Relativity of simultaneous?

[univeral theory]

If you measure the state of particle A then you immediately know the state of B. Since the two measurements are non-local, you can only confirm that B is in the state you expect when the two observers come together to compare results. It doesn't matter "when" each observer did the measurements because the results always agree. Indeed you can find valid frames in which the order of measurements is reversed and the results still agree. "When" the states of each particle were measured has no bearing on the measurements.

 

 

Your argument is perhaps correct. But its explanation depends on an already known framework of these particles in question. Such that; when we have A at hand, we can automatically predict B.

 

But then how can you explain this framework in a predictable way, such that; the entanglement of the particles in question can have the prediction you are arguing about such that the phenomena you are talking about can be completely predictable?

[swansont]

I have no idea why you would think that as it was not what I was saying, that was more of what other people were saying.

Sam, this has happened twice now in this thread where you address me as if I was correcting you, but where I quoted somebody else. When I quote someone, I am addressing their point, and the information quoted. This isn't about you.

 

Since you are rarely wrong and I have no clue I am going to assume you are correct but if the spin states are only two possibilities and they have to be different then how is it relevant they are unknown until you check them, the different colored balls are unknown as well until they are checked...

 

But for an object like a ball, not knowing that it's red is not the same as not being red. When you open the box and see it's red, you conclude it was red all the time it was in the box, not that its color was undetermined.

[SamBridge]

I suppose the scenario boils down to "can all frames of reference measure disentanglement happening at the time "time" because the correlation is true regardless of time?" I mean, it's an instantaneous process, and the disentanglement happens for both instantaneously simultaneously yet time is still relative, so far I have not seen any clear solutions, the issue mainly stems from this http://en.wikipedia.org/wiki/Relativity_of_simultaneity

[Przemyslaw.Gruchala]

But then how can you explain this framework in a predictable way, such that; the entanglement of the particles in question can have the prediction you are arguing about such that the phenomena you are talking about can be completely predictable?

 

In pion 0 decay to electron and positron example that he gave in #9 post it's very easy, second particle is exact mirror of first one, in the all parameters..

 

Imagine it in computer program: you're reading bit from memory, it can be 0 or 1. When you read 0, you know that opposite of it will be 1, if you read 1, you know opposite of it will be 0.

Or chess- you can pick up white or black, once somebody pick up from hidden hand white, you know what will be second hidden hand result in advance.

Edited February 12, 2013 by Przemyslaw.Gruchala

[swansont]

I suppose the scenario boils down to "can all frames of reference measure disentanglement happening at the time "time" because the correlation is true regardless of time?" I mean, it's an instantaneous process, and the disentanglement happens for both instantaneously simultaneously yet time is still relative, so far I have not seen any clear solutions, the issue mainly stems from this http://en.wikipedia.org/wiki/Relativity_of_simultaneity

Simultaneity is an issue in scenarios because c is finite and the limiting speed of information transfer, but the disentanglement is instantaneous. That's a stronger statement than saying the disentanglement happens at the same time in a single frame of reference.

[Iggy]

I don't know much QM -- does it matter who collapses the wave -- where the disentanglement happens first? One frame could say A looked first and found spin up and predict that if C looks he would find spin down, and another frame could say C looked first and found spin down and predict that if A looks he'll see spin up. Either way, the observables are the same, right? Two ways of describing the same thing?

Edited February 12, 2013 by Iggy

[swansont]

I don't know much QM -- does it matter who collapses the wave -- where the disentanglement happens first? One frame could say A looked first and found spin up and predict that if C looks he would find spin down, and another frame could say C looked first and found spin down and predict that if A looks he'll see spin up. Either way, the observables are the same, right? Two ways of describing the same thing?

That scenario might run into trouble, because C should observe spin up half the time.

 

edit: No, on second thought, I'm not sure it matters.

[Moontanman]

That scenario might run into trouble, because C should observe spin up half the time.

 

edit: No, on second thought, I'm not sure it matters.

 

 

Swansont i guess my own ignorance of the math involved is my main stumbling block but to me it seems like much ado about nothing...

[swansont]

___

 

If someone sees C observe first they still can't communicate this to A, so perhaps there's no problem.

[Iggy]

That scenario runs into trouble, because C should observe spin up half the time.

 

I don't follow what you mean, but I suspect my use of the word 'predict' could be the trouble. How about this:

 

An observer in one frame sees A measure spin up and B measure spin down and concludes (from the distance and the time it took the information to reach him) that A made the observation first. He says "in my frame A collapsed the wave"). Another frame also sees A measure up and B measure spin down, but concludes on the same basis that it was rather B who made the observation first and collapsed the wave.

 

If both frames are essentially two ways of describing the same thing the QM should offer no difference in observables between the two 'scenarios'. Who collapses the wave shouldn't matter.

 

___

 

If someone sees C observe first they still can't communicate this to A, so perhaps there's no problem.

 

And I believe C couldn't know if A actually looked at the entangled pair until the information arrived via light from that event.

[SamBridge]

Simultaneity is an issue in scenarios because c is finite and the limiting speed of information transfer, but the disentanglement is instantaneous. That's a stronger statement than saying the disentanglement happens at the same time in a single frame of reference.

But if instantaneously simultaneous doesn't mean the same from multiple frames of reference, what does it mean?

[Iggy]

Researching I find...

A 2007 experiment ruled out a large class of non-Bohmian non-local hidden variable theories.^[23]
If the hidden variables can communicate with each other faster than
light, Bell's inequality can easily be violated. Once one particle is
measured, it can communicate the necessary correlations to the other
particle. Since in relativity the notion of simultaneity is not
absolute, this is unattractive. One idea is to replace instantaneous
communication with a process that travels backwards in time along the
past Light cone. This is the idea behind a transactional interpretation
of quantum mechanics, which interprets the statistical emergence of a
quantum history as a gradual coming to agreement between histories that
go both forward and backward in time.^[24]

Bell's Inequality -- theoretical challenges

 

So it sounds, if Bell's inequalities are true, that the paradox of the OP has yet been considered sufficient to rule out some interpretations of QM. Huh....

[elfmotat]

 

So it sounds, if Bell's inequalities are true, that the paradox of the OP has yet been considered sufficient to rule out some interpretations of QM. Huh....

 

They're not just interpretations. Bell rules out all local hidden variable theories, i.e. theories in which the state of particles is determined by some unobservable deterministic variables. I believe Feynman said something along the lines of "Nature itself doesn't know what the answer is going to be."

[Iggy]

They're not just interpretations. Bell rules out all local hidden variable theories,

 

The article was referring to non-local hidden variables. It said explicitly.

[elfmotat]

The article was referring to non-local hidden variables. It said explicitly.

 

Bell's Theorem applies to local hidden variable theories. The article discusses possible ways around this, with non-local variables etc.

Edited February 13, 2013 by elfmotat

[swansont]

But if instantaneously simultaneous doesn't mean the same from multiple frames of reference, what does it mean?

 

Ignoring the QM for a moment, instantaneous communication removes the simultaneity issue. Simultaneity is intimately tied in with information traveling at c. In a way, instantaneous collapse is the same behavior as having the items co-located.

[Iggy]

Bell's Theorem applies to local hidden variable theories. The article discusses possible ways around this, with non-local variables etc.

 

Yes it does and yes it did, but the portion I quoted started "A 2007 experiment ruled out a large class of non-Bohmian non-local hidden variable theories.^[23]"

 

If you don't understand that sentence to mean "non-local hidden variable theories" (as it so plainly says) being ruled out then I don't know what I could say to make it more clear to you.

[elfmotat]

 

Yes it does and yes it did, but the portion I quoted started "A 2007 experiment ruled out a large class of non-Bohmian non-local hidden variable theories.^[23]"

 

If you don't understand that sentence to mean "non-local hidden variable theories" (as it so plainly says) being ruled out then I don't know what I could say to make it more clear to you.

This is getting annoying now. YOU were the one who brought up how Bell rules out some hidden variable theories. The only hidden variables Bell applies to are local. Your original comment on the article had nothing to do with the 2007 experiment, and my response was completely valid.

 

It seems like you're just trying to find nonsense to argue with.

[Iggy]

This is getting annoying now. YOU were the one who brought up how Bell rules out some hidden variable theories. The only hidden variables Bell applies to are local. Your original comment on the article had nothing to do with the 2007 experiment, and my response was completely valid.

 

It seems like you're just trying to find nonsense to argue with.

 

I see. I should have said 'leggett inequalities' perhaps. The one sentence summary, and not the many sentences that preceded it, were your only concern, and all you were replying to. Your pedantic incessant writing is exhausting.

 

Look at the quoted material and the post history and figure out the context! The relativity of simultaneity does matter when choosing between non-local theories. "instantaneous" (which is by one account different from "simultaneous" ) is non-local. Nobody here is talking about anything other.

Edited February 13, 2013 by Iggy

[md65536]

I suppose the scenario boils down to "can all frames of reference measure disentanglement happening at the time "time" because the correlation is true regardless of time?" I mean, it's an instantaneous process, and the disentanglement happens for both instantaneously simultaneously yet time is still relative, so far I have not seen any clear solutions, the issue mainly stems from this http://en.wikipedia.org/wiki/Relativity_of_simultaneity

I don't know if a better answer to this has already been given.

 

I don't think "measuring disentanglement" at a particular time makes sense? You seem to be assuming that if a measurement at A is made, then there is an instantaneous change at B that is measurable at B, as if B can detect (ie "know") that A has made a measurement. That's not how it works. That would constitute a transfer of information.

 

It should be simple to set up an experiment where each of A and B can be certain that each measures one of a pair of entangled particles "first" before the other. So there is no absolute "at the same time". There is no measurable information at either A or B in isolation that says what happened at the other, except when information from the two is combined by "normal" means (information transmitted at speeds <= c). I guess there's a paradox if you're stuck using classical intuition... what is described happening by A is not the same as what is described happening by B... BUT bring their information together and it will be consistent. I guess the description of what's "really" happening and the resolution to any paradox depends on a particular interpretation of QM.