Is the instantaneous collapse of the wave function frame dependent?

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Discussion Overview

The discussion centers around the nature of wave function collapse in quantum mechanics and its relationship with the theory of relativity. Participants explore whether the instantaneous collapse of the wave function is frame dependent, particularly in the context of entangled particles and the implications of the relativity of simultaneity.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that synchronized clocks in an inertial frame could indicate simultaneous collapse, questioning if this is perceived differently by observers in relative motion.
  • Others argue that the EPR paradox illustrates that one cannot determine if the wave function has collapsed due to a measurement elsewhere, nor when it collapsed.
  • There is a suggestion that collapse interpretations are not naturally compatible with relativity, leading to their predominance in non-relativistic quantum mechanics.
  • Some participants express concern that mixing relativity with non-relativistic quantum mechanics complicates the question of whether wave function collapse is an invariant phenomenon.
  • Participants discuss the implications of measuring entangled particles, noting that certainty about the correlated state of another particle is interpretation dependent and not guaranteed until measurements are compared.
  • There is a contention regarding the certainty of correlated states, with some asserting that claims about these states without measurement are misleading and depend on interpretation.
  • Questions arise about the knowledge of observers regarding measurements, emphasizing that correlation is only established through comparison of results.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the relationship between wave function collapse and relativity, with no consensus reached on whether the collapse is frame dependent or invariant.

Contextual Notes

Limitations include the potential mixing of concepts from relativity and non-relativistic quantum mechanics, as well as unresolved interpretations regarding measurement and correlation in quantum systems.

timmdeeg
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In a thought experiment one could arrange synchronized clocks in an inertial frame of reference such that they show the same time when the collapse happens. Does that mean that according to the relativity of simultaneity from the perspective of an observer in relative motion to that frame the collapse doesn't occur instantaneous?
 
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No. Take the EPR paradox for example. When measuring one spin you have no way of telling that the wave function has collapsed due to a measurement somewhere else or not - or when it collapsed.
 
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timmdeeg said:
In a thought experiment one could arrange synchronized clocks in an inertial frame of reference such that they show the same time when the collapse happens. Does that mean that according to the relativity of simultaneity from the perspective of an observer in relative motion to that frame the collapse doesn't occur instantaneous?
Mostly it means that collapse interpretations aren’t naturally compatible with relativity - this is why we only see them in non-relativistic QM.
 
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The very question mixes relativity and non-relativistic QM. This is problematic.
 
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Vanadium 50 said:
The very question mixes relativity and non-relativistic QM. This is problematic.
Does that mean the question whether or not the collapse of the wave function is an invariant phenomenon doesn't even make sense?
 
Orodruin said:
No. Take the EPR paradox for example. When measuring one spin you have no way of telling that the wave function has collapsed due to a measurement somewhere else or not - or when it collapsed.
Not even when an entangled particle is measured? We don't have two measurements but have the certainty that the other particle has the correlated state in the same instant of time.
 
timmdeeg said:
Not even when an entangled particle is measured? We don't have two measurements but have the certainty that the other particle has the correlated state in the same instant of time.
Neither “the other particle” nor “at the same time” are in the math (as opposed to the misleading natural language we use when we aren’t doing the math), so it’s a stretch to say that we know any such thing.

What we do know is that we have measured our quantum system at one point in space and that this measurement will be correlated with a measurement that might or might not ever be made or already have been made at at some distant location.
 
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timmdeeg said:
We don't have two measurements but have the certainty that the other particle has the correlated state in the same instant of time.
No, you don't. The only "certainty" you have is that if you measure the other particle you will see the appropriate correlated statistics. Any claim about the "correlated state" of the other particle in the absence of a measurement is interpretation dependent.
 
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timmdeeg said:
Not even when an entangled particle is measured? We don't have two measurements but have the certainty that the other particle has the correlated state in the same instant of time.
Who are ”we”? There is no way for the other observer to know that you have measured. It is not until you compare the measurements that you actually find correlation.
 
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Orodruin said:
Who are ”we”? There is no way for the other observer to know that you have measured. It is not until you compare the measurements that you actually find correlation.
Ah, understand.

My thanks to you to @Nugatory and @PeterDonis for clarifying this matter.
 

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