Is Bell's Theorem a Valid Solution to the Locality Versus Nonlocality Issue?

[Rap]

Experimentally, I can measure with a very high precision the position of a single photon on the screen after going through a double slit. QM can't predict the position of a single photon on the screen, therefore QM is not a be-all and end-all theory. Period. Single events happen all the time, yet QM can not predict any single events. That should be enough to humble QM worshipers.

...claiming that QM is the final physical theory which is good enough and we should stop looking for a better theory which can explain single events is worshipping QM. Claiming that anything in nature which is not explained by QM is not real, is worshiping QM. It is also called the Mind Projection Fallacy. Jaynes explains in the article I cited above:

The fact that QM cannot predict a single event does not constitute a proof that it is "incomplete". I am open to the possibility that it is, however, but not by this route.

The statements:

*If A is true then X is false.*
*If A is false then X is true.*

Have only one truth value (true or false). They can not be valid at one time and invalid at another time. They can not be true at one time and false at another time. They are statements about the logical relationship between the truth values of two entities (A and X). They are not a statements about X only, or about A only.

Of course, that is true, but these are not the statements I am referring to. I am referring to the ones that I wrote, which distinguish between prediction (the first set) and measurement (the second set), a distinction which Jaynes urges you to make in the quote that you provided.

To see this, give the statements to Alice and Bob. Alice enters the room and performs the experiment without Bob knowing that an experiment has been performed.

According to you, Bobs knowledge has instantaneously been changed (made irrelevant) just because Alice made a measurement. So how then is Bob ever supposed to know what part of his knowledge is relevant and what part is not, if he does not have access to all the experiments that have been performed?

The wave function is not ontological, it is a mathematical compilation of the scientists knowledge resulting from measurements on a system over which he has control e.g. the ability to isolate the system. When Alice makes a measurement, her wave function collapses. If Bob doesn't know that Alice made a measurement, then his control of the system is incomplete, and his compiliation of knowledge (his wave function) will be incorrect. If he does know that Alice made a measurement, then she and her results will be a superposition of possibilities. When he learns of Alice's measurement outcome, he can call that part of his knowledge and collapse his wavefunction accordingly.

- Every QM prediction is conditioned on the experimental preparation: *If x is measured you obtain y* etc as I have explained.
- QM predictions for P(a,b), P(b,c), P(a,c) can never be simultaneously measured, therefore, according to you, as soon as Alice and Bob set their devices to (a,b) and do the measurement, P(b,c) and P(a,c) become *irrelevant*.

Yes. Now you are making the distinction between prediction and measurement, and I agree.

If we are to go with your CFD definition and approach, we will end up with the conclusion that Bell's inequalities require irrelevant parameters to be used at the same time as relevant ones. So why is that the problem of any local realistic theory rather than Bell's problem? Why is that natures problem rather than Bell's?? (cf. Mind Projection Fallacy)

We will not require irrelevant parameters to be used. They are to be ignored, because they are irrelevant. They are counterfactual. They are post-measurement, not pre-measurement predictions, a distinction Jaynes urges me to make. To ignore them is to reject CFD.

My main argument in this thread has been to point out to you that it is impossible to test Bell's inequality experimentally because it uses three simultaneous values in its derivation where only two can ever be measured experimentally. Why is this not sufficient reason to you why a violation is obtained. You haven't responded to this argument yet. Nobody has.

I will respond
1) I agree with you totally, it is impossible to test Bell's inequality experimentally, unless you assume that counterfactual (unmeasured) correlations have meaning, even if the statement about the correlations is true as a pre-measurment prediction.
2) The fact that it is impossible does not automatically imply a violation of Bell's inequalities.

 

[billschnieder]

Of course, that is true, but these are not the statements I am referring to. I am referring to the ones that I wrote, which distinguish between prediction (the first set) and measurement (the second set), a distinction which Jaynes urges you to make in the quote that you provided.

I see that we are making some progress but for this one issue concerning the meaning of CFD, which you are bent on defining in a manner that it becomes convenient to reject. But my point to you has been to point out that if CFD is what you say it is, it can be rejected immediately without any inequality or other test because it is nonsensical.

I also notice that you carefully rewrote the statements I wrote so that they involve an aspect of prediction in them, and despite my deliberate effort to generalize, you want to restrict CFD to only the predictive case. But this is wrong because CFD is not restricted to what you are suggesting. The correct meaning of CFD applies to the statements as I phrased them as well and you can not reject CFD for "your" type of statements without rejecting it for "my" type of statements as well.

If Bob doesn't know that Alice made a measurement, then his control of the system is incomplete, and his compiliation of knowledge (his wave function) will be incorrect. If he does know that Alice made a measurement, then she and her results will be a superposition of possibilities. When he learns of Alice's measurement outcome, he can call that part of his knowledge and collapse his wavefunction accordingly.

I'm surprised you still do not see the problem in the scenario where Bob makes a valid prediction such as *If the setting is B then the outcome will be X*, Alice makes a valid prediction such as *If the setting is A then the outcome will be Y*. Then just because only one of setting A or B but not both can be applied, you are suggesting above that if Alice performed the experiment with setting A, then Bobs prediction is incorrect! I'm baffled that you still do not see the problem with this faulty logic.

*We will not require irrelevant parameters to be used. They are to be ignored, because they are irrelevant.*

On what grounds? To be used for what?

They are counterfactual. They are post-measurement, not pre-measurement predictions

So then you agree that according to this view, previously valid QM predictions become invalid post-measurement if they are counterfactual? If you do, then I think you are just playing semantic games here because the following two statements are equivalent CFD statements about the initial proposition:

- If X is measured on the result will be Y
CFD1: Had X been measured yesterday, Y would have been obtained
CFD2: Prior to Yesterday, it was predicted that if X is measured the result would be Y, but X was not measured, and can no longer be measured.

You can not reject CFD1, without rejecting CFD2.
In short, I'm trying to get you to admit that *rejecting CFD* is not the same as *rejecting the use of CFD variables in Bell's inequalities*. The former is making a statement about logic as a whole, the second is making a statement about the compatibility between Bell's inequalities and CFD
[/quote]

I will respond
1) I agree with you totally, it is impossible to test Bell's inequality experimentally, unless you assume that counterfactual (unmeasured) correlations have meaning, even if the statement about the correlations is true as a pre-measurment prediction.
2) The fact that it is impossible does not automatically imply a violation of Bell's inequalities.

1) The statement in bold is false. It is impossible whether or not counterfactual correlations have meaning or not. If you still think it is only impossible if you assume that counterfactual correlations have meaning, please explain how to perform such an experiment. This is what you haven't understood.
2) Then you did not understand the triangle inequality example which was meant to explain precisely this point. It demonstrates clearly that a violation of a trivial inequality is obtained as soon as you replace unmeasurable properties with averages from three different populations, as is commonly done in Bell test experiments. This has been proven rigorously for the Bell case, in the paper mentioned in the opening post.

I've just about exhausted my explaining capabilities and if it is still not clear, then I guess you do not want it to be clear, or your mind is made up and nothing I say matters.

 

[Rap]

I see that we are making some progress but for this one issue concerning the meaning of CFD, which you are bent on defining in a manner that it becomes convenient to reject. But my point to you has been to point out that if CFD is what you say it is, it can be rejected immediately without any inequality or other test because it is nonsensical.

I also notice that you carefully rewrote the statements I wrote so that they involve an aspect of prediction in them, and despite my deliberate effort to generalize, you want to restrict CFD to only the predictive case. But this is wrong because CFD is not restricted to what you are suggesting. The correct meaning of CFD applies to the statements as I phrased them as well and you can not reject CFD for "your" type of statements without rejecting it for "my" type of statements as well.

"Counterfactual" refers to a statement which has no basis in measured fact. It is a hypothetical, not an actual. It always involves the word "if". It can only apply to predictive statements. There can be no counterfactual statement about a measurement after the measurement has been made. After a measurement is made, it is factual, not counterfactual. There is no "if" involved. Counterfactual definiteness means that the counterfactual statement may be used as if it were factual. In classical physics, a true counterfactual statement is generally true post measurement, because a measurement does not alter a probability distribution regarding future measurements. Measurements are yes/no, a delta function probability. To reject CFD is not to declare a counterfactual statement false, it is to render its truth value null. "If Bob had set his detector to A he would have measured X" is a counterfactual statement. To reject CFD is not to declare that it was false pre-measurement, it is to declare that it has no standing post-measurement. It cannot be used in the same way as "Bob set his detector to A and measured X"

I cannot think of any more ways to express it right now. I dislike semantic arguments, so, for the sake of this argument, I will call this concept whatever you wish, like RAPCFD and you can define counterfactual and CFD to your liking, call it BILLCFD Just so long as we are clear on definitions, I don't care what name tag a concept is wearing. I am curious as to why RAPCFD is nonsensical?

I'm surprised you still do not see the problem in the scenario where Bob makes a valid prediction such as *If the setting is B then the outcome will be X*, Alice makes a valid prediction such as *If the setting is A then the outcome will be Y*. Then just because only one of setting A or B but not both can be applied, you are suggesting above that if Alice performed the experiment with setting A, then Bobs prediction is incorrect! I'm baffled that you still do not see the problem with this faulty logic.

According to you, Bobs knowledge has instantaneously been changed (made irrelevant) just because Alice made a measurement. So how then is Bob ever supposed to know what part of his knowledge is relevant and what part is not, if he does not have access to all the experiments that have been performed?"

No that's not the scenario I responded to. You wrote "To see this, give the statements to Alice and Bob. Alice enters the room and performs the experiment without Bob knowing that an experiment has been performed.I wrote: "We will not require irrelevant parameters to be used. They are to be ignored, because they are irrelevant."
You wrote: On what grounds? To be used for what?
I repeat: We will NOT require irrelevant parameters to be used. You seem to be responding to what you expect me to say rather than to what I am saying.

So then you agree that according to this view, previously valid QM predictions become invalid post-measurement if they are counterfactual? If you do, then I think you are just playing semantic games here because the following two statements are equivalent CFD statements about the initial proposition:

- If X is measured on the result will be Y
CFD1: Had X been measured yesterday, Y would have been obtained
CFD2: Prior to Yesterday, it was predicted that if X is measured the result would be Y, but X was not measured, and can no longer be measured.

You can not reject CFD1, without rejecting CFD2.
In short, I'm trying to get you to admit that *rejecting CFD* is not the same as *rejecting the use of CFD variables in Bell's inequalities*. The former is making a statement about logic as a whole, the second is making a statement about the compatibility between Bell's inequalities and CFD

Ok, yes, I am not saying that all counterfactual statements are null and void (nor am I saying some are). I agree that rejecting all RAPCFD is not the same as rejecting the use of CFD variables in Bell's inequalities.

1) The statement in bold is false. It is impossible whether or not counterfactual correlations have meaning or not. If you still think it is only impossible if you assume that counterfactual correlations have meaning, please explain how to perform such an experiment. This is what you haven't understood.

You cannot perform such an experiment - that is exactly what makes them counterfactual, by definition. To assume RAPCFD is to say that those counterfactual correlations can be used AS IF they were factual. This is what must be done to obtain the Bell paradox, and then go about resolving it with superluminal action at a distance, non-locality, etc.

2) Then you did not understand the triangle inequality example which was meant to explain precisely this point. It demonstrates clearly that a violation of a trivial inequality is obtained as soon as you replace unmeasurable properties with averages from three different populations, as is commonly done in Bell test experiments. This has been proven rigorously for the Bell case, in the paper mentioned in the opening post.

Then in that sense, you have succeeded. I agree that you cannot replace unmeasureable properties with averages from three different populations. But I do not agree that a violation of a trivial inequality will always be obtained when you do. In the case of Bell, for example, hidden variables might cause no violation of the inequalities, even tho the averages are from different populations.

I've just about exhausted my explaining capabilities and if it is still not clear, then I guess you do not want it to be clear, or your mind is made up and nothing I say matters.

Third possibility: I want it to be clear, my mind is not made up, and we are not communicating very well.

 

[billschnieder]

"Counterfactual" refers to a statement which has no basis in measured fact.

Wrong!

counterfactual (plural counterfactuals)

1. A claim, hypothesis, or other belief that is contrary to the facts.
2. (philosophy) A conditional statement in which the conditional clause is false, as "If I had arrived on time ..."

There is nothing about measurement!

It always involves the word "if".

Yes, it must be a conditioning statement (cf definition (2) above).

It can only apply to predictive statements.

Wrong! There is no restriction. A counterfactual statement is simply a conditional statement in which the conditioning clause is actually false. It can be any kind of statement. For example:

"If I were a woman, then I won't be called Bill" is a counterfactual statement, and has nothing to do with a prediction or measurement. All that you need is for the condition/protasis to be *contrary to fact* -- ie, I am actually not a woman.

There can be no counterfactual statement about a measurement after the measurement has been made.

Wrong!

"If I had measured x, I will have obtained y" is a counterfactual statement so long as x was actually not measured. What classifies the statement as "counter-factual" is the fact that the condition/protasis/antecedent is contrary to fact, ie -- I did not measure x. It is obvious therefore that unless a measurement was actually made, you do not have any counterfactual statement, contrary to your claim. In other words, a measurement contrary to the protasis is required, in order to render the statement counterfactual. So you are woefully mistaken, not only can a counterfactual statement be made about a measurement after the measurement has been made, in the above example, it depends on the measurement having been made already.

After a measurement is made, it is factual, not counterfactual.

You are confused. After a measurement, the protasis may be true or false without changing the validity of the statement as whole. If the protasis is true, then the statement as a whole is not counterfactual, otherwise the statement as whole is counterfactual. A counterfactual statement is not the opposite of a factual statement since a counterfactual statement can also be factual.

There is no "if" involved.

Wrong again! You are separating the apodosis from the protasis and that is what is getting you confused. Note a counterfactual statement does not mean the statement is False. It simply means the protasis "If ..." is in fact false. A counterfactual statement can be a factual statement as well. Remember that "counterfactual" is describing the whole statement not parts of it. The truth value of the whole statement is different from the truth value of it's parts.

Let "If X is True, then Y is true" be the root statement under consideration.

The counterfactual statement (in the situation in which X is in fact False) is then:

"If X were True, then Y would be true".

Three different facts are involved:
1) X is True
2) Y is True
3) (X=True) implies (Y=True)
The counterfactual statement only makes claims about statement (3) ie, the relationship between the truth values of X and Y. (3) can be True even if X is false. Just because X is false, does not mean the relationship between the truth value of X and that of Y is not as claimed in statement (3).

Counterfactual definiteness means that the counterfactual statement may be used as if it were factual.

Exactly. But you are confused because you assume that if the counterfactual statement is factual, it means the all parts of it are individually factual. Which is naive and I have been trying to point out to you. Statement (3) above encapsulates a different "fact" from statements (1) and (2). (1) encapsulates the truth value of X, (2) encapsulates the truth value of Y, (3) encapsulates the relationship between the truth values of X and Y. The third fact does not care whether X or Y are true or false. All it cares about is the relationship between their truth values. The counterfactual statement makes that even more apparent by making the claim even when it is a fact that X is false. A counterfactual statement does not mean the whole statement is contrary to fact. It simply means the condition/protasis/antecedent is contrary to fact not the whole statement.

To reject CFD is not to declare a counterfactual statement false, it is to render its truth value null.

This is nonsense. What does it mean to for the truth value of a statement to be null? There is no such thing. A statement is either True or False, there is no middle ground. You are trying to sneak in a third "null" option.

"If Bob had set his detector to A he would have measured X" is a counterfactual statement. To reject CFD is not to declare that it was false pre-measurement, it is to declare that it has no standing post-measurement.

Again this is nonsense. What does it mean for a statement to have "no standing". You are simply inventing on-the-fly ways of describing statements. Apparently you are finding it even more difficult to "reject CFD" or even explain what you mean by "reject CFD" -- which means you at least understand some of what I have been explaining.

I cannot think of any more ways to express it right now. I dislike semantic arguments, so, for the sake of this argument, I will call this concept whatever you wish, like RAPCFD and you can define counterfactual and CFD to your liking, call it BILLCFD Just so long as we are clear on definitions, I don't care what name tag a concept is wearing. I am curious as to why RAPCFD is nonsensical?

I have already explained above. But RAPCFD is nonsensical because if you define CFD such that the statement's truth value changes upon measurement from true to "null" (whatever that means), and the only part of the statement which was actually affected by the measurement was the protasis/antecedent/conditioning clause, then you are saying the relationship between the truth values of the protasis and the apodosis depends on the individual truth value of the protasis. Which is illogical.

You cannot perform such an experiment - that is exactly what makes them counterfactual, by definition. To assume RAPCFD is to say that those counterfactual correlations can be used AS IF they were factual. This is what must be done to obtain the Bell paradox, and then go about resolving it with superluminal action at a distance, non-locality, etc.

But if the QM predictions result in violation then according to the above, they are also not "factual"!? So by rejecting RAPCFD, you are rejecting QM as well. However, as I have explained over and over, the problem with Bell inequalities is not because the correlations are not factual. You still haven't understood the difference between a statement being "True"/"Factual" and a statement being "Actual". That is why I spent a lot of time trying to point to you the error in your view about the meaning of CFD because this misunderstanding is at its root. What must be done to obtain Bell paradox is to use correlations which although all "factual", cannot all be simultaneously "actual". Just because a statement is factual does not mean it can be used in Bell's inequalities. This is the origin of the violation. The inequalities represent relationships between ACTUAL correlations since they are derived from the perspective of an omniscient being who has knowledge of them without needing any measurements. However, those ACTUAL correlations can never be measured because only pairs can be measured in any actual experiment.

If you take anything at all out of this discussion it should be this: "Everything that is actual is factual, but not everything that is factual is actual" In this statement lies all of your misunderstanding, that the explanation for the violation of Bell's inequalities. When QM makes predictions about P(a,b), P(b,c), P(a,c), each of those predictions is accurate/factual/True. But only one of those can be actual at a given moment. It is therefore a logical error to take all those terms and use them simultaneously in the same expression which was based on three actual correlations. QM can not give you three actual correlations because it is impossible to measure them. This is the origin of the violation. It has nothing to do with "realism" or "locality" whatsoever.

 

[DrChinese]

... When QM makes predictions about P(a,b), P(b,c), P(a,c), each of those predictions is accurate/factual/True. But only one of those can be actual at a given moment. It is therefore a logical error to take all those terms and use them simultaneously in the same expression which was based on three actual correlations. QM can not give you three actual correlations because it is impossible to measure them. ...

I entirely agree with this statement. So when you try to run calculations assuming all 3 true simultaneously, Bell obtained his famous violation. So our conclusion would be that realism fails.

 

[billschnieder]

I entirely agree with this statement. So when you try to run calculations assuming all 3 true simultaneously, Bell obtained his famous violation. So our conclusion would be that realism fails.

Wrong! You are confused between "possiblities" and "actualities" If anything, what should have been clear from the above discussion is the following:

"Everything that is *actual* is *possible*, but not everything that is *possible* is actual"

You are also confused between "hidden particle properties" and "experiment outcomes".

A prediction about an experimental outcome such as P(a,b) is a conditional statement, premised on the exact experimental conditions -- of the form:

If Alice and Bob measure along a and b, the result will be P(a,b)
Such statements are not *actualities*, but *possibilities*. All *possibilities* are simultaneously true. Again remember that to say a *possibility* is true, means the relationship between the antecedent and the consequent is correct and valid. It does not mean the antecendent alone is true or the consequent alone is true. (See my previous post on more about this). It is easy to get confused about this if you erroneously strip of conditioning clauses. This is fully consistent with realism. Since the prediction is relying on the existence of hidden properties in the particles and the instrument, which together with the settings will give the results.

However, you run into problems when you confuse such predictions with properties. And expect each particle to *possess* an outcome. This is obviously what you and most Bell proponents are doing, and I hope it is becoming apparent to you from the other De Raedt thread about datasets.

Having naively confused such *possiblities* to be *actualities*, you start wondering why they violate Bell's inequality which is also based on *actualities*. You then naively conclude that since these "actualities" (according to you) violate Bell's inequality it means realism is false, since realism requires that *actualities* be simultaneously actual.

But as I have pointed out to you and explained a hundred different ways in this thread already, the violation is not due to the failure of the realistic statement that:

"All actualities are simultaneously actual"

The violation is due to the faulty and naive understanding of realism to be equivalent to:

"All possibilities are simultaneously actual"
Where in your mind you haven't made the clear distinction between an actuality and a possibility. I find that this mistake is made mostly by those who do not have a clear grasp of the difference between ontology and epistemology. An actuality is ontological, a possiblities is epistemological.

NOTE! All possibilities ARE simultaneously TRUE, but that does not mean all possibilities are simultaneously *actual*. Realism implies simultaneous actuality, and since everything that is simultaneously actual is simultaneously possible, everything that is real is simultaneously possible as well. However, this does not mean everything that is simultaneously "possible" is simultaneously "actual". This is the syllogistic fallacy often committed by Bellists when they try to interpret the EPR paper. In the case of Bell's inequalities, we just happened to have an expression in which all the "possible" terms were not and can NEVER be simultaneously "actual". So when a violation is obtained, Bellists fallaciously proclaim the failure of realism.

The terms in Bell's inequality are actualities to an omniscient observer who does not need to make any measurements. But to QM and Experiments, those terms can NEVER be realized in any experiment because only two measurements can be made for any particle pair. Therefore Bell's inequalities can NEVER be tested in any experiment which is possible. It is limited to the realm of impossible gedanken experiments and omniscient beings. The results from real experiments and predicted by QM, therefore correspond to a different experiment than that modeled by Bell, hence the violation. All attempts to derive inequalities compatible with these experiments have resulted in inequalities which are never violated by QM or experiment as mentioned in the article linked from the OP.

Case closed. If the above is still not clear to any Bellist, I will be happy to explain from yet another perspective.

-------
Truth can never be told so as to be understood, and not be believed. -William Blake

 

[DrChinese]

Case closed.

Can you close the JonBenet case as easily? Now that would be helpful.

You live in an interesting world. I mean an interesting fantasy world. One which, by most folks definition, is NOT realistic. Get it? You are not a realist! You just think you are. By my definition, you and I agree that Bell realism is not tenable and that there is no sense to ascribe reality to observables which cannot be measured simultaneously. That is fully consistent with the HUP. The point of EPR was that the HUP could be beaten (since QM was not complete in their eyes). But we now know that is not true.

(By the way, you are sounding more like Yoda every day. Actualities, possibilities...)

 

[billschnieder]

Can you close the JonBenet case as easily? Now that would be helpful.

You live in an interesting world. I mean an interesting fantasy world. One which, by most folks definition, is NOT realistic. Get it? You are not a realist! You just think you are. By my definition, you and I agree that Bell realism is not tenable and that there is no sense to ascribe reality to observables which cannot be measured simultaneously. That is fully consistent with the HUP. The point of EPR was that the HUP could be beaten (since QM was not complete in their eyes). But we now know that is not true.

No. You live in a fantasy world. I see that you agree with everything I said (since you have no argument against it) yet you just do not accept it. Instead of changing your previously held misconceptions, you persist and try to imply that the reason you agree with me is because I really believe the same things like you do. I wonder what that is called?

You call me a non-realist just because that is what you are, but let us see -- you believe particles do not have properties independent of measurement (cf the moon is not there where nobody is looking), I believe particles have properties independent of measurement. That makes you a non-realist, and makes me a realist. It will become evident (if not already) from the "dataset request" thread, that we are worlds apart. So if you want to agree with me and stay honest, you will have to shed some of your misconceptions.

(By the way, you are sounding more like Yoda every day. Actualities, possibilities...)

Thanks for the compliment. I like Yoda.

-------
Truth can never be told so as to be understood, and not be believed. -William Blake

 

[harrylin]

[..]
You call me a non-realist just because that is what you are, but let us see -- you believe particles do not have properties independent of measurement (cf the moon is not there where nobody is looking), I believe particles have properties independent of measurement. That makes you a non-realist, and makes me a realist. It will become evident (if not already) from the "dataset request" thread, that we are worlds apart. So if you want to agree with me and stay honest, you will have to shed some of your misconceptions.

Thanks for the compliment. I like Yoda.

I also like Yoda, and datasets - what became of that? [edit] Oh OK I now see that it's in the thread on Boole vs Bell. I'll try to follow it and discover what it has to do with Boole, if anything .

 

[billschnieder]

I also like Yoda, and datasets - what became of that? [edit] Oh OK I now see that it's in the thread on Boole vs Bell. I'll try to follow it and discover what it has to do with Boole, if anything .

Yes it has to do with Boole because Boole derived Bell-like inequalities and called them "conditions of possible experience". ie, according to Boole, Bell-like inequalities can never be violated if the variables involved can be *simultaneously experienced* (cf. actualities, simultaneous existence, realism); But if the "dataset" being requested is not from an experiment and can not be simultaneously experienced (cf. DrC's dataset request), a violation should be expected.

 

[billschnieder]

By my definition, you and I agree that Bell realism is not tenable and that there is no sense to ascribe reality to observables which cannot be measured simultaneously.

So then let us see exactly what you have conceded to:

a) What you call "Bell Realism", is the idea that all "observables", even those which can not be measured simultaneously are simultaneously real. I have explained why such a definition of "realism" is ridiculous and does not need any inequalities or experiments to reject outright.

b) "Realism" as used by EPR means particles have objective properties independent of measurement. I have explained why the fact that "observables" correspond to "real" properties of particles does not and can not be assumed to mean the corresponding "observables" must be simultaneously real themselves.

So then the following are obvious implications and you have also conceded these (by not contesting them)

c) Since the EPR "realism" is obviously different from what you call "Bell realism", violation of Bell's inequality can not and should not be interpreted to mean "particles do not have objective properties independent of observation". Rather, it should be interpreted to mean "particles do not have observables independent of observation". Phrased correctly as such, it becomes obviously an tautology, without need of any fanfare. Since by definition, an observable is an outcome of an observation and if no observation is made, the observable can not be said to exist.

d) The terms contained in Bell's inequality involve observables which can never by simultaneously measured. Therefore a genuine Bell test is impossible.

 

[DrChinese]

Since the EPR "realism" is obviously different from what you call "Bell realism", violation of Bell's inequality can not and should not be interpreted to mean "particles do not have objective properties independent of observation". Rather, it should be interpreted to mean "particles do not have observables independent of observation".

Einstein would appreciate the humor of your words. And of course Bell realism and EPR realism are considered equivalent for all practical purposes. I think everyone knows that an observable is different from a particle property, just as a word is different than what it represents. It is the correspondence between these that is relevant.

But hey, you can lead a donkey to water but you can't make him drink. But he still looks funny with that straw hat.

 

[billschnieder]

Einstein would appreciate the humor of your words. And of course Bell realism and EPR realism are considered equivalent for all practical purposes.

I had missed this ridiculous response. If as you insist Bell realism means "observables exist independent of observation", then Bell realism is definitely different from EPR realism and anyone who considers them equivalent does not deserve to be called a scientist.

I think everyone knows that an observable is different from a particle property, just as a word is different than what it represents. It is the correspondence between these that is relevant.

Apparently not everyone understands correspondence is difference from equivalence. I'm baffled that you are so stubborn you do not want to swallow your pride and accept that you were wrong. As the following illustration demonstrates:

- Elements of reality = Wide spectrum wavelength photons from the sun
- Observation = DrC wears red goggles and looks at the sun
- Observable = Red Sun

- EPR: we can predict the observable with certainty, therefore there is an element of reality corresponding to that observable. We can predict that if DrC wears red goggles and looks at the sun, he will certainly see a red sun. Therefore there exists an element of reality (photons in the red-wavelength region) from the sun.

- DrC: Realism means the "Red Sun" observable exists even if DrC never wears red goggles and never looks at the sun.

- EPR: No. Realism mean the "elements of reality" ie, the red-wavelength photons, exist independently of the observation. Just because the "photons from the sun" exist independent of measurement, does not mean all observables like "red-sun" exist simultaneously independent of the actual observation.

- Drc: But hey, you can lead a donkey to water but you can't make him drink. But he still looks funny with that straw hat. (translation: my mind is made up, stop confusing me with the truth)

 

[DrChinese]

Realism mean the "elements of reality" ie, the red-wavelength photons, exist independently of the observation. Just because the "photons from the sun" exist independent of measurement, does not mean all observables like "red-sun" exist simultaneously independent of the actual observation.

My laff for the day! Thanks!

 

[harrylin]

[..]
- DrC: Realism means the "Red Sun" observable exists even if DrC never wears red goggles and never looks at the sun.

- EPR: No. Realism mean the "elements of reality" ie, the red-wavelength photons, exist independently of the observation. Just because the "photons from the sun" exist independent of measurement, does not mean all observables like "red-sun" exist simultaneously independent of the actual observation.
[..]

Great example - we thus detect "red sun" or "brown sun", but not simultaneously

 

[DrChinese]

Great example - we thus detect "red sun" or "brown sun", but not simultaneously

I am happy to agree that observables don't exist independent of the act of observation. We live in an observer dependent universe. Which is, by EPR's definition, non-realistic.

By the way, not only do I have 2 eyes... I also have friends with 2 eyes.

 

[harrylin]

I am happy to agree that observables don't exist independent of the act of observation. We live in an observer dependent universe. Which is, by EPR's definition, non-realistic.

By the way, not only do I have 2 eyes... I also have friends with 2 eyes.

That illustration doesn't apply in the sense of observations by friends of the same reality - and we know that you know that very well from your comments on the illustration with dissolved tablets in the other thread.
Note also that observer-dependence is perfectly compatible with realism, EPR or otherwise. The only thing that remains is your happy agreement that observables don't exist independent of the act of observation - Good!

 

[DrChinese]

Note also that observer-dependence is perfectly compatible with realism, EPR or otherwise. The only thing that remains is your happy agreement that observables don't exist independent of the act of observation - Good!

Again, your statement is directly contradicted by EPR's assertion that such view is "unreasonable". Of course, we now know EPR was wrong about observer independence *doesn't exist) and that [local] realism is INCOMPATIBLE with the facts.

 

[Gordon Watson]

I am happy to agree that observables don't exist independent of the act of observation. We live in an observer dependent universe. Which is, by EPR's definition, non-realistic.

By the way, not only do I have 2 eyes... I also have friends with 2 eyes.

..
Let's take you word on these alleged matter of fact; aware that you do have form at PF.

BUT harrylin wrote "Great example - we thus detect "red sun" or "brown sun", but not simultaneously!"

So I take it that you, DrC, are unaware that relativity prevents your "friends" being of any use to you re "simultaneity".

If you were less one-eyed, you might have use your alleged "two" eyes -- a different filter over each.

Alas: You'd still not observe "red" or "brown" simultaneously.

 

[DrChinese]

...
If you were less one-eyed, you might have use your alleged "two" eyes -- a different filter over each.

Alas: You'd still not observe "red" or "brown" simultaneously.

I might agree, but in all honesty that's a bit of semantics. Basically you are saying nothing is simultaneous in a technical sense. But I think that really begs the question. The realist says a particle has definite properties at all times, even where the related observables are non-commuting. And implied is that these exist simultaneously, and a more complete description of the particle would supply the values of the observables. So, do they exist simultaneously or not? If they do, then it is a bit unfair to require that their observation also be simultaneous - as that is not practical.