Talk:Afshar experiment/Archive 21

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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

To anonymous

Hello anonymous. I perfectly agree with what you say that there is no which way information at first place, so please see my PhilSci paper. I have proved much more than this actually. Since 2004 I am leading alone this battle to mathematically show that the "which way" claim is wrong at first place, but I was met with ridicule by Afshar, Unruh, Drezet and others who claim themselves expert physicists and fail to see that they do inconsistent mathematics. Danko Georgiev MD 09:24, 18 January 2007 (UTC)

  • p.s. Please register yourself in Wikipedia and sign your posts. My paper has been systematically removed from the critique list by Afshar himself, and unfortunately my paper was the only one who shows Afshar's error, all other objections are not valid due to flawed reasons. Danko Georgiev MD 09:25, 18 January 2007 (UTC)
I think the anonymous user was itself Tabish Qureshi, who initially added the link to his own article (well, I might be wrong). If so, I am glad to continue this discussion with him, since I have read his paper, and he insists that the thin wires block the "canceling each other components" coming from the opposite slits. Yes, true, but the central argument in the whole discussion is that there is NO which way information even if you do not put wires at all. This is evident in the Unruh's setup that I discuss in detail. Tabish Qureshi in his paper is afraid that someone "might argue these components do not cancel each other". Yes, it is possible, but then one argues that the density matrix of the qubit is "mixed state". Therefore if one does so, he must also postulate metaphysical immunization in the form "mixed state density matrix cannot be distinguished by pure state density matrix". This second claim remains hidden for Afshar, Unruh, and others, and I hope that when they realize that, they will withdraw their false statements, and appologize for posting nonsense. Danko Georgiev MD 10:35, 18 January 2007 (UTC)

Warning on OR

Again, I repeat for the last time: Danko's assertion that there is nor which-way information in the absence of the wires is Original Research and absolute nonsense. Not a single physicist disputes presence of WWI due to conservation of linear momentum. Danko, no amount of your punditry and stubborn refusal to accept verified laws of physics will stop me from moving your misleading and patently erroneous arguments to your own talk page. You are more than welcome to post whatever you wish there, but OR is not allowed in this page.-- Prof. Afshar 15:06, 22 January 2007 (UTC)

Whether it is OR is subject to debate and is not for you to pronounce upon. --Michael C. Price talk 15:31, 22 January 2007 (UTC)
Michael, let's make it clear right here, right now. Are you as Danko saying that there is no which-way information even in the absence of the wires?-- Prof. Afshar 15:57, 22 January 2007 (UTC)
As I said, whether it is OR is subject to debate and is not for you to pronounce upon.--Michael C. Price talk 16:43, 22 January 2007 (UTC)
Afshar, the argument of conservation of momentum can only be invoked if you KNEW that the particle started from a particular slit, and it had a well defined momentum. This is the case when only one slit is open. With both the slits open, the particle is in a superposition of two distinct momentum states. So, I don't quite see how you can invoke conservation of momentum here. Tabish q
In addition to this, have a look at my e-print quant-ph/0701109, and you will see why there is no which-way information without the wires. —The preceding unsigned comment was added by Tabish q (talk • contribs) 16:02, 22 January 2007 (UTC).
  • Dear Prof. Qureshi, With all due respect I wish to point out a few issues: When the two beams no longer overlap spatially, and in the absence of the wires, the linearity of QM and conservation laws demand that each photon in each beam trace back to a particular slit. Of course, in the overlap region the which-way information is washed out due to the equal amplitudes from the other beam. Einstein, Bohr, Heisenberg, Dirac, and later Wheeler, Greenberger, Zeilinger, Hardy, and all other well-published physicists in the field agree with the above. If you disagree, then you are making a much bigger claim than mine, and should duly undergo peer-review and publish your paper on the subject. I suggest you think a little harder before publicly announcing your view on this issue, as it may do more harm to your career than good. If you were not a physicist, as is the case with Danko, I would not care much about what you said, but you must realize that this is an extremely serious field with major players, all of whom have very little patience with half-cooked ideas, unless of course the announcer of such ideas has a disclaimer that he/she is just thinking aloud and not making any claims at the moment. Anything short of a refereed publication on the subject is Original Research, which should be discussed in user talk pages. BTW/ it would be nice if you setup a Wiki account. Best regards.-- Prof. Afshar 16:32, 22 January 2007 (UTC)
Dear Prof. Afshar, I agree with you that IF the beams do not overlap, the which-way information is contained. So, you agree that in the overlap region, the which-way information is washed out. Then, if the information is washed out, there is no way it can be recovered later in time evolution. In your experiment, the beams do cross (which is why you have interference), and so the which-way information is lost. So, how do you claim a violation of complementarity? And I am a physicist. See for instance, my resolution of the controversy surrounding Popper's experiment - quant-ph/0405057 (Am. J. Phys. 73 (6) (2005) 541-544) To my knowledge, your experiment has not been published in a peer reviewed journal yet (plz correct me if I am wrong). So, does it count as OR (whatever it means)?Tabish q
  • Dear Tabish, My paper has been accepted by an important refereed journal and will be published in February. Unfortunately, their Embargo policy does not allow me to announce the journal's name. On the issue of which-way information, if you observe the photon in the interference (overlap) region, then the which-way information is not available, and you see an interference pattern buildup. However, if you do not observe the photon destructively, and allow the wavefunctions to evolve unitarily, as they diverge from each other and no longer overlap, each beam carries the which-way information regardless of the fact that the two beams had earlier overlapped. This is ensured by the linearity of QM formalism. If you claim that becuse of the earlier overlap the which-way information is lost, then you are challenging the linearity of QM, which is totally unacceptable. I will certainly read your paper on Popper's experiment and appreciate your efforts to claify foundational issues. Best regards. P.S.From time to time, Danko finds a new critic of my work, and tries to use them, without regard to their reputation, to push his discredited OR. He was rebuffed by Prof. Unruh, Drezet, Motl and others, yet he insists on polluting this page with his nonsense. As a heads up, it would be best not to align yourself with such an unsavory character, who was warned of being banned from Wikipedia by an admin. for posting his OR. -- Prof. Afshar 17:11, 22 January 2007 (UTC)
Dear Afshar, thanks for the info on the status of your paper. To understand why an earlier overlap causes loss of which-way information, and yet everything is unitary, just look at the example I described in the "Sorry about that" section. The two pieces of the wave-function are in distinct momentum states initially. Because of the overlap (interference), the part which makes them orthogonal is gone. The two pieces left are identical! But interestingly, each of these identical pieces is made up of two oppositely moving waves. In the end, you are still left with a superposition of a wave with momentum k and a wave with momentum -k. But you can no longer claim that this wave with momentum k comes from the piece of the wavefunction which was moving with momentum k - the mathematics clearly shows that it does not. Anyway, I think this is not the right place sort out the issue. In my paper I have done an analysis of your experiment, without approximation and with full unitary evolution. Tabish q
  • Dear Tabish, I will read your paper and respond accordingly, but for now, are you saying after the two beams no longer overlap, each beam is a 50/50 superposition of the two initial wavefunctions?! If that is your claim, then you are indeed in a heap of trouble, as that would violate the QM formalism without question. Such a scenario was discussed by myself, Prof. Unruh, Drezet, and others two years ago, and was shown by all to be false. Please take a look at my blog to read the threads related to this issue. -- Prof. Afshar
  • Dear Afshar, I don't know why you feel that the QM formalism will be violated. That the contribution of each slit becomes a 50/50 superposition of the two initial wavefunctions, is quite trivial to see from just the three equation displayed in the "Sorry about that" section. QM is perfectly followed here. Tabish q

Repeated Vandalism and OR pushing by Danko Georgiev

FOR ADMIN.S' RECORD: I reverted Danko's OR on which-way information. He tried to use Prof. Qureshi who is new to Wikipedia to rewrite the article while removing links to my rebottles to critics (sneaky vandalism) without any discussion. This type of behavior should not be tolerated. As for Prof. Qureshi, the above discussion seems to have resolved the issue, but putting OR on the article page or here is totally unacceptable, and I will be forced to remove it. Even Wikipedia must have standards that disallows cranks from defacing an article. Best regards.-- Prof.Afshar 17:47, 22 January 2007 (UTC)

Dear Afshar, nothing has been resolved, it is obvious that you do not read what others post, but you try to impose them your own words. T. Qureshi just several lines above has written "To understand why an earlier overlap causes loss of which-way information" which is translated "there is NO which way information" something that I have stated explicitly, and now another expert physicist explicitly formulates too. Read his paper before you post. Nothing is resolved, Qureshi's editing called "fundamental flaw in Afshar's interpretation" already has been removed by you and your company from the main article. I hope you yourself revert my last edit, where I have presented the both types of objection against your interpretation in relatively neutral way. You cannot go against mathematics, and insult others. Danko Georgiev MD 05:22, 23 January 2007 (UTC)

Neutrality discussion

I opened a request for comments on this article, as there seems to be a lot of contention. -Dmz5*Edits**Talk* 03:56, 23 January 2007 (UTC)

Thank you for the NPOV tag. It is about time this page gets some balance. Although I have not written a single sentence of this article, I wish to know why Danko Georgiev removes my responses to the critics? Since I do not wish to write anything in the article, there needs to be a safeguard process in which an ill-wisher cannot just go ahead and throw his/her slanted opinions in the article. Regards.-- Prof. Afshar 06:16, 23 January 2007 (UTC)
Please format your replies correctly, without asterisks, in the future. Also of note, do not conduct major revisions that require the extensive removal of text without discussion; doing so can be considered vandalism and pushing your point of view, violating the neutral point of view policy. Let's keep a level head; edit warring will get anyone nowhere. Seicer (talk) (contribs) 06:38, 23 January 2007 (UTC)
See the WP:ANI entry here. Seicer (talk) (contribs) 04:32, 23 January 2007 (UTC)
A discussion regarding the neutrality was posted at ANI. In my best judgement, Afshar has been pushing his original research into the article, deleting critisms and objections which violates the neutral point of view policy. There is considerable weight towards Afshar's additions. Afshar also does not have any other edits sans what he has contributed in this article only and seems to have claimed this article to be his own -- which is against policy.
Step back and breathe Afshar. Others will edit, and will continue to edit, to bring balance back into this article. If you disagree, please see the ANI entry or add your comments here - but please cease your edit warring. Seicer (talk) (contribs) 04:39, 23 January 2007 (UTC)
Dear Seicer, I do not own the article, and certainly have not written a single sentence of it. However, if you had kindly looked over the edit history and the discussion archive, you will have realized that Danko Georgiev has been pushing his own OR as confessed by himself to admin. Garzo. He promised to have his paper published in a peer-reviewed journal before bringing it back to Wiki. As for my research it is not an OR, as the criteria for notability was met and two deletion bids--one of which was initiated by Danko-- failed, as it was determined the article was important enough to stay on Wikipedia. Furthermore my manuscript has been accepted by a reputable peer-reviewed journal and will be published in February. As for my other edits in Wikipedia, I have no interest in doing so, and that is perfectly in line with Wiki rules. As the individual whose name is on the article's title, I have every right to ensure accuracy of the article as regards the details of the research I carried out, and as an expert in the field, I reserve the right to delete the utter nonsense the likes of Danko put on the article, even going as far as removing the links to my rebuttals to critics without any discussion whatsoever. If you believe I have been unfair to anyone, please point out the instance and the individual with whom I had an unjust edit war. If anything, this article is dotted with unsubstantiated and vague claims of my cirtics, all of whom have been replied to in various forms elsewhere, and there is not a single mention of my rebuttlas to those arguments. Furthermore, I reserve every right to defend my reputation against crackpots like Danko, and will not hesitate to take the necessary action to stop his irresponsible behavior that has been criticized by a number of editors, Professors and admin Garzo. You could not possibly be suggesting that I cease and desist and allow any uninformed individual to put absolute garbage in the article, do you? As for your own ability to judge the veracity of the claims by Danko, I hope you are qualified enough (which is doubtful judging from the contents of your myspace page) to have an educated look at his statements. Needless to say, if you believe science is a democratic process in which just anybody can participate, then allow me to inform you that is certainly NOT the case. Science is the dictatorship of Truth, obtained by a well-established scientific methodology of observation and verification. In the same way you may not trust me with your Nikon camera, physicists have no patience with patently wrong ideas and those who push them. Such standards are the norm in academia and it is high-time they were applied to this "Encyclopedia." Sorry if I have sound a bit harsh, but certain facts need to be made clear if Wikipedia is not to turn into Mikipedia. Wishing you all the best in your field of studies. Best regards. -- Prof. Afshar 05:57, 23 January 2007 (UTC)
Ah, I see with the ad-homimem attacks you are well known for, Afshar? I provided an outsider's glance into the article, much like others have, which have been refuted. As an 'expert' in this specialised field, I would have hoped you could be more civilised in stating your opinions, and to allow others to edit the article, add citations and relevant viewpoints that you seem to want to erase. There are no 'vague' claims when it is cited with specific sources, as it has been clearly done. Without these opposing viewpoints, the article essentially contains numerous references towards your work and two or three others. For an article of this length and nature, equal weight needs to be put on both. As stated in the ANI report, I'm not the only one seeing this.
As for my "MySpace" page, I am an artist and an information-technology employee. I maintain the page solely for my artistic and writing endavours, not for your pure enjoyment. Sorry if I am not a research student or grossly in-debt to this article, but frankly, I don't give a damn what you think of my web-sites. As for this quip --
"...if you believe science is a democratic process in which just anybody can participate, then allow me to inform you that is certainly NOT the case."
I hate to inform you, but that sounds very much like owning the article or at the very least, your admitting that you refute Wikipedia's democratic processes or the openness that allows anyone to edit. If you have trouble with those basic, common principles, I suggest you take the time to review Wikipedia policies. Seicer (talk) (contribs) 06:25, 23 January 2007 (UTC)
Dear Seicer, I simply stated the facts, which seems to have upset you, and for that I am sorry. However, don't you think Wikipedia's democratic input must be tempered by verifiable facts? Would you stand for a statement like "apples fall away from the center of the Earth" in the "gravitation" page? Such is the nature of the "paper" by Danko Georgiev, and this fact has been stated by a number my own critics including Prof. Unruh, and others. If you think such nonsense belongs to Wikipedia, then we've got a serious problem on our hands. The role of Wikipedia is informing the public of established facts and notable research. Allowing false statements to reach the public will not serve the cause of this "Encyclopedia." Wishing you all the best.-- Prof. Afshar 06:43, 23 January 2007 (UTC)
Yes, you stated the facts. Let others do the same with verifiable sources of opposing viewpoints. The articles for the opposing viewpoints are considered reliable and will remain; otherwise, the balance of the article becomes tilted towards your viewpoint. Again, this is not your article; democracy will play in action here, as well as Wikipedia policy. Violations of that will be reported, as well as your edits being reverted. Seicer (talk) (contribs) 06:46, 23 January 2007 (UTC)
I think that Wikipedia is not media, but Afshar's media pushing should be reflected in the main article.
* Lecture: Afshar Experiment: Einstein's Rebellion Lives On At Rowan!
* New Scientist:The Quantum Rebellion (what a "bloody-like style" rules?)
* Excerpt from the New Scientist article: " .. is there any such thing as a photon? The photon detectors in Afshar's experiment "click" when they detect a photon. But if there is no photon, what are they seeing? It comes down to the interpretation of Einstein's photoelectric effect, the experiment that "proved" the existence of the photon - and won him the 1921 Nobel prize. Afshar says the American physicist Willis Lamb and others have explained these particle-like clicks as a result of the interaction of unquantised electromagnetic waves and quantised matter particles in the detector. So although Einstein was right to doubt Bohr's complementarity, he was "right for the wrong reasons", Afshar says. "In order to declare Einstein the winner of the Bohr-Einstein debate, we must take back his Nobel prize. We have no other choice but to declare the idea of Einstein's photon dead."
*Since the experiment is interesting by the fuss around it, not with the correct mathematical exposition itself done also by T. Qureshi, I think that the bolded Afshar's quotation from the New Scientist article fully described at what Afshar aims. He takes the Nobel Prize of Einstein, declares the "idea of photon dead", and now tries to continue this propaganda in Wikipedia. As he admitted that he does not want to edit anything in Wikipedia, and I have suggested Afshar to be blocked from editing his own article, then I don't see him to be prone for any future cooperation. Danko Georgiev MD 06:36, 23 January 2007 (UTC)
I wouldn't go as far as to block him from Wikipedia entirely, but to continue to monitor his edits. Any 3RR's should be reported, as well as edit wars, blatant NPOV pushing and OR. Seicer (talk) (contribs) 06:44, 23 January 2007 (UTC)
I DID NOT WRITE ANY OF THE ABOVE. YOU SHOULD COMPLAIN TO NEWSCIENTIST ETC. AS FAR AS THE EDITS ARE CONCERNED, OK YOU GUYS WIN. I HAVE NOTHING TO DO WITH THIS ARTICLE OR WIKIPEDIA ANYMORE. DANKO THE STAGE IS YOURS. GOOD LUCK.--Prof. Afshar 06:49, 23 January 2007 (UTC)
Personal attacks removed by User:ScienceApologist—The preceding unsigned comment was added by 71.70.208.65 (talk • contribs).
Personal attacks removed by User:ScienceApologist--Michael C. Price talk 19:10, 23 January 2007 (UTC)

FWIW, I have found Prof. Afshar to be a reasonable and well-tempered personality. Unfortunately, his ideas attract negaitve attention. I've attempted to mediate in the past, with little success. Danko should be barred from the article AND from this talk page; and from editing any physics or math related articles; he is incompetent on this subject matter. His knowledge is at the level of freshman physics, which can be readily determined through conversation with him. I have found Micheal C. Price, an editor I otherwise respect, to have crossed the line, repeatedly, in being uncivil, and in repeatedly adding his own original research in attempting to (incorrectly) debunk the Afshar experiment. I'm sorry to say, he should also probably be banned from editing this article, at least temporarily. Although it is difficult to wade through the arguments, for the most part I think Afshar has acted with nobility, and is not the party at fault here. (Full disclosure: yes, I've got a doctorate in quantum, yes, my initial reaction, like the rest of the world, was to disparage the topic. I've since warmed enough to it to realie that it should not dismissed out-of-hand; the arguments are subtle, and my impression is that the WP nay-sayers don't have the background to appreciate the subtlties. I find this to be remeniscent of te Hanbury-Brown and Twiss controversy, which had a similar classical-quantum weird flavour to it) linas 02:03, 25 January 2007 (UTC)

Dear Linas, I admire your numerous contributions in Wikipedia on math topics. But please be sure that you are not the single person who loves and uses mathematics. At least you can take a look of my detailed exposition in the PhilSci paper, and you will see that the so well cherished by you and others non-linear evolution of quantum amplitudes is not argument for which way information as you, Unruh, and Afshar used to point out. Complementarity is beyond all this, it is linked with axioms dealing with decision which waves should cancel, and which waves will be squared to produce observed intensities. By the way do not consider yourself the only evolving unit here, for two years it is quite like "incompetent" subject like me, to become "compentent" ... Danko Georgiev MD 07:34, 25 January 2007 (UTC)

Re: Linas' comment I'm sorry to say, he should also probably be banned from editing this article, at least temporarily. FYI I have not editted the article since the 11 December 2006. Re: SA's judgement about my comment about Afshar's behaviour being a personal attack, I still believe that Afshar's behaviour, whilst being civil, could be much improved if he stopped assuming all his critics were incompetent. Is that a personal attack, or a plea to Afshar to improve his attitude? And BTW I made the same criticism of Danko in the past. --Michael C. Price talk 13:56, 25 January 2007 (UTC)

Hmm, I've been reading through the archives and it seems to me that you might consider carefully whether kettles may apply to your comments above. Likewise, it may be a good idea to refresh your memory on what personal attacks imply. Sometimes it is easy to lose sight of these things when one has been heavily involved in talkpages or articles for a long period of time. (I know I have had occasions where I have lost sight of such.) --ScienceApologist 14:15, 25 January 2007 (UTC)
Good points both, although with regard to losing sight I have recently cut back my involvement here (article and talk page) considerably. Final point: I am glad that some editors with the appropriate background are taking an interest here; in that regard please consider that Wheeler's delayed choice experiment, which is conceptually identical to Afshar's experiment, does not violate complementarity. --Michael C. Price talk 20:26, 25 January 2007 (UTC)

Reference style updated

I have done a lot of work to convert all the references into ordered bibliographic information. Please use one of the ready templates that I have incorporated in the main article when you insert new reference. Thanks in advance! Danko Georgiev MD 05:14, 24 January 2007 (UTC)

Cross-posting from Wikipedia Talk: WikiProject Physics

As a completely uninvolved party, and with admittedly only half a semester of graduate-level quantum mechanics under my belt, I would be willing to mediate this dispute. I have come across the Afshar experiment only once before, in reference to Freeman Dyson's suggestion that the uncertainty principle would not hold for suitably large scales. I've read through the article and the related pages and have to say that a lot of the arguments seem to not be over the physics (except where some obvious errors are made by User:Danko Georgiev MD) or the point-in-fact science of the work but rather the philosophical interpretations or original research connections. As with all quantum articles, normal "philosophy warnings" associated with quantum mechanics should be followed. I'll e-mail Ashfar and cross-post this suggestion at the article in question. --ScienceApologist 03:14, 25 January 2007 (UTC)

Dear ScienceApologist, please tell me where are the obvious errors. Please point a specific claim, formula, etc., and then say - "it is wrong". Regards, Danko Georgiev MD 05:28, 25 January 2007 (UTC)
Dear Danko, I'm not going to point out specific errors because I have no desire to start a protracted argument. This is not USENET. However, in the last few sections, you have made a few "liberal" interpretations of Qureshi's posts and "translated" them in manners which superficially appear to be errorneous. While it may be that you can "explain away" the superficial errors, the damage is already done by your advocacy which is too forward. In any case, if Afshar does not agree to mediation, I will not be staying long at this page. --ScienceApologist 12:53, 25 January 2007 (UTC)
Dear ScienceApologist, I will not argue with you unless you provide a specific claim or sentence of mine that is wrong. What about Tabish Qureshi's thesis, please note in the main article that I have summarized the critique into 2 groups - then please note that Tabish Qureshi himself BOLDED them, see the history of edits, plus pay attention to the fact that Tabish Qureshi himself added a NEW post of physicist Daniel Reitzner who proves the same thesis originally raised by me in 2004. So I am not "liberally" interpreting nobody, prof. Qureshi himself supports my thesis. The propaganda of my incompetence was started by Afshar and Linas, based on the fact that I don't have PhD in physics. Yet, Afshar's PhD shows only one thing - that the University where he obtained it was quite poor educational institution since its graduates make simple math errors. And last, but not least, be aware that Carl Looper, computer programmist, who was convinced similarly to Linas that I am wrong, have changed his opinion after reading my PhilSci paper. I think that possibly Afshar contacted you for some help, well I agree to help him, but please first be acquainted with the facts. Regards, Danko Georgiev MD 14:17, 25 January 2007 (UTC)
I'm glad you have decided not to argue with me. As for your narrative explaining where you and Qureshi coincide, it would be better if you let Qureshi speak for himself. You're bordering very close on treating this talkpage as a soapbox, which is not very helpful nor does it aid your cause at all. For the record, I first heard of this disagreement at Wikipedia:WikiProject Physics. Afshar did not contact me, but I have contacted him yesterday and have yet to receive a reply. As I said before, if he does not agree to return to Wikipedia, you won't be seeing much more of me. --ScienceApologist 14:24, 25 January 2007 (UTC)
ScienceApologist, my view on Afshar's experiment should be very clear from the short dialogue I had with Afshar on this talk page itself - please have a look. In case there is any doubt regarding that, let me summarize it here: There is no which-way information in Afshar's experiment, with or without the wires. If you follow Afshar's comments over time, you will notice that he emphasises on the which-way information (WWI) becuse of conservation of linear momentum. I had told him why momentum conservation doesn't apply to the the WWI argument here, and he had no reply to that. If somebody thinks that he can infer the results of the experiment with both slits open just from the WWI result of the experiment with only one slit open, doesn't understand how quantum mechanics works. I quote Afshar from this talk page: "Of course, in the overlap region the which-way information is washed out due to the equal amplitudes from the other beam... if you do not observe the photon destructively, and allow the wavefunctions to evolve unitarily, as they diverge from each other and no longer overlap, each beam carries the which-way information regardless of the fact that the two beams had earlier overlapped." If the which-way information is washed out at any point in time, it can never be recovered later through unitary quantum evolution - this is just basic quantum mechanics. So, there is no question of Bohr's complementarity being violated. Afshar's interpretation of his experiment is fundamentally flawed. --Tabish q 18:12, 25 January 2007 (UTC)
I appreciate your summarization of your perspective, Tabish. It seems to me that what you are saying is that as a unitary value, if which-way information "variable" doesn't exist at any point in time (or space, for that matter) that it simply doesn't exist for all time and space. You believe that Afshar is saying that this is untrue because he thinks that the which-way information "variable" is wave-like with a phase (or a real and imaginary part) and therefore destructive interference at some event for which-way information can be associated with constructive interference at some other event for which-way information. Have I summarized your perspective on the dispute fairly? --ScienceApologist 18:40, 25 January 2007 (UTC)
I will put it in a nontechnical way. When two waves interfere, some parts cancel out due to destructive interference, and some parts add up (constructive interference). So, because of interference, only the constructive interference part is left. And the two added parts are NOT ORTHOGONAL to each other (that is why they could add up) - they could of course be complex, and ARE complex. Now these two non-orthogonal parts evolve in time - QM says that they can never becomes orthogonal. There is no other "WWI variable" other than this part of the state which forms the bright fringes. It so happens that this total added part evolves in such a way that it again gives two orthogonal pieces at the detectors - and Afshar seems to think that each of these orthogonal pieces is coming from the a different slit. This thinking is wrong - this thinking comes because people make the mistake of using "classical" intution while dealing with quantum systems. How this total added part evolves in such a way that it gives two orthogonal parts, is not intuitive at all - and I don't blame Afshar or anybody else for not seeing it. You can see my paper for more details. PS: Forgot to mention that two parts have to be orthogonal to give two distinct measurement results. Parts which are not orhtogonal, cannot give distinguishable results. --Tabish q 19:02, 25 January 2007 (UTC)
Let me try again. I'm trying to phrase this as plainly as possible so there is no confusion. You are saying that two observable parts of a system have to be orthogonal to be distinguishable. However, orthogonal parts of a system can be measured in any system you care to name. What you are saying then is that the orthogonal parts that are measured result from the superposition of two wavefunctions that are not orthogonal, so that there is a mixing of A and B in both orthogonal pieces. You are claiming that Afshar believes that the two orthogonal pieces are uniquely A and B. Is this correct? --ScienceApologist 21:40, 25 January 2007 (UTC)
  • Dear ScienceApologist, I have very little time to spend on this article, however, thank you very much for the offer to settle the dispute. I have nothing to tell Danko, and will separately discuss his edits. For now, the sentence "This refutation of Afshar's claims falls short on its aim since it starts from flawed assumption of which way information at first place." in the "Specific Critiques" section should be removed as utter OR. There is NO peer-reviewed publication that supports this assumption. The only legitimate Ref. for the "No WWI without wires" is that of Prof. Qureshi who has submitted his work to a peer-reviewed Journal. I can directly address Prof. Qureshi here, however, I'd rather respond to him by the request of the Journal's editor, who has requested me to act as one the referees for the paper. Briefly, Qureshi should be able to write the wavefunctions for each image as a 50/50 mixture of the two original wavefunctions emerging from the two pinholes. If he shows that, then his hypothesis would be supported by QM formalism. My suggestion to Prof. Qureshi is to avoid making emotional statements either here or any other public forum. The fact that his argument can be shown to be erroneous (this fact supported by Prof.s Wheeler, Unruh, Drezet, Hardy, Greenberger, etc., as well as myself) should be sufficient due diligence on his part to refrain from further subjective statements until the results of the peer-review process have been sent to him. Best regards.-- Prof. Afshar 19:53, 25 January 2007 (UTC)
Okay, so what you are saying is that in order for Qureshi to be correct the wavefunctions need to be in superposition, but you claim that the wavefunctions are not in superposition. Is that correct? --ScienceApologist 21:40, 25 January 2007 (UTC)
ScienceApologist, you have correctly summarized my argument. I do believe that such question are settled through peer reviewing, but since no work related to Afshar's experiment, including his own work has appeared in such a journal yet, it may not be a bad idea to exchange views here. Let me try to give a brief idea how each detector can get contributions from both slits: Let the two plane waves be the ones that come out of the two slits (it should be wave-packets, but the argument is similar):
ψ(x) = aexp(ikx) + bexp( − ikx)
Let us suppose this is how they look in the interference region. To see which parts cancel out and which parts add up, we can write this as
ψ(x) = acos(kx) + iasin(kx) + bcos(kx) − ibsin(kx)
ψ(x) = (a + b)cos(kx) + i(a − b)sin(kx)
\psi(x) = {a+b\over 2}\exp(ikx) + {a+b\over 2}\exp(-ikx) + i(a-b)\sin(kx)
one detector gets (a+b)/2 exp(ikx) and the other gets (a+b)/2 exp(-ikx). (a+b)/2 tells you that it is an equal mixture of contribution from the two slits. (a-b) term gives you the dark fringe when a is approximately equal to b.
Putting it in Afshar's language, if one calls "a" part as beam coming from slit A and "b" part beam coming from slit B, what is left of the beam from A is acos(kx), which can also be written as
ψ(x) = (a / 2)exp(ikx) + (a / 2)exp( − ikx)
Clearly, this is a 50/50 superposition of two states which will go to different detectors.
--Tabish q 04:43, 26 January 2007 (UTC)
Let's make sure I understand this. We are looking at a plane wave which emanate from the slits in the classic intereference treatment. Are you saying that the mixing happens between these two forms in a 50/50 superposition due to the bald fact that there is intereference? --ScienceApologist 09:28, 26 January 2007 (UTC)
Dear ScienceAppologist, let me add one more clarification to prof. Qureshi's thesis, because in his paper, he does not work with density matrices, while I have worked. Yes, if the density matrix is pure state one it is describing a coherent superposition (see for this definition Motion Mountain textbook, prof. C Schiller PhD), in this case there is no which way information. Yes, if the density matrix of the setup is mixed state one either it describes an incoherent superposition (e.g. putting different polarization filters on each of the pinholes making them distinguishable), or it describes no superposition but statistical mixture of two single slit experiments, in this case there is which way information! Now, look at Afshar's claim, he does not accept none of the two conclusions above, but Afshar wants one "to show mixed state in order to prove that there is no which way information". This is outright ignorance of quantum mechanics, and shows he does not understand the density matrix formalism, which has been proven to be equivalent to the usual differential equation formalism as given by the Schrodinger's equation. Personal attack removed by User:ScienceApologist. I couldn't find any information in the web, better Afshar himself posts his dissertation title Danko Georgiev MD 05:42, 26 January 2007 (UTC)
Please keep things civil and deal only with the substance not with the people please. Thank you. --ScienceApologist 09:28, 26 January 2007 (UTC)
Dear ScienceApologist, I am glad we are having this discussion and things are getting clarified. But, first of all, let us all keep the discussion civil. Afterall we are all in search of the truth. If I am proved wrong, I will only be happy to learn something which I did not understand before. So, all of us should refrain from personal attacks. The truth is more important than the question whether it is my thesis or somebody else's. You ask, "Are you saying that the mixing happens between these two forms in a 50/50 superposition due to the bald fact that there is intereference?" Yes, you are right. Just the fact that interference is there, makes this mixing happen. That is perfectly in agreement with the spirit of complementarity. If nature has complementarity built in, it will find ways to destroy the which-way information if it gives you interference. We can guage the depth of Niels Bohr's understanding of QM, when decided to elevate the complementarity to the level of a separate principle. --Tabish q 12:31, 26 January 2007 (UTC)