Uncertainty principle - Nature of observer

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Discussion Overview

The discussion revolves around the nature of the observer in the context of the uncertainty principle in quantum mechanics. Participants explore how observation affects the state of electrons and whether the concept of an observer is dependent on human measurement or can include non-measuring interactions.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that an observer is defined by any interaction, suggesting that even non-measuring objects can act as observers.
  • Others argue that the concept of observation in quantum mechanics implies a mark left in a macro world that exists independently of human observation, though this view has its complications.
  • A participant mentions that being "watched" implies interaction with a photon, indicating a specific type of observation.
  • One viewpoint expresses skepticism about the observer-dependent nature of the universe, suggesting that the universe does not care about observation and that observers are dependent on the universe instead.
  • Another participant critiques the historical perspective of the observer's role, referencing Von Neumann's work and suggesting that modern interpretations place the observer's role differently, particularly after decoherence.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of the observer and its implications for quantum mechanics, indicating that the discussion remains unresolved.

Contextual Notes

There are limitations in the assumptions made about what constitutes an observer and the implications of decoherence, which are not fully explored in the discussion.

freeelectron
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Uncertainty principle -- Nature of observer

About the fact that electrons have a determined position only after having been observed/measured, I don't understand how they make the difference between being watched by an eye/instrument or any non-measuring object just sitting there.
 
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Welcome to PF;
I don't understand how they make the difference between being watched by an eye/instrument or any non-measuring object just sitting there.
The "observer" is an interaction.
If an electron does not interact with anything, then how do you know it exists at all?
 
Just to expand on what Simon said, there is a bit of a fine point some treatments don't make clear. In QM an observation is when a 'mark' of some sort is left here in an assumed common sense macro world that exists independent of human observation. There are some issues with this view but that is a whole new thread. So as to not entirely leave it up in the air decoherence has a lot to say about it:
http://www.ipod.org.uk/reality/reality_decoherence.asp

Thanks
Bill
 
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I agree with you freeelectron, it doesn't make a difference. Any flotsam in the experiment is an effective "observer".

I believe you can find this definition at the end of the quantum textbook written by Sakurai or Shankar where he discusses the Bohm interpretation.

Being "watched" means the electron has already interacted with a photon.
 
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Nature got along just fine before observers happened along. The whole observer dependent thing is pure hubris, IMO. Seriously, why would the universe 'care' about 'peeping'? My view: the universe is not observer dependent, observers are universe dependent.
 
Chronos said:
The whole observer dependent thing is pure hubris, IMO. Seriously, why would the universe 'care' about 'peeping'? My view: the universe is not observer dependent, observers are universe dependent.

Mate I think that IMO isn't really required - of course you are correct.

This whole observer thing came from Von Neumann's classic - Mathematical Foundations of Quantum Mechanics. I actually learned QM from that book - I now wish I didn't for various reasons, but because of that I know what it says.

He showed the cut between classical and quantum can be placed anywhere (that's the so called Von Neumann cut) and in tracing it back the only place different was an observers conciousness - so guess where he placed it. Without going into the dubiousness of that line of reasoning, which I believe is hogwash despite my great admiration for Von Neumann, modern developments have shown a place different - just after decoherence - so the argument these days is not valid.

Thanks
Bill
 
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