way, more real/physical than in an epistemic interpretation.

In any case, we're discussing some subtleties behind Barandes' formulation, so if you think we're going around in circles, I have no problem "agreeing to disagree" on that.

Lucas.

 

[iste]

In that sense, a measurement on one of the particles of an entangled system that causes a discontinuous change in the transition matrix has a direct consequence on the dynamics of the other particle,

But Barandes' seems to show in his locality paper that the measurement doesn't affect the transition probabilities for the spatially distant system. There's no evidence for what you're saying in these papers. If anything, the factorization of the transition matrix is a requirement for locality. If the system remained non-factorizable then the measurement would directly affect the other system. The change to factorization is a requirement to stop the systems communicating like that, its not a sign of communication.

 

[selfsimilar]

Barandes in one of his papers says(https://arxiv.org/abs/2402.16935)

"plausibly resolves the measurement problem, and deflates various exotic claims about superposition, interference, and entanglement"

My question is, he talked about these subjects but did not elaborate on superposition. So How does superposition looked upon in his theory. For instance does a particle has a specific spin, or is it flip flopping up and down.

 

[pines-demon]

Barandes in one of his papers says(https://arxiv.org/abs/2402.16935)

"plausibly resolves the measurement problem, and deflates various exotic claims about superposition, interference, and entanglement"

My question is, he talked about these subjects but did not elaborate on superposition.

I commented on this recently in post #637

For the double slit this is what Barandes says:

According to the approach laid out in this paper, the particle really does go through a specific slit in each run of the experiment. The final interference pattern on the detection screen is due to the generic indivisibility of time evolution for quantum systems. One cannot divide up the particle’s evolution into, firstly, its transit from the emitter to the slits, and then secondly, conditioned on which slit the particle enters, the particle’s transit from the slits to the detection screen. The interference that shows up in the double-slit experiment may be surprising ,but that is only because indivisible stochastic dynamics can be highly nonintuitive. In the historical absence of a sufficiently comprehensive framework for describing indivisible stochastic dynamics, it was difficult to recognize just how nonintuitive such dynamics could be, or what sorts of empirically appearances it could produce.

After having read and listened to Barandes, I still do not have a clear toy model in my head on how indivisibility gives rise to quantum stuff.

So How does superposition looked upon in his theory. For instance does a particle has a specific spin, or is it flip flopping up and down.

If particles have a spin or not is not part of Barandes interpretation. He says he is agnostic to the fundamental constituents, it could be particles, fields, qubits, particles with spin or anything else. You provide the fundamental degrees of freedom and then you use his formalism. If you want a particle with a spin, then the spin will be determined stochastically. So I guess yes, flip-flopping around, but again I do not think he has given a simple picture of how that looks yet.

 

[Fra]

IMO, I would definitiely say that in Barandes view the configuration is "physical" as in real - but it's hidden - thus a kind of beable.

But the important difference between deterministic HV theories where the outcomes are determined by a hidden random variable, in the "stochastic HV theory" that you might call Barandes picture, is that the outcomes are NOT pre-determined, it's the time-evolution of the conditional probabilities (transition matrices) of the two systems that are "pre-correlated", this does not pre-determinie the outcomes themself(ie for any given detector setting etc), but it ensure the correlation of outcomes - without needing any action at distance.

So I wouldsay the "interaction" at Alice and Bob, are each determined by a combination of however Alice and Bob decices to set their detectors, and the two incoming precorrelated "stochastic evolving sytems".

And not here that in this pictire there is note ONE shared hidden variable - like the anzats in bells theorem, there are several ones, corresponding to each subsystem, that have independent samplings. This is why this is very different from deterministic HV theoreis where you have a shared global HV.

The exact deeper insight in the mechanism here, is not explained by Barandes, nor by QM, but it must be related to explaning the time dependent evolution of the transition matrices, and their interaction with the transition matrix of the "detectors" because we should assume it as one two. But this problem is now new. But Baranders provides a fresh angle to this all IMO, that may aid even more progress.

/Fredrik

 

[pines-demon]

And not here that in this pictire there is note ONE shared hidden variable - like the anzats in bells theorem, there are several ones, corresponding to each subsystem, that have independent samplings. This is why this is very different from deterministic HV theoreis where you have a shared global HV.

Bell's theorem works for as many hidden variables as you want, having a single one, two or more, as long as the variables are local, it does not allow to avoid the theorem.

The exact deeper insight in the mechanism here, is not explained by Barandes, nor by QM, but it must be related to explaning the time dependent evolution of the transition matrices, and their interaction with the transition matrix of the "detectors" because we should assume it as one two. But this problem is now new. But Baranders provides a fresh angle to this all IMO, that may aid even more progress.

I agree with this, but I cannot yet fully distill what's new in Barandes angle.

 

[Fra]

Bell's theorem works for as many hidden variables as you want, having a single one, two or more, as long as the variables are local, it does not allow to avoid the theorem.

Lets not forget the realism assumption, this is IMO the questionable one to me without going into details again, as i have seen this difficult-to-discuss topic without fleshing out a real toy model.

So the view I have from all this, is not a "realist stochastic HV model", but and interaction of multiple stochastic HV model, where the HV does not qualify as "real" as per Bells notion. And in a way each subsystem has its own "model" of reality. Such a picture would as a correpondence mate well with Baranders correspondnece in some limit. But such full models has not been show to be ruled out by bells ansatz.

So I supposed that what I envision would by most people be consider a very non-realist view, but while I personally see it as real, its just that I think that reality itself is subjective and emergent. This is very FAR from the "realism" as in "reveal pre-existing states" that bell entertains with his lambda.

Edit: I found another way of explaining my stance. Perhaps I could also say that the picture i try to paint is not really a hidden variable theory at all! I guess my point is that the word "hidden variable" has become claimed to mean something specific, but for me it more is a good way to label "emergent reality", which is hidden from other subsystems. But lets suppose reality is emergent in some way, and where this emergence happens in parallell in subsystems, then the "local reality" wouldnt be less real. And the connection to Barandes view is that someone I think that the transition matrices must somehow be emergent but this neither Barandes nor QM nor QFT explains. And here one also associates to what if this emergence can be built from self-organised scramblers? Ie. just like the only LAW the requires not further "explanation" is stochastics; the only form of "computation" that might not required any furher "explanation" seems to be scrambling, or random permutations. All these things... I find MUCH easier to thinkg about, in Barandes picture, than in hilbert picture for example. At least for me, it mates better with my intuition and agent based models.

/Fredrik

 

[Sambuco]

If the system remained non-factorizable then the measurement would directly affect the other system. The change to factorization is a requirement to stop the systems communicating like that, its not a sign of communication.

I agree with you that a measurement on one of the entangled particles constitutes a division event that restores factorization in the system, i.e. $\Gamma_{A,B}(t) = \Gamma_{A}(t) \otimes \Gamma_B(t)$ for $t > t_1$, where $t_1$ is the time at which Alice measures particle A, so as you said, this measurement stop any causal influence between A and B for $t > t_1$. However, what I want to enfatize is that what you called "change to factorization" is a nonlocal phenomenon. In other words, the question is whether the transition matrix $\Gamma_B(t)$ inmediately after the remote measurement on A performed by Alice, depends on the measurement outcome obtained by Alice. As the stochastic-quantum correspondence directly translates the wavefunction $\Psi_B(t)$ into $\Gamma_B(t)$, and we know from the math of QM that $\Psi_B(t)$ inmediately after Alice's measurement depends on the measurement outcome obtained by her, then, the transition matrix for particle B in Barandes' formulation also depends on the result of a remote measurement performed on the other particle.

But Barandes' seems to show in his locality paper that the measurement doesn't affect the transition probabilities for the spatially distant system.

That's not true. What Barandes proved is that QM formulated as a unistochastic process satisfies his new principle of "causal locality" which states that, if two localized systems remain spacelike separated during the time of a given physical process, they do not causally affect each other, in the sense that the conditional probabilities of one particle do not depend on what happens to the other.

There's no evidence for what you're saying in these papers.

I think it is quite the opposite. In the case of entanglement, Barandes says:

"The breakdown (60) in tensor-factorization for t ≥ t′ is precisely entanglement, as manifested at the level of
the underlying indivisible stochastic process. The factorization (58) therefore also breaks down, and so one can conclude that the two subsystems Q and R exert causal influences on each other, stemming from their local interaction at the time t′."

Lucas.

 

[iste]

However, what I want to enfatize is that what you called "change to factorization" is a nonlocal phenomenon.

Why? If I synchronize two clocks so they are in time and corrrlated ans then bring them far apart ans then mess with one of them so they are no longer synchronized, is that a non-local phenomenon? No. Nothing suggests the loss of (Edit)Non-factorization needs to involve some kind of non-local communication

In other words, the question is whether the transition matrix ΓB(t) inmediately after the remote measurement on A performed by Alice, depends on the measurement outcome obtained by Alice.

They don't.

What Barandes proved is that QM formulated as a unistochastic process satisfies his new principle of "causal locality" which states that, if two localized systems remain spacelike separated during the time of a given physical process, they do not causally affect each other, in the sense that the conditional probabilities of one particle do not depend on what happens to the other.

That's what I said!

As the stochastic-quantum correspondence directly translates the wavefunction ΨB(t) into ΓB(t), and we know from the math of QM that ΨB(t) inmediately after Alice's measurement depends on the measurement outcome obtained by her, then, the transition matrix for particle B in Barandes' formulation also depends on the result of a remote measurement performed on the other particle.

Yes but there is no explicit non-locality that cauases instantaneous changes either in quantum mechanics or Barandes' formulation. You don't need collapse to do quantum mechanics as Many World proponents will vehemently tell you. Beyond these facts then its just talking about a deeper underlying interpretation which is not inherent to Barandes' formulation.

The breakdown (60) in tensor-factorization for t ≥ t′ is precisely entanglement, as manifested at the level of
the underlying indivisible stochastic process. The factorization (58) therefore also breaks down, and so one can conclude that the two subsystems Q and R exert causal influences on each other, stemming from their local interaction at the time t

But those arent the measurement devices. The measurement devices dont affect the spatially distant system's probabilities. Q and R are correlated because their composite transition matrix remembers the initial locally induced correlation.

 

[iste]

Barandes in one of his papers says(https://arxiv.org/abs/2402.16935)

"plausibly resolves the measurement problem, and deflates various exotic claims about superposition, interference, and entanglement"

My question is, he talked about these subjects but did not elaborate on superposition. So How does superposition looked upon in his theory. For instance does a particle has a specific spin, or is it flip flopping up and down.

There is no metaphysical superposition. Everything about superposition is related to the interference stuff he describes on page 31 of that paper you pink, where interference describes a statistical discrepancy between the system's indivisible dynamics and divisible (Markovian) ones.

 

[Sambuco]

That's what I said!

Ok, I misinterpreted what you said.

Nothing suggests the loss of factorization needs to involve some kind of non-local communication

I wasn't clear enough about this. What I mean is that the global change in the wavefunction/transition matrix is a nonlocal phenomenon. I wouldn't call it "communication". Of course, this is not a problem if the wavefunction/transition matrix is interpreted simply as information about the outcome of future events, given the outcome of past events. That is, conditional probabilities and nothing more.

You don't need collapse to do quantum mechanics as Many World proponents will vehemently tell you.

I know that! Personally, I prefer some $\Psi$-epistemic proposals, so I don't consider collapse to be physically real.

They don't.

Maybe I'm misrepresenting something. Suppose we have the state $\Psi_{A,B}(t) = \Psi_{A}^{\uparrow}(t) \otimes \Psi_{B}^{\downarrow}(t) - \Psi_{A}^{\downarrow}(t) \otimes \Psi_{B}^{\uparrow}(t)$. Now, if Alice measures $\uparrow$, the state of particle B becomes $\Psi_{B}^{\downarrow}$. Do you agree? Then, given the stochastic-quantum correspondence, the transition matrix should reflect this change in the wavefunction. We can interpret this epistemically, but the change is there. Am I right?

Q and R are correlated because their composite transition matrix remembers the initial locally induced correlation.

Well, my point is that this statement amounts to saying that the non-separable wavefunction remembers the locally-induced correlation. For a hidden-variables interpretation, it is usually a form of nonlocality.

Beyond these facts then its just talking about a deeper underlying interpretation which is not inherent to Barandes' formulation.

I agree

Lucas.

 

[Fra]

2) The unistochastic constraint on the transition matrix is something left to ponder on for me. it somehow is a constraint on the "predictive model" or its origin, or on the internal structure of the system (particle/agent). I have yet to think about this to find a deeper motivation for this (beyond correspondend), and the link to permutation matrices is indeed deeply interesting as permutation or scrambling is IMO indeed conceptually related to the most basic form of computation or action, scrambling, which is again ocnnecting to black holes as beeing thought of as t he optimal scramblers in nature. I think there is alot of food for thought there to think about, that may or many not lead to deeper progress. So can we understand computation, and emergent laws as somehow origitnating from som fundamental scrambling that gives emergence that looks nothing like scrambling from a macroperspective it will be interesting. This is why i enjoyed the conceptual connection to computing as well in one of the early youtube talks.

I was contemplating upon this yesterday and the positioning of Barandes correspondence in the bigger picture is getting a bit clearer I think.

First of all, Baranders noted that unistochastic process can usually be created from an embedding, if you at least have a bistochastic process; and bistochastic processes are not the most general, they are rather often associated to dynamics in equilibrium, or the timelessness that is characteristice of system dynamics or the newtonian schema. After the state evolution in Qm is deterministic - so nothing really happens! Once we know the initial conditions or boundary condititions, the future is "knonwn".

This appear closely related to the bistochastic constraint.

Barandes proved the correspondence with unistochastic(bistochastic via embedding) processes and a the hilbert picture of QM.

And as I looked at some toy models, of very general stochastic processing, they are certainly not even bistochastic in the general case! But bistochastic processes likely are related to "steady states" ir limiting cases of more general processes. Also related to why QM specifically works for small subsystems, and in cosmological perspectives, the framework itselt runs into deep touble. why?

If we use Baranders correspondec to think about the "problem" of hte QM side, but on the stochastic side the natural conclusion seems to be that it is related to deviations from biostochasticity, or even distributions.

In terms of biostochasticity from the perspective of a hypothetical "networks" of interacting "computing nodes", it seems to associate also to that the distribution of memory capacity is stationary. Which it would often be, on short time scales, but not in the evolutioanry perspective as memory might be gained or given up. And it seems there is a close analogy to energy density distribution. IF this is not stationary, we likely need more general stochastic models, and we need to "explain" during what conditions we get steady states which are bistochastic; and thus where QM or QFT are expected to hold; then it can be used via Baranders correspondence as a kind of "classical limit" - where by "classical" here i refer to normal QM/QFT - as opposed to the theory we still dont have.

But I think to move on with unification. We need also on the stochastic side, look for more genereal models that are NOT bistochastic.


/Fredrik

 

[PeterDonis]

If I synchronize two clocks so they are in time and corrrlated ans then bring them far apart ans then mess with one of them so they are no longer synchronized

Then you are doing something that can't violate the Bell inequalities. But measurements on entangled quantum systems can violate the Bell inequalities. So whatever is going on with entangled quantum systems, it can't be explained by the kind of simple local model you are implicitly using in your clock scenario.

 

[PeterDonis]

a measurement on one of the entangled particles constitutes a division event that restores factorization in the system

This statement is interpretation dependent; it's true only for interpretations where collapse is a physically real process. But you say in a later post that you prefer interpretations where it isn't. You can't have it both ways.

 

[iste]

Maybe I'm misrepresenting something. Suppose we have the state Ψ�,�(�)=Ψ�↑(�)⊗Ψ�↓(�)−Ψ�↓(�)⊗Ψ�↑(�). Now, if Alice measures ↑, the state of particle B becomes Ψ�↓. Do you agree? Then, given the stochastic-quantum correspondence, the transition matrix should reflect this change in the wavefunction. We can interpret this epistemically, but the change is there. Am I right?

No, because the wavefunction doesn't have to change like this for a description of a system using random variables to make sense. There is no requirement to use collapse for the physical picture to make sense. If you chose to do a conditioning exercise, that has nothing to do with the physical situation and is not required. Its something a statistician chooses to do.

According to Barandes: "Because the corresponding transition matrix ΓQR(t) encodes cumulative statistical effects starting at the initial time 0". The only other thing that happens apart from the loss of factorization is that the system dynamics divide / become ""momentarily divisible".

For a hidden-variables interpretation, it is usually a form of nonlocality.

Well all I am saying is that there is no explicit situation where there are influences that explicitly cause instantaneous changes to happen elsewhere in the paprts as of yet. There is a non-local correlation, sure, and it is ambiguous why that non-local correlation occurs; but then that requires additional interpretation beyond the theory, albeit we know so far that it results from a local interaction. The most one could gather I think is that presumably, any system with indivisible stochastic dynamics can evince these kinds of non-local correlations regardless of the exact mechanism that produces indivisible dynamics - you could have a local mechanism that would cause non-local correlations so long as there was indivisibility. So, essentially that is ambiguous, but there is no explicit kinds of non-local behaviors of the kind you have in Bohmian mechanics.

 

[iste]

Then you are doing something that can't violate the Bell inequalities. But measurements on entangled quantum systems can violate the Bell inequalities. So whatever is going on with entangled quantum systems, it can't be explained by the kind of simple local model you are implicitly using in your clock scenario.

I wasn't trying to explain Bell violations I was trying to convey the point that a loss of non-factorizability or loss of correlations between spatially distant things doesn't necessarily imply some kind of communication. You don't need communication to explain why clocks become unsynchronized. Presumably you don't need non-local communication to explain why correlations in an entanglement experiment might be degraded due to external noise.