Is the instantaneous collapse of the wave function frame dependent?

[timmdeeg]

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?

 

[Orodruin]

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.

 

[Nugatory]

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.

 

[Vanadium 50]

The very question mixes relativity and non-relativistic QM. This is problematic.

 

[timmdeeg]

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?

 

[timmdeeg]

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.

 

[Nugatory]

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.

 

[PeterDonis]

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.

 

[Orodruin]

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.

 

[timmdeeg]

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.