EPR statements to agree/disagree with or to comment on:

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Discussion Overview

The discussion revolves around the implications of conservation laws in quantum mechanics, particularly in the context of the EPR paradox and Bell's theorem. Participants explore the relationship between conservation laws, quantum correlations, and the nature of locality in quantum processes.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant argues that conservation laws necessitate correlations between outcomes of separated quantum processes, citing examples like Compton scattering.
  • Another participant suggests that Bell inequalities violate conservation laws by treating separated quantum processes as independent, questioning the role of local hidden variables.
  • Concerns are raised about the difficulty of disproving locality and proving non-locality, emphasizing the need for a full path history of particles to account for conservation laws.
  • Some participants express skepticism regarding the relevance of conservation laws to the EPR/Bell discussions, asserting that orthodox quantum mechanics inherently violates Bell locality without dependence on conservation principles.
  • A participant challenges others to propose alternatives that would account for correlations while preserving conservation laws, indicating a search for a deeper understanding of the underlying mechanisms.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the role of conservation laws in quantum mechanics and their relationship to EPR and Bell's theorem. Some participants support the connection between conservation laws and quantum correlations, while others argue that conservation laws are not fundamentally relevant to the EPR/Bell framework.

Contextual Notes

Participants' arguments depend on various interpretations of quantum mechanics and the definitions of locality and correlation. The discussion reflects differing assumptions about the foundational principles of quantum theory and their implications for conservation laws.

Hans de Vries
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1) The origin: Conservation laws → Correlation

It’s the laws of conservation of energy, momentum, angular momentum,
that necessitates a correlation between the outcome of separated random
quantum processes. Specifically, the random process which is known under
various names as the projection, the Born rule, the collapse of the wave
function.

e.g: The Compton scattering of a photon on an electron is governed by the
conservation of energy and momentum, once the direction of the scattered
photon is detected we also know the direction of the electron hit by the
photon.
2) Bell inequalities violate the laws of conservation

They violate the conservation laws because they consider the separated
random quantum processes as being independent. The Bell type local
hidden variables can not be responsible for the required correlation because
they are merely input parameters for independent random processes while
they should actually override the randomness of the process.

e.g: The polarization angle of a photon is used as an input parameter when
the photon passes a polarizing filter or a Wollaston prism. Being merely an
input parameter is not sufficient to override the randomness of the process
and as a consequence the laws of conservation are violated. (There is not
enough correlation)
3) Locality vs non-locality

The process responsible for the correlation can either be local or non-local.
It is difficult to disprove locality (and prove non-locality) because there is
always a common origin, (The physical interaction between the two particles)
4) The full path history is required for the conservation laws

It is not sufficient to have a “last moment non-local communication” in
order to preserve the conservation laws. In general each particle can go
through several devices which modify direction (momentum), the angle of
polarization, et-cetera. All these changes must be accounted for.

e.g: If one particle is detected with spin up then the other particle must be
detected with spin down in certain experiments to conserve the angular
momentum. However, if a “spin-flipper” is placed in the path of one of the
particles then both particles must be detected with the same spin. The
history of the particle along its entire path is required.Regards, Hans
 
Last edited:
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Looks pretty good to me. I am interested to hear what others say since my opinions are well known.
 
I don't think conservation laws have anything to do with this, really. Of course, it's because of the conservation of ang mom that we believe certain pairs produced in certain decays must be in (something like) spin singlet states.

But all of this EPR/Bell stuff just takes that initial state for granted. That orthodox QM violates Bell Locality, for example, is just a fact about how QM works -- it really has nothing to do with experiment or conservation laws or anything like that.
 
ttn said:
I don't think conservation laws have anything to do with this, really. Of course, it's because of the conservation of ang mom that we believe certain pairs produced in certain decays must be in (something like) spin singlet states.
But all of this EPR/Bell stuff just takes that initial state for granted. That orthodox QM violates Bell Locality, for example, is just a fact about how QM works -- it really has nothing to do with experiment or conservation laws or anything like that.

What is your alternative then? What does determine the correlations?

The conservation laws of energy, momentum and angular momentum need
the correlations to coexist with the quantum randomness of Born's rule.
What else should save the conservation laws then?Regards, Hans
 
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