I A new realistic stochastic interpretation of Quantum Mechanics

[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.