How Does Decoherence Affect Our Perception of Quantum Superpositions?

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Discussion Overview

The discussion revolves around the effects of decoherence on the perception of quantum superpositions, particularly in the context of how observers might perceive objects that are in a superposition of states. Participants explore theoretical implications and interpretations of decoherence as presented in M. Schlosshauer's paper.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question whether decoherence occurs before light reaches the observer's eye, suggesting that perception may not be the primary cause of decoherence.
  • Others argue that objects in the everyday world are already decohered to have definite positions, independent of observation.
  • A hypothetical scenario is proposed where an object exists in a spatial superposition, raising questions about when decoherence occurs in relation to perception.
  • There is a contention regarding Schlosshauer's example of retinal cells being in superposition, with some participants expressing confusion about its implications.
  • Some participants assert that light interacting with an object decoheres it, resulting in a definite position, and that this process is unrelated to perception.
  • There is a discussion about whether it is possible to detect superpositions with human senses, with some participants clarifying that while all states can be in superposition, detecting a superposition of position is not feasible.
  • One participant draws an analogy between the human eye and a double-slit screen, suggesting that the eye registers definite positions rather than superpositions.
  • Concerns are raised about the timing of light transmission and decoherence, questioning if light can convey information about interference before decoherence occurs.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the relationship between decoherence and perception, with no consensus reached on the implications of Schlosshauer's example or the nature of superpositions in relation to human observation.

Contextual Notes

Participants acknowledge the complexity of quantum mechanics and the potential for misunderstanding terms related to superposition and interference. The discussion highlights the need for clarity in definitions and concepts related to decoherence.

durant35
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I was reading a M. Schlosshauer paper on decoherence and he does an effort in explaining perception by decoherence, in a example od an observer perceiving a spatial superposition. Here is the link of the paper:
http://arxiv.org/abs/quant-ph/0506199

Now my question is wouldn't the decoherence occur even before the light hit the observers eye unlike Schlosshauers example where he states that the retinal cells are in a superpositionThanks in advance.
 
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Isn't it rather that the perception is one cause of the decoherence? Perhaps I am reading it differently!
 
durant35 said:
Now my question is wouldn't the decoherence occur even before the light hit the observers eye

As I have explained many many times objects in the everyday common-sense world are decohered to have an actual position regardless of perception by an observer.

Thanks
Bill
 
bhobba said:
As I have explained many many times objects in the everyday common-sense world are decohered to have an actual position regardless of perception by an observer.

Thanks
Bill

I understand that. I was wondering about a hypotethical where we actually achieved the spatial superposition and after the light hit the object which is in two locations where would the decoherence regarding our perception happen? Or our perception practically wouldn't even work because it would be too cold to keep us alive?
 
durant35 said:
which is in two locations where would the decoherence regarding our perception happen?

Its got nothing to do with perception. The photons would decohere it and give it an actual position.

Thanks
Bill
 
bhobba said:
Its got nothing to do with perception. The photons would decohere it and give it an actual position.

Thanks
Bill

Then why did Schlosshauer give that particular example? Can you please check the document I posted (maybe you already have since I know you're a huge fan of his).
I don't really understand what he is referring to since he mentions superpositions of retina cells etc.

Thanks
 
durant35 said:
Then why did Schlosshauer give that particular example?

One can place the classical quantum cut anywhere. Decoherence says you place it just after decoherence. He is looking at what happens if you don't and place it in the brain. Its interesting but IMHO just that - it leads to a very weird view of the world if you do.

I suggest before delving into such exotica you learn some of the formalism of QM.

Thanks
Bill
 
Last edited:
bhobba said:
Its got nothing to do with perception. The photons would decohere it and give it an actual position.

Thanks
Bill

So the light that reflects of the object would actually transmit information to our eyes about the decohered stated of the object that is in one position rather than the past state of the object that was in two locations?
 
durant35 said:
the object that was in two locations?

You need to learn some QM. Things are not in two locations.

Light that reflects of the object interacts with it decohering it so it has an actual position.

Thanks
Bill
 
  • #10
bhobba said:
You need to learn some QM. Things are not in two locations.

Light that reflects of the object interacts with it decohering it so it has an actual position.

Thanks
Bill

I know I need to learn it, we agreed on that. I was referring to the example of Schlosshauer where he clearly (but hypotethically) mention an object in two spots. So the light interacts with it giving it a definite position and then the light transmits information about the decohered object about it to our eyes. Right?
 
  • #11
durant35 said:
mention an object in two spots.

If he said that he is wrong.

bhobba said:
One can place the classical quantum cut anywhere. Decoherence says you place it just after decoherence. He is looking at what happens if you don't and place it in the brain. Its interesting but IMHO just that - it leads to a very weird view of the world if you do.

Its what I said before. If that isn't clear then I can't explain it better.

Thanks
Bill
 
  • #12
bhobba said:
If he said that he is wrong.
Its what I said before. If that isn't clear then I can't explain it better.

Thanks
Bill
The part you mentioned is clear, of course. The part I don't understand is the issue can we detect a superposition with our senses. And yes, I know, that in ou everyday common sense world there are no quantum effects but if we went to the lab and put an object in an excited state would the light transmit the information about the interference to our eyes before it decoheres the object our would the propagation of light to our eyes occur after the object decoheres? Thats my question.
 
  • #13
durant35 said:
The part you mentioned is clear, of course. The part I don't understand is the issue can we detect a superposition with our senses.

Again you are misunderstanding what a superpoition is - every state is in superposition.

Hopefully you mean a superposition of position. No we cant.

Thanks
Bill
 
  • #14
bhobba said:
Again you are misunderstanding what a superpoition is - every state is in superposition.

Hopefully you mean a superposition of position. No we cant.

Thanks
Bill

Misuse of terms on my side, I apologize. I meant interference. Why we can't, physically speaking?
 
  • #15
durant35 said:
Why we can't, physically speaking?

Your eyes are like the screen in a double slit - it registers a definite position.

Thanks
Bill
 
  • #16
bhobba said:
Your eyes are like the screen in a double slit - it registers a definite position.

Thanks
Bill

Ok, thanks, that's a great analogy. But of course that doesn't change the fact that the object will decohere to a definite outcome long before we even have a chance to observe it and that the photons will send the information not about the interference, but about the decohered object, right? So as you say, after decoherence everything is classical, and in an attempt to see interference we neccessarily need to interact with light and that light would 'collapse' the object and it wouldn't send any information about the interference. Please correct my reasoning if I am wrong
 

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