Copenhagen - What qualifies as "measurement" and "observer"?

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Discussion Overview

The discussion revolves around the Copenhagen interpretation of quantum mechanics, specifically focusing on the definitions of "measurement" and "observer." Participants explore the implications of these concepts on the existence of matter and the formation of larger units from quantum particles, questioning whether sentience is necessary for measurement and the resulting collapse of wave functions.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question whether sentience is required for measurement in the Copenhagen interpretation, suggesting that non-sentient devices can also perform measurements.
  • Others argue that the distinction between classical and quantum realms is crucial, with only the classical part being considered "real."
  • There is a recurring inquiry about the formation of larger units of matter from particles whose wave functions remain uncollapsed, with some suggesting that this is not possible within the Copenhagen framework.
  • Some participants propose alternative interpretations, such as Bohmian Mechanics and Many-Worlds, as potentially more suitable for explaining the formation of matter without the need for an observer.
  • Concerns are raised about the implications of the Copenhagen interpretation, with some suggesting it leads to unsettling conclusions about the nature of reality and observation.
  • Several participants express a preference for deterministic interpretations like Bohmian Mechanics, while acknowledging the limitations and unresolved issues within all interpretations of quantum mechanics.

Areas of Agreement / Disagreement

Participants express a range of views, with no consensus on the necessity of sentience for measurement or the implications of the Copenhagen interpretation. Multiple competing interpretations are discussed, and the conversation remains unresolved regarding the nature of measurement and reality in quantum mechanics.

Contextual Notes

Participants highlight various limitations and unresolved questions, such as the criteria for what constitutes a measurement, the role of observers, and the implications of different interpretations on the existence of matter and the universe.

Who May Find This Useful

This discussion may be of interest to those exploring quantum mechanics, interpretations of quantum theory, and the philosophical implications of measurement and observation in physics.

  • #61
atyy said:
OK, perhaps it is just semantics.

That's all much of this is IMHO.

Thanks
Bill
 
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  • #62
bhobba said:
That's all much of this is IMHO.

I'm not sure. If you agree with my analogy with GRW/CSL versus Copenhagen Continuous Measurement, then in the former we can have a state of the universe including the observer (ie. quantum mechanics without observers), while in the latter there is no meaning to the state of the universe.

Also, GRW and CSL and Bohmian Mechanics, as I understand, do eventually lead to deviations from quantum mechanics, which I think can be in principle tested (maybe even in practice as discussed by the link http://arxiv.org/abs/1410.0270 posted by Jimster41).
 
Last edited:
  • #63
Jimster41 said:
It is an intriguing open question whether the linearity of quantum mechanics extends into the macroscopic domain.

The key point of assuming its a proper mixture is there is some process that makes it a proper mixture - that linearity breaks down is one way to explain it - but not the only one.

Thanks
Bill
 
  • #64
bhobba said:
The key point of assuming its a proper mixture is there is some process that makes it a proper mixture - that linearity breaks down is one way to explain it - but not the only one.

The idea is that so far assuming one world, if one is to seriously solve the factorization problem as BM, GRW and CSL try to do, then the linearity does break down. This is why the factorization problem is stressed by some for the emergence of classical reality without a privileged status for observers.
 
  • #65
atyy said:
I'm not sure. If you agree with my analogy with GRW/CSL versus Copenhagen Continuous Measurement, then in the former we can have a state of the universe including the observer (ie. quantum mechanics without observers), while in the latter there is no meaning to the state of the universe.

Also, GRW and CSL and Bohmian Mechanics, as I understand, do eventually lead to deviations from quantum mechanics, which I think can be in principle tested (maybe even in practice as discussed by the link http://arxiv.org/abs/1410.0270 posted by Jimster41).
Just want to mention that @bhobba (as well as others) pointed me to that paper.
 

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