EPR Debate: Nature Agrees with Einstein

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In summary: It appears that Nature agrees with Einstein.In summary, Nature agrees with Einstein that the measurement of one photon affects the polarization of the other.
  • #1
JohnBarchak
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We have one big advantage over what Bohr and Einstein had in the 1935
EPR debate. We can actually perform the experiment. Let's see what Nature decides.

The Einstein point of view is that when the two photons are created, they both have a definite polarization that is negatively correlated with the other due to conservation of spin, but we do not know what they are. When one is measured, we then know the polarization of the other (it is the opposite polarization). Since both photons have a definite polarization from birth, there is no question of whether the measurement of one photon affects the polarization of the other. This is the core of Einstein's "element of reality" argument:
"If, without in any way disturbing the system, we can predict with certainty (i.e. with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity."

The QM point of view is that, after they are created, both photons exist in a state of superposition of all possible polarizations. Until measured, neither photon has a definite polarization. When one photon is measured, we now have the question of whether the polarization of the unmeasured photon is determined by the polarization of the measured photon. Here is Bohr's argument:
"The criterion of physical reality proposed by EPR contains an ambiguity as regards the meaning of the expression "without in any way disturbing the system." Of course, there is in a case like that just considered no question of a mechanical disturbance of the system under investigation during the last critical stage of the measuring procedure. But even at this stage there is essentially the question of an influence on the very conditions which define the possible types of predictions regarding the future behavior of the system.
Since these conditions constitute an inherent element of the description of any phenomena to which the term "physical reality" can be properly attached, we see that the argumentation of the mentioned authors does not justify their conclusions."

What does Nature say? Bennet, Brassard and Ekert did the foundation work for a famous crypto-system that is now the basis for several commercial products. Bennet, Brassard and Ekert say this:
"The EPR effect occurs when a spherically symmetric atom emits two photons in opposite directions toward two observers, Alice and Bob. The two photons are produced in an initial state of undefined polarization. But because of the symmetry of the initial state, the polarizations of the photons, when measured, must have opposite values, provided that the measurements are of the same type. For example, if Alice and Bob both measure rectilinear polarizations, they are each equally likely to record either a 0 (horizontal
polarization) or a 1 (vertical), but if Alice obtains a 0, Bob will certainly obtain a 1, and vice versa."

It appears that Nature agrees with Einstein.

All the best
John B.
 
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  • #2
JohnBarchak said:
It appears that Nature agrees with Einstein.

I missed the part where you connected Einstein's view to an experiment. Did you use a quantum eraser to eliminate that from the post? :smile:
 
  • #3
JohnBarchak said:
It appears that Nature agrees with Einstein.

No, it is exactly the opposite ! This is what Einstein took as an example of an absurd prediction of QM, to illustrate how absurd QM was. And when you do the experiment, the "absurd prediction" is verified !
 
  • #4
vanesch said:
No, it is exactly the opposite ! This is what Einstein took as an example of an absurd prediction of QM, to illustrate how absurd QM was. And when you do the experiment, the "absurd prediction" is verified !
Hmmm ... I'm afraid the problem here is that there are doubts regarding what really does happen in the experiments! When you use "entangled particles" in quantum key encryption, it is not, when you come to look into it, necessary that they obey QM. Ordinary correlation will do perfectly well so long as you have detectors able (when suitably orientated) to distinguish between vertical, horizontal and +-45 deg plane polarisation. No single orientation will enable you to actually find out what polarisation any particular signal has (this problem has always been with us: with polarising filters you need either a whole set of measurements or the use of crossed filters to find out the direction of polarisation of a beam). The QKD people cleverly get around this difficulty.

But I fear that what they say about the results of actual experiments may be just an approximation to the truth! The experimental behaviour, when they use PDC sources, is good enough for their purposes. They have no interest in the kind of source Aspect used, and little, I fear, in with whether or not a valid Bell test is violated.

With a source producing truly random polarisation directions, the statement that when you measure coincidences using parallel polarisers you always get perfect correlation is not quite true. For one thing, of course, most of the time when you get a count for one "photon" you get nothing registered for the other.

No, as far as I know, what you actually get (with a genuinely "rotationally invariant" (RI) source) is consistent with Einstein's idea but you have to make proper allowance for the operating characteristics of your apparatus before this becomes clear. You have to allow for the fact that when a polarising cube is used maybe any losses are concentrated around those signals that are not almost parallel or orthogonal to the cube axis. In addition, you have to allow for the likelihood that when the initial signals are very weak, after passage through a polariser and consequent reduction in intensity by (approximately at least) cos^2 (angle) only those signals whose polarisation direction was within, say, 30 deg of one of the polariser axes have a significant chance of detection. [See http://en.wikipedia.org/wiki/Local_hidden_variable_theory] [Broken]

But with PDC sources I have reason to believe that we very often get situations that are not rotationally invariant. The statistical properties of the outputs are quite different from the RI case. From the point of view of coincidence measurements, they are, in the extreme case, the same as sources in which the polarisation takes only one fixed direction. See:

Thompson, C H, “Rotational invariance, phase relationships and the quantum entanglement illusion”, http://arxiv.org/abs/quant-ph/9912082

Caroline
http://freespace.virgin.net/ch.thompson1/
 
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  • #5
Caroline Thompson said:
Hmmm ... I'm afraid the problem here is that there are doubts regarding what really does happen in the experiments!

Ok, the claim was that this cryptothing clearly indicated that Einstein was right and QM wrong. That's a fully wrong statement.

The experiments are fully in agreement with QM predictions (that means, the QM predictions of the experiment, including the QM prediction of the behaviour of all components in the experiment such as the source, the beam splitters, the polarizers, the detectors), and yes, there is still a possibility that one might, one day, find a theory, the way Einstein hoped, that also explains all of it, as the results do not rule that possibility out. In order to do so, one should need photodetetors which have a higher efficiency than 87%, and the current state of affairs is around 50%. As far as I know, no such theory is yet known, but you never know what might be invented in the future.

Is that a correct statement of the current state of affairs, Caroline ?

cheers,
Patrick.
 
  • #6
vanesch said:
... Is that a correct statement of the current state of affairs, Caroline ?
Yes, it looks fair enough, but I believe I've read somewhere that the people doing the QKD work recognise themselves that works even if there is no entanglement. If we want to satisfy ourselves finally as to whether or not entanglement of separated particles is a fact of this universe, we should look at actual Bell test experiments and not rely on QKD.

Caroline
 
  • #7
Hi Caroline

Hi Caroline
The EPR crypto-system is heavily time gated and coincidence checked, so they are definitely not dealing with raw photons. The commercial EPR crypto-systems behave exactly as Bennet, Brassard and Ekert say:
"If Alice and Bob both measure rectilinear polarizations, they are each equally likely to record either a 0 (horizontal polarization) or a 1 (vertical), but if Alice obtains a 0, Bob will certainly obtain a 1, and vice versa."

If it did not behave this way, it could not be a commercial product. If raw photons were being used, it just would not work. Between the time gating and coincidence detection, all of the wayward photons are culled out.

The really important LR issue is that these commercial crypto-systems are quite deterministic and causal. The fact is that if I want to build a deterministic and causal quantum system, I can. The universe is NOT stochastic as von Neumann's "silly" proof would lead you to believe.

Nice to see that you are still kicking and even having some fair successes - keep it up - LR *WILL* win out - All the best
John B.
 
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  • #8
You know, a great deal of this controversy could be eliminated by a higher quantum efficiency in detecting the photons, is that correct, Caroline?

If so, then photodetectors are the wrong way to go. CCDs are currently being made with QE in excess of 90%. With CTE (charge transfer efficiency) of over 99.999%, and similar signal amplifier efficiency and accuracy, this indicates that it should be possible to achieve the level of measurement that would prove or disprove the case for Aspect once and for all. Do you agree?

On edit: oops, forgot a http://www.calypso.org/~neill/cameras/hrcam/HRCamQE.html [Broken] to a private observatory's CCD specs. Note that this is not a government-funded observatory!
 
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  • #9
Einstein's Hypothesis

Here is Einstein's Hypothesis:
When the two photons are created, they both have a definite polarization that is negatively correlated with the other due to conservation of spin, but we do not know what they are. When one is measured, we then know the polarization of the other (it is the opposite polarization). Since both photons have a definite polarization from birth, there is no question of whether the measurement of one photon affects the polarization of the other.

Does anyone have a different hypothesis?

Regards
John B.
 
  • #10
JohnBarchak said:
Hi Caroline
If it did not behave this way, it could not be a commercial product.

Proof by sale I like that :smile: let's hope the buyer gets what they pay for :biggrin: (ofcourse I understand they did, just couldn't resist)
 
  • #11
Schneibster said:
You know, a great deal of this controversy could be eliminated by a higher quantum efficiency in detecting the photons, is that correct, Caroline?

If only. :smile: I think this is her mission in life.
 
  • #12
JohnBarchak said:
Here is Einstein's Hypothesis:
When the two photons are created, they both have a definite polarization that is negatively correlated with the other due to conservation of spin, but we do not know what they are. When one is measured, we then know the polarization of the other (it is the opposite polarization). Since both photons have a definite polarization from birth, there is no question of whether the measurement of one photon affects the polarization of the other.

Does anyone have a different hypothesis?

Regards
John B.

I do. It is called QM. The description above is not compatible with what has been observed in the lab, and has nothing to do with cryptography.
 
  • #13
You've left out one very important piece of information: spins in separate planes are conjugate under uncertainty; if the spin in one plane is known, then the spin in other planes is indeterminate. Now, remember, it is not unmeasureable- it is undefined, i.e. it is an eigenstate of two eigenvalues, whose mixing angle is the angle of the planes.

On edit: DrChinese got in in front of me a couple times. This was in response to JohnBarchak's question, "Does anyone have a different hypothesis?"
 
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  • #14
JohnBarchak said:
Hi Caroline
The EPR crypto-system is heavily time gated and coincidence checked, so they are definitely not dealing with raw photons ...
The reason they get such neat answers is, I'm fairly certain, that their sources do not have rotational invariance, only "binary rotational invariance". Because they are interested in commercial applications and not pure theory, they have no incentive to look into this. They can happily set the detectors at selected angles and have no need to ask what might happen in between.

JohnBarchak said:
... The really important LR issue is that these commercial crypto-systems are quite deterministic and causal. The fact is that if I want to build a deterministic and causal quantum system, I can. The universe is NOT stochastic as von Neumann's "silly" proof would lead you to believe.
Without seeing the actual experiments, I currently think it likely that there is just one stochastic element at work here: the system "chooses" randomly between two possible phase relationships. Of course, even this choice probably isn't truly random, but the factors causing the final decision are way beyond our reach. [See my new paper (not yet submitted for publication): http://freespace.virgin.net/ch.thompson1/Papers/Homodyne/homodyne.pdf ]

JohnBarchak said:
Nice to see that you are still kicking and even having some fair successes - keep it up - LR *WILL* win out - All the best
John B.
Thanks! If you've got a moment, perhaps you could have a look in wikipedia? Certain people (including DrChinese) are of the opinion that the pages I put there last summer contravene wikipedia's Neutral Point of View policy. I can't really deny this yet I think they have every right to be there. See the discussion pages associated with:
http://en.wikipedia.org/wiki/Clauser_and_Horne's_1974_Bell_test
and
http://en.wikipedia.org/wiki/Bell's_Theorem

Caroline
http://freespace.virgin.net/ch.thompson1/
 
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  • #15
Schneibster said:
You know, a great deal of this controversy could be eliminated by a higher quantum efficiency in detecting the photons, is that correct, Caroline?
As a matter of fact, I think one could get by quite happily with imperfect detectors if only the experimenters would read and take note of the message of Clauser and Horne's 1974 paper! The CH74 Bell inequality does not depend on the fair sampling assumption. See http://en.wikipedia.org/wiki/Clauser_and_Horne's_1974_Bell_test and various paper on my web site.

Schneibster said:
If so, then photodetectors are the wrong way to go. CCDs are currently being made with QE in excess of 90%. With CTE (charge transfer efficiency) of over 99.999%, and similar signal amplifier efficiency and accuracy, this indicates that it should be possible to achieve the level of measurement that would prove or disprove the case for Aspect once and for all. Do you agree?
You may well be right. I don't know all that much about CCDs. However, an alternative way of getting an "outcome" every time is to re-define what you are going to consider to be the outcome! This is, I think, done in a perfectly legitimate manner (I can't see that any of the necessary assumptions are violated) in the Sanchez et al proposed "loophole-free" Bell test. [Another chance to plug my new paper, which discusses this proposal! See http://freespace.virgin.net/ch.thompson1/Papers/Homodyne/homodyne.pdf ]

BTW, DrChinese, you are quite right! I shall have difficulty knowing what to do with myself if I ever succeed in my mission. :smile:

Caroline
 
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  • #16
Hi Caroline
Show me anything in Wikipedia that is "neutral." If Bohr's views are in Wikipedia, then your views are totally appropriate. Your work conforms to real science far more than any of Bohr's work. Bohr did not believe in the scientific method - you do!
All the best
John B.
 
  • #17
Help me understand EPR

I’d just like to understand the EPR debate. Allow me to diagram a test as I understand the debate.

Our observers will still be Alice and Bob each in one of two houses on opposite sides of a resort. Carol and Ted are leaving the resort to visit both houses separately, and have agreed that only answer Yes or No questions about what happened at the resort and one of them shall always answer “Yes” the other always “NO”. Now during there visits it happens that Ted goes to Bob’s house while Carol arrives at Alice’s. Bob gets YES answers and later meets up Alice to learn that Carol gave NO answers to the same questions! The resulting conflict clearly a part of Ted and Carol’s design.

Einstein View :

Carol and Ted simple agree in advance as they departed the resort who would say YES and who would say NO.

QM View:

Carol and Ted only agreed to answer the opposite from the other's. But would pick Yes or NO based on odd or even on the nearest clock when first is asked. But - When the first question was asked the other new how the respond without checking for Odd or Even based on some unknown FTL link between them. Note: At the time they are asked their first question the houses are Space-Like separated.

Now I can see where EPR tests have shown that they answer as predicted. But I do not see how the tests are insuring the answers could have been different if questioned differently in order to show that the QM view is better.

If you make this clear I’d appreciate it.
 
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  • #18
RandallB said:
Now I can see where EPR tests have shown that they answer as predicted. But I do not see how they are insuring the answers could have been different if questioned differently in order to show that the QM view is better.

If you make this clear I’d appreciate it.

I would humbly recommend my first posts in this thread: Bell's THeorem and Negative Probabilities

You will see that the scenario you describe last above has 8 permuatations per the Einstein view, 2 of which must be negative to agree with the predictions of QM. QM says there are only 4 permutations and all are non-negative.
 
  • #19
JohnBarchak said:
Hi Caroline
Show me anything in Wikipedia that is "neutral." If Bohr's views are in Wikipedia, then your views are totally appropriate. Your work conforms to real science far more than any of Bohr's work. Bohr did not believe in the scientific method - you do!
All the best
John B.
Thanks for the encouragement, John! I do hope DrChinese agrees.

Caroline
 
  • #20
RandallB said:
I’d just like to understand the EPR debate. Allow me to diagram a test as I understand the debate.

Our observers will still be Alice and Bob each in one of two houses on opposite sides of a resort ...

But nobody "understands" how entanglement works! If you ask me (which I know you didn't!) the reason is that entanglement simply does not happen. Einstein et al were right about the existence of hidden variables (though slightly wrong in that, in the actual Bell test experiments, the hidden variables don't completely determine the outcomes, only determine their probabilities). Bell's Theorem is also correct, so something has to be wrong and this, in my book, is quantum theory.

Yes, I know the experiments are supposed to show that entanglement does happen, but once you understand the various "loopholes", the way is open for hidden variable explanations, based on very ordinary classical physics.

See my wikipedia pages, e.g. http://en.wikipedia.org/wiki/Bell_test_loopholes and http://en.wikipedia.org/wiki/Local_hidden_variable_theory.

RandallB said:
If you make this clear I’d appreciate it.
I'm afraid I haven't tried to follow your analogy in any detail. The answer, I suggest, is that you can't expect anyone to be able to make this clear since you are trying to explain the impossible. The real experiments are another matter. Notwithstanding anything you may have read, there is nothing weird or impossible about them.

Caroline
 
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  • #21
DrChinese said:
You will see that the scenario you describe last above has 8 permuatations per the Einstein view, 2 of which must be negative to agree with the predictions of QM. QM says there are only 4 permutations and all are non-negative.
DrChinese
I appreciate your at least looking at my question in detail I just get a little lost in the permutations of statistical scenarios that even include cos and sin’s of most explanations.
Thus I’m tring to make as simple an example as possible, in the hope I can analyze it correctly. And your insight on 8 vs. 4 permutations may be where I need the most help , as I do not think I can name them. So I will try to start defining them and allow you to correct me.

Alice and Bob are interested only in the answer not who gives it.
We must evaluate both answers.
We must test from one Primary Observer.
The Three variables that generate 8 permutations are:

A) Primary Observer is Alice PO is Alice=A+ PO is Bob=A-
B) Answer received by Primary Yes = B+ NO=B- (odds 50-50)
C) Answer reported to PO by other Yes = C+ NO=C- (odds 50-50)

[1] A+ B+ C+ Never 0%
[2] A+ B+ C-
[3] A+ B- C+
[4] A+ B- C- Never 0%
[5] A- B+ C+ Never 0%
[6] A- B+ C-
[7] A- B- C+
[8] A- B- C- Never 0%

From the Einstein View with as answers preset at departure 1,4,5,or 8 couldn’t occur.

Clearly my 8 permutations do not agree with yours as my results are nothing like the one you gave. So before I try to define the QM permutations can you detail what the 8 you referred to are.

Also, when you say “2 must be negative” I’m assuming you mean “NOT” or never as in Zero probability. Instead of a “Negative Probability” as I think this example is too simple for any of those to appear - or do they?

And if you would detail the 4 permutations for QM . I having a little trouble understanding how we can define the test such that the number of outcome permutations can be different based on QM or not QM.

I don’t expect this analogy to resolve the ‘correct’ view of the test. Just do a better job of describing EPR in the simplest possible analogy to understand the two conflicting views QM and Non-QM and maybe the intent of the test being done.

Thanks RB
 
  • #22
RandallB said:
DrChinese
I appreciate your at least looking at my question in detail I just get a little lost in the permutations of statistical scenarios that even include cos and sin’s of most explanations.
...

Clearly my 8 permutations do not agree with yours as my results are nothing like the one you gave. So before I try to define the QM permutations can you detail what the 8 you referred to are.

Also, when you say “2 must be negative” I’m assuming you mean “NOT” or never as in Zero probability. Instead of a “Negative Probability” as I think this example is too simple for any of those to appear - or do they?

And if you would detail the 4 permutations for QM . I having a little trouble understanding how we can define the test such that the number of outcome permutations can be different based on QM or not QM.

...

Thanks RB

Randall,

I will take us through step by step. You don't need the sin/cos stuff to see the paradox. For sake of our discussion, you can ignore Caroline because she is trying to distract you. Let me know after which steps seem confusing to you and which steps seem OK. We can then focus on that step in more detail.

1. You can see the 4 basic permutations easily with Alice (A) and Bob (B):

A+ B+
A+ B-
A- B+
A- B-

These are agree upon by all, including QM.

2. Suppose you believe that the measurements of Alice and Bob were not particularly fundamental to the outcome. Then you could have also had observers Chris (C) and Dan (D) and as many more as you like, and they could have made measurements and not affected the results of Alice and Bob.

This is called the local realistic or hidden variable interpretation, and it is immenently reasonable. Follow so far?

3. It is reasonable - in fact so reasonable that it took 30 years for Bell to see the mistake here.

So let's forget Dan and the others, and focus on Chris. Chris makes - or could have made, according to 2 above, observations on one of the photons. I mean after all, the particular angles measured by Alice and Bob shouldn't have been the only angles testable should they? So what IF Chris could have made a measurement at some other angle? Then he would see a + or a -. If you THEN combine his results with the possible results of Alice and Bob, you get the following 8 permutations:

[1] A+ B+ C+
[2] A+ B+ C-
[3] A+ B- C+
[4] A+ B- C-
[5] A- B+ C+
[6] A- B+ C-
[7] A- B- C+
[8] A- B- C-

So hopefully you see that all of the above have a chance of occurring between 0 and 100% and that they are the only permutations possible for Alice, Bob and Chris. Therefore, they total to 100%. Do you see this step?

4. We have no know way to measure all 3 (A, B and C) simultanueously and directly by experiment. So we measure it indirectly, two at a time.

Alice and Bob - we get correlations and non-correlations, each as a % adding to 100%

Alice and Chris - we get correlations and non-correlations, each as a % adding to 100%

Bob and Chris - we get correlations and non-correlations, each as a % adding to 100%

We measure the A & C correlated cases, the A & B non-correlated cases and subtract the B & C correlated cases. When we do this, we end up with cases (2*[3] and 2*[6]).

If it helps, let me know and I will re-explain how this adds up. This is the step that involves the adding and subtracting of a bunch of cases, but it does work out. I want you to be confortable with this.

5. But you would definitely think that the lowest value you could get for (2*[3] and 2*[6]) would be zero. Do you see this?

6. We arrived at 5 without any reference to QM whatsoever - QM does even need to exist as a theory to get this last result. Do you see this too?

7. Now we simply conduct an actual experiment. Anyone can do it, anywhere, anytime although it is not something you can do at home. But the experiments have been run many times over the past 30 years. The results are always the same. The value you get for cases (2*[3] and 2*[6]) is always less than zero. The results are indisputably at variance with the reasonable assumption that Alice and Bob are not fundamental to the results - which we made in step 2 above. Therefore, our assumption was invalid. Therefore, LR fails.

Conclusions

8. As you can see this has nothing whatsoever to do with QM. On the other hand, in QM there is this thing called the Heisenberg Uncertainty Relations. It states that observations DO affect the results. Therefore it does not acknowledge our assumption 2. above as valid and specifically disclaims it. As a result, it has no paradox.

9. As icing on the cake: the observed values in the experiments above exactly match the predictions of QM to 30 standard deviations, but that doesn't change the paradox at all. Also, the predictions of QM also just happen to match classical optics (but without the fallacious LR assumption of 2.).

Let me know the step numbers you would like some additional clarification on.
 
  • #23
JohnBarchak said:
Hi Caroline
Show me anything in Wikipedia that is "neutral." If Bohr's views are in Wikipedia, then your views are totally appropriate. Your work conforms to real science far more than any of Bohr's work. Bohr did not believe in the scientific method - you do!
All the best
John B.
Hi JohnB.

I've not yet come across the concept of 'neutrality' wrt Wikipedia, or indeed physics. Would you care to let us know what you consider the key aspects of 'neutrality'?

For myself, I am quite 'agnositic', and totally disloyal ... I can be 'bought' by good concrete, specific, testable predictions; by clear demonstrations of self-consistency and (more important) consistency with good experimental and observational results; by 'utility' (not in the economic sense; I mean can we use it to do stuff like make computers?); and by 'fecundity' - does it open the door to (a.k.a. give birth to) lots of interesting and wonderful ideas, which our telescopes and microscopes can help us tease apart?

Call me a 'whore', call me a 'slut', I don't care ... just turn me on with the number of decimal places your theory matches the experimental results!
 
  • #24
Neutral point of view!

Nereid said:
Hi JohnB.

I've not yet come across the concept of 'neutrality' wrt Wikipedia, or indeed physics.

For a statement of wikipedia policy on this, see http://en.wikipedia.org/wiki/Npov

They seem effectively to take "neutral" to be synonymous with "dominant". I suggested that they could solve the problem in one of the pages currently under dispute (http://en.wikipedia.org/wiki/Bell's_Theorem, which I had, with considerabl labour, re-written) by having a short introduction followed by links to two alternative pages, one from the QM point of view, another from my local realist one. Perhaps there are other alternatives that others could put in as similar links. They did not think much of the idea! Their policy, it seems, does not allow "forks". Apparently http://www.wikinfo.org/ was set up in order to accommodate valuable pages rejected by wikipedia, and this does allow forks.

Nereid said:
Would you care to let us know what you consider the key aspects of 'neutrality'

For myself, I am quite 'agnositic', and totally disloyal ... I can be 'bought' by good concrete, specific, testable predictions; by clear demonstrations of self-consistency and (more important) consistency with good experimental and observational results ...
I'm with you there, except that (a) I am unashamedly "local realist" and (b) am not too terribly bothered about producing general formulae that are useful or predict anything new. Instead, I'm content with general rules of operation, general approaches to the matter of finding of plausible explanations for actual experiments.
... by 'utility' (not in the economic sense; I mean can we use it to do stuff like make computers?); and by 'fecundity' - does it open the door to (a.k.a. give birth to) lots of interesting and wonderful ideas, which our telescopes and microscopes can help us tease apart?
I think the potential fecundity of classical electromagnetic theory has largely been thrown away by the acceptance of QM. It would have been more productive not to rush into creating a "formalism", instead just leaving things blank and gradually refining classical ideas to fit new experimental facts.

Call me a 'whore', call me a 'slut', I don't care ... just turn me on with the number of decimal places your theory matches the experimental results!
This is, I fear, a very dangerous attitude! Decimal places do not necessarily mean anything! Can you be absolutely certain there was no uncontrolled bias in the experiments? In the Bell test experiments it is, in my view, certain that there is bias present, and the neat reproduction of the QM predictions is obtained partly by reproduction of the same biases each time. [Another important factor is that the local realist prediction is, in any event, closer than most people realize to the QM one.]

Caroline
 
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  • #25
There's a need here for a basic "course on the scientific method 101" :-)

Caroline Thompson said:
I'm with you there, except that (a) I am unashamedly "local realist" and (b) am not too terribly bothered about producing general formulae that are useful or predict anything new. Instead, I'm content with general rules of operation, general approaches to the matter of finding of plausible explanations for actual experiments.

It is a good thing that you state, what I was trying to point out, so clearly yourself! It explains all the endless discussions we're having and the hopelessness to lead us somewhere in doing so. What you propose is not physical science, if you're not "terribly bothered about producing general formulae that are useful or predict anything new". THAT is namely the very purpose of science!

This is, I fear, a very dangerous attitude! Decimal places do not necessarily mean anything! Can you be absolutely certain there was no uncontrolled bias in the experiments?

Again, the purpose of science is not to be absolutely certain that there are no angels pushing the planets, but to reject theories which make WRONG predictions (and to encourage temporarily theories that make RIGHT and PRECISE predictions). The point is that a theory that predicts an outcome of 3.88230470+/-0.000001 and a corresponding measurement that gives you 3.88230488 has more chances to have some predictive value than a "theory" that predicts that the result must be somewhere between 0.1 and 502.8. This last theory has more value than one which says that the result must be 8.302913402349234 +/- 0.0000000001.

The reason is that the first one "puts its money where its mouth is" :tongue:

Really, if you do not understand this, then you have no understanding of what science is all about, according to the universally accepted definition of science, and explains also why you have such difficulties communicating with scientists. You're simply talking about something else (call it theology :-)

cheers,
Patrick.
 
  • #26
The Most Precise Measurements Ever Made

Hans Dehmelt Plays the Music and the Particles Dance
Let's take a close look at the most precise measurements ever made. In 1989, Hans Dehmelt won the Nobel Prize in Physics and in 1995, the National Medal of Science, the nation's highest scientific honor, for measuring the magnetic moment of the electron. Niels Bohr had declared this impossible in 1929. Hans Dehmelt's experiments proved that there are definite problems with Heisenberg's claims.

The fields in Dehmelt's ion trap are very low in energy and it is necessary to cool the electrons/ions to a 4K in order to keep them in the trap. For an order of magnitude estimate that means that the well depth is of the order of less than 2 cm-1 or < 0.00025 eV. The electrons are not zipping about.

Corralling the Elusive Electron
http://www.washington.edu/research/pathbreakers/1973c.html [Broken]

Hans Dehmelt Bio
http://nobelprize.org/physics/laureates/1989/dehmelt-autobio.html

Early Work of Hans Dehmelt
http://fangio.magnet.fsu.edu/~vlad/pr100/100yrs/html/chap/fs2_04069.htm [Broken]
http://fangio.magnet.fsu.edu/~vlad/pr100/100yrs/html/chap/fs2_04073.htm [Broken]

Hans Dehmelt Paper on the Monoelectron Oscillator
http://fangio.magnet.fsu.edu/~vlad/pr100/100yrs/html/chap/fs2_04103.htm [Broken]

The Penning Trap
http://www.physik.uni-mainz.de/werth/g_fak/penning.htm

Stability Conditions for the Penning Trap ==>
http://webphysics.davidson.edu/Projects/SuFischer/node42.html

Here are Dehmelt's own words:
"As the man who first found a way to catch an electron, bring it to rest in free space for a year and measure its magnetism in order to study its structure, I naturally would like to tell you a little bit about it. At the University of Gottingen, my teacher Richard Becker, in one of his lectures, drew a dot on the blackboard declaring 'Here is an electron ...' or rather 'Hier ist ein Elektron ...'. This appeared to be drastically at odds with the famous Physicist Heisenberg's claim that an electron truly at rest could not be localized and could be found anywhere in space."

All the best
John B.
 
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  • #27
JohnBarchak said:
Hans Dehmelt Plays the Music and the Particles Dance
Let's take a close look at the most precise measurements ever made ... Hans Dehmelt's experiments proved that there are definite problems with Heisenberg's claims ...
It's clear that Dehmelt was able to get very accurately reproducible measurements of something, but what? The interpretation in terms of gyromagnetic ratio depends on a wealth of theory. I've tried reading a few relevant papers. I wonder how many people understand the actual experiments? They are not straightforward!

Hans Dehmelt Bio
http://nobelprize.org/physics/laureates/1989/dehmelt-autobio.html

See also his Nobel lecture, on the same site.

Cheers
Caroline
http://freespace.virgin.net/ch.thompson1/
 
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  • #28
Hi Caroline
"THAT I MAY KNOW THE INMOST FORCE THAT BINDS THE WORLD AND GUIDES ITS COURSE"

See:
http://faculty.washington.edu/dehmelt/all1.html
for much more from Dehmelt.
All the best
John B.
 
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  • #29
Hi Again Caroline
Dehmelt originally got his big idea from what goes on inside radio vacuum tubes (I guess you call it a valve) and the effect was known long before his experiments. I don't remember if I've told you that I am a ham - W9PI. I have many tubes from the 1920s & 30s (I build transmitters & receivers) - the physics we would know if we really understood everything that goes on in those tubes.

All the best
John B.
 
  • #30
Hi Again Caroline
The part that Dehmelt provided can be explained by the analogy of a marble in a bowl.

The part that is provided by Nature is harder to understand is explained by Dehmelt:
"A free electron by itself, even when nominally at rest, always moves spontaneously in an irregular circle at the speed of light. This circle is much smaller than a hydrogen atom. The spontaneous circular motion explains the electron spin. The electric ring current associated with the moving charge of the electron produces the spin magnetism just like a current in a coil produces magnetism."

This characteristic of the electron is called zitterbewegung (ZBW) and I can help if you want to know more about it.

All the best
John B.
 
  • #31
JohnBarchak said:
Here are Dehmelt's own words:
"As the man who first found a way to catch an electron, bring it to rest in free space for a year and measure its magnetism in order to study its structure, I naturally would like to tell you a little bit about it. At the University of Gottingen, my teacher Richard Becker, in one of his lectures, drew a dot on the blackboard declaring 'Here is an electron ...' or rather 'Hier ist ein Elektron ...'. This appeared to be drastically at odds with the famous Physicist Heisenberg's claim that an electron truly at rest could not be localized and could be found anywhere in space."

All the best
John B.

In the presence of a troll? That would be someone stirs up the pot with no intention of producing any meaningful discussion.

The title of this thread="A fresh look at EPR". Above, we have a quote by one Nobel winner commenting on another. Is there any point being made here? What, that science marches forward? How zzzzzzzzzzzzzzzzzzzzz interesting.
 
  • #32
REF post #22

Dr Chinese

Allow me to modify my analogy to make it as fair a comparison to testing spins, polarizations, etc. at diff angles etc. Let me know if my analogy makes any unfair or ‘unrealistic’ comparisons or assumptions.

Instead of having Alice and Bob ask questions they will only test for male or female coming in their area on their side of the resort. We have very high confidence that only couples of male and female depart the resort and that they separate in opposite directions. We also have very high confidence that only females wear perfume and males wear cologne (useful only to Chris and Dan as only they can test for smell). Chris test locale is near Alice while Dan’s locale is near Bob. During testing Alice and Chris are Space-Like Separated from Bob and Dan. A constraint on testing is that only one test can be performed in a locale.
Testing reports are always given as a “+ “ for Female going by Alice’s area, whether observed directly or implied by the local observation. Therefore Dan directly detecting perfume would imply that Bob would have seen a Female, implying Carol would see a Male - therefore Dan report’s the result as a “-“. Thus correlation is when same signs are reported. Non-correlation is when conflicting signs are reported.

Now to your items:
1) Yes very simple 4 permutations for Alice (A) and Bob (B)
Only one question here: For 2 and 3 (A+B- & A-B+) the actual results are showing near Zero results for those permutations correct? How many non-correlation results are acceptable at this level of testing to consider the tests themselves viable?

2) LR ‘local realistic’ was this introduced by Bell ? No I’m not sure I see this as “imminently reasonable”. One issue of concern, C cannot conduct all his own tests, when A is also testing D must stand in. Is running a test as in #1 and getting Zero non-correlations good enough to consider this substitution reasonable? Just looking to know in general how Bell or the testers – no need to explain the real tests.

3) The 8 permutations are clear and that statically they must total 100%. From a testing view I’m a little unclear as to how to interpret a “non-correlation”.
Even on an individual result, is there a level of these that we should start to question the viability of out tests being used?

4) Proceeding with the above results being “acceptable”
………………………CORR NON-CORR
A&B [1,2,7,8] [3,4,5,6] (C unknown)
A&C [1,3,6,8] [2,4,5,7] (B unknown)
B&C [1,4,5,8] [2,3,6,7] (A unknown)

A&C(Corr) + A&B(Non) – B&C(Corr) = [1,3,6,8] + [3,4,5,6] - [1,4,5,8]
Result = [3] [3] [6] [6]

Yes I agree with the statistical math here, it only requires that there are acceptable “Non-correlations”.

5) and 6) Yes, valid sampling of valid tests should be able to have their stat % calculated in this manner. And should give %’s that are Zero or greater.

7) Now maybe this is where part of my confusion comes in. The use of an LR is based on a Non-QM assumption that Alice or Bob in their testing are NOT affecting the results. Is this why LR should be useful? And when tests are performed and give a Negative % of probability for ANY permutation provides us with some evidence that LR is not valid and implies QM is correct because the testing is influencing the results??
If this is the point – I guess I can see the point, IF non-correlation results are useful.
What do testers consider is going on when the get non-correlation results back at item one when there is only 4 permutations? Are they considered valid?


ON TO QM.

8) Sure QM says once an out come is seen it is known in both test areas “At the same time”. Although I’d expect QM to agree that it cannot define which test was first or ‘controlling’ since the tests were space-like separated. Thus even if the test are not space-like separated but only time or distance separated, nether test would be “First” nor “Controlling” according to QM. Do I understand this part of QM correctly?

9) I don’t know what this means – since QM is rejecting the use of a LR, how could it be able to predict anything based on an LR?
Or are you saying that in this particular type of optical EPR test, that the new angle test is flawed based on QM. Flawed such that QM already knows that the test by Chris for perfume won’t work because QM knows that in fact some women actually do wear cologne while the Non-QM view would not recognize that?

I hope this is detailed enough to show what areas I need help in.
Appreciate your time in helping me.

Thanks RB
 
  • #33
RandallB said:
Dr Chinese

Allow me to modify my analogy to make it as fair a comparison to testing spins, polarizations, etc. at diff angles etc. Let me know if my analogy makes any unfair or ‘unrealistic’ comparisons or assumptions.

Instead of having Alice and Bob ask questions they will only test for male or female coming in their area on their side of the resort. We have very high confidence that only couples of male and female depart the resort and that they separate in opposite directions. We also have very high confidence that only females wear perfume and males wear cologne (useful only to Chris and Dan as only they can test for smell). Chris test locale is near Alice while Dan’s locale is near Bob. During testing Alice and Chris are Space-Like Separated from Bob and Dan. A constraint on testing is that only one test can be performed in a locale.
Testing reports are always given as a “+ “ for Female going by Alice’s area, whether observed directly or implied by the local observation. Therefore Dan directly detecting perfume would imply that Bob would have seen a Female, implying Carol would see a Male - therefore Dan report’s the result as a “-“. Thus correlation is when same signs are reported. Non-correlation is when conflicting signs are reported.

Now to your items:
1) Yes very simple 4 permutations for Alice (A) and Bob (B)
Only one question here: For 2 and 3 (A+B- & A-B+) the actual results are showing near Zero results for those permutations correct? How many non-correlation results are acceptable at this level of testing to consider the tests themselves viable?

2) LR ‘local realistic’ was this introduced by Bell ? No I’m not sure I see this as “imminently reasonable”. One issue of concern, C cannot conduct all his own tests, when A is also testing D must stand in. Is running a test as in #1 and getting Zero non-correlations good enough to consider this substitution reasonable? Just looking to know in general how Bell or the testers – no need to explain the real tests.

3) The 8 permutations are clear and that statically they must total 100%. From a testing view I’m a little unclear as to how to interpret a “non-correlation”.
Even on an individual result, is there a level of these that we should start to question the viability of out tests being used?

4) Proceeding with the above results being “acceptable”
………………………CORR NON-CORR
A&B [1,2,7,8] [3,4,5,6] (C unknown)
A&C [1,3,6,8] [2,4,5,7] (B unknown)
B&C [1,4,5,8] [2,3,6,7] (A unknown)

A&C(Corr) + A&B(Non) – B&C(Corr) = [1,3,6,8] + [3,4,5,6] - [1,4,5,8]
Result = [3] [3] [6] [6]

Yes I agree with the statistical math here, it only requires that there are acceptable “Non-correlations”.

5) and 6) Yes, valid sampling of valid tests should be able to have their stat % calculated in this manner. And should give %’s that are Zero or greater.

7) Now maybe this is where part of my confusion comes in. The use of an LR is based on a Non-QM assumption that Alice or Bob in their testing are NOT affecting the results. Is this why LR should be useful? And when tests are performed and give a Negative % of probability for ANY permutation provides us with some evidence that LR is not valid and implies QM is correct because the testing is influencing the results??
If this is the point – I guess I can see the point, IF non-correlation results are useful.
What do testers consider is going on when the get non-correlation results back at item one when there is only 4 permutations? Are they considered valid?


ON TO QM.

8) Sure QM says once an out come is seen it is known in both test areas “At the same time”. Although I’d expect QM to agree that it cannot define which test was first or ‘controlling’ since the tests were space-like separated. Thus even if the test are not space-like separated but only time or distance separated, nether test would be “First” nor “Controlling” according to QM. Do I understand this part of QM correctly?

9) I don’t know what this means – since QM is rejecting the use of a LR, how could it be able to predict anything based on an LR?
Or are you saying that in this particular type of optical EPR test, that the new angle test is flawed based on QM. Flawed such that QM already knows that the test by Chris for perfume won’t work because QM knows that in fact some women actually do wear cologne while the Non-QM view would not recognize that?

I hope this is detailed enough to show what areas I need help in.
Appreciate your time in helping me.

Thanks RB

The only thing about your example is that it is a specific case in which the LR and QM and experiment predictions/results all overlap anyway. So it makes it harder to distinguish the scenarios.

1) Not sure, but I would guess well less than 1% in experiments.

2) Not sure I follow the point.

3) Non-correlations - you have them pegged properly in 4). You don't expect any when your special case is considered.

4) We are OK on this too.

5, 6) Ditto.

7) "And when tests are performed and give a Negative % of probability for ANY permutation provides us with some evidence that LR is not valid and implies QM is correct because the testing is influencing the results??"

Not just that testing affects the results, the results at one place appear (when pulled together) to be dependent on the results at another.

Not sure I follow about the "testers consider..." comment.

8) No one knows if A causes B or B causes A, or something else.

9) QM is not based on LR, and classical optics does not match LR. The pre-Bell mistake was that people ASSUMED that classical optics and LR were the same, and Bell shows they cannot be the same. Classical optics being essentially classical experimental results, which match the predictions of QM.

a. If you accept Bell, then QM and LR must yield different predictions (at least at certain specific angles).
b. If QM is wrong, then classical optics is wrong too (since the predictions of the two are identical).
c. For LR to be right, then existing experiments (Aspect et all) must be flawed in some way.
 
  • #34
DrChinese said:
... 9) QM is not based on LR, and classical optics does not match LR. The pre-Bell mistake was that people ASSUMED that classical optics and LR were the same, and Bell shows they cannot be the same. Classical optics being essentially classical experimental results, which match the predictions of QM.
I'm not the only person in this forum to think you've got this wrong! I'm afraid I forget who else pointed out, with me, that the classical prediction does not support QM. Classical optics is not incompatible with local realism -- in fact, it would be very strange if it were!

The mistake you make is in thinking that the classical optics prediction for coincidences between plane polarised "photons" in an experiment such as Aspect's obey the same cos^2(angle) law as QM. The law in fact obeyed, if you make all the idealised classical optical assumptions, together with (a) equal probability for all angles and (b) detection probabilities proportional to beam intensities, is not a cos^2 law but cos^2 + constant. The constant makes all the difference! It means that whereas the QM prediction gives curves with visibility 1, classical optics gives (in the ideal case) ones with visibility less than 1 (in fact, as shown in http://arXiv.org/abs/quant-ph/9903066, 0.5).

This constant term is the reason that local realists do not find it easy to produce models to fit the actual results. In order to fit them, there is no escaping the necessity to depart from the ideal case and consider the likely behaviour of real instruments.

Caroline
http://freespace.virgin.net/ch.thompson1/
 
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  • #35
Caroline Thompson said:
I'm not the only person in this forum to think you've got this wrong! I'm afraid I forget who else pointed out, with me, that the classical prediction does not support QM. Classical optics is not incompatible with local realism -- in fact, it would be very strange if it were!

The mistake you make is in thinking that the classical optics prediction for coincidences between plane polarised "photons" in an experiment such as Aspect's obey the same cos^2(angle) law as QM. The law in fact obeyed, if you make all the idealised classical optical assumptions, together with (a) equal probability for all angles and (b) detection probabilities proportional to beam intensities, is not a cos^2 law but cos^2 + constant. The constant makes all the difference! It means that whereas the QM prediction gives curves with visibility 1, classical optics gives (in the ideal case) ones with visibility less than 1 (in fact, as shown in http://arXiv.org/abs/quant-ph/9903066, 0.5).

This constant term is the reason that local realists do not find it easy to produce models to fit the actual results. In order to fit them, there is no escaping the necessity to depart from the ideal case and consider the likely behaviour of real instruments.

Caroline
http://freespace.virgin.net/ch.thompson1/

First, what is classical optics to QM anyway? It is like Newtonian gravity to Einsteinian gravity. It is ultimately not that critical that QM coincide with classical optics other than in cases in which correspondence would be expected.

Second, if you can get classical optics to yield a different prediction for Aspect-like correlation percentages, go for it.

None of the above affects the fact that all extant tests support the predictions of QM, or that the QM formula [tex]cos^2[/tex] is the same applied in classical optics in cases in which polarized light is passed through a second polarizer.

As to who originally pointed out that LR and classical optics were at odds, I see that as being Bell. Before Bell, the LR prediction was [tex]cos^2[/tex] matching classical optics. After Bell, the LR predicted value changed (to something that no LRist is willing to stand behind).
 
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<h2>1. What is the EPR Debate?</h2><p>The EPR Debate refers to the debate surrounding the Einstein-Podolsky-Rosen paradox, a thought experiment proposed by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935. The paradox challenges the principles of quantum mechanics and raises questions about the nature of reality.</p><h2>2. What is the main argument in the EPR Debate?</h2><p>The main argument in the EPR Debate is whether quantum mechanics allows for non-local interactions, meaning that two particles can influence each other instantaneously regardless of the distance between them. This contradicts Einstein's theory of relativity, which states that nothing can travel faster than the speed of light.</p><h2>3. What is the role of nature in the EPR Debate?</h2><p>Nature plays a crucial role in the EPR Debate as it is the source of the phenomena that are being studied. The debate centers around whether the laws of nature, as described by quantum mechanics, are sufficient to explain the behavior of particles or if there are additional hidden variables at play.</p><h2>4. How does Einstein's view differ from the prevailing interpretation of quantum mechanics?</h2><p>Einstein believed that quantum mechanics was an incomplete theory and that there were hidden variables that could explain the seemingly random behavior of particles. This view is in contrast to the prevailing interpretation of quantum mechanics, which states that particles do not have definite properties until they are observed.</p><h2>5. What is the significance of the EPR Debate in modern physics?</h2><p>The EPR Debate has had a significant impact on modern physics, as it has led to further research and experiments to test the principles of quantum mechanics. It has also sparked discussions about the nature of reality and the role of observation in shaping it. The debate continues to be a topic of interest and controversy in the scientific community.</p>

1. What is the EPR Debate?

The EPR Debate refers to the debate surrounding the Einstein-Podolsky-Rosen paradox, a thought experiment proposed by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935. The paradox challenges the principles of quantum mechanics and raises questions about the nature of reality.

2. What is the main argument in the EPR Debate?

The main argument in the EPR Debate is whether quantum mechanics allows for non-local interactions, meaning that two particles can influence each other instantaneously regardless of the distance between them. This contradicts Einstein's theory of relativity, which states that nothing can travel faster than the speed of light.

3. What is the role of nature in the EPR Debate?

Nature plays a crucial role in the EPR Debate as it is the source of the phenomena that are being studied. The debate centers around whether the laws of nature, as described by quantum mechanics, are sufficient to explain the behavior of particles or if there are additional hidden variables at play.

4. How does Einstein's view differ from the prevailing interpretation of quantum mechanics?

Einstein believed that quantum mechanics was an incomplete theory and that there were hidden variables that could explain the seemingly random behavior of particles. This view is in contrast to the prevailing interpretation of quantum mechanics, which states that particles do not have definite properties until they are observed.

5. What is the significance of the EPR Debate in modern physics?

The EPR Debate has had a significant impact on modern physics, as it has led to further research and experiments to test the principles of quantum mechanics. It has also sparked discussions about the nature of reality and the role of observation in shaping it. The debate continues to be a topic of interest and controversy in the scientific community.

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