Talk:Afshar experiment/Archive 27

Request for Danko to be banned from editing this article and contributing to the talk page

I believe Danko has shown himself incapable of understanding wikipedia policy, incapable of civilised discussion and obstructive to the process of creating a good article. He is attacking personally anyone who disagrees with his point of view. He refuses to answer questions asked to help clarify what he is actally saying if it does not suit him to attempt to do so.

Thus I propose that we make a formal request to ban Danko from this article. This would be regretable, however I can not see how we can possibly make progress if we are fending Danko off all the time.

Even if this formal request is met, it will not stop Danko from contributing to other articles in Wikipedia or indeed follow the constructive suggestion I made of starting a new article to deal with more detailed counter arguments related to the Afshar Experiment, which can be assessed by editors on its own merrit, but would at least allow us to complete our task here.

The mission here is to create an article that conforms to wikipedia policy. There has been a recent streamlining of wikipedia policy with regards to editing articles. For :those who are not aware, these are now Wikipedia:Attribution and Wikipedia:Neutral point of view. Attribution now covers the previously seperate articles Wikipedia:Verifiability, Wikipedia:No original research and Wikipedia:Reliable sources. I believe it is clear by reading through these articles that Danko is persistently ignoring wikipedia policy and worse than that attacking anyone who tries to explain this policy to him.

What choice can there really be but to ban him?

Please add your choice below, either BAN or DO NOT BAN. This can then be used to help wikipedia admins reach a decision of what to do. Dndn1011 12:09, 4 March 2007 (UTC)

I'm afraid I agree. Sorry Danko, but once you've published your claims in a reputable peer-reviewed journal you are welcome to include your thesis in the article. Your constant personal attacks are an eyesore, and detrimental to progress on the article. BAN from the current article and talk page. -- Prof. Afshar 12:28, 4 March 2007 (UTC)

I agree too, D. Georgiev confused the role of wikipedia with a monograph. The aim of the 'Afshar experiment page' is to present objectively and neutrally the result of the experiment and not to humiliate always its author. Georgiev is passionate but this is not sufficient to excuse all. Why also to play like that? Additionally if the theory of Georgiev was right it would not be necessary to create all this senseless debate .This is more than enough: BAN Drezet 12:47, 4 March 2007 (UTC)

DO NOT BAN - What Danko is saying regarding the science is completely correct (in my view) - but his abuse of Prof Afshar is completley incorrect - and Danko is incapable of separating the two. I should also add that Prof Afshar, in my view, is also completely correct. Danko - if the wave function is always valid (quantum realism) the path function is never valid - other than as an approximation of the wave function - and therefore complementarity is just redundant or incorrect. But Bohr's Complementarity implys the wave function can have an ontological leave of absence, in the inter-measurement interval by virtue of the epistomological holiday it otherwise enjoys during this interval. But Afshar holds the wave function to account, for the entire duration of the experiment. So it has no opportunity to have a holiday. It is ontologically always there. In quantum realism the wires are not necessary since the formalism is interpreted as ontological rather than epistomological. An ontological formalism always holds the wave function to account - it can never have a break. So quantum realism already violates complementarity. Bohr was not a quantum realist ("there is no quantum world") but you are - by virtue of the ontological status you give the formalism, and the Afshar experiment is as well, but by different means - by epistomolgically holding the wave function to account (using the wires). If there is a problem exposed in the Afshar experiment it's not to be found in any error by Afshar. Or in any error by yourself. --Carl A Looper 01:43, 5 March 2007 (UTC)

PLACE ON PROBATION - I would like to see a probation tried first where Danko is enjoined to refrain from personal attacks. If he violates this, then an administrator should ban him. We need to take measured steps here and I believe that probation is the right way to go. If this were being done through Arbcomm, I'd be willing to bet that this would be the solution the arbitrators would agree to. --ScienceApologist 13:29, 5 March 2007 (UTC)

ABSTAIN - I haven't interacted with Danko long enough to know how valuable his insights are or whether it is possible to work with him on editing the article. I do agree that he is guilty of making personal attacks. I would admonish him to keep a civil tone and assume good faith. If he persists, then a ban might be necessary. --Art Carlson 08:41, 5 March 2007 (UTC)
Change vote to PLACE ON PROBATION. That sounds like a plan. --Art Carlson 14:26, 5 March 2007 (UTC)

BAN PLACE ON PROBATION(Flexibility is important in the process of reaching a concensus) Dndn1011 12:09, 4 March 2007 (UTC)

BAN I was not aware that he had already been on probation. I am taking Linas's comment in good faith and so changing back to Ban. Dndn1011 23:11, 5 March 2007 (UTC)

DO NOT BAN Please see Wikipedia:Template_messages/User_talk_namespace. I will add the {{uw-npa2|Please see WP's no personal attacks policy.}} tag to the talk page. Please follow proper procedure for trying to get a user banned. Sdirrim 17:58, 5 March 2007 (UTC)
As a mediator, I shouldn't vote on this. Sdirrim 02:47, 6 March 2007 (UTC)

Please be advised that the proper proceedure has been followed, and that Danko hit level 4 more than a year ago. You may review the voluminous talk page archives for support for this claim. He has consistently failed to heed those warnings. linas 18:20, 5 March 2007 (UTC)

Sdirrim, I would suggest that both as mediator and as a relative newcomer to this situation it may be best for you not to vote on this topic. Please also note that we do not have the power to ban anyone. The attempt here is to see if there is a concensus (and failing that a Supermajority) for escalating this matter futher. It is quite correct for me to suggest this and to see what current opinions are. It can be seen that this question is being taken seriously by editors. Dndn1011 23:07, 5 March 2007 (UTC)

A consensus to escalate the matter is one thing. Voting on whether someone should be banned is something else. There is no need to have a consensus on whether a user should be reported, and that is really all the power that we have, to SUGGEST that editors take action. But it still is a nice idea to get a consensus. It just implies that we are directly voting on whether Danko should be banned. And I realize (and agree) that as a impartial mediator, I should have no vote in this. Sdirrim 02:47, 6 March 2007 (UTC)

If a concensus is shown to ban, then admins can more quickly reach a decision, hence the reason for this being stated in the way that it is. Dndn1011 12:08, 6 March 2007 (UTC)

BAN. He's been on probation for more than a year, and it appears to have done nothing whatsoever to discourage him. linas 18:20, 5 March 2007 (UTC)

I can find no evidence that Danko has ever been put on probation. For example, his name does not show up on WP:Probation, and there are no notification notes on this page or his own Talk page. Could you give us some details, please? --Art Carlson 09:44, 6 March 2007 (UTC)

• Dear Art, back in March 2006 admin Gareth Hughes mediated a dispute that ended with a request by him to Danko "to cease from unsubstantiated claims". Danko then agreed to "prepare an article on complementarity in Afshar's experiment that I hope will be strong enough to pass a peer-reviewing and get published in journal - therefore I do not consider anymore Wikipedia as a suitable place this debate to be continued". It wasn't long before he broke his agreement and continued to push his OR, and make personal attacks. The rest is too cumbersome to mention, but it is all in the archives. Just take a quick look at this to see what I mean!-- Prof. Afshar 20:57, 6 March 2007 (UTC)

• Technically, a mediator does not have power to impose sanctions on a user. So it appears that technically, Danko has not been placed under probation per administrator or arbitrator fiat. --ScienceApologist 21:29, 6 March 2007 (UTC)

• However, the "mediator" in this case actually was an administrator. Sdirrim 23:45, 6 March 2007 (UTC)

DO NOT BAN Danko's claims are not unsubstantiated. Since people here are insisting only on published reference, this published, peer-reviewed paper by Danko
Single Photon Experiments and Quantum Complementarity
shows that there is no which-way information in Afshars experiment. Can somebody clarify that before Afshar's paper appeared in Foundations of Physics in 2007, was his work OR, and hence not fit for Wikipedia? --Tabish q 15:25, 9 March 2007 (UTC)

Is this correct:

BAN = 4 (Afshar, Drezet, Linas, dndn1011)

DO NOT BAN = 1 (Carl)

PROBATION = 2 (Art, ScienceApol)

(updated by Dndn1011 23:11, 5 March 2007 (UTC))

(reupdated due to vote withdrawal by sdirrim. --Carl A Looper 02:53, 6 March 2007 (UTC))

--Carl A Looper 22:37, 5 March 2007 (UTC)

Disputed Piece #5

As there was discussion on this section in /* Disputed Piece #2 */, I am adding this for debate.

• "Afshar's experiment does not yield which way information and demonstrate interference effects for any individual particle (the photon), any more than the classic double slit experiment does, since we already know the photon propagates according to a wave-equation between the slits and any screen (i.e. behaves like a wave until it hits the screen, whereupon is observed as a particle.) The claim of complementarity violation in Afshar's experiment is a statistical argument that applies only to large numbers photons, not to individuals (cf "the particle" above in Bohr's statement is a reference to a single photon, not to groups of photons).

"To conclude, in spite of Afshar's claim we still need two experiments in order to exploit the totality of the phenomenon. As pointed out originally by Bohr, we can not use information associated with a same photon event to rebuild in a statistical way (i.e. by an accumulation of such events) the two complementary distributions of photons in the image plane and in the interference plane. The hypothesis of Afshar that we only need some partial information concerning the interference pattern in order to reconstruct the complete interference is only based on the idea that the fringes already exist. The whole reasoning is circular and for this reason misleading." - Aurelien Drezet

Sdirrim 00:08, 7 March 2007 (UTC)

DELETE. Two reasons. 1. It mangle's Drezet's argument - which is otherwise a relatively good one (even though I actually disagree with Drezet) and 2. It is also radically silly.

(re-edited for comprehensibility)

The second part of the argument is saying that Afshar's statistical demonstration of interference (used to violate complementarity) is invalid because Bohr is talking about single particles. If we are to accept this logic then ALL demonstrations of interference I can think of are invalid, including the archetypal double slit experiment.

The first part of the argument seems to be something like this. Since the twin slit experiment doesn't violate complementarity, and there is no difference between Afshar's experiment and the twin slit experiment, then Afshars' experiment doesn't violate it either.

But how is there no difference?

"since we already know the photon propagates according to a wave-equation between the slits and any screen (i.e. behaves like a wave until it hits the screen, whereupon is observed as a particle."

In what way does "already knowing" how the wave function propogates (and particles observed), make Afshar's experiment no different from the twin slit experiment?

Nowhere is this explained. It's as if one had just argued:

"A cat and dog can't be regarded as animals (or a vegetable), any more than a rabbit, since we already know the Earth is round"

Are we to be this radical? I guess what I'm trying to say is that this text, which quotes Drezet, is proposing a very different argument from Drezet - while subsequently pretending to be a summary of Drezet. It is actually OR and should be removed on this basis. This is not to say it is completely devoid of merit but without reference material to support it, it becomes worse than OR - it is OR without the R.

--Carl A Looper 22:56, 7 March 2007 (UTC)

DELETE Dndn1011 02:59, 7 March 2007 (UTC)

DELETE, because (1) the source is an (unreliable) preprint, and no arguments have been advanced that suggest it should be included anyway, and (2) the passage as it stands is incomprehensible. --Art Carlson 08:43, 7 March 2007 (UTC)

DELETE It will be too long to explain this too the reader I guess and I have no time to teach QM here. However i did not ask any one to quote me out of the context (I should have remove that my self) . As i told you this is the page of Afshar not the page of the anti-Afshar(s). Certainly it will enough to give a list of people at the end of the article only as suggested reading (like that the reader of the page will be free to choose his best interpretation more objectively). NB: I am conviced thatthis page is like a perpetum mobile : the same discussions are coming again and again without any progress (is for this reason that i stopped to edit things in this page). Drezet 10:36, 7 March 2007 (UTC)

I think that this time we will succeed in finally wrestling this to the ground, especially as Sdirrim is doing a good job. I agree with you completely, also, that listing people at the end of the article would be appropriate. This article should simply state what the Afshar experiment is; what Afshar claims it shows; a few key *relevant* arguments to counter Afshar's claims (and only Afshar's claims, and only where attributible); rebuttles from Afshar (only where attributible) and links for further reading. Some of these things are not so clear to decide but I don't think it will be that hard as long as we stay focused.

An example of a difficult issue is the inclusion of Unruh's argument, which has not been published in a peer reviewed paper and additionally appears to not be relevant to the argument at all. Until Afshar's paper was published in a peer reviewed journal, it perhaps was relevant to include Unruh's argument. However this is no longer the case, and to have NPOV we should not have a peer reviewed article countered by an argument presented a few years ago on a blog, even if the personal presenting it is notable. There is of course nothing to prevent the article including links to Unruh's argument. Dndn1011 14:19, 7 March 2007 (UTC)

Does anyone else wish to contribute? I would like to make sure that I have heard all sides (even if I think I know what they will say) before a decision is made. Sdirrim 16:43, 7 March 2007 (UTC)
Does anyone disagree with deleting this? Anyone at all? I will delete this tomorrow unless I get some disagreement (not that you need to disagree). Sdirrim 16:26, 8 March 2007 (UTC)

As much as I respect Drezet, to be consistent with Wiki rules, DELETE, especially becuase he himself doesn't mind. Drezet is a scholar who will have plenty of opportunities to publish his peer-reviewed views in light of the Found. Phys. paper, and add to the healthy debate. We can add those views at that point. Thanks Aurelien!-- Prof. Afshar 17:35, 8 March 2007 (UTC)

KEEP - the argument is sound; no individual photon yields both which-way and interference effects any more than any individual photon in the classical double slit experiment does (i.e. they don't). Perhaps the argument can be clarified; fair enough, so improve don't delete. --Michael C. Price ^talk 18:02, 8 March 2007 (UTC)

Hi Michael, was wondering when you would show up again... I believe you are completely wrong in your interpretation, and in any way it is Afhsar's interpretation which is of importance here, not that of any editors. But here is a counter to your point that is directly connected to Afshar's interpretation, in a form that non-expert readers might find easy to digest: Some of the photons do yield both which-way and interference effects in the experiment. If 100 photons are measured as hitting the targets with the wires in place, it is known that statistically a certain percentage (I think it was around 7%) must have interfered with themselves in order to avoid the wires. So in fact 7% of photons do exhibit both which-way and interference effects. The only thing that is not known is precisely which photons of the 100 have done so. However, the paradox is exposed even without this knowledge. Since the paradox is exposed, BPC is violated, as we can no longer avoid concluding a paradox. Dndn1011 20:37, 8 March 2007 (UTC)

Your argument would apply equally without the wires: the photons must interfere with each other to produces the fringes, yet we can tell which-way they go by looking through the lens .... so what gives? The flaw (of course) is that no photon observed through the lens contributes to a fringe -- and this also applies when the wires are present. So no dice, I'm afraid. --Michael C. Price ^talk 01:00, 9 March 2007 (UTC)

Once again you present a different experiment to the one that we are discussing in thia article. Fringes do not form an important part of Afshar's experiment as I understand his experiment to be. You are not actually counterting my point at all. But in any case you need to get your interpretation published in a peer reviewed paper for it to get it included in the article. But a further point: since all photons are detected, then any photons contributing to a fringe would also be detected. Otherwise, what happens to your supposed photons that do contribute to a fringe? Do they just vanish or something? Dndn1011 10:20, 9 March 2007 (UTC)

An important difference is that, in the twin slit experiment, no which way information (or path function) can be postulated since each and every detection can be traced back to two apertures rather than one. But this is not the case in the Afshar experiment. Each and every detection, in the Afshar experiment, can only be traced back to a single aperture. It is this capacity (to trace paths back to a single aperture) that otherwise defines the path function as such, ie. as distinct from a (time reversed) wave function. So there we have the difference. For single photons neither experiment can demonstrate interference - but as Michael has previously argued "we already know single photons interfere". --Carl A Looper 01:13, 9 March 2007 (UTC)

You misunderstand me -- I was referring to the Afshar experiment without wires, not the twin slit experiment which has no lens.--Michael C. Price ^talk 01:17, 9 March 2007 (UTC)

Or you are misunderstanding me. I am talking about the Afshar experiment (which has wires) and the archetypal twin slit experiment (which doesn't have a lens). I am talking about your original argument - not this discussion you are having with dndn. --Carl A Looper 01:55, 9 March 2007 (UTC)

If it is important that we retain the underlying argument for the sake of neutrality, I propose that we remove the quote, especially given that the person who was quoted has stated that it is a statement taken out of context. We may find other material to back it, but the quote is inappropriate. Sdirrim 17:30, 19 March 2007 (UTC)

Disputed peice #6

I'm submitting the following for deletion:

• Niels Bohr stated "an adequate tool for a complementary way of description is offered precisely by the quantum-mechanical formalism"[11]

If the photons in the experiment obey the precise mathematical laws of quantum mechanics (the formalism), how can Bohr's principle of complementarity be violated by the experiment?[13][14][15]

DELETE This is either an innocent question for which the author does not have an answer or it is a rhetorical question. As a rhetorical question the absence of any answer merely serves to bolster the rhetorical force of the question - which is to imply BPC is equivalent to HUP - but without arguing the case.

Instead of the rhetorical answer I had in response to this question (which has been deleted) I seek here to answer the innocent question.

While it is true Bohr identifys the formalism with complementarity it is not in the manner of an equivalence. In Bohr's words the formalism is an example (or an instance) of a concept that is otherwise bigger than the formalism. If the principle were no more than the formalism then there would be no need for the principle. However, Bohr has articulated the principle across a number of texts, (not just in quotable phrases) and the principle emerges as saying MORE than the formalism. It is that aspect of the principle, in surplus to the formalism, that can be challenged without necessarily challenging the formalism. One can not to do the reverse. One can not use the formalism to protect this surplus aspect of complementarity. Or maybe one can - but where is that argument? Not here.

--Carl A Looper 04:37, 8 March 2007 (UTC)

Carl's last paragraph here makes a lot more sense to me than the the way the article reads now. In the sense of being comprehensible, whether or not it is right. I think the distinction between BPC and HUP is essential to making sense out of the Afshar experiment and needs to be expounded in the article. The tricky part is either to make what we say attributable or at least to come to an agreement among the editors that our summary is accurate.

I vote for a qualified DELETE. This particular passage doesn't contribute much, but it needs to be replaced with something better. (Or the first bullet point in this section expanded.)

--Art Carlson 08:44, 8 March 2007 (UTC)

DELETE this one has been bugging me since I first read the article. Carl A Looper has presented a very eloquent, succinct and in my opinion unarguable position on the matter. Dndn1011 10:33, 8 March 2007 (UTC)

KEEP The quote from Bohr -- the originator the term "complementarity" -- is sourced; the rhetorical question can be converted to a statement if you wish. --Michael C. Price ^talk 11:11, 8 March 2007 (UTC)

As Michael suggests elsewhere the formalism predates complementarity but this does not mean complementarity must be understood as only derivable from the formalism. It can also be regarded as expanding the formalism. The quote from Bohr does not provide enough information (despite Michael's claim) to suggest only Michaels reading is applicable. Consider the following sentence:

An adequate method for painting abstract art is offered precisely by a can of paint manipulated in the manner of Jackson Pollack.

To follow Michael's logic, we must conclude that abstract art can only be defined in terms of the way that Pollack painted. But this is not the case. There is implied in the statement, if not otherwise mentioned, other ways of producing abstract art. And the articulation of such other methods does not invalidate the above statement.

Note that the word "adequate" can be read as excluding not just "inadequate" but also "perfect".

The point is that we need more information about what Bohr said - not just isolated quotes - if the question is to be resolved. But Michaels' argument is that we don't need any more information - that the quote says it all. It doesn't.

--Carl A Looper 23:57, 8 March 2007 (UTC)

I believe your analogy fails because many artists would disagree with your reformulated statement, whereas physicists accept the validity of Bohr's statement. --Michael C. Price ^talk 00:51, 9 March 2007 (UTC)

Artists may disagree with the statement, and so to may scientists, eg. to copy Pollack is not to produce abstract art at all but to participate in Neo Abstract Expressionism (or form of postmodern art). But this is not the point of the analogy. The category "abstract art" or more specifically, "abstract expressionism" has a number of participants only one of which is Pollack. In other words Pollack's art does not define Abstract Art. It is the concept of Abstract Art which defines or otherwise categorises Pollack's art (amongst others) as an example of abstract expressionism. in similar fashion, it is Bohr who is categorising the formalism as a "complementary way of description". Furthermore the validity of the statement is not necessarily in question. And is not made any less so by the participation of other complementary ways of description. The point of the analogy, is that Bohr's statement does not rule out everything else Bohr has said in relation to complementarity. The issue is whether everything else Bohr has said confirms the meaning that Michael (and others) have otherwise extracted from the quote. But nowhere is this research demonstrated - a single quote is supposed to constitute the argument. And it doesn't. --Carl A Looper 01:32, 9 March 2007 (UTC)

The point is (as you mention) that other people also interpret BPC in the same way I have. Since some of them are reliable sources this should be reported in the article. --Michael C. Price ^talk 10:31, 11 March 2007 (UTC)

DELETE. After the current cleanup of OR from the article, it would be apt to mention the distinction between HUP and BPC, and how BPC is imposed on the formalism and not the other way around. That text can also be included in the PC article. This is a subtle issue that needs to be written very carefully. It is important to point out that the main point of my papers have been to highlight this important separation in that BPC can be shown to be violated without a violation of the formalism. I can expound on this point further if other editors wish me to.-- Prof. Afshar 11:32, 8 March 2007 (UTC)

BPC is imposed on the formalism and not the other way around is completely wrong, and that's why the quote needs to stay. BPC in no way alters the formalism (the dynamics of the wave-equation) -- it's something that you derive from the formalism. Historically the formalism (e.g. Schrodinger wave-equation) came first, a decade or so later came complementarity. --Michael C. Price ^talk 11:42, 8 March 2007 (UTC)

Michael, please kindly answer the following questions with "yes" and "no" only: (1) Is HUP an integral part of QM? (2) Is it true that every time Bohr defended his arguments against Einstein he used HUP to show Einstein's errors? (3) Is it true that it was recently shown that HUP does not ALWAYS enforce BPC (theoretically suggested by Scully et al. and experimentally verified by Rempe et al)? (4) Is it not likely that those who made the claims in the disputed text (Motl, Unruh and others including yourself) were not aware of the distinction between HUP and BPC at the time? (I have direct evidence from the Blogs and Wiki archives that you did not know about the distinction before I brought it up.) P.S. Another important distinction that needs tobe made is the deterministic QM formalism on wavfunction Unitary evolution, and the quantum measurement theory involving the abrupt collapse of the wavefunction, but that's another bag of worms I'm writing an invited paper on for a pedagogical physics journal. -- Prof. Afshar 12:14, 8 March 2007 (UTC)

Yes, yes, yes, no; none of which contradicts or is relevant to the point I made: complementarity is derived from the formalism, not the formalism from complementary. Complementarity is not imposed on the formalism. What part of the wave-equation is altered by BPC???? --Michael C. Price ^talk 13:43, 8 March 2007 (UTC)

I think Afshar's position is not that complementarity alters the formalism. On the contrary, no one in this discussion seems to question that the formalism always gives the correct result, in particular that the outcome of Afshar's experiment is consistent with the formalism. I think he is saying that BPC is derived from the formalism plus additional assumptions. (Please correct me if I'm wrong.) --Art Carlson 14:33, 8 March 2007 (UTC)

And what additional assumptions are those? --Michael C. Price ^talk 14:43, 8 March 2007 (UTC)

The assumption that you can not observe the paradox, if I understand correctly. Basically BPC is meant to allow us to avoid concluding a paradox. BPC becomes irelevant should an experiment allow us to observe the paradox. If it were logically impossible for an experiment to disprove the valididty of BPC, then BPC would not be falsifiable. However it can be seen that it is logically possible for an experiment to demonstrate a violation of BPC by simply demonstrating the precise paradox that BPC otherwise allows us to escape. The paradox in question is a photon passing through both holes to cause interference while also appearing to have come from only one hole. The statement being debated here has no relevance to Afshar's claims, because it is not actually stating anything that contributes to the argument. In fact, this statement suggests that violation of BPC would mean violation of the QM formalism, which it seems fairly apparently not to be the case. What is relevant is the question of whether Afshar's experiment does in fact demonstrate the paradox. If it does, then BPC is violated. This can happen and still leave the rest of the formalism intact, but incomplete. Dndn1011 16:57, 8 March 2007 (UTC)

• Art is completely correct in that I believe there are "additional" false assumptions that led to Bohr et al.'s error. The assumptions are: (i)NECESSITY for irreversible collapse/decoherence of the wavefucntion upon detection of the photon in ensemble spatial distributions such as the Interference pattern i.e. the need for destructive measurement for ensemble properties, and (ii) the NECESSITY for a collapse/decoherence to take place in order to make a measurement. In my experiments the wires make a classic measurement without a "quantum measurement"(i.e. the kind of measurement that causes the collapse of the wavefucntion) which I have termed "Contextual Null Measurement" (see my Perimeter Institute talk for more details.) The major assumption up until my experiment was that any kind of measurement causes either decoherence, or collapse of the wavefucntion. I have shown this assumption to be at variance with QM formalism (see section 3.3 of http://arxiv.org/abs/quant-ph/0701027) and experimental results (all three published papers). -- Prof. Afshar 17:08, 8 March 2007 (UTC)

• Once again, completely wrong: decoherence does not make the assumption of wavefunction collapse. Decoherence theory explains how the appearance of wavefunction collapse emerges from the formalism.--Michael C. Price ^talk 18:08, 8 March 2007 (UTC)

I think you are completely wrong, but hardly alone. It seems to be en vogue to believe that decoherence explains collapse. I think it doesn't (and I am willing to wager that Prof. Afshar agrees with me). But it doesn't matter what either of us believes. The important thing is to understand that there are (at least) two ways of looking at decoherence, so, if it is relevant to the article and they are attributable, we should report both of them. --Art Carlson 19:52, 8 March 2007 (UTC)

Every one's entitled to their own belief when it comes to wavefunction collapse; what is clear, though, is that those researchers who worked on decoherence (such as Wojciech H. Zurek) developed it to explain collapse. --Michael C. Price ^talk 23:56, 8 March 2007 (UTC)

As a physicist, I see both HUP and BPC as convenient shorthand that becomes unuseable when push comes to shove. How can we resolve a bet of whether either concept is violated in an experiment? The only way is with a mathematical formulation where the deltas in the HUP are precisely defined and BPC is expressed in terms of the Greenberger-Yasin inequality. For this reason, the latter inequality needs to find its way back into the article, either in this section or another. --Art Carlson 20:04, 8 March 2007 (UTC)

Again I fully agree with Art. BTW/ it would be nice to change the name of the article on the duality relation to a more factual name as "Greenberger-Yasin inequality." I think Englert himself had voiced some conternation on that Wiki article. -- Prof. Afshar 20:33, 8 March 2007 (UTC)

I also agree the Greenberger-Yasin inequality should find it's way back into the article. --Michael C. Price ^talk 10:31, 11 March 2007 (UTC)

• It is quite depressing to see the state of confusion regarding collapse and decoherence. Decoherence is just that, loss of coherence in a wavefcuntion that leads to loss of interference effects and nulls in the off-diagonals. It is quite possible to have a collapse of the wavefunction in a coherent state, as you see when a photon is observed in a bright fringe. The wavefunction disappears completely (collapses) yet superposition state is observed in an irreversible manner. I think the confusion has been caused by two different uses of the term collapse. In short, collapse is not the same as decoherence. -- Prof. Afshar 20:21, 8 March 2007 (UTC)

• Yes, the level of confusion is quite depressing. The collapse of a coherent photon is still caused by decoherence -- the decoherence is present in the device that measures the photon. --Michael C. Price ^talk 00:01, 9 March 2007 (UTC)

The theory of decoherence is a complicated subject and I dont think that it is the aim of this wiki page to discuss in details this here. However I agree with Carlson the decoherence is only relevant here if asar mention it as a active part of the interpretation of his own experiment. In general this is something which should be change in the page i think: One should in this wiki project first find (after the introduction) a section describing the actual facts (i.e., the set-up and the results) and secondly a section presenting the interpretation and the potential consequences. Finally at the end a section further readings would be advicable. this last section should be without any quote (a list including article preprint is more than enough ).

PS: for Afshar concerning the duality formula the name that you prefer is not relevant because in general this formula is very often called with different names (Englert, Grenberger-Yasin, Wooters-Zurek, and others... ) Drezet 21:26, 8 March 2007 (UTC)

Here are some more quotes by Bohr, in the same vicinity as the one quoted.

"In a lecture on that occasion, I advocated a point of view conveniently termed "complementarity," suited to embrace the characteristic features of individuality of quantum phenomena, and at the same time to clarify the peculiar aspects of the observational problem in this field of experience."

"For this purpose, it is decisive to recognise that, however far the phenomena transcend the scope of classical physical explanation, the account of all evidence must be expressed in classical terms."

"It must here be remembered that even in the indeterminacy relation we are dealing with an implication of the formalism which defies unambiguous expression in words suited to describe classical physical pictures."

While these quotes are quite inadequate for a full understanding of complementarity, they do help to illustrate that Bohr is talking about something in addition to HUP, and the formalism.

"While the combination of these concepts into a single picture of a causal chain of events is the essence of classical mechanics, room for regularities beyond the grasp of such a description is just afforded by the circumstance that the study of the complementary phenomena demands mutually exclusive experimental arrangements. "

--Carl A Looper 06:01, 9 March 2007 (UTC)

Not too illuminating, unfortunately. On the basis of these statements alone, I can't discern if Bohr thought that complementarity is a consequence of the formalism or something additional to it. --Art Carlson 08:28, 9 March 2007 (UTC)

I agree. Not too illuminating, but it is indicative (without a full eassy) to get an idea. One should try to read the full account from which these quotes are extracted for a better idea. But in case one does not do this I'm hoping that give an idea. For example:

"It must here be remembered that even in the indeterminacy relation we are dealing with an implication of the formalism which defies unambiguous expression in words suited to describe classical physical pictures."

Note the phrase "... even in the indeterminacy relation ...", in which Bohr is citing such -ie. bringing it into the discussion, in order to show the difficultys involved in using classical concepts to describe the overall situation. But a classical (or semi-classical) account is what he is hoping to demonstrate is, at least, partially possible. He is arguing, in spite of the ambiguitys, (not becasue of them) that a semi-classical description is still possible. And it will be the principle of complementarity that will provide for this possibility. I am not saying this is evident in the pargaraph cited but I am encouraging anyone with questions here to actually read Bohr if they want to get the drift of what I'm saying here.

--Carl A Looper 02:33, 11 March 2007 (UTC)

We should not remove or exclude material just because Bohr's statements are not crystal clear. It's the nature of QM and complementarity -- as Bohr observed -- to be confusing! --Michael C. Price ^talk 09:34, 9 March 2007 (UTC)

Nowhere does Bohr say QM is "confusing". The ambiguitys about which he is speaking concern the way in which aspects of QM can not be rendered in a classical manner - ie. in an unambiguous manner. But that doesn't mean there isn't room for "regularities beyond the grasp of such a description " :

"room for regularities beyond the grasp of such a description is just afforded by the circumstance that the study of the complementary phenomena demands mutually exclusive experimental arrangements." --Carl A Looper 02:33, 11 March 2007 (UTC)

Perhaps you are unaware of Bohr's pronoucement that if you're not confused by QM you haven't understood it? --Michael C. Price ^talk 10:31, 11 March 2007 (UTC)

It is only those those who claim to understand quantum physics who do not understand it. For example, those who misquote Bohr. I'd also add that those who want to be confused by QM will always be confused. Which one are you? --Carl A Looper 23:42, 11 March 2007 (UTC)

How have I misquoted Bohr? --Michael C. Price ^talk 23:56, 11 March 2007 (UTC)

Bohr is not here to comment an Afshar's experiment, thus to include material from Bohr requires arguments to be presented that link the ideas of Bohr to the experiment's interpretation. However this can not be done in this article. To do so is to introduce original research. If Bohr were able to make comments on the experiment now, these comments, however unclear, would to attributable to him, so no problem. However the application of things Bohr said a long time ago to this experiment requires an interpretation by some third party. In this case that party is you Michael. This is also fine, providing such interpretation is attributable according to wikipedia policy. I suspect that you can not provide such attributable sources. Dndn1011 10:44, 9 March 2007 (UTC)

On a side note, observe the statement by Bohr "For this purpose, it is decisive to recognise that, however far the phenomena transcend the scope of classical physical explanation, the account of all evidence must be expressed in classical terms.". This is key to understanding Bohr. What he is saying here is that it does not matter how much the nature of the universe transcends classical physical explanations (i.e. is an extension of classical interpretations), we must account for all evidence in classical terms. There is a major assumption. The assumption that any explanations of the nature of universe must be explained in terms of classical concepts. What if that assumption is wrong? And what is there to actually support this assumption? BPC was created to allow us to maintain this classical explanation without facing the which-way / interference paradox, because if we can not measure the paradox then it is not important. If Afshar's experiment allows us to measure the paradox then Bohr's argument falls apart. It is no longer possible to account for all evidence in classical terms. Dndn1011 10:44, 9 March 2007 (UTC)

So, when I present statements from Bohr they are not admissible, but when you present statements from Bohr they are? --Michael C. Price ^talk 10:48, 9 March 2007 (UTC)

Er no, I am not trying to present statements from Bohr in the article. In this talk page we are both equally able to submit arguments about the article. It is your presentation of statements from Bohr both in the in the talk page and in the article I have countered with my own presentation of statements from Bohr in the talk page only. The purpose of me doing so is to get the presented statements from Bohr in the article removed for the reasons I have stated, i.e. Bohr may have said them but their application to this experiment represents OR. Additionally, there is no patently clear, unarguable case for making the connection, which I am attempting to demonstrate with my counter arguments in the talk page. I believe neither my arguments nor yours should appear in the article, but this discussion is never-the-less necessary in order to advance concenus on the article itself. I hope that clarifies everything. Dndn1011 11:59, 9 March 2007 (UTC)

This discussion is in principle legitimate, but it's getting out of hand. My tally is: 4 editors favoring deletion, one lonely sole favoring retention, and 200 lines of discussion. I propose that the mediator delete the passage in question while putting understandable, accurate, and attributable comments about the connection between HUP and BPC in relation to the Afshar experiment on the To-Do list. --Art Carlson 12:43, 9 March 2007 (UTC)

AGREED Dndn1011 13:05, 9 March 2007 (UTC)

DISAGREE Wikipedia is not a democracy --Michael C. Price ^talk 13:38, 9 March 2007 (UTC)

Nor is it a platform for every individual view. Dndn1011 13:53, 9 March 2007 (UTC)

I agree, we should debating the issues here, not performing a head count of people struggling to understand physics. The formalism of non-relativistic quantum mechanics was finished by c 1927. Complementary, c 1930+, was -- as Bohr said -- an attempt at a description of what the formalism models precisely. Complementarity's development had no impact or feedback onto the formalism. The HUP and other complementarity-related topics can be derived from the formalism; they are not required as separate, additional assumptions.--Michael C. Price ^talk 13:59, 9 March 2007 (UTC)

While someone here is implying he has given up on understanding physics it is not the case that anyone else here should likewise do so. Bohr is difficult but he is not impossible. The principle of complementarity concerns the way in which the "regularitys" otherwise associated with classical concepts can be extended, if only partially, into the quantum theoretical domain. The back traced path function, for example, is a classical function one can use under certain conditions. This idea is impossible to do with the formalism alone. The "god plays dice" concept of quantum theory is not embodied in the quantum theoretical formalism (for obvious reasons). One needs the physical version of this concept in order to instantiate a back trace on a particle detection. One can employ pseudo-noise functions in a computer simulation but these functions are just that - pseudo noise functions. --Carl A Looper 03:35, 11 March 2007 (UTC)

Break it up! Dndn1011 and Michael C. Price! Stop fighting! Now, how about this suggestion: We keep the quote from Bohr, because it is sourced and relevant. We are not here to pick a fight with Niels Bohr. The following rhetorical question can be thrown out, unless it is a quote from either of the three references. If it is not a quote, then it seems to be an original analysis of published works, something that qualifies as OR. Also, the rhetorical question seems to be the text at issue, rather than the quote from Niels Bohr. So again, how about we remove only the rhetorical question, as it is most inflammatory part of this debated piece, and it is also OR. What do you think? Sdirrim 17:21, 9 March 2007 (UTC)

I think I am out of here. The only one who wanted to keep the reference is Price, and now you are ignoring the voice of the majority. Additionally you are telling me to stop fighting when I have only presented reasonable arguments. My faith in the mediator is now lost and I am frankly tired of this mess. By all means keep the irrelevant reference, and additionally if presenting well reasoned arguments in a non disrespectful way by me is suddenly to be called fighting, than I shall stop fighting by ceasing my contributions altogether. I have had enough. Dndn1011 23:07, 10 March 2007 (UTC)

As I said, improve not delete; reformulating the question as a statement is okay with me. The pertinent points are 1) what Bohr said 2) the formalism is obeyed by the experiment 3) what other people have said (such as Unruh) on the subject of the formalism and complementarity in the experiment. --Michael C. Price ^talk 17:56, 9 March 2007 (UTC)

Would you support including my rebuttals as well? If not, it would be a violation of NPOV. -- Prof. Afshar 18:31, 9 March 2007 (UTC)

If your unpublished, unpeer-reviewed rebuttals are allowed then there can be no question that Unruh's, Motl's at al criticisms are also allowed. --Michael C. Price ^talk 23:18, 9 March 2007 (UTC)

I fail to see your point. A rebuttal is a response to someone e.g. Motl, Unruh, etc. If you put those quotations, then I should be able to respond, otherwise, neither their quotes, nor my rebuttal have any place in the article. Please clarify what you mean. Maybe Mediator can help here?-- Prof. Afshar 04:07, 11 March 2007 (UTC)

My point is that the rebuttals need to be peer-reviewed and published -- otherwise we are opening the floodgates to OR. What is it to be? --Michael C. Price ^talk 10:31, 11 March 2007 (UTC)

Correct. Any material included in the article must be sourced. However, the rhetorical question is not directly sourced. Rather, it is a paraphrasing of a point made by Unruh (I believe), and thus is an "original analysis of published work" and is therefore OR. By Wikipedia guidelines, the quote needs to be removed. It may be replaced, but that is debatable. A counter-point sourced from a peer-reviewed and published work may also be included. But the rhetorical statement should be removed. Sdirrim 05:13, 12 March 2007 (UTC)

The rhetorical question was my paraphrasing of Unruh's, Motl's etc, criticisms. My understanding is that paraphrasing counts as reporting and does not violate OR? If you agree then I will recast the question as a statement and we can debate the content. Do you agree that this is a way forward? --Michael C. Price ^talk 08:02, 12 March 2007 (UTC)

Afshar can consider writing a paper specifically to respond to the criticisms of various people, including Danko's latest published paper, and put it on ArXiv.org. This Wikipedia article can then quote from that paper - I think that would be fair. --Tabish q 06:12, 11 March 2007 (UTC)

• Dear Tabish, so you consider "Progress in Physics" a reputable journal in physics? This is a journal with Smarandache on its editorial board who believes there is an "INTERNATIONAL MAFIA IN SCIENCE" who has blacklisted him from the arXiv. He also believes "There is no speed barrier in the universe and one can construct arbitrary speeds" a clear violation of special relativity. Such utter garbage as "Measurement of the Earth's Absolute Velocity" by Stefan Marinov ("inventor" of perpetual motion machines) is published in "Progress in Physics", that even hinting at publishing there would be a death blow to one's career in the US. I advise you to check the background of the sources you consider reliable before you announce them here. I'm afraid in this case, the cure is worse than the disease, although I must say Danko's paper is an apt addition to the collection, especially when authors have to pay for their "papers" to be published there. I hope you do not wish to publish your paper in "Progress in Physics", but then again...-- Prof. Afshar 07:06, 11 March 2007 (UTC)

http://arxiv.org/find/math/1/au:+Smarandache_F/0/1/0/all/0/1

       1. math.GM/0702536 [abs, pdf] : 
          Title: Bases of Solutions for Linear Congruences
          Authors: Florentin Smarandache 

          2. math.GM/0702488 [abs, pdf] : 
          Title: Algorithms for Solving Linear Congruences and Systems of Linear Congruences
          Authors: Florentin Smarandache

          3. math.GM/0702343 [abs, pdf] : 
          Title: Linguistic-Mathematical Statistics in Rebus, Lyrics, Juridical Texts, Fancies and Paradoxes
          Authors: Florentin Smarandache

                                       ...Danko Georgiev MD 10:37, 12 March 2007 (UTC)

• Dear Afshar, I think we are not here to discuss the reputablity of journals. Did anybody ask you why you did not publish your work in Phys.Rev. or Eurphys. Lett. or Phys. Lett.? And as far as my publishing is concerned, I am not sure I want to publish in Found. Phys. too (unless there is dire need! ;-) ). As far as Wikipedia is concerned, a peer-reviewed journal is enough. -- Tabish —The preceding unsigned comment was added by 220.224.81.1 (talk) 16:46, 11 March 2007 (UTC).

• Dear Tabesh, "As far as Wikipedia is concerned, a peer-reviewed journal is enough." Not true! It depends on whether the "peers" are reliable. A journal that publishes papers that violate special relativity is a sure sign of the type of referees it has. Publication in this journal is also a clear indication of the type of author it attracts. No self-respecting physicist would even refer to "Progress in Physics" let alone publish there. And as to your desire not to publish in Found. Phys. all I can say is that you may have reason to stay away from the community of Nobel laureates; well I don't. -- Prof. Afshar 13:11, 12 March 2007 (UTC)

• Dear Afshar, I had pointed out two papers, one of which "showed" a violation of the uncertainty principle, and the other "showed" the resolution of the quantum measurement problem. You seem to have conveniently forgotten where they were published.
  

And seeing the references posted by some kind soul below, the "inventor of perpetual motion machine" does publish in Foundation of Physics! Seriously Afshar, please stop being so biased against individuals. --Tabish q 11:38, 14 March 2007 (UTC)

Dear Tabish, the poor soul committed suicide in 1997 apparently because his perpetual motion designs failed to work (see SCHNEEBERGER's note). Marinov published some legitimate papers nearly 20 years before his passing as shown below, but then he pushed some patently cranky ideas later on which led to his ostracism by the scientific community. As sad a story of his tragic death happens to be, nonetheless he was aptly regarded as a pseudo-scientist and the publication of his utterly error-filled manuscript in Progress in Physics is a clear demonstration of the kind of crackpottery they publish. No physicist can regard Progress in Physics as anything but a fringe, and misguided adventure by a few outsiders, who are not taken seriously by the mainstream physics community whom its editor considers as “Mafia”-like conspirators. If you believe otherwise, then you must share their values, and therefore their pitfalls. I’m glad our views on this matter are on the record here. As for bias, I am not biased against individuals, but rather the legitimacy of their claims, which can be safely gauged by the type of company they keep. -- Prof. Afshar 18:47, 14 March 2007 (UTC)

       Stefan Marinov. The coordinate transformations of the absolute space-time theory 
       FOUNDATION OF PHYSICS 1979; 9(5-6): 445-460; DOI 10.1007/BF00708535
       ARTICLE
       
       Stefan Marinov. The light Doppler effect treated by absolute spacetime theory 
       FOUNDATION OF PHYSICS 1978; 8(7-8): 637-652; DOI 10.1007/BF00717587 
       ARTICLE 

Danko Georgiev MD 13:31, 12 March 2007 (UTC)

Under a principle of complementarity Bohr introduces ideas not otherwise implicit in the quantum theoretical formalism. In particular is the idea that "regularitys" otherwise associated with classical physics (eg. the path of a particle) can be partially deployed in the quantum theoretical domain.

Nowhere does Bohr suggest a retrospective path function is in anyway derived from, or limited by the formalism itself. Our only limit is whether we can actually construct such a function, ie. whether we can actually draw an unambiguous path, from a particle detection, back to an aperture (ie. a single aperture).

Furthermore, it is not the formalism which necessarily suggests, implys or otherwise imposes on us that a setup, which allows such a retrospectively constructed path function, is also a setup which prevents us from demonstrating the wave function.

But it is definitley Bohr who does suggest this.

And it is this idea, otherwise understood as "Bohr's principle of complementarity", which the Afshar experiment challenges.

If Michael thinks this idea belongs to the formalism then it is Michael who must answer the rhetorical question. How does the Afshar experiment both violate the formalism (ie. the idea under challenge) and not violate the formalism?

The only answer is that they are not the same thing.

--Carl A Looper 08:28, 11 March 2007 (UTC)

You seem confused by what the formalism is. You don't need the BPC to generate empirical predictions from QM -- that's what the formalism is there to do. The BPC is there to help us grasp or understand what's going on in terms of classical or pseudo-classical concepts. --Michael C. Price ^talk 10:31, 11 March 2007 (UTC)

Dear Michael, I am not confused by the formalism at all. I realise your recurrent fallback position (to fictionalise critics of your position as "confused") might seem entirely justified to you but repeatedly telling yourself this won't help you in the long run. The formalism itself represents the fundamental structure of signals otherwise implied in the data produced by actual experiments. It is given an "a priori" status by virtue of it's implicit fundamentalism. However the formalism does not, (and can not) embody the complete de-scription of an experiment. The formalism is a pre-scription. And as you say, you don't need BPC to pre-scribe the outcome of experiments - as that is the role of the formalism (it defines the formalism). The idea that BPC helps us to interpret the formalism is justified. But BPC is also MORE than this. It introduces ideas in addition to the formalism. And (with deep regret) I have argued in the past (if you go back through the history of this talk page) precisely something similar to what you are currently arguing - that Bohr is merely interpreting the formalism - in classical terms for an audience incapable of thinking in any other way. And that Heisenberg was doing the same thing. But on further reflection I found that this was not entirely justified - was not entirely true. In fact, could not be true at all. Bohr was not just a psuedo semi-classicist. He was a real one. If Bohr was aware that the formalism might impose limits on the very possibility of a post measurement classical path nowhere does he provide a warning in this respect. One would always find (incorrectly) that any actual setup which allowed a constructable post-measurement path function occured only in setups in which the wave function was prevented from being demonstrated. This is was not just a metaphor for the classical mind. It is (or was) supposed to be a fundamental principle, ie. a principle without exception. A precisely defined IDEA. And that IDEA is precisely what you find embodied in the Yasin Greenberger formula. --Carl A Looper 22:46, 11 March 2007 (UTC)

Dear Carl, I said you were confused because you rhetorically asked me How does the Afshar experiment both violate the formalism (ie. the idea under challenge) and not violate the formalism?. The simple answer is that the experiment does not violate the formalism. As for what we are now calling the Yasin Greenberger formula, I have no problem with it being mentioned in the article; as I pointed out, each individual photon obeys the duality relation. It was Linas who saw fit to remove this statement from the article, not me. --Michael C. Price ^talk 00:11, 12 March 2007 (UTC)

Ok Michael, perhaps we are emerging from the deadlock in which we've been engaged. The simple answer, as you say, is that the experiment does not violate the formalism. That's exactly right. It is due to misunderstandings that the experiment has been framed this way - as if it was claiming to violate the formalism. The result has been ongoing inherent confusion - as embodied by my rhetorical question. But the experiment violates that aspect of complementarity otherwise embodied in the Yasin Greenberger formula. The YG formula itself is not at issue. The formula provides a precise mathematical definition of Bohr's IDEA. It is a formula anyone can derive from a close reading of Bohr. And it is this IDEA (Bohr's idea) which the Afshar experiment challenges. --Carl A Looper 00:47, 12 March 2007 (UTC)

I am glad that we all seem to agree that the formalism is not violated in the experiment. Whether it also violates some aspect of complementarity is the crux of the claim which is disputed. --Michael C. Price ^talk 08:10, 12 March 2007 (UTC)

Dear Michael. As far as Prof Afshar goes, the formalism has never been in dispute - it is only the claim that complementarity and the formalism are equivilant that re-renders the formalism as in dispute. But who is providing that argument? Not Prof Afshar. You are. Or you have been. Or you want to. Basically, if your postulate was correct (that complementarity and the formalism are equivalent) then you would need to show how the formalism is violated by the Afshar experiment. Otherwise it is not the formalism being violated. It is something else - call it what you will - a figment of our collective imagination, but otherwise understood as derived from what Bohr has written. In the long run it doesn't even matter whether Bohr authored this idea or not. It is an idea that exists and is demonstrated, by the experiment, as a not very good idea. Irregardless of who authored it. However, the idea does not belong to me, you, Prof Afshar or anyone else. It is an idea that been floating around since Bohr wrote about his ideas - about a principle of complementarity. It has an existence in the realm of ideas and is (without an essay) merely stated here that Bohr invokes this idea in thost texts which otherwise constitute what we otherwise call Bohr's Principle of Complementarity. --Carl A Looper 21:43, 12 March 2007 (UTC)

I've never said the formalism and BPC are equivalent. As for whether the experiment obeys the formalism: this has been questioned by other people, not me and perhaps not Afshar.--Michael C. Price ^talk 00:26, 13 March 2007 (UTC).

Well, ok then. Then vote for deletion of the rhetorical question. Because that is what is being implied by such - it is implying that an experiment which fails to violate the formalism, is an experiment which fails to violate complementarity. --Carl A Looper 01:59, 13 March 2007 (UTC)

No, the implication stays because that is precisely the implication that Unruh and others are making. And correctly so, IMO. --Michael C. Price ^talk 11:19, 13 March 2007 (UTC)

You claim you've "never said that BPC and the formalism are equivalent" (see above). Ok. Then perhaps you should say so. Otherwise, how do you propose maintaining the claim (of yourself and others) that a failure to violate the formalism is equivalent with a failure to violate BPC? --Carl A Looper 23:28, 13 March 2007 (UTC)

This is basic logic: Formalism => complementary does not imply complementary => formalism.--Michael C. Price ^talk 07:22, 14 March 2007 (UTC)

That's right Michael. They do not commute. --Carl A Looper 21:52, 14 March 2007 (UTC)

Equivalence (<=>) commutes, implication (=>) does not. The formalism and complementarity are not equivalent even though the formalism implies complementarity. --Michael C. Price ^talk 05:30, 15 March 2007 (UTC)

A useful analogy is the Aether. If an experiment claims to violate the concept of the Aether, the onus is not on the author of the experiment to demonstrate a violation of Relativity. The onus is on those who claim the Aether and Relativity are equivalent concepts. --Carl A Looper 22:11, 12 March 2007 (UTC)

I believe that the main reason to delete the rhetorical statement is that it is an original analysis of published works, thereby qualifying as OR. In that light, it is irrelevant as to whether or not it is true. Under Wikipedia standards of content and Original Research, the rhetorical statement should not be included in this article. Sdirrim 17:45, 13 March 2007 (UTC)

Paraphrasing of existing sources is not OR. As I said it is precisely the implication that Unruh and others are making. I agree that whether is it correct or not (although I believe it is) is irrelevant. And as I also previously said, I am happy to recast it in a non-rhetorical form. --Michael C. Price ^talk 21:05, 13 March 2007 (UTC)

If the counter-argument is to remain deleted then so too should Michael's argument. The counter-argument is no less derived from what Bohr has written than Michael's argument. --Carl A Looper 23:28, 13 March 2007 (UTC)

Which counter-argument? --Michael C. Price ^talk 07:22, 14 March 2007 (UTC)

Well that's one way of silencing the counter-argument. Postulate it's non existance. And I suppose we could interpret the debate here as just Michael entertaining an argument all by himself. And perhaps if I (and/or others) stopped responding to Michael's argument that would be the case. But Michael's argument is not a single voice in an otherwise silent universe. It is but one voice amongst many. Why is this vote still pending? Michael does not appear to have anything more substantial to argue in defense of his argument. Are we waiting for something of more significance to emerge in Michael's otherwise increasingly rhetorical contributions? --Carl A Looper 21:46, 14 March 2007 (UTC)

I take it you're not going to tell me which counter-argument you're referring to? --Michael C. Price ^talk 05:32, 15 March 2007 (UTC)

?

The counter-argument can be argued as a postulate. The postulate is that: the formalism and complementarity are not interchangeable concepts. Now, being framed this way, as a postulate, it is not actually necessary for us to "believe" in it. We merely note that when we postulate this idea (ie. entertain it as correct) we are unable to maintain that a claim of BPC violation is interchangeable with a claim of formalism violation. And likewise, we can't maintain a claim that a failure to violate the formalism is interchangeable with a failure to violate complementarity. Keep in mind that this is just a logical result of the postulate.

But the real argument I've been putting forward is not this logic, as basic as it is. It is about what can be understood as BPC. Complementarity is not an implicit echo of the formalism. Bohr advances particular concepts under the name of "complementarity". And these are certainly interpretive but these concepts are not in any way ambiguous or a byproduct of the formalism. For example, in what way is the idea that "experiments must be defined classically" spring forth from the formalism? It doesn't. Yet is a central part of complementarity. Indeed, it is through experiments, defined classically, that the formalism itself becomes constructable in the first place. Or that's how Bohr can be understood. But even if this were not the case, (ie. postulating it the other way) then the reverse question remains. How does the formalism produce this idea? Or more specifically, since we're talking about BPC, how would you use Bohr to answer this question?

So simply put, on purely logical grounds there is a counter-argument. And on more substantial grounds - there is more to Bohr's complementarity than a mere echo of the formalism. And on the basis of both these propositions one can understand how BPC can be challenged without challenging the formalism. And that's before we've even challenged BPC!!! --Carl A Looper 06:07, 16 March 2007 (UTC)

Classical concepts (such as Newton's second law) emerge from the formalism via Ehrenfest's theorem. And wavefunction collapse emerges from decoherence. So complementarity is an echo of the formalism. --Michael C. Price ^talk 10:35, 18 March 2007 (UTC)

The collapse of a decoherent wave function is no more formalised by the formalism than the collapse of a coherent wave function. --Carl A Looper 22:33, 18 March 2007 (UTC)

It doesn't sound like you understand decoherence; no matter, that wasn't the central issue. I note that you avoided commenting on the emergence of classical concepts, such as Newton's laws of motion, from Ehrenfest's theorem, which is part of the formalism of QM. --Michael C. Price ^talk 23:52, 18 March 2007 (UTC)

I've read Zurek and others and have no problem following their argument. That doesn't mean I must agree with it. Disagreeing with something is not necessarily the same as confusion. I might say that decoherence theory is confused but I'll leave that for another day. Also, classical concepts emerge within classical thought. Our capacity to theorise alternative modes of emergance - eg. through non-classical means is useful but doesn't change anything. BPC says nothing about this mode of derivation. When BPC speaks of classical concepts should we really be interpreting it as meaning non-classically theorised classicism? This is not to say we can't entertain neo-rationalist fantasms. But can we attribute such to Bohr? --Carl A Looper 03:07, 19 March 2007 (UTC)

What relevance does this speculation have with regards to improving the proposed text? BTW Bohr and Ehrenfest were particularly close, so Bohr undoubtly draw on Ehrenfest's theorem from the 1920s in developing his ideas on complementarity.--Michael C. Price ^talk 06:40, 19 March 2007 (UTC)

The only speculation I can see demonstrated here is in attributing a fundamental aspect of Bohr's principle of complementarity to Ehrenfest. Perhaps you are onto something. It's always possible. But it is hardly proved on the basis that they knew each other. Do you know any other reason why Bohr felt might have felt correct application of the formalism was dependant on a full and unambiguous specification of experiments in classical terms? I mean, other than he knew Ehrenfest and therefore must have appropriated the idea from him? To answer this question requires understanding how one might specify an experiment in non-classical terms - and how one might do so without introducing the formalism as part of the specification. Any guesses? Any math you can dig up? Or literature? It can be done. But can you do it? --Carl A Looper 21:32, 19 March 2007 (UTC)

Here is a rewrite that addresses the previous objections: it entirely sourced, with the exception of one sentence which links the statements by the founding and modern commmentators -- and that sentence is enirely couched in the language of Bohr's quote.

Proposed text start:

• Niels Bohr stated "a complementary way of description is offered precisely by the quantum-mechanical formalism"

In this view, since the photons in the experiment obey the precise mathematical laws of quantum mechanics (the formalism), they can be described by Bohr's principle of complementarity. Cf:

• "I think Bohr would have had no problem whatsoever with this experiment within his interpretation. Nor would any other interpretation of quantum mechanics. It is simply another manifestation of the admittedly strange, but utterly comprehensible (it can be calculated with exquisite precision), nature of quantum mechanics."
• "There is absolutely nothing mysterious about Afshar's experiment. [....] And of course, the conventional quantum mechanics is compatible with the principle of complementarity."
• "It was claimed that this experiment could be interpreted as a demonstration of a violation of the principle of complementarity in quantum mechanics. Instead, it is shown here that it can be understood in terms of classical wave optics and the standard interpretation of quantum mechanics."

Proposed text end. --Michael C. Price ^talk 10:35, 18 March 2007 (UTC)