Understanding Barandes' microscopic theory of causality

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Discussion Overview

This thread explores Barandes' microscopic theory of causality as presented in his pre-print "New Prospects for a Causally Local Formulation of Quantum Theory." The discussion focuses on the implications of Barandes' claims regarding causal locality in quantum mechanics, particularly in relation to Bell's theorem, and seeks to understand the interpretation of entanglement within this framework.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants express skepticism about Barandes' assertion that his theory deflates Bell's theorem, questioning how he can claim a causally local hidden-variables formulation of quantum theory.
  • Barandes distinguishes between causal locality and Bell's local causality, which raises concerns about whether he is merely restating the no-signaling theorem.
  • There is a suggestion that Barandes' interpretation could lead to a fundamentally different understanding of the universe compared to general relativity.
  • One participant notes that Barandes does not translate "entanglement" into his new framework, implying that it remains an unresolved aspect of his theory.
  • Another participant proposes that Barandes' hidden variables differ from those in Bell's theorem, suggesting a violation of the assumption of "divisibility" into an objective beable.
  • Concerns are raised about the difficulty of explaining causal locality through a Bayesian network analogy as attempted by Barandes.
  • Some participants emphasize the need for an open-minded approach to understanding Barandes' principles rather than dismissing them outright.

Areas of Agreement / Disagreement

Participants generally do not reach consensus, with multiple competing views regarding the implications of Barandes' theory and its relationship to established concepts in quantum mechanics and relativity. The discussion remains unresolved on several key points, particularly concerning the interpretation of entanglement and the validity of Barandes' claims about causal locality.

Contextual Notes

Participants note limitations in understanding Barandes' framework, particularly regarding the translation of established quantum concepts into his proposed language. There are unresolved questions about the implications of his theory for existing interpretations of quantum mechanics and the foundational assumptions underlying Bell's theorem.

  • #451
If the issue is that Barandes seem to wants the metaphysical benefit of "real trajectories" without supplying the formal machinery that would make those trajectories like objective beables rather than underdetermined stuff?

Then, my opinion is that it is a key feature here is that a subsystem’s real trajectory is fundamentally non-inferrable from an external perspective. It is therefore not an objective beable in the Bohmian or Bell-style sense. I see this as a feature, not a problem.

The difficulty is to accept that there can indeed be a hidden reality of a subsystem that is fully real, while the single realized trajectory of that subsystem is not itself the level at which the nomological structure lives. So it is not treated as an objective state-variable whose value directly influence via dynamical law another subsystem, as in Bohmian mechanics.

In Barandes’s picture, law is not a deterministic law for the actual microstate, as in an ordinary system dynamics. Rather, the nomological structure resides at the level of indivisible stochastic transition probabilities, which in turn is associated to each decomposed "subsystem". Causal structure is encoded in the relations among these probabilities, as defined by the global constrained Gamma, not in a trajectory-to-trajectory mechanism at the level of single realized events. The single-event level is irreducibly (Barandes chose the word indivisible to avoid confuison with other use of the term) stochastic.

For me this can be conceptaully plausible if you imagine interacting information processing systems. But not human observer, rather any physical subsystem; as it interacts with fellow subsystems. This is totally "classical" at each subsystem level, the magic lies in the insight "interaction rules" are defined at the level of inteacting information processing subsystems, ie at nomological descision level. This guarantees that we have no FTL pathologies. non-local correlations OTOH can be understood as an artifact from insisting on describing this from external view as system dynamics and "effective laws", that really does not reflect the true "causal relation".

Now, the problem i see is: this pushes all the "problems" into one point. What is the origin and explanation of the global constraint Gamma? Clearly Gamma encode non-trivial information/constrains, that begs a first principle answer; that encodes te same thing that is normally encoded in hilbert space structure and hamiltonians.

Barandes does not explain Gamma beyond the correspondence via alternative constructions, it follows from the hilbert picture, and it is not the task of the quantum-stochastic-correspondence alone to supply one. As I mentioned before, I see this as an alternative handle. Question is, what can we do with this new handle? If this new handle is more weird than the other handle of hilbert formalism, then of course it is hard to see the point.

This is why for me, the value of Barandes picture pivots on wether we can find a way to explain Gamma - without referring to the other side of the correspondence; ie regular hilber/hamiltonian stuff.

My "interpretation/understanding" here however is that Gamma probably need to be understood as emergent (in some way that isnt clear), from a process that is more general (=more crazy, less constrained) that the unistochastic picture. Personally, its the only viable direction I distinguish.

/Fredrik
 
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  • #452
javisot said:
The feeling I get is as if we took Copenhagen and changed everything written in English to Spanish, and then said that the result is a new interpretation....

What do you mean by interpretation? (Many Worlds and Copenhagen, while describing the same thing, are based on remarkably different physical realities)
He shows we can interpret quantum systems as systems with a definite, classical configuration, evolving unistochastically in time. The ontology is similar to Bohmian mechanics, but without the guiding nomology.
 
  • #453
Morbert said:
He shows we can interpret quantum systems as systems with a definite, classical configuration, evolving unistochastically in time. The ontology is similar to Bohmian mechanics, but without the guiding nomology.
I reconstruct the sentence then: "the feeling I get is as if we took BM and changed everything written in English to Spanish, and then said that the result is a new interpretation..."
 
  • #454
javisot said:
I reconstruct the sentence then: "the feeling I get is as if we took BM and changed everything written in English to Spanish, and then said that the result is a new interpretation..."
But the absolute KEY difference is what you omitted "but without the guiding nomology".

I'd say the key difference is not in "hidden variables" themselves. Ie i think the difference lies at the level where law-constraint applies. This is a major difference in the take on causal mechanisms.

In BM, the trajectory follows system dynamical law. In Barandes stochastic, no law rule individual trajectories, law only constrains the stochastic structure in which actual trajetories are realized.

This is why i think Barandes reformulation of microphysical causation is central to all this. The nature of causation is just as muchm, if not the bigger mystery as microphysical ontology itself.

/Fredrik
 
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