Talk:Afshar experiment/Archive 30

From Wikipedia, the free encyclopedia

Archive This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Contents

"pre-print" labels for arXiv

I think all this quite un-necessary, as it pushes bad meanings. Everyone knows that arXiv is pre-print. Redundancy of such info, is like underline the fact, with possibly bad meaning. Imagine what will look-like to put after Unruh's and Motls's posts in brackets the following remakr: (web blogs). Is it aesthetic? Is this extra info manifesting good intention. Will anyone vote for inserting this (web blogs) after Unruh's and Motl's posts? And what about characterization of Drezet's preprint? Why it has no label? And what about putting After Afshar's two proceesings this labels "(proceedings)" and after the New Scietist and Cramer's Analog column this label (yellow press)? I vote for removing all this extra categorization of sources. One can check them without any prejudice and decide for himself. Danko Georgiev MD 13:51, 28 March 2007 (UTC)

Incorrect text

"But in the Afshar experiment it is actually impossible to reconstruct a pseudo-wave function from Afshar's particle detections." I don't want to check who has written this text, but it is obvious misunderstanding of physics. If you don't know the wavefunction of the setup, how can you calculate and predict the outcome? The text is erroneous, and represents one's own thought activity, i.e. OR. I hope the person who inserted this reverts/deletes himself this text. Explanation: physical theories have major purpose to predict the future outcomes of physical experiment, the theories do not have major purpose to be tested or recovered by experiments. All theories say more that can be derived by experiment, that is why theories have explanatory power. Wave-function Ψ is NOT observable, what is observable is | Ψ | 2, so the wavefunction is constructed by the theory, given that you know the conditions of the original setup. The wavefunction is NOT reconstructed with what you observe as | Ψ | 2. So the wavefunction is NOT constructible by the observations, it is constructible [at 100%] from the theory plus the setup conditions. That is why what you will observe does NOT change the conclusions/predictions of the QM formalism. Arithmetics cannot be disproved by experiment - see the basics of math logic. Observations can prove/disprove only the standard QM formalism as "corresponding to reality", but this is another issue. That is why Bohr's complementarity cannot be experimentally disproved without experimentally disproving QM formalism first, yet this is another topic. Danko Georgiev MD 06:11, 29 March 2007 (UTC)

A pseudo wave function is not the same thing as the wave function. PLEASE DO NOT CONFLATE THE TWO IN YOUR ARGUMENT. A pseudo wave function CAN be reconstructed from detector data. The wave function can't since it is an a priori concept. By way of analogy one can reconstruct the pseudo-radius of a circle already drawn on a peice of paper. The actual radius is the one used to draw the circle in the first place. Both the pseudo-radius and the radius, as here explained, in extraordinarily simple language, are both profound and deep scientific concepts. --Carl A Looper 23:56, 29 March 2007 (UTC)
Dear Carl, my sincere regards, however the word "pseudo-wavefunction" is NOT a term in the standard QM formalism. I didn't understand what this term implies, and as this is NEVER used in standard texts on QM, it appears to be your original idea. It is not my fault, that without explicit note I didn't recognize your original thoughts. I hope this clarifies, a lot. Concerning your paper, if you want, I can discuss in e-mail, I do believe as I usually formulate my claims in very strict math language, we can discuss and enjoy the dialogue, as we will exchange meningful information. Danko Georgiev MD 04:38, 30 March 2007 (UTC)
The point I'm making is that, unlike the twin slit experiment, from which one can derive a pseudo-wave function, the same can not be said about the Afshar experiment. In other words, any warning regarding reconstruction of pseudo wave functions, from detector data, and the possibility of confusing such with the wave function, is only relevant to the twin slit experiment - not the Afshar experiment - since in the Afshar experiment, a pseudo wave function is not constructible. Hope you understand. --Carl A Looper 00:08, 30 March 2007 (UTC)
I've just re-read the quote to see what is causing the confusion and am surprised to find no confusion whatsover. Here is the full quote:
Bohr's "interference effect" is, in his own words, a statistical effect (see below). An interference effect is not the same thing as the wave function. One should not (normally) attempt to reconstruct a wave function from an ensemble of photon detections. Such reconstructions will invariably be psuedo-wave functions - especially in non-solid state experiments. But in the Afshar experiment it is actually impossible to reconstruct a pseudo-wave function from Afshar's particle detections.
Can critics please take off their blinkers when scanning text for errors and actually READ texts at the paragraph level - at the very least. --Carl A Looper 00:22, 30 March 2007 (UTC)
And just so we're clear here is reproduced a previous commentary (from the talk pages) on this point:
One of the major problems with Michael's argument is that he conflates an "interference effect" with the wave function, and an "observed particle" with "tracing a path". The formalism embodys the wave function - it does not embody (in a formal sense) the "interference effect". The interference effect is, of course, predicted by the formalism. Now BPC (and Afshar's experiment) is more specifically, about the "interference effect" and it's supposed complementary relationship with the construction (tracing) of a semi-classical path (rather than a particle detection per se). Drezet's argument is an important one which Michael mangles. According to Bohr (which Drezet notes) one can not reconstruct the wave function from a set of individual particle detections. One can, of course, reconstruct composite or "pseudo-wave functions". And this happens quite a lot in information theoretic terms. But in Afshar's experiment, unlike the conventional twin slit experiment, it is actually impossible to reconstruct even a pseudo-wave function. In many ways Afshar's experiment is better than the twin slit experiment since it elliminates the very possibility of reconstructing a pseudo-wave function (I'm ignoring the minor fourier components discernible). In other words, Bohr's warning is actually irrelevant here. Another important point is that, in solid state experiments such as the Afshar experiment, (and the twin slit experiment), the wave function associated with any single detection is mathematically equivalent to the wave function for any other particle detection - ie. in the same solid state experiment. This does not mean they are the same (in a formal sense) - but it does mean one can recycle the math from such, for use in constructing a brand new wave function for prescribing a new particle detection - on the proviso that each is understood as a brand new wave function. But back to BPC. BPC concerns the "interference effect" which IS A STATISTICAL EFFECT. What Bohr was warning against was reading the formal wave function as a statistical effect - if only by definition - by it's very postulation as an a priori concept for predicting single particle detections. But in the Afshar experiment, the wave function (and the formalism) is not at issue. Michael wants it to be but he's wrong. One of the key strategys in the Afshar experiment is to produce an "interference effect" via the intensity of photons detections (per unit area of space or ideally at a point) rather than via the traditional method ie. by a statistical distribution of detections over space. It is the production of an "interference effect" and what's more it even prevents any "illegal" reconstruction of the wave function. And that is how it should be because that is what BPC is all about. It is about just such effects - and the conditions in which just such effects are physically realisable. On the other side is the path function. A semi-classical path not to be confused with Feynman's path integral. Feynman's path integral is a way of constructing the wave function. Bohr's path is a different beast. But it is not important here. I merely wish to show up how Michael's argument is confused at best and deliberately misleading at worst. --Carl A Looper 00:17, 27 March 2007 (UTC)
So you see, if only on this point, (regarding detector defined "wave functions") we really should be in agreement with each other. --Carl A Looper 02:51, 30 March 2007 (UTC)

Ongoing debate

The whole section was voted for deletion, as it was written by editors, who even don't have any scientific contribution to QM or at least to Afshar's experiment. Still I expect to see Carl Looper's forthcoming paper promised in 2006, yet until then, I don't think that specific critiques section must be 3 times shorter than the non-expert written ongoing debate section. Danko Georgiev MD 10:06, 29 March 2007 (UTC)

I agree. Delete the whole thing. But someone else needs to do it - but without destroying the links. Re - scientific contribution. It is true that I haven't completed my paper but there is far more material I need to go through than a re-exposition of the QM formalism. I'm writing from the point of view of information theory (a well defined science) and in particular signal theory - and even more specifically, - semiotics. The main problem is this. In terms of the QM formalism alone, one could argue that no "interference effect" can be said to have taken place in the Afshar experiment since the shape of the wave function, which normally determines the presence/absence of an interference effect (at the detector site) is determined only by the apertures and lens/detector arrangement - the wires playing no role whatsoever in shaping the wave function. And since the shape of the wave function, at the detector site no longer carrys any intrinsic interference information (other than minor fourier components) one must conclude that no "interference effect" is demonstrated. But if one is to claim an "interference effect", then one must look wider than the formalism, back in the setup - which is where Bohr is otherwise pre-occupied. And sure enough - there are the wires. We can't erase our knowledge of the wires - but the wave function does - insofar as it never carrys any information regarding the wires in the first place. What we find is that it is the combination of our knowledge regarding the wires (a pre wave function structure), and the information embodied in the data (the intensity level) , plus our understanding of the wave function, which collectively construct our conclusion that an "interference effect" is demonstrated. But this can't be demonstrated by the QM formalism. It can, however, be demonstrated in terms of what Bohr is talking about. And what Bohr is talking about, as well as Heisenberg, involves a good deal of theory beyond the formalism. And to expose such requires a good deal of research which I can only lightly touch upon here in the hope that someone else is capable of picking up on it. For everyone else they must wait for the paper and reponder their equations. --Carl A Looper 23:27, 29 March 2007 (UTC)

Introduction

There was an error in the introduction regarding the Greenberger-Yasin relationship. I corrected the text to factually reflect my claims that is mentioned in section 5 of the Found. Phys. paper. Here's the new text with the changes in boldface: "...appears to be in accordance with the standard predictions of quantum mechanics, however, it is claimed to violate the Englert-Greenberger duality relation." -- Prof. Afshar 12:48, 29 March 2007 (UTC)

Kastner

Kastner writes:

Nevertheless, even with the grid removed, since the photon is prepared in a superposition S, the measurement at the final screen at t2 never really is a "which-way" measurement....

That's about as clear as can be that she doesn't belong in the "grid erases info" camp but in the "never any WWI" camp. I think it will be necessary to move her and to resurrect that point of view from the footnote back into the regular text. Any comments before I do that? --Art Carlson 19:45, 29 March 2007 (UTC)

Dear Art, my regards, but Kastner's argument is flawed. It is NOT the superposition that erases the which way. Imagine AS AFSHAR POINTED OUT the two non-overlapping beams, for example arm 1 and 2 of the Mach-Zehnder interferometer, or the two slit beams before they overlap i.e. very close to the slit. Yes, they are superposied in the form Ψ = α1 | 1 > + α2 | 2 > , however because |1> and |2> are NON-OVERLAPPING i.e. orthogonal, at this stage the ww info is NOT erased, as these two wavefunctions [kets, |1> and |2>] do NOT manifest interference effects. Only after the overlap region the ww info is erased. This is clearly expressed in the equations 3 and 4 in my published article. As you have PhD in physics, you can check for yourself the calculations, they are not too complex after all. Danko Georgiev MD 04:43, 30 March 2007 (UTC) p.s. Kastner consulted Cramer, and Cramer said the ww info is there in many articles and lectures of him! So "never really" if understood literally, then Kastner should provide thesis exactly opposite to Cramer, yet Cramer was one of the consusltants. I am not sure whether Kastner has clear idea of what she is proposing. Simply if she relies only on superposition to erase the ww info, then she provides wrong argument, which is to be classified in 3rd group, separately! Danko Georgiev MD 04:47, 30 March 2007 (UTC)
We are not discussing here whether Kastner is right or not, simply that her argument is improperly characterized in the current version. In addition, I don't think your description here is accurate. She is not saying that the superposition erases which-way-information, but that the wave function always contains both "ways" - at the slits, at the wires, in front of the detector, all the way up till the collapse of the wavefunction in the detection process. --Art Carlson 07:27, 30 March 2007 (UTC)
Dear Art, the which way concept is one-to-one correspondence concept. It has nothing to do directly with superposition of paths, i.e. much more other stuff is needed in order to prove the required bijection. Superposition existent or not, by itself is not directly linked to idea of bijection. For bijection, you must at first define two sets mathematically, then you must verify they have the same cardinality, and then describe a mapping. See bijection for details. I had the impression that Cramer was major consultant of Castner, so I thought that Kastner supports Cramer's view which are exactly clear for which way. Of course all these objections from this group are math inconsistent, so I am not surprized that confusions arise. p.s. feel free to classify Kastner's work any way you like. And reply to Afshar, yes there are two camps of objections, the fact that Kastner does not fit anywhere, is simply because her analogy is hardly seen or understood by anybody, as it is provably incorrect. In contrast Unruh's setup is crystally clear in disproving Afshar's analysis, however not in the way originally proposed by Unruh. Danko Georgiev MD 08:33, 30 March 2007 (UTC)
The "grid erases info" was put there by Danko to create an illusion of two major camps! The fact is the arguments presented by Unruh, Motl, Kastner, Drezet and others in that section are varied, subtle and usually contradictory to the other critics' argument. Kastner is using Cramer's Transactional Interpretation discussing an allegedly analogous experiment using Spin 1/2 particles and Stern-Gerlach apparatus. I have previously discussed the lack of analogy between my experiment and her suggested one's at the APS March 2006 meeting chaired by Prof. Greenberger, and separately my colleagues have responded to her in http://arxiv.org/abs/quant-ph/0702210. Her argument is very different from the fringe DQD argument, which is questioning the conservation of momentum argument espoused by Einstein and later used by Wheeler discussed in the article on Wheeler's delayed choice experiment. I suggest we remove the "grid erases info" from the text, and leave the fringe DQD argument in the footnotes, until they publish in a reputable peer-reviewed journal. BTW/ Unruh is a very famous and well-respected theoretical physicists who worked with Hawking and Davies (see Unruh effect)...-- Prof. Afshar 20:03, 29 March 2007 (UTC)
And Tabish Qureshi is famous and well-known researcher, who has disproved many other incorrectly solved foundational problems in QM. Now it seems to have spotted another incorrect solution done by Afshar et alia, that has been properly solved and math inconsistency revealed. Danko Georgiev MD 08:36, 30 March 2007 (UTC)


It seems that once again D. Georgiev try to monopolize the discussion here. I have only two comments concerning his paper . First, watching the submission date (march 01 )and the acceptance date (march 05) it is celar that there is no reviewing process . Also it means that this paper is not more valuable that a preprint on arxiv. It would be nice if danko could calm down a bit and simply be open for other points of view. Secondly, (but this is a detail ) the fact that Tabish Qureshi is famous or not is not relevant in your argumentation because Unruh for exampl is for sure much more known. Reference to specialist as proof per se is not science (this is a well known fact) and this works in both directions Drezet 10:03, 30 March 2007 (UTC)

Drezet, I am "copying" Afshar's argument, as it is one of my favourite ways to lead discussion, use the tools of the opponet, and force him into self-contradiction. Please comment on Afshar, not me. BTW, acceptance date with 2 years delay, is NOT a criterion either. I am exhausted to point out that science is to be decided in scientific way. Danko Georgiev MD 11:41, 30 March 2007 (UTC)
You guys, have nice time here. Continue to be "objective" wiki-editors, I will not lose my precious time here. I VOTE for Afshar being able to edit the article any way he likes, and retract my previous vote for him to be banned from editing the Critique section. Regards to all, Danko Georgiev MD 11:47, 30 March 2007 (UTC)
Probably no one will object to your removing the reference to your work, but I hope you realize that the editors have every right to put it back if they want to. --Art Carlson 12:46, 30 March 2007 (UTC)

additional references

Qureshi writes:

As expected, there has been skepticism towards Afshar’s experiment, and a heated debate is currently going on7,8,9,10,11.

7 “Why the Afshar Experiment Does Not Refute Complementarity” R. E. Kastner, arXiv.org:quant-ph/0502021.

8 “Logical analysis of the Bohr Complementarity Principle in Afshar’s experiment un- der the NAFL interpretation” R. Srinivasan, arXiv.org:quant-ph/0504115.

9 “Complementarity and Afshar’s experiment” A. Drezet, arXiv.org:quant-ph/0508091.

10 “Afshar’s Experiment does not show a Violation of Complementarity” O. Steuernagel, arXiv.org:quant-ph/0512123.

11 “Entanglement and quantum interference” P. O’Hara, arXiv.org:quant-ph/0608202.

I was always a bit worried about the possibility that our choice of criticisms could be biased, so I am grateful for a verifiable selection. We already have Kastner, Drezet, and Steuernagel. I will now add Srinivasan and O'Hara. --Art Carlson 09:34, 31 March 2007 (UTC)

Recent improvements

Thank you to both Art and Carl. The new specific critiques section is now logically structured, and carries useful information regarding the crux of each author's criticism. My hat's off to Art for having spent a good deal of time and effort to actually read and reflect upon each entry. Now, from a NPOV standpoint, I believe it would be necessary to inform the reader of my rebuttals to each. But before that, I'd like to ask one of the editors to add a small graphics and short description of an experiment (explained in the AIP paper) that was performed to simplify the experiment and use the conservation laws more clearly. I call it the Crossed Beams experiment in which no imaging lens is used. Please let me know who would like to take on this task, and I will provide the graphics that needs to be reformatted to the Wiki version. I'm not well-versed in the process myself! We discuss the related text here first. Thanks. P.S Qureshi paper should be properly flagged as a fringe argument, one which Unruh and all experts in the field reject. More importantly, it belongs in the article on Wheeler's delayed choice experiment since he actually criticizes Wheeler's setup and arguments, not mine... -- Prof. Afshar 14:18, 31 March 2007 (UTC)

Carlson's edit on Unruh is FALSE

Carlson: "In other words, he [Unruh] accepts the existence of an interference pattern but rejects the existence of which-way information."
Note - this is EXACTLY 1-to-1 formulation of Georgiev's thesis, NOT of Unruh's thesis, see below for details

Dear Carlson, obviously you make BIG error in claiming that Unruh rejected the "which way" claim. What is written is exactly one-to-one MY OWN WORK. I can send you also the submitted to PP comment by Unruh, and my send you personal correspondation from Unruh, and you can even find exact claim that if there is NO obstacle on path 5, the which way information exists. Please be aware of what you are writing, as the current opinion on Unruh's setup is MY OWN conclusion, conclusions of Unruh are exactly the opposite. Read the PP article, for details, and compare my thesis vs. Unruh's thesis. I insist at least NOT to present my opinion as Unruh's opinion. This is a lie, and misleads the readers. If this "parody" continues, I am fully in my right to send complaint to editor of PP, and request, speeding up of on-line release of Unruh's comment, so that everything will be clarified. In the PP comment and in letters to me and the Editor of PP Unruh said "states |1> and |2> are the eigenstates of detectors D1 and D2, respectively, so they are orthogonal and there is which way information". I believe my request for you to immediately repair your false posting is acceptable, as now I am speaking about verifiable historic facts, as all these exchanges are officially received by prof. Rabounski, and are hence official peer-reviewed scientific discussion. Danko Georgiev MD 07:13, 1 April 2007 (UTC)

  • For the recrod, Danko is right about Prof. Unruh's argument. -- Prof. Afshar 17:50, 1 April 2007 (UTC)

p.s. Additional clarifying (for non-acquainted reader)

  • Unruh says [i] IF there is no obstacle on path 5, [ii] there IS interference PLUS [iii] there IS "which way" because "states |1> and |2> are the eigenstates of detectors D1 and D2" - (I have proved this is INCONSISTENT mathematically)
  • Unruh says [i] IF one puths obstacle on path 5, [ii] there is interference, BUT [iii] there is NO "which way"
  • Georgiev thesis - in both cases, obstacle on path 5, or obstacle NOT present on path 5, there is interference and there is NO which way. (i.e. Georgiev thesis = Qureshi's thesis = that the existent interference deletes the which way, not the obstacle put on the path) The fact that there is NO obstacle does NOT change the mathematical calculation of the evolution of the quantum amplitudes. The obstacle at path 5 changes nothing, as it is located in region where the amplitudes are destructively interfering so quantum amplitude is ZERO already. My mathematical proof in PP is rigorous in showing "states |1> and |2> are NEVER eigenstates of detectors D1 and D2 in COHERENT SETUP"
ONLY in MIXED STATE SETUP i.e. where one involves polarization filters, the "states |1> and |2> are the eigenstates of detectors D1 and D2" - for curious readers, this is due to external entanglements with the polarization filters [Zeh 2000, Zurek 2003, Tegmark and Wheeler 2001], and we speak of reduced density matrices in this case Danko Georgiev MD 07:19, 1 April 2007 (UTC)
Well, welcome back. It sounds like you would like to put the reference to your article back in. Is that the case? As for any private correspondence among you, Unruh, and Rabounski, that is not verifiable and thus cannot be used as a basis for a Wiki article until it is published. (Although it could possibly help clarify misunderstandings.) As for my paraphrase of Unruh's position, I can't see any other way to interpret the line I quoted. You state that Unruh believes there is which-way information as long as there is no obstacle in the dark path. Can you attribute that position to any particular statement on Unruh's website? --Art Carlson 08:53, 1 April 2007 (UTC)
It is NOT well, as I did NOT want to back. However seeing MY OWN work, to be misattributed to Unruh, this is something I have least expected!!!! After all, take into account that I am involved in this study since 2004, and I am scientist at first place - I never lie on what others have said. I DO NOT WANT MY PAPER BACK. I WANT YOU TO REVERT YOUR FALSE POST. HERE IS THE PROOF - EXACT QUOTATION FROM "Q-REBEL" by W.G. UNRUH:
"Similarly, in figure 1a, a similar situation is true if beam 1 is blocked so that photons only traverse path 2 and all of those photons finally fall on the detector in path 6. This is thus in analogy with Afshar's system where the lens is designed so that travel through slit 1 falls on photo-detector 5 and travel through slit 2 falls on photo-detector 6. The measurement of the final location of the photon thus would tell us which path, 1 or 2, the photon followed... The system is arranged so that the interference at the second half silvered mirror is such that now all of the photons go on path 3. path 4, like the dark fringes in Afshar's setup, contains no photons. These will fall on detectors 5 and 6. Furthermore, one can still argue that any photon which fell on detector 5 came from path 1 and those on 6 came from 2."

Unruh speaks here on case where NO obstacle is there [attention: in Unruh's article the obstacle is put on path labelled as 4, in my PP paper the nomeration is a little bit different, so for MY paper the path with interference has the label 5!]. The detectors in Unruh's bolded words provide which way information for the path 1 or 2. Before you ironically comment me, please be sure you have read really the already available source. I NEVER post without having in mind EXACT QUOTATION. Please remember this fact, Regards Danko Georgiev MD 09:07, 1 April 2007 (UTC) p.s. Obviously for me, you have analized yourself the setup, so you have reached to my conclusions [as logically following] and then you have misattributed the correct analysis to Unruh, without being aware of the fact that Unruh claims exactly the opposite. If Unruh have said what you have summarized [and you well can verify from my published paper, that what you have written is 1-to-1 Georgiev's thesis sec 3.2, page 100, PP], then I would never have published my paper at first place - because I will not say something new. Danko Georgiev MD 09:13, 1 April 2007 (UTC)

I agree that the position attributed to me in the current article is misleading. IF there is no impediment in the paths ( wires in Afshar's experiment and blockage in path 5 in my description) then the detection at the detectors IS a measurement, in the sense of von Neuman, of the "which way" information of whether the photon went along paths 1 or 2. IF there is a an impediment then you can no longer infer from the detection which way the photon went. Ie, what you can infer from the detection of the photons at the detectors depends on what the experimental setup is. WG Unruh(1 Apr 2007)

All sides agree that I misread Unruh. I took another stab at it. Happy now? --Art Carlson 19:11, 1 April 2007 (UTC)

Other than that in the section on Luboš Motl you claim that I reject which way information in all cases, sure. W Unruh Apr 2 07

Have I got it right now? --Art Carlson 07:05, 3 April 2007 (UTC)

On the specific critiques

I am very glad that removing my work, restored back all the critiques in the main article. So thank you Art! I have seen insertion of researcher's that propose very bizzare and hardly understandable "novel" versions of QM analyzing Afshar, accept "paradoxes" etc. For the sake of truthness you have missed one such "novel" paper by professor Matti Pitkänen Double Slit Experiment and Classical Non-determinism. The proposal of prof. Matti Pitkänen for those who even slightly understand QM formalism is ULTRA Afshar's, as Matti Pitkänen SUPPORTS Afshar like Cramer. Matti Pitkänen says "If the possibility of macroscopic quantum entanglement between measurement instrument and quantum system is accepted, complementary principle becomes un-necessary.". For me this is pseudoscience, as all the math clothing does NOT lead to this ULTRA-Afshar conclusion, however as the author is Ph.D. in physics, I might well be wrong in my judgement. prof. Matti Pitkänen is the sole author of novel TGD theory. I hope I have helped with some good INFO. Afshar may well vote that prof. Matti Pitkänen works supports Afshar's claims! And for Art, surprizingly professor Matti Pitkänen has a Wiki-entry! Strange world, isn't it? So according to Art's criteria the paper should be necessarily be inserted in the main article. Danko Georgiev MD 09:36, 1 April 2007 (UTC)

Regarding "acceptance of paradoxes". Finding or otherwise demonstrating a paradox is not the same thing as accepting that paradox. When Einstein proposed the EPR experiment it represented a subtle change in direction with respect to what he was hoping to achieve. In EPR Einstein sought to demonstrate a paradox in QM. This does not mean he wanted to accept such a paradox. If one can demonstrate a paradox it is simply the construction of a problem - something to solve. But according to Bohr there is no paradox in EPR since the "paradox" (or pseudo paradox) only occurs when the two datasets (Alice and Bob) have been combined and a correlation found. The correlation implys FTL but this can not be physically demonstrated until the two datasets are combined. And this combination can't occur until the information (Alice and Bob), travelling at conventional sub-light speed, can reach each other, ie. by which time superluminal flow of information has failed. Weird as it is. If one can demonstrate a paradox then one next step is simply to solve that paradox - if it's not already solved within the scope of QM. This is not to accept the paradox. For example, Bohr's solution to the EPR "paradox" is to turn our attention to the information signified by the QM formalism - away from the formalism itself. And that is one of the directions QM can take - into information theory. To explore the information side of the equations (the pseudo wave functions, etc). The other is something akin to Einstein's agenda where the formalism itself is targeted for revision, re-scoping or re-engineering by firstly identifying a paradox and then, secondly, re-solving such. And, of course, one could pursue both directions. --Carl A Looper 00:25, 2 April 2007 (UTC)
From the point of view I'm adopting there is no paradox in the Afshar experiment. A suitably prepared wave function interacting with the experimental specification predicts no "interference effect" will be observed in the detector data. And none is (other than minor ones). But when you connect the detector data with the presence of the wires (ie. with the specification of such) an "interference effect" is produced. And BPC implys one should therfore see no which way information. But lets just stay with the interference effect. Unlike EPR, the wire specification is not something that has to arrive anywhere. It is omni-present. It is embedded in the epistomological conditions (the setup) which determine how the wave function is conventionally prepared - but the wire spec is redundant data as it does not affect the wave function. In information theory the wire specification can be regarded as "client-side" data that is ignored by a wave function "server". Or not passed as arguments to it in the first place. Only the aperture states and lens are processed by the wave function server. As a result the server returns a "no interference result". The problem is that this result can still be passed back through the client specification - which includes the wire spec - resulting in a client side "interference effect". The server can't be used to predict that aspect of the client side setup (the wires) to which it is a priori oblivious. So it can't be used to predict what the combination of that data, and the detector data (which it can predict) would produce. --Carl A Looper 03:54, 2 April 2007 (UTC)
Here's an even simpler analogy. Suppose we have a machine gun, with a fixed frequency of bullets per second, firing bullets into a single spot on a wall. Using such a spec we can design a shutter in front of the machine gun, that opens and closes in syncronisation with the machine gun, the phase offset being such that it is always open when a bullet fires. And the shutter can operate at any harmonic of the gun's frequency (up to a certain point). Well, from the bullet holes in the opposite wall we can't tell what the frequency of the machine gun was - nor the frequency of the shutter. There is no "interference effect" as such. But from the phase/frequency of the shutter, and the fact that all bullets arrived at the wall (no bullets hit the shutter) we can conclude the machine gun was indeed firing at some harmonic of the shutter frequency (and vice versa). From the spec of the machine gun we can predict the magnitude of the hole in the wall. From the spec of the shutter we can predict that the shutter will have no effect on this magnitude. But we can't predict, from the spec of the machine gun, or the shutter's spec, the exact frequency of the other. But we can conclude they must have been syncronised at some (if unknown) harmonic - which is effectively a measurement on interference - an interference effect. --Carl A Looper 07:33, 2 April 2007 (UTC)

Congragulations to Art and everybody else involved. Absolutely well done. Clear. Concise. Even handed. Intelligent. --Carl A Looper 23:35, 1 April 2007 (UTC)


Things are much better now ! Could it be possible to say a bit more on the point of view of Cramer?. Indeed there is a strong unbalance between the arguments pro and against the afshar interpretation Drezet 16:50, 2 April 2007 (UTC)

How about the following:

Developed in the 1980s, Cramer's Transactional Interpretation of the QM formalism is an alternative to the Copenhagen Interpretation, and as such it is an alternative to Bohr's principle of complementarity. The transactional interpretation seeks to exhaust the meaning of the formalism, not in otherwise mutually exclusive setups or observables, but in mutually inclusive inferences. Within the ontological domain of a QM experiment can be understood a classical-like path, analysable in terms of two time symmetric interfering wave functions which otherwise reproduce that path, everywhere else cancelling each other out. The time reversed component of the dual wave function has it's origin in a particle detection and can be thought of, in chronological terms, as "travelling backwards through time".
Cramer regards the Copenhagen Interpretation (which includes Bohr's principle of complementarity) as inconsistent with the QM formalism, and that the Afshar experiment is a confirmation of that. The Transactional Interpretation, on the other hand, is considered by Cramer as consistent with the Afshar experiment.

--Carl A Looper 05:08, 4 April 2007 (UTC)

Dear Carl, If you want to contribute to Transactional interpretation let us lead the discussion at that talk page. As big part of my investigation was on Transactional interpretation as applied to brain process (original idea by prof. Chris C. King, math dept, Uni of Auckland, New Zealand). Your summary is not correct. First, note that the birth paper of TI in 1986 never says that TI and CI are different because they violate the complementarity. The difference is that TI relies on relativistic QM (RQM), while CI on ordinary QM. Hence TI with standing waves is realised in RQM (e.g. QFT, etc.), not ordinary QM. Nevertheless, the cancelling of the waves and formation of the standin wave is [process 1]. As you may see exact solutions of the RQM equations will always preserve the original probabilities in the amplitude of the wave. So the standing wave will have amplitude of ψψ * , which is not 1. There is second nonlinear process [process 2] that trasnforms irreversibly the state \psi \psi^* \rightarrow 1, hence Cramer uses the word "collapse". The standing wave formation itself is concept different from the "collapse" which is non-unitary "sudden" change of the standing wave amplitude into 1. Also this is the "early" Cramer of 1986-2003. In 2004 Cramer suddenly realized that "Bohr's principle is NOT part of TI", which well might be wrong, as objections to Afshar are now available. So this "late" Cramer, may well be wrong, which will NOT destroy the basis of the "early" work. Indeed the "late" Cramer did NOT add any equation to TI, it is just philosphy and speculation provided that Afshar's analysis is true. If Afshar's analysis collapses due to inconsistency, then this "late" Cramer will be wrong too. Danko Georgiev MD 07:34, 4 April 2007 (UTC)
Hi Danko. I've considerably simplified TI here in an effort to keep it as a candidate for inclusion in the paraphrasing of papers of interest to the Afshar experiment. Perhaps you might like to have a go at it. I'm not particularly attached to it. It's a first draft. Regarding complementarity, TI doesn't specifically mention BPC but BPC is an important part of the Copenhagen deliberations and is, by implication, targeted by TI. And I was careful to characterise it this way in the paraphrasing (if you re-read it). None of this changes the equations (ignoring adjustments for relativity). The Copenhagen Interpretation can be extended into the relativistic domain as well, although this was not done at the time. But then the debate has never really been about the equations anyway - at least not explicitly. It has always been about interpretation (philosophy). At the equation level, TI and CI are said to be equivalent (again ignoring relativity). And at the equation level the Afshar experiment is consistent with the formalism. Where the "trouble" begins is at the level of interpretation. But one can't just ignore such as "just philosophy". Without interpretation the equations can't be applied. They just fold back into pure mathematics. It is only via philosophy (which I call theory) that one can hope to specify a dividing line between physics and other disciplines (such as "philosophy") - if indeed one wants to propose that such should exist anyway. To call something "just philosophy" is to have theorised there is a difference - or otherwise appropriated that theory. But it's a particularly regressive theory (philosophy) that pretends or is otherwise ignorant of it's own philosophical origins - that positions everything else, other than itself, as "just philosophy". --Carl A Looper 00:20, 5 April 2007 (UTC)
I might just add (as I do) that I'm not a proponent of TI but I do admire it. My paraphrase does need some work. I indicated that the dual wave functions are "mutually inclusive" but this is only in terms of their mutual interference. But a complementary aspect is still embodied in the time component of the wave functions - ie. one is reversed with respect to the other. But this is not Cramer's take on Bohr's particular discussion of complementary - Bohr is focused on setups and observables. Cramer's later support for the Afshar experiment only reveals Cramer's already articulated rejection of the Copenhagen Interpretation (the CI emphasis on observables). Cramer turns our attention back to the ontological domain - where the state vector is imagined as operating - as does the Afshar experiment - and I still find this extremely interesting even if I can't help but see the interpretational conflict this induces. Bohr implicitly turns our attention back on this domain as well. What is an "interference effect" if it's not something which turns our attention back to the interference we otherwise imagine as overlaying or occupying the ontological domain? Certainly it could just mean anything which is an "effect" of interference but then any single particle detection, in the twin slit experiment, would be just such an "effect" and this is obviously not what Bohr means. So it can only be that which enables an "illegal" inference of interference - ie. something which a single detection does not allow. Bohr's primary emphasis remains on the predicted data but he allows that data to fold back into the ontological domain or to at least to overlay that domain - wherein we can retroject a classical path or a classical wave depending on the setup. The question is whether such retrojection necessitates that we choose mutually exclusive setups, or whether we have no choice (Bohr's position), or whether we have a choice - but depending on what choice we make the result is ... ? --Carl A Looper 01:54, 5 April 2007 (UTC)
Dear Carl you say "Afshar experiment is consistent with the formalism". No - it provides value for V^2 + D^2=1.34, which is VIOLATION of formalism. If you read my published paper, you will see that no bijection = no which way! V=1, D=0. I will not argue anymore. Afshar violates the formalism, what I have said is published, now I write follow up to Unruh's letter, both will appear in vol.3 of PP, also I have some other work under peer-review. I will not edit anything on TI, or CI, in Wikipedia. Please contact me by e-mail. p.s. link to my published articles at my user page. Regards, Danko Georgiev MD 05:05, 6 April 2007 (UTC)
Hi Danko, my apologies for any misunderstanding. When I say the "experiment is consistent with the formalism" I only mean by such that the detectors in the Afshar experiment (which could also include the wires as photon detectors) produce the formally predicted results - ie. almost no photons are detected by the wires and all other photons are detected in the lens detectors. Now how you interpret the formalism and more specifically, BPC, determines how you will initialise V and D. The equations don't change. Afshar's initialisation of V and D is consistent (I'm arguing) with what Bohr requires even if it leads to a paradox/violation which would be very inconsistent with Bohr. In Afshar's experiment, V and D are classically initialised rather than using any quantum theoretical assumptions. And this is consistent with Bohr's articulation of BPC - that any use of the formalism requires it be initialised classically. But this is not the end of the story. I don't know what Afshar is doing to resolve the paradox but it would require novel solutions because the conventional one - BPC - doesn't work. I have my solution which I've hinted at in the above discussions and on my talk page - but the full exposition belongs to my research paper. And I believe it interoperates with your solution but I could be wrong about that. --Carl A Looper 23:00, 10 April 2007 (UTC)