Graduate Interpretation of a state in quantum entanglement

[Boing3000]

Your statement is not responsive to the scenario I described, and the question I asked. Again, the scenario is that we have two entangled particles, which are then separated quite widely, perhaps all the way to alpha Centauri. Later, a measurement is done on one particle, achieving a "u" result, such that it is known the other particle will yield "u" if measured similarly.

You don't need to make extravagant and un-testable scenario with undefined "later it is known". You can do physics with 15km remote location for example.
In such a context the synchronization procedure is not questionable.

Then I posed this question: when did the second particle acquire the property "u"? You have not answered this question, nor is it true that there is some "unique proper coordinates" that provides an answer to the question I posed.

I did, but the simplicity of the response eludes you: proper time. If we are talking of photon, there is no way to modify the setup, because proper time is 0 anyway.
I propose we test using a perfectly non-arbitrary definition of time used along both beam. Thus you need massive particle like electron in a similar setup, and you need a beam twice as fast and twice as long, keeping both detector at equal distance from the source (yes that require some mirror)
Then we can test if the correlation still only dependent of the synchronization of filter clock, or if the proper time of the electron change the correlation.
It is possible (maybe not easy technologically) two distinguish between the time of the measurement, and the time of the measured. (in short sorting out between non-locality and realism)
I you test the "younger" particle first (frame lab) (even so lightly), is is no surprise (as per proper non-locality) that the correlation is reflected on the "older" particle
But if you test the "older" first, it is surprising that the correlation still holds. If it does hold non-locality loose some point. Does it ?

The issue is not if we can detect proper time, it is if we can detect when the property was acquired. That can only be done via the measurement, which then cannot tell you when it was acquired it can only tell you when the measurement was done.

Yes and measurement are done at some precise timing to know which pair of electron we measure, and where (in the lab frame). There is no issue to decide when the property is acquired, what "speed" that correlation is bound with, in whatever frame you see fit to analyse.
The example is more obvious with GR and gravitational time dilatation, but I think that is also quite a far-fetched experiment...

No, it isn't. A foliation is a way to parse the spatial and temporal coordinates separately, it is akin to choosing coordinates. Normally, we think of the "trunk" of the tree as the proper time of some observer, and we then "branch out" spatially in some way that has the flavor of being perpendicular to the proper time stream, but that perpendicularity is only local in GR.

You lost me there. As PeterDonis said, I probably meant the principle of relativity; where all clock ticks at one second per second, whatever your preferred coordinate choice is, there is only on time per word-line.

I would also want you to respond to how would you "align" filter detector orientation. (I understand how you would synchronize clock (you need SR/GR for that). I would like you to do so only by using QM, and not the proper geometry of beams. Because all I am saying is to take at face value that you cannot ignore SR/GR when doing any position/angle/timing measurement.

 

[Boing3000]

Proper time does not give a foliation of a spacetime. It doesn't even make a valid time coordinate, since an event that lies on multiple worldlines can have multiple proper times.

I am only interested in a hypothetical proper time of entanglement. Of testing/measuring it. I am pretty sure I will need to use detectors world line labelled with their own proper time and intersecting with it. That's the point actually.

 

[PeterDonis]

I am only interested in a hypothetical proper time of entanglement.

Proper time along the worldline of each entangled particle is well-defined, yes. But it doesn't give you a foliation of spacetime.

 

[Ken G]

You don't need to make extravagant and un-testable scenario with undefined "later it is known". You can do physics with 15km remote location for example.

I don't understand what you are claiming here, I do need the scenario I mentioned to bring up the issue that I wish the scenario to bring up. It is not relevant that other scenarios are possible that do not encounter this question.

 

[zonde]

Yes, what we know from experiment is that the constraint is applied somehow, and the issue for the discussion is more "when" is it applied, rather than "how" it is applied, as the former would seem to be easier to establish. However, my point is that it is not easier to establish, unless we say either that the "when" is "whenever the scientist used the notion", or for those with a more realist bent, the "when" is "whenever the measurement was done on the particle acquiring the property in question."

What type of improvement is it that you are arguing for? Do you mean it is better interpretation, better theory or just a better convention in communication?

But that's what Bell's theorem says it cannot be, in the sense that it cannot be a hidden local variable. So even if you hold that the property is intrinsic to the individual particle once acquired, it cannot be that the constraints on that acquisition are entirely intrinsic to the individual particle.

Yes, constraints can't be intrinsic to the particle. I completely agree with this. I believe I was not claiming anything like that.

The freedom to choose here is in asserting when the property is acquired. You are choosing to answer that by looking for a preferred foliation of spacetime that is unknowable, and although that is common in the language found, it suffers the same problems as all preferred reference frames in relativity: they never show up when you look for them. They are like the person on the roll call whose name is always called but never says "present and accounted for."

Problems like that are common for all interpretations. Non-local collapse is not an exception.

But why does checking against facts imply the properties are intrinsic to the particle? Properties are testable elements of experiments, so can only be said confidently to be intrinsic to the experiment. The experiment demonstrably involves particles, and an apparatus, and a scientist forming expectations and testing them. So the property can be intrinsic to any of those, or their combination, and still be a perfectly self-consistent element that is true to the scientific process.

I am not claiming certainty where there is none.
And no, properties are not testable elements of experiments. Only calculated expectations are.

Not entirely in the mind, no, but the mind is involved or it is not an experiment and cannot be shown to involve properties. So perhaps your objection is my claim that the properties are intrinsic to the analysis, but note that when I say that, I include in the analysis more than just the mind, there is also everything that the mind is making sense of-- they are all part of the analysis. So the analysis involves a mind that is considering data that comes from an apparatus that acts on a particle, those are all elements of the analysis so to say the property is intrinsic to the analysis means it is intrinsic to all of that. But the key point is, the "when" the property is acquired then has a clear answer: it is when the analysis is completed.

Experimentalist of course is involved in design of experiment. But beside that mind is not involved in experiment. Just like physical processes outside laboratory happen even when nobody is analyzing them with some model.

Sure, so "reality" is also part of the analysis.

No. Only correspondence to reality is analyzed. But that analysis is completely different. It's analysis about our confidence in the model.

But when you discover that properties cannot be said to be acquired by particles at particular times other than when you need to use the property, you can also start to speculate that your thinking process is playing a role in the meaning of a property. And that is the point where I start to think that this "property" is intrinsic to the analysis, and the analysis, which includes my mind, the apparatus, and the particles, is all I ever meant by "physical reality."

You can speculate whatever you want. Just check that at the end you can calculate the right expectations.

But I realize that last bit is not going to be accepted by realists, which is why my actual point here is a strong objection to the common language that when property u is measured on one particle, that property is "instantaneously" or "simultaneously" acquired by the other particle. That language is arbitrary, undefinable, and pretty close to meaningless, given what we know about relativity. So the realists should instead hold that properties are always acquired at the time of measurement on the particle in question, and nonrealists can hold that the property is acquired just when the information is available in the analysis, as properties are only a form of information and nothing more. Neither of those approaches requires giving some unknowable meaning to "simultaneity" across large distances.

That language (that a property is "simultaneously" acquired by the other particle) is meaningful within certain interpretation. You are free to not accept particular interpretation if you don't like it.
If you say that this language is common in interpretation independent descriptions of phenomena maybe you could give some example?

 

[Ken G]

What type of improvement is it that you are arguing for? Do you mean it is better interpretation, better theory or just a better convention in communication?

The improvement is the elimination of language that rests on the existence of an unknowable preferred reference frame. As such, it is precisely the same improvement that language about light propagation received when reference to an aether frame was dropped from the Lorentz transformation. So that would be a better interpretation and a better convenction in communication, though not a different theory because what is being dropped is unknowable and untestable.

And no, properties are not testable elements of experiments. Only calculated expectations are.

That's a what a property is. What else would be scientific?

Experimentalist of course is involved in design of experiment. But beside that mind is not involved in experiment. Just like physical processes outside laboratory happen even when nobody is analyzing them with some model.

This is a crucial aspect of nonrealism that a lot of people get wrong. To have a mind be involved does not require the mind be part of the apparatus, it only requires that a mind be used to say that an experiment happened and what that means. In fact, the mind is more important than the apparatus-- that's the whole concept of a "gedankenexperiment" after all! Certainly in a gedankenexperiment, a mind is not involved in the experiment, as there is no experiment, but that's not what mind "involvement" means-- one has no gedankenexperiment if there is no mind. Similarly, if we say the environment carried out an experiment when no one was around, it is we who are saying it, so our minds are demonstrably involved even when no mind is present on the scene-- as no mind is present on the scene in a gedankenexperiment either. I find it ironic that realists never object to gedankenexperiments, so they don't seem to recognize the inconsistency in allowing hypothetical apparatuses carrying out some measurement when there is no physical experiment present, while disallowing hypothetical minds doing the analysis when there is no physical scientist present!

No. Only correspondence to reality is analyzed. But that analysis is completely different. It's analysis about our confidence in the model.

You say "correspondence to reality," I just say "reality." My words are more direct, and more scientific as a result. Nonrealism is so much more pragmatic, more agnostic, more precise, and downright more realistic as a result.

You can speculate whatever you want. Just check that at the end you can calculate the right expectations.

We certainly agree that all science does is create and test expectations. That you want it to be expectations that "correspond to reality" is outside of the scientific method, as I pointed out above. What you are doing is distancing the results by forcing them to "correspond" to something, instead of just being what they are: results, period. But since I know you are going to do that, as you are a realist, I offer the alternative interpretation, that the properties are intrinsic to the particles, that the constraints on the particles are intrinsic to the system as a whole, and above all, that the properties are conveyed by the measurements on each particle individually.

That language (that a property is "simultaneously" acquired by the other particle) is meaningful within certain interpretation. You are free to not accept particular interpretation if you don't like it.

I can say precisely the same thing about the aether for light propagation. Indeed, I would, it is precisely the same attitude, and should be rejected for precisely the same reason: it never shows up when looked for. The scientist should never build their prejudices into their models-- if the prejudice never presents itself in any of the data, it is inevitable that it will eventually be dropped altogether.

If you say that this language is common in interpretation independent descriptions of phenomena maybe you could give some example?

Where did I say the language is common in "interpretation independent" descriptions? Would I say that reference to an aether is interpretation independent? I said only that it is common, which it clearly is. Here are quotes from several of the first google hits on entaglement:
https://en.wikipedia.org/wiki/Quantum_entanglement
"Recent experiments have measured entangled particles within less than one hundredth of a percent of the travel time of light between them.[7] According to the formalism of quantum theory, the effect of measurement happens instantly."
https://www.quantamagazine.org/entanglement-made-simple-20160428/
"We will, according to quantum theory, get those results even if great distances separate the two systems, and the measurements are performed nearly simultaneously."
https://www.sciencedaily.com/terms/quantum_entanglement.htm
"As a result, measurements performed on one system seem to be instantaneously influencing other systems entangled with it."

All three of those are expert articles, loaded with important insights into entanglement, and to be fair, the second one can be interpreted as saying that in some reference frame the measurements can be regarded as simultaneous, not that they are simultaneous, while the third one throws in the words "seems to", but nevertheless the casual reader will miss the significance of these subtle escape acts, and easily fall into the common trap of imagining that simultaneity is an unambiguously defined element of the entanglement phenomenon. It should instead be enough to state that the measurements are made outside each other's light cones, or that neither could send a subluminal message to the other. So why say that quantum mechanics predicts the outcomes occur "instantaneously" or "nearly simultaneously"? Those are strikingly naive remarks in contrast with the herculean efforts to describe the profound subtleties of entanglement. I understand why they are there, the nonexistence of simultaneity is simply not the point of the articles, but my point is that this kind of language is so widespread it becomes ossified into the lexicon, and pushing back against that is the purpose of this discourse.

 

[Boing3000]

I don't understand what you are claiming here, I do need the scenario I mentioned to bring up the issue that I wish the scenario to bring up. It is not relevant that other scenarios are possible that do not encounter this question.

Your question is "Then I posed this question: when did the second particle acquire the property "u"?" have been answered many times now. It have been answered for photon in the experiment referenced by synchronized clock reading on site A & B (some arbitrary choice)
In your impossible mind experiment, the easiest thing it that the electrons (I suppose) traveled to alpha centaur inside a boxes fitted with a clock.

Now let's not forget you haven't yet answer the very simple question about the same implicit rational you made in that statement:

Later, a measurement is done on one particle, achieving a "u" result

"Later" with respect to what ? And most importantly "up" with respect to what ? You don't seem to realize that "up" is as a relative notion than "time". And you don't seem to realize that relativity have a unique answer for both questions because it have a unique way to describe space-time geometry.

I take the simpler view not only to acknowledge you can define an absolute local "up" in both cases as you can define an absolute local "age" in both case. They came from the same theory.

 

[Ken G]

And most importantly "up" with respect to what ? You don't seem to realize that "up" is as a relative notion than "time".

Yes, I don't realize that-- because it isn't. There is a unique way to parallel transport the meaning of "up" along a worldline, otherwise conservation of angular momentum would be meaningless.

And you don't seem to realize that relativity have a unique answer for both questions because it have a unique way to describe space-time geometry.

Yes I don't realize that either. We have connections in relativity that allow parallel transport to be defined, but we do not have any connection that defines simultaneity in an invariant way.

I take the simpler view not only acknowledge you can define an absolute local "up" in both cases as you can define an absolute local "age" in both cases.

Of course you can define local age, that's called proper time. I've invoked that concept over and over, I invoke it to pose the question you seem to imagine you have answered but you have not: when in the proper time of each particle did they acquire the "u" property? If you think you've answered it, I'd sure like to hear what that answer was.

 

[Boing3000]

Yes, I don't realize that-- because it isn't. There is a unique way to parallel transport the meaning of "up" along a worldline, otherwise conservation of angular momentum would be meaningless.

Finally, we are making progress. Although computing it may be quite difficult, it is uniquely defined.

Yes I don't realize that either. We have connections in relativity that allow parallel transport to be defined, but we do not have any connection that defines simultaneity in an invariant way.

So you can defining alignment (which also is a identity of value) across large distance is OK. But strangely the other invariant "proper time" is not ?
What allows you to make a distinction between both ?

Of course you can define local age, that's called proper time. I've invoked that concept over and over, I invoke it to pose the question you seem to imagine you have answered but you have not: when in the proper time of each particle did they acquire the "u" property? If you think you've answered it, I'd sure like to hear what that answer was.

Well, you don't seem to be hearing the answer: The proper time of the particle at the event "interacting with the filter".
If you think you cannot use connections in relativity that allow proper time to be uniquely defined, you are just contradicting yourself.

 

[Ken G]

Finally, we are making progress. Although computing it may be quite difficult, it is uniquely defined.

Computing what? What are you talking about?

So you can defining alignment (which also is a identity of value) across large distance is OK. But strangely the other invariant "proper time" is not ?

You keep confusing the invariant proper time with the ability to mark simultaneous moments across two different proper time streams. It is the latter that does not exist, and that is what I am talking about. Obviously proper time itself is invariant, as I've said many times now.

Well, you don't seem to be hearing the answer: The proper time of the particle at the event "interacting with the filter".

This was one of the possibilities I offered above, so how could I not hear it? But unfortunately it's not what I'm talking about, I'm talking about the stress put on simultaneity in common descriptions of entanglement breaking. I don't think you have understood, simultaneity is quite different from proper time.

If you think you cannot use connections in relativity that allow proper time to be uniquely defined, you are just contradicting yourself.

I cannot contradict something I never said.

 

[zonde]

That's a what a property is. What else would be scientific?

Look, you take polarizer and test linearly polarized beam of light. Detector does not tell you polarization of beam. It tells you intensity of light (or number of "clicks" per time period if you use single photon detectors) with particular orientation of polarizer. This intensity is what you get as a result, not polarization (a property).

This is a crucial aspect of nonrealism that a lot of people get wrong.

I will not participate in discussion about nonrealism.

I can say precisely the same thing about the aether for light propagation. Indeed, I would, it is precisely the same attitude, and should be rejected for precisely the same reason: it never shows up when looked for.

Original "luminiferous aether" was falsified by experiment. This is the "eather" that was rejected exactly the way science works.
Then there was updated Lorentz version. It was never rejected because it made the same predictions as SR. It just dropped out of fashion probably because people got stuck on unanswerable question about preferred reference frame. People who quit asking that question just found other testable predictions and moved forward.
So if you claim that your approach should be accepted for the same reason just come up with interesting predictions using your approach that can be tested experimentally.

 

[Boing3000]

Computing what? What are you talking about?

I am talking at computing the curvature along the path of beams to align filter/mirror. I am quite sure that LIGO has done such homework.

You keep confusing the invariant proper time with the ability to mark simultaneous moments across two different proper time streams.

I don't confuse them at all. I can use any unambiguous mark of time to define simultaneity in experiment as well as any unambiguous mark of space to define alignment in experiment. Both are identity of non-local value (and both value are no event defined by QM)
Can you please give me a reference which explain why I cannot ?

But unfortunately it's not what I'm talking about, I'm talking about the stress put on simultaneity in common descriptions of entanglement breaking.

And that identity of timely value can be asserted by experiment as "easy" as can be asserted identity of alignment.
By doing so you can (in)validated by experiments whole categories of explanation. Bell simultaneous non-locality for example.

I don't think you have understood, simultaneity is quite different from proper time.I cannot contradict something I never said.

Your notion of simultaneity is as vague as the one used in QM. I don't think you understand that I suggest a way to get out of vague and undefined notion.
This way is totally identically to aligning filter. I do believe that if computing the alignment of detector leads us to setup our detector to face a totally different azimuth (with respect to the CMB for example). This is absolute direction with respect to the quantity tested. You have no ground to reject using the same physics with respect to identical time stamp (unambiguous simultaneity for the quantity tested).

 

[Ken G]

I can use any unambiguous mark of time to define simultaneity in experiment as well as any unambiguous mark of space to define alignment in experiment.

No.

Can you please give me a reference which explain why I cannot ?

Any special relativity textbook.

 

[Ken G]

I will not participate in discussion about nonrealism.

I didn't think you would, that's why I gave the realist possibility that does not involve arbitrary spacetime foliations: properties of particles are only acquired during measurements on the particle in question, even when entanglement exists.

Original "luminiferous aether" was falsified by experiment.

No, as soon as the Lorentz transformation was discovered (by experiment), the luminous aether became unfalsifiable. This is a fact, the Lorentz transformation completely covers the tracks of any preferred aether frame, so we cannot say such a frame is falsified, instead it is rendered unknowable in exactly the same way as the preferred foliation you spoke of for entanglement. The status is identically the same in both cases, but the aether is widely rejected because is it both unknowable and unnecessary-- just like your preferred foliation is.

Then there was updated Lorentz version.

The updated Lorentz version was simply the use of the Lorentz transformation to cover the tracks of the aether frame, as I said. The sole testable element is the Lorentz transformation, all else is interpretation, including the aether. Nevertheless, it is always inevitable that unknowable and unnecessary elements of any interpretation will eventually be dropped under the weight of its own uselessness.

It just dropped out of fashion probably because people got stuck on unanswerable question about preferred reference frame.

Exactly what I'm saying.

People who quit asking that question just found other testable predictions and moved forward.

Oh they did quite a bit more than quit asking the question! They concluded the aether frame was a red herring. This attitude is quite commonly found in textbooks.

So if you claim that your approach should be accepted for the same reason just come up with interesting predictions using your approach that can be tested experimentally.

As I said, the aether frame cannot be tested experimentally either, yet see what the textbooks have to say about it. Or consider the Wiki on the luminiferous aether:
"With the development of the special relativity, the need to account for a single universal frame of reference had disappeared – and acceptance of the 19th century theory of a luminiferous aether disappeared with it."
Nevertheless, Lorentz never abandoned the aether concept because what
"the theory of relativity has to say ... can be carried out independently of what one thinks of the aether and the time."
Yet special relativity is always devoid of an aether, all the same, and for no other reasons than what we are currently discussing about quantum entanglement. On this basis, I conclude there are only three internally consistent languages to talk about the acquisition of properties when entanglement breaks:
1) realists who believe in an aether can hold that there is some kind of instantaneous or simultaneous acquisition of properties by both particles, but their basis is no stronger than their belief in an aether,
2) realists who reject the aether must hold that the properties are acquired, for each particle, only at the time of measurement for that particle, or
3) nonrealists can hold that properties are elements of a scientific analysis and are acquired exactly when they are used in said analysis, i.e., the issue doesn't really even appear.