Uncertainty principle - Nature of observer

In summary, uncertainty principle states that a particle's position cannot be known with absolute certainty until after it has been observed.
  • #1
freeelectron
10
1
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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  • #2
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?
 
  • #3
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 independant 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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  • #4
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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  • #5
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.
 
  • #6
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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Related to Uncertainty principle - Nature of observer

1. What is the uncertainty principle?

The uncertainty principle, also known as Heisenberg's uncertainty principle, is a fundamental concept in quantum mechanics that states that the more precisely we know the position of a particle, the less precisely we can know its momentum, and vice versa.

2. How does the uncertainty principle relate to the nature of the observer?

The uncertainty principle is often linked to the role of the observer in quantum mechanics. It suggests that the very act of observing a particle inherently disturbs its state, making it impossible to accurately measure both its position and momentum simultaneously. This brings into question the role of the observer and their impact on the behavior of particles.

3. Can the uncertainty principle be explained by classical mechanics?

No, the uncertainty principle is a fundamental principle of quantum mechanics and cannot be explained by classical mechanics. In classical mechanics, it is possible to know the exact position and momentum of a particle at any given time. However, in quantum mechanics, the laws of nature are probabilistic, and the uncertainty principle becomes a necessary component of understanding the behavior of particles.

4. How does the uncertainty principle impact everyday life?

The uncertainty principle has no noticeable impact on our everyday lives because it only becomes significant at the quantum level. It is relevant in the behavior of subatomic particles, atoms, and molecules, but for larger objects, the effects are negligible. However, technologies such as MRI machines and transistors rely on our understanding of the uncertainty principle.

5. Is the uncertainty principle a limitation of our understanding or a fundamental aspect of nature?

The uncertainty principle is considered a fundamental aspect of nature, and it is not a limitation of our understanding. It has been extensively tested and proven through experiments, and it is a crucial component of our current understanding of the quantum world. However, there are ongoing debates and research about the interpretation and implications of the uncertainty principle in different contexts.

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