QM laws fundamental vs effective

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Discussion Overview

The discussion revolves around the nature of quantum mechanics (QM) laws, specifically whether they are fundamental or effective laws that emerge from some underlying processes. Participants explore various interpretations of QM, including the implications of these views on the understanding of quantum phenomena.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants express the impression that QM laws are considered fundamental, suggesting a realization of their mathematical form in reality.
  • Others propose that QM could be viewed as an effective theory, with references to interpretations such as GRW and de Broglie-Bohm (dBB) that suggest QM laws result from some evolutionary process.
  • A participant mentions the idea of apparent purposefulness in the context of dBB, raising questions about whether unitary evolution serves to fulfill the Pauli exclusion principle.
  • One participant acknowledges that while many consider QM laws fundamental, there are interpretations like Primary State Diffusion that challenge this view, indicating uncertainty about the fundamental nature of QM.
  • Another participant questions the coherence of quantum systems in the context of Primary State Diffusion, suggesting that it may imply a natural coherence despite interactions with the environment.
  • There is mention of interpretations that assume a sub-quantum world from which QM emerges as an approximation, with examples like Primary State Diffusion and Nelson stochastics being cited.
  • Concerns are raised about potential deviations from QM that might be experimentally verified if these alternative interpretations hold true.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether QM laws are fundamental or effective. Multiple competing views remain, with some advocating for the fundamental nature of QM and others supporting interpretations that suggest it is effective or emergent.

Contextual Notes

Participants highlight limitations in understanding the implications of various interpretations, including the dependence on definitions and the unresolved nature of certain mathematical aspects related to the emergence of QM.

zonde
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I have impression that physicists consider QM laws as fundamental, meaning that there should be a way how QM mathematical form is realized in reality.

On the other hand QM laws could be effective laws resulting from some process of evolution. In that case it should be possible to characterize QM laws by apparent purposefulness.

Is my impression justified? - that second option is not considered.
 
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The option that QM is only an effective theory is considered by GRW and dBB. In Valentini's picture of dBB, the QM laws do result from some evolution. It may be possible to view dBB as arising from apparent purposefulness, but one would have to solve an inverse calculus of variations problem. (I was recommended to look at Enzo Tonti's work for the inverse calculus of variations problem some time ago on PF).

http://arxiv.org/abs/quant-ph/0403034
Dynamical Origin of Quantum Probabilities
Antony Valentini, Hans Westman
 
Last edited:
atyy said:
The option that QM is only an effective theory is considered by GRW and dBB. In Valentini's picture of dBB, the QM laws do result from some evolution. It may be possible to view dBB as arising from apparent purposefulness, but one would have to solve an inverse calculus of variations problem. (I was recommended to look at Enzo Tonti's work for the inverse calculus of variations problem some time ago on PF).

http://arxiv.org/abs/quant-ph/0403034
Dynamical Origin of Quantum Probabilities
Antony Valentini, Hans Westman
I had some questions on mind and I wanted to find out if there is meaningful context in which I can ask these questions. So if you say that in context of dBB it is meaningful to ask questions about apparent purposefulness of QM laws let me ask this:
Does it seems reasonable to say that apparent purpose of unitary evolution is to fulfill Pauli exclusion principle?
 
zonde said:
I have impression that physicists consider QM laws as fundamental, meaning that there should be a way how QM mathematical form is realized in reality.

Most, including me, consider them fundamental. But the fact is we simply do not know - we have interpretations where its not the case eg Primary State Diffusion.

Thanks
Bill
 
zonde said:
Does it seems reasonable to say that apparent purpose of unitary evolution is to fulfill Pauli exclusion principle?

Its a theorem from QM's basic axioms, nothing to do with the Pauli Exclusion Principle:
http://arxiv.org/abs/0808.0779

Thanks
Bill
 
bhobba said:
Most, including me, consider them fundamental. But the fact is we simply do not know - we have interpretations where its not the case eg Primary State Diffusion.

Thanks
Bill
But this Primary State Diffusion interpretation still considers that quantum systems are coherent sort of "naturally", right? And in that sense they consider QM as fundamental.

What I mean by QM not being fundamental is something like this. Quantum systems are interacting with environment constantly and so they become somewhat random. But they maintain coherence by some rather sophisticated mechanism. Sort of decoherence on it's head.
 
zonde said:
But this Primary State Diffusion interpretation still considers that quantum systems are coherent sort of "naturally", right?

I have no idea what you mean by that.

The issue is some interpretations assume a sub-quantum world from which QM emerges as an approximation. Primary state diffusion is one example, Nelson stochastics is another, and even BM is often viewed that way.

Of course if true there will be deviations from QM that may be able to be experimentally checked one day.

Thanks
Bill
 

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