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Post by abacus9900 on Dec 1, 2010 19:24:30 GMT 1
STA (or anyone else), do you know if, when EPR experiments are performed, such as the version conducted by Alain Aspect using entangled pairs of photons, that a non entangled version is performed as well? The point to remember is that non-entangled pairs differ statistically in their correlations to such a significant extent to entangled pairs that something very different is going on between the two.
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Post by nickcosmosonde on Dec 5, 2010 22:00:41 GMT 1
I'm not airing my own opinions. I'm simply pointing out that your opinions about what QM means - including the Copenhagen Interpretation of what the so-called "tests" of Bell's Theorem means - are just one of a range of various interpetations. You seem to think this was some sort of "crucial experiment", deciding between two differing theories. It wasn't.
I am not criticising the basis of scientific theories. At least, this is not what I think I am doing. I am criticising your interpretation of them, presented as fact. Your interpretation is that the tests confirm the Copenhagen Interpretation of QM, that the wavefunction collapses upon measurement, that quantum systems do not have a spatio-temporal ontic existence until an observer somehow induces by his conscious interaction a localised state of reality. At least, I take it from what you've said so far this is what you mean by it being "proven time and time again" that the QM that the old dinosaur Einstein couldn't accept is true "within several decimal places" and so on.
The fact is however that the "tests" can equally be said to "confirm" Schrodinger's interpretation of what his wave equation means. The quantum objects are "entangled" just as much on his interpretation as on Heisenberg's. Yet on his interpretation we have no need to think in terms of "collapsing" the wave-function, of creating any measured parameters by our observations. The mathematics are identical, the observations are identical - the theoretical interpretation, and the interpretation only, is what is different. Similarly, on Bohm's Implicate Order theory, the observed non-local pairing of the "entangled" objects should be equally expected - and it is from Bohm that this phrase "hidden variables" first arises. So, in response to your demand for "legitimate alternative theories", take David Bohm's Implicate Order for just one - confirmed "time and time again" by every observation and prediction yet made.
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Post by nickcosmosonde on Dec 5, 2010 22:17:36 GMT 1
What's so controversial is that this is the locus of the major split between physicists who were and are Realists and those who were and are Idealists. Now this dispute occurred at a very late date in science, around about 1925, which was unfortunate, because it happened to coincide with the most disturbing paradigm shift in scientific understanding of observational data that had ever occurred. As an additional misfortune the populist centre of the paradigm consensus had shifted to Germany, where there was a significant majority of university trained physicists, heavily influenced by Mach and Pearson, who believed - almost as an intellectual Jihad against metaphysical notions - that phenomenalism was the only rational foundation to scientific knowledge. You have expressed this philosophical viewpoint quite forcibly, and, like its supporters, have been unable to present any supporting evidence or rational warrant for it.
The fact remains, whether you are aware of it or not, is that the phenomenalism of Mach and Pearson that so determined the Copenhagen Intepretation of Bohr and Heisenberg et al, which was in turn simply a rehashing in physicists' simplistic terms of a much older and more sophisticated philosophical doctrine deriving from Hume and Locke and Berkeley from the 18th Century, was even by the 1920s intellectually redundant. Einstein's rejection of the Copenhagen Interpretation was not in the least an inability to accept the mathematics of QM - it was due simply to the fact that by that time he had read a great deal more philosophy, and had acquired a deeper understanding of what scientists did when they formulated a theory.
We are forced to think with our brains. Of course. Do you believe in some way that this is a novel or startling or even significant insight? Something that has only occurred to physicists that believe in the Copenhagen Interpretation of QM? We think with our brains, yes. This does not mean what you assert it to mean, that therefore we have no possible access to an external reality. If you were within kicking distance I'd wait until you turned your back and kick you up the arse, and I'd bet you felt it too, whether your brain had an "idea" of it coming or not. That's because I believe we share an objective reality, the operation of which has nothing to do with our "ideas" of it, but which continues irrespective of our individual subjective expectations, where I and anything else in reality can intrude on your particular world.
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Post by nickcosmosonde on Dec 5, 2010 23:25:28 GMT 1
Yes, many. They're all as incoherent and illiterate as most other theoretical physicists' interpretations of what they do, and always have been, and the popularisers' so-called translations of what they say.
You've misunderstood my point. I was saying that Einstein's objection to Copenhagen was not a logically coherent alternative theory, giving rise, for example, to the EPR paradox as a gedankenen deduced from it.
Entirely comprehensible, I'm sure. It must be my problem.
I'm sorry SaT, but I'm beginning to see what Nay means when he criticises you about your level of English comprehension.
And now I've more or less ended up agreeing with him.
These "assumptions about locality" entail what, exactly? Whose assumptions are they? Newton, for example, assumed as a consequence of his dynamics that every particle influenced every other particle in the entire universe, at all times, across all distances. So did the arch-phenomalist Mach - it's even called Mach's Principle. The notion of "locality" that you are asserting has been eliminated by these tests is a highly theory-laden one; but I do not know which theory is generating it. It's certainly not in any that Einstein elaborated, of course, though I don't disagree that he may have held such an "assumption", deriving naturally from GR. My point was that the elimination of this assumption does not confirm the alternative interpretation that Einstein was originally objecting to. This is an elementary point of logic.
My nor anyone else's "logic" has nothing to say about empirical reality. What I want to know is what you mean by "non-locality"?
From what you say above, insofar as I can decipher it, you are saying nothing more than what the classic double-split experiment revealed - that photons are distributed waves, interfering with each other, passing through two different apertures at once, and so on. This would not have surprised Newton, of course. The Bell tests go considerably further than this - they suggest that the waves interfere or influence each other beyond the possibilities of physical communication as understood by classical (or relativistic) theory. But again this would have been no surprise to Schrodinger, or Bohm - it is what their theoretical interpretations of QM predict. If this is all that you mean by "non-locality" then I have no objection - my objection is to the illegitimate inference that many physicists and commentators have made that this somehow demonstrates or confirms the Copenhagen Interpretation of QM, where "non-locality" means something considerably different.
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Post by nickcosmosonde on Dec 5, 2010 23:33:52 GMT 1
Abacus, you may understand what this means, but I'm fairly sure no one else alive does. I have to say, you often give me the strong impression that in fact you don't. If you can't understand what you've written, how can anyone else?
Now, Abacus, put simply, statistical data cannot be "violated", whatever that means. Data is data. A theoretically derived expectation of what the statistical data ought to be might be "violated" - except of course it wasn't. It was entirely predictable, was it not? In fact, it was, precisely, predicted - was it not? What does this confirm? The mathematical predictions of QM? Yes. That "the behaviour of entangled pairs cannot be subject to a 'classical' and by implication 'local' interpretation"? No. This would be logically impossible - no theory has the power to exclude possible factors of explanation in this manner. The most we could say is that by the principle of Occam's Razor there is no need and so no rational justification for supposing there are other factors involved - if and only if we can satisfactorily explain our observations with the explanatory factors used in our theory.
And that's the crux of the dispute. The Copenhagen Interpretation asserts that no realist hypotheses are required - the wavefunction is a measure of probability which is all there is "in reality". Its critics disagree. The tests of Bell's Theorem do not advance us in the slightest in deciding between the sides of this dispute - for the critics of Copenhagen the problem of what the underlying causal reality giving rise to our predicted observations might be remains. The philosophical dispute - a dispute about how to rationally interpret the mathematics of the theory - remains exactly what it was.
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Post by speakertoanimals on Dec 7, 2010 14:34:10 GMT 1
Well, if this is all you have to say, I don't see the point of trying to have a discussion with you, if you are really arrogant enough to dismiss a whole section of science in that way. DO you think you can do better, I think not, given the incomprehensible rubbish you've posted so far about Bells theorem.
Except we no longer do that. And I don't see why you are trying to muddy the water by bringing Newton and the infinite speed of propogation of Newtonian gravity into it. And I note again that I'm the one that has to make clear what it is you are wittering on about.
If you want to know about assumptions of locality in Bells theorem, you just have to read the physics literature. So, as Clauser et al say:
Comprehension is not the same as composition, do pay attention! I was saying that Bells theorem (derivations of) say nothing about quantum theory, and you don't NEED to know anything about quantum theory to understand or test them.
That was a perfectly straightforward sentence, I don't know why you would want to pretend otherwise!
We get correlations that are inconsistent with our original assumption of non-locality (which is the whole bloody point of Bells theorem!). We don't need to KNOW that the photons are entangled, or have ANY knowledge whatsoever of quantum theory, we can treat the 'entangled photon pair' source as just a black box (although of course designed or finding the right source without a knowledge of quantum theory and what sort of source was likely to give the correlations we wanted, would be rather difficult in practise!).
What part of relativity and the difference between spacelike and timelike separations and the meaning of relativity of simultaneity did you miss? Seems like all of it! See Clauser above.
This does not mean that the speed of light has to be the upper speed limit, just that there is one (unlike Newtonian gravity, where there is not).
Seems to me, I'm afraid, that you have a superfluity of (apparent) knowledge of philosophy of science, but very little knowledge of the actual science, without which the former is totally useless.
Then you'd be wrong. Because the simple double-slit can be explained using classical waves. You seem to be confusing the possible wave-nature of objects, with non-locality, the two are NOT the same.
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Post by nickcosmosonde on Dec 10, 2010 18:20:17 GMT 1
I'm not the one being arrogant, you are, with your apparent belief that abusive insult is a substitute for rational debate. If you don't wish to have a debate with me, I shan't lose sleep over it - just cease to respond to my posts, as you've done elsewhere when your ignorance and absurdly erroneous comprehension of physics (such as your claim that the time dilation predicted by Special Relativity is a consequence of accelerated motion!) has been demonstrated to you.
I have not dismissed any "section of science". You simply indicate once again that you seem unable to distinguish between the mathematical contents of a descriptive theory and the theoretical interpretations of those contents. As this has been the prevailing intellectual ailment of theoretical physicists for the past century, it shouldn't be surprising. But incoherent and illiterate it remains.
What "incomprehensible rubbish" have I posted about Bell's Theorem? Nothing anywhere near as the rubbish I've just read in your posts, that's for certain, where you claim repeatedly that this experiment "rules out" the possibility of there being any hidden variables. It does nothing of the sort, and could not possibly do so, empirically or logically. This is a basic indisputable fact concerning the relations of mathematics, empirical observation, and explanatory theory, that any undergraduate with the slightest philosophical training could have told you.
No one's wittering, I asked you a simple question - what you mean by non-locality.
Newton did not suppose that gravity "propagated" with an infinite speed, any more than Mach or Einstein did. They all saw gravitation as a universal effect acting locally as a result of the general conditions of a ubiquitous field - called the aether by Newton, somewhat more mathematically defined (Gik) for Einstein, but no different in meaning; Einstein was quite happy with the term aether. Gravitation was produced by the overall universal curvature of space-time, or vice versa. The point is, its effects were always local, an intrinsic part of the tension at any one point of the field - nothing had to travel or propagate anywhere, at any speed.
These notions that you consider "we no longer do" are "muddying the water" for you because you seem wedded to the Copenhagen Interpretation of these tests of Bell's Theorem. This idea that "non-locality" has been demonstrated.
So you can't or won't answer it?
So you agree that "non-locality" means a lack of any causal relation between two events? And that they are separated in space? Why couldn't you just say that, then?
My original question remains then. How is it possible for any mathematical theorem or any empirical observation to definitively demonstrate an absence of a causal relation? Does this mathematical formula have some sort of magical talismanic property that it's able to command objective reality in this way? Are our observational "tests" of it in some way so penetrating and all-embrasive of the Universe that it is no longer possible for there to be something hidden behind the observation that we are in this experiment unable to see? Have the physicists become Matrix wizards or Supermen, with X-Ray vision, able to observe into the workings of the universe itself, to such a total extent that they can see at the same time that there is nothing else to see?
You believe this nonsense, but I can assure you it has nothing to do with "science". This is religious faith of the supernatural magic kind.
Whether there is any causative link between entangled pairs of quantum objects is a matter to be decided by empirical investigation, not by mathematical deduction. Now, Schrodinger's interpretation of QM would say that there is, and that the results of the Bell's Theorem tests should have been exactly what they turned out to be. The same goes for David Bohm's interpretation. Formally, in fact, there is an infinite number of possible theoretical interpretations of any finite number of observations. The Copenhagen Interpretation is just one, and these tests no more confirm it than they do Schrodinger or Bohm. What they do falsify is Einstein et al's supposition that such entangled pairs are separate - but that's all. They falsify a naive and unelaborated notion about local distinct systems - this is the notion of "locality" that has been falsified, not any others. In particular, the notion of "non-locality" that it confirms is not that of the Copenhagen Interpretation of QM as opposed to any other.
Are you attempting to correct my English with this clumsy effort?
This is a ridiculous statement. (As I see you realise yourself, below.) The whole concept of "entangled pairs" has no meaning apart from within quantum theory.
It was ungrammatical and generally poorly constructed. These are the lessons most English people learn in "English Comprehension" at secondary school. But this isn't an English lesson - I don't object to your language skills particularly. I would simply prefer you to be clear.
That is so, indeed - with original naive assumptions, such as those of the EPR paradox. But, you see, this is saying something completely different to your claim that this therefore demonstrates that there can be no hidden variables. This was the whole point of my pointing this out - the "incomprehensible rubbish" you seem unable of grasping.
You seem very confused (which, by the way, is the whole purpose of English Comprehension lessons in the first place.) On the face of it, you appear to be claiming here that if we had conducted the Bell tests without ever having invented quantum theory, we would by their results be led to construct it as a deduction. Not only that, we'd also be led to infer the Copenhagen Interpretation as an implication of that theory. Is that right, or have you got carried away here? I find it difficult to believe that your understanding of the scientific process is that back to front.
Is this supposed to mean something? What? Please give me an intelligible definition of "spacelike" and "timelike" and we might be able to get somewhere. As it is it's an extremely vague and obviously circular self-fulfilling prophecy.
Einstein's formulation of his paradox was not a consequence of any mathematical notion of "locality" that he had - certainly not one deriving from relativity. It was, as I said, a commonsense notion, not a coherent theoretical objection. There is no alternative theory that these tests have falsified, confirming at the same time Copenhagen.
I'm reasonably confident of my knowledge of the actual science. It exceeds your own, at least in the fields of relativity and QM, of that much I'm certain - you've demonstrated it several times already. As for your philosophy of science, you declare in everything you say on this board that you're a complete novice - you're such a novice that you don't even realise how essential to understanding science such knowledge is.
Exactly my point.
FFS! That is what I was asking you! In what sense are you using this term "non-locality"? A pair of entangled photons influence each other as Schrodinger waves in a sense that the Copenhagen Interpretation of QM would say is "local" - "non-locality" means something different in that interpretation. And this has not been confirmed at all by the Bell's Theorem tests. To the extent that it has been "corroborated" in the Popperian sense, so has Schrodinger's interpretation. So has Bohm's.
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Post by speakertoanimals on Dec 13, 2010 13:19:21 GMT 1
Still utter bilge!
WHY you think this is the case, I don't know, and you have not made any attempt to expain this.
The case is very simple -- we have the underlying assumptions as to what we mean by a classical theory of hidden variables. Based on those assumptions, we can place a bound on possible correlations. Actual measurements disagree. Hence could you please explain why logically, that result does not show that our original assumptions are incorrect? If we get measurements that disagree without prediction, then that shows that the assumptions behind our prediction are incorrect.
The depths of ignorance,and just plain wrong! Seems you have never heard of gravitational aberration.
In simple terms, the gravitational force of the sun on the earth has to point towards not where the sun is seen to be now ( a delay of eight minutes), but where the sun IS, else conservation of angular momentum goes straight out the window. Newton of course knew this, and it is implicit in any statement of Newtonian gravity that it is instantaneous positions that are being referred to, within the context of Newtons universal time.
Saying that nothing had to propogate anywhere is just uuter bilge, since a simple measurement of the gravitational force, according to Newton, will give you the instantaneous position of the sun, BEFORE any possible light-signal can propagate between the two.
GR gets round it by having a finite speed of transmission of information, but what is transmitted is, in effect, the position and speed in the past, by which the laws are able to predict current, instantaneous position to a close enough degree to get round the question of gravitational aberration.
The observations show that the assumptions behind the classical hidden variables theory are wrong. Absence of causal relation? You do seem to be getting confused, because the whole point is that a classical hidden variables theory says there is no relation, yet experiment proves it wrong. Hence what it proves is the presence of an unexplained, unclassical causal relation, not the absence of one.
Why you think philsophy has such power, when you don't seem to understand even the BASICS of classical physics is beyone me! Like Newton, for example.
no one ever said otherwise, you numpty!
you realy do seem to have a very odd idea of where the mathematical deduction comes into this, which makes me suspect yet again that you've never actually read (or at best not understood), the basic derivation.
Of course we could have, that was the whole point! Because Bells theorem tells us not that a particular quantum theory is correct, but that classical theories are just plain wrong. There is something weird going on, that is the clear message, and we can't sweep that under the carpet by invoking hidden variables.
How it happened historically is a different matter, doesn't alter the fact that logically, it could have been performed pre quantum theory IF someone had happened to chance upon a suitable source of entangled pairs. Then someone would have had to go and invent quantum theory in order to explain the results.
Again, you don't seem to understand the basic terms being used. You are quite happy to pontificate about what relativity supposedly means or does not mean, yet don't appear to know what spacelike and timelike refer to.
Inside and outside the lightcone, go look it up...............
Well, then your confidence is sorely misplaced, because to date I've seen nothing that indicates any knowledge of the actual physics!
HOW you could make such daft statements about newtonian gravity nis beyind me, it's the very BASICS that underlie the problems that relativity has with newtonian gravity, the fact that as well as time being absolute, newtonian gravity also assumes an infinite speed of propagation -- saying it doesn't is just utter nonsense.
As regards relativity and time dilation, I think you';ll find that the point was that it is acceleration that breaks the symmetry in the twins paradox non-paradox, hence allows a different net elapsed time to be measured. I never said it caused the tinme dilation, speed does that, just that without acceleratiuon as well, the two can never get back together in order to unequivocally compare clocks.
(Actually, there is one further case, where the universe is topologically a cylinder, where that allows a comparison, and breaks assumptions of relativity globally, but not locally).
Except you don't understand the science, or even seem to know much of the basics, that is becoming increasingly clear! Else WHY would you make such stupid statements about Newtonian gravity........................
Nor can you explain these supposedly great insights from philosophy that are supposedly obvious to any philsophy undegraduate..........I have to say, it's just the usual bunk that we get from philsophy undergraduates, who always try to have a poke at physicists, despite not knowing any physics. Soon becomes tedious........................
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