Talk:Afshar experiment

This article was nominated for deletion on December 19, 2005. The result of the discussion was keep. An archived record of this discussion can be found here.

This article was nominated for deletion on 19 January 2006. The result of the discussion was KEEP. An archived record of this discussion can be found here.

Old discussions are archived at Talk:Afshar experiment/Archive1, Talk:Afshar experiment/Archive2.

Please limit discussions to topics directly concerning the content and structure of the article Afshar experiment. This page is not the place to have general discussions on quantum mechanics or its interpretation, nor to debate the correctness of Afshar's findings and conclusions. (linas 15:49, 20 January 2006 (UTC))

Problems with the theory section

There are problems with the theory section. I tried to clean it up, but promptly got tangled. I'll try to fix it in time, but any discussion here would help clarify what the intent of this section was. linas 02:06, 7 December 2005 (UTC)

The theory section was apparently added by anonymous user User:143.50.61.66 around 28 June 2005, but no matter how I try to fix it, it just seems broken. I'm punting for now. linas 04:03, 7 December 2005 (UTC)

So... anyone care to help fix, or at least discuss, the theory section of this article? linas 15:25, 16 January 2006 (UTC)

Hey, linas - I have provided as much theory that you may write down a full length chapter on complementarity. Open your eyes, and stop calling me vandal. I have clearly shown that interference existense is NOT synomym of which-way or no-which way info - see the 4 slit experiment. I have clearly shown that IF Afshar's is right, then there will be E,t violation of Heisenberg's principle. I have shown that Afshar does not understand what is momentum in QM, and that it is not classical vector with well defined both magnitude and direction. I have contributed enough theory against this self-promotional article, and I think this is essential battle against pseudo-science, not vandalism. Danko Georgiev MD 11:03, 27 January 2006 (UTC)

Interpretive Section

I suggest an additional section with an interpretive angle (ie. in addition to the math) - one that summarises Afshar's interpretive approach. The debate regarding the math depends on what interpretive angle is chosen. The math one might use for Afshar's experiment can require a slightly different approach.

One can construct wave functions from the detector data and project them back towards the pinholes, in order to determine what information can be interpreted as in the detector data. Of course, the reconstruction of the pinhole plane requires data from both detectors.

Two pinholes - not one - would be reconstructed.

In other words, one can not tell, from BOTH detector's data, any which way information.

But in Afshar's experiment only the data from one detector would be used, so only one pinhole would be reconstructed. This establishes "which way" information. It is, however, completely analogous to the complementarity of forward computation in which one chooses whether one pinhole will admit light or both.

One chooses whether to use one detector's data - or both.

In Afshar's experiment it is the decision between whether to use the data from one or both detectors - for the reconstruction - that determines whether "which way" information is demonstrated (or not).

The "which way" information is not in the data - but in the decision.

This is the principle of complimentarity.

Carl Looper 22 January 2006

Why one cares about math of complementarity?

Dear Carl, I will NOT agree that which way is not in the data - but in the decision. See again the right mathematical formulation of complementarity that nobody wants to see. All this available in basic QM course held by prof. Bob Eisenstein. All the math below not only captures naive complementarity, but has more than this. In this paper[[1]] is presented the original idea of prof. Eisenstein that clearly explains HOW the seemingly wave-particle duality appears. ALL IS COMPLEX ALGEBRA - usually a complex number can be written as $e^{ix}$ or $cos(x)+isin(x)$. Now depending on the way you compute probability which way, or not, you may obtain "clumping" distribution with P depending on $e^{x}$ or "wave-like" distribution depending on $cos(x)$. Seeing these deep roots of complementarity in the nature of complex numbers per se is more than simple wording done by various pseudo-physicists.

No which way is charachterized by probability distribution of pure state - so $P=|\psi _{1}+\psi _{2}|^{2}$ where $\psi$ are complex numbers and denote the quantum amplitude. THIS IS CONTINUOUS FUNCTION IN SPACE!!!

Which way is characterized by probability distribution of mixed state - so $P=|\psi 1|^{2}+|\psi 2|^{2}$. THIS IS CONTINUOUS FUNCTION IN SPACE!!!

So the which way or not is OBJECTIVELY THERE in space, and Afshar uses exactly this - he puts grid in the space before the lens absorbing some photons.

Below I present two scenarios with polarization filters [which way] and without filters [no which way] and you will see clear difference of the probability distribution [i.e. light intensity in space]. NOTE: the two tiny lines accompanying the central Airy disc in the first "which way" image stand for the DIFFRACTION single slit pattern, sorry for the ugly hand drawn images, but they are very useful for direct seeing of complementarity!

Now as I have said in my previous post, polarization filters produce mixed state, but you can do it by first closing on slit, record some light, then close the second slit, record some light, and then take the average of the two single slit experiments. In this time you have mixed state because the distinguisable photons have different time arrival/detection.

UNLESS there is clear link with density matrix formalism, distinguishability of q-particles, and probability distribution you do not speak of complementarity but some WRONG popular wording. Exactly the OBJECTIVE math criteria are forcing you in your holographic experiment to project from special position behind the "virtual pinhole". I do not want to repeat myself, there is pdf of mine in the web also [[2]].Danko Georgiev MD 07:19, 22 January 2006 (UTC)

• Dear Carl, you may insert the link to my pdf in the main article - it was deleted by Afshar, because it is the only REAL math objection to his wrong math. There are numerous quotations by Afshar - where you may notice that he does not understand the difference between mixed state, and pure state - he gives award of 1000$ but he says "if you prove that the photon's density matrix in a mixed state" - but this is exactly what ONE SHOULD NOT DO in order to SHOW that Afshar is WRONG - he must show that the photon is in superposition - hence no which way info! I consider this as equivalent to previous offers that he gives 1000$ to one that disproves him. But corectly interpreted the quoted text in my pdf shoul mean "I give 1000$ to one who proves I am right". So the conclusion is that he has not correct idea of what density matrices mean - so whatever you write down, Afshar cannot understand whether the equation proves him or not. Funny, isn't it? Danko Georgiev MD 07:37, 22 January 2006 (UTC)

Density matrix

By the way - untill there is ONLY ONE density matrix - the experiment will be either WHICH WAY or NOT WHICH WAY. If Afshar wants to disprove complementarity he MUST prove that the photon HAS 2 DIFFERENT DENSITY MATRICES AT THE SAME TIME i.e. being in mixed state and pure state AT ONCE. What is this - new math, or new physics? Danko Georgiev MD 07:43, 22 January 2006 (UTC)

Retrospective Wave functions

Forward wave functions.

The wave functions used to predict downstream data are constructed from information regarding the upstream constraints one has imposed on the lightwaves/photons/electromagentic radiation/electron waves/carbon molecules ...

To the extent that one might introduce polarisers, pinholes, mirrors, lenses, holograms (etc.) one will accordingly adjust the way the wave function is computed.

At the end of the day there is a real life pattern on the screen with which to compare both one's mathematical model and/or the accuracy of one's measurements ...

Retrospective wave functions.

These waves are used to "predict" the upstream constraints that were in place, eg. whether one pinhole was open or two. Of course, if you know that then there's no point predicting it. You have to sort of, turn off any information, that you know about the pinholes and determine it just from the detector data. Therefore you are not permitted to use any forward wave functions in determining what is represented in the detector data. Otherwise you will be cheating!

Now obviously, if we only choose one detector's data, we could only determine if one pinhole was open, (or not). Think about it. You are not permitted to know what lies in the pinhole plane, or further upstream. So you are not allowed to use the wave functions that you might have otherwise industrially computed, eg. the interference patterns (in front of the apertures).

Remember, waves pass through one another, and other than the region where they interfere, don't affect each other.

If you project the data back, from BOTH detectors, they WILL interfere with each other. They will also give you the status of both pinholes - telling you whether they were both open, one closed, or the other, or both closed.

Now I don't know what it really means to superimpose the forward wave function from two pinholes, with the backward wave function from just one detector.

It's not that it's "incorrect" - it's just that it's not clear what it would demonstrate.

Carl

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Dear Carl, there are some important issues, and actually if you see the work of Lev Vaidman [3] you will see that this superimposing of forward and backward wavefunctions is very essential to properly define/understand the pure state, that quantum coherent superposition. Actually if you have quantum interference [NOTE: THIS IS NOT CLASSICAL ONE!] then this is expressed by NON-ZERO off-diagonal elements in the density matrix. This means that $\psi _{1}\psi _{2}^{*}$ and $\psi _{2}\psi _{1}^{*}$ are not zeroes. The forward wave could have passed through one pinhole and then returned through the other, or could have passed by half through both pinholes, and returned by half through both pinholes - it does not matter. If you have mixed state density matrix however YOU HAVE ZERO off-diagonal elements in the density matrix. In this case $\psi _{1}\psi _{2}^{*}$ and $\psi _{2}\psi _{1}^{*}$ are ZEROs, so you cannot have the situation when the wave have passed through pinhole 1 forward, and then returned back through pinhole 2. Actually the transactional interpretation makes the picture more intuitive, and more imaginable, yet this is not something new and you have it in the matrix formalism of standard QM - ket is forward function $|\psi >$ or just $\psi$, while bra is $<\psi |$ or $\psi *$, where it is transposed and complex conjugated ket - J.G. Cramer is not the first one to notice that bra is time inverse of ket, Wigner has already shown this. So there the superimposition that you wonder about is the ESSENCE of quantum coherence/pure state/interference. Note - in quantum interference you add quantum amplitudes and then square the result to produce the observable probability distribution e.g. light intensity, in classical interference you add classical amplitudes that are observables, so you add the squared probabilities [i.e. mixed state density matrix, see the complementarity principle in which way case where $P=|\psi _{1}|^{2}+|\psi _{2}|^{2}$. Danko Georgiev MD 03:31, 24 January 2006 (UTC)

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Hi Danko. Thanks for the comments. The backward waves about which I was speaking were not the back moving waves (or wavelets) of the quantum waves (computed from the pinholes) - but the waves (classical or complex) one might compute from transforms of the observables (ie. from the detector data). It is the superimposition of the complex waves (from the pinholes), with the "classical" waves (from a single detector's data (or both!)) which I'm questioning. It is this sort of superimposition that is difficult to assign a meaning.

I guess what I'm trying to get at is not *how* Afshar is wrong but *why* is he wrong. It's not enough to say that he is using the wrong math. How do we know it's the wrong math? Because Bob Eisenstein said so? Or Heisenberg/Bohr? Well sure, but it's too easy an answer. We have to know why. And that's harder.

Why does Afshar mix the functions?

As far as I can tell it's by way of a circular argument. To prove complimentarity wrong one just uses the math that violates the principle. To justify the math we use the supposed "fact" that a particle captured by one detector means it "came from" the pinhole opposite that detector. But of course, it's just not demonstrateable. That same particle might not have appeared where it did. It could have just as easily appeared in the other detector - as we know. The particles/data in a given detector are just the result of that particular detector's point of view. That doesn't mean it came from the corresponding pinhole. It only means we can image the corresponding pinhole (ie. reconstruct a pinhole from the data).

The wave from which a particle is otherwise plucked (so to speak) is spread across *both* detectors. So the particle doesn't "come from" the pinhole. We know that. It's just standard QM, albeit, with it's so called "measurement problem".

But it's not about whether Afshar's math is right or wrong - but why. Why use such math? What is one trying to say with such. Or what causes someone to use such math? What is it about quantum theory that is so unsatisfying that it must be turned in on itself?

I mean it's not as if there is anything surprising in Afshar's experimental data that should cause us to run back to the drawing board. But it's a tradition going back to Einstein's debate with Bohr. It's to do with what can be thought as much as what can be seen. And it's okay. It's an okay tradition. It's an ongoing debate between Cartesian rationalism on the one hand and empericism on the other. Heisenberg puts it well but who cares?

it requires stepping back from the physics, back into a wider context. To speak outside of physics is not be a pseudo-physicist. But of course one can inadvertently bring back into physics something that doesn't quite work. But we can't know that in advance. Otherwise we'd still be living in caves and explaing to some young ape that the reason his wheel won't work is because the ape in the tree yonder said so. On the other hand the ape in the tree might be right! One way is to test the wheel.

But there is no observable/testable wheel in Afshar's experiment. Afshar's wheel is a mathematical entity. There is nothing necessarily wrong with this. It's just difficult to determine what the picture is that he's trying to paint.

There are clues in his simulations.

The fact is that a branch of physics is moving towards what can be *simulated* rather than what the ape in the tree yonder says. As such we need to apply a form of criticism that draws on domains of knowledge traditionally beyond physics. Information theory is a young "science" but it is also one of the oldest "arts". In computer animation, for example, one uses algorithms that trace rays from the eye out into the world. It's an ancient Greek idea. But why? Because that which is being simulated is a point of view image. What does the world look like from here? It's also because it's less intensive on computer resources. But one of the main reasons is that many people like point of view images. It underwrites the computer game industry and hollywood special effects.

Anyway, I'm raving on. We're supposed to be talking about the article ... but heh, lets just call this an extended discussion of context regarding what might, or might not end up in the article.

Carl

The Question is WHY?

Dear Carl, thanks for your reply. You ask WHY Afshar makes the error. I have already provided the answer WHY [4]. I have shown that wave functions CANNOT be distinguished ONLY by having a probability distribution at a single plane, no matter whether it is image plane, or any other plane. The probability distribution function is defined in 4D [I speak about the probability distribution function which changes in time!] so knowing the probability in just a single 2D plane does not give you the spatial 3D behavior of this function [neither gives you the temporal behavior]. TYPICAL EXAMPLE is Afshar - he sees two well formed pinhole images and like little child say "here it is the which way info". The WHY of your question, is answered by BECAUSE Afshar is ignorant in basic math principles. Alas, this is common feature to others as well like Aurelien Drezet, that connects the image plane with which way info, and Fourier plane with no which way info. I ALREADY HAVE SHOWN in my pdf quoted above that IF you have polarized photons the lens CANNOT provide REALLY full Fourier transform, but creates TWO INDEPENDENT FOURIER TRANSFORMS i.e. the typical mixed state. Actually Drezet is not the only one who makes this labeling of lens planes with names "which way one", "no which way one", "bla bla one". This even presented in Anton Zeilenger's papers, but what can I do. Nothing! This is WRONG math, based on WRONG clasical and popular misunderstandings, only math can open the eyes of these people, but they do not want to see it. In simple sentence - IF you want to SEE the probability distribution LOOK at the whole 3D space, otherwise you cannot make claims about what function you have [i.e. which way one, or no which way one - lens planes do not have which-way/no-which-way property, the probability distribution function has which-way/no-which-way property and it is described by the nature of the density matrix of the quantum state] Danko Georgiev MD 05:59, 25 January 2006 (UTC)

Addendum: This principle - LOOK in the whole 4D space [here I include also the time] explains the Q-non locality or backward causality, where the future in some sense causes the past - this is expressed also in the inseperable nature of the quantum coherent state. If one do not understand this quantum "wholeness" better find another hobby, not QM.

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Hi Danko, I don't know why you need to keep SHOUTING. I understand what you are saying. Believe me. But how about listening for a change?

One of the things Afshar is doing (although he may not agree) is using quantum theory to question Bohr's interpretive concession to classical theory.

There is no which way information in Afshar's experiment. But then there is no such thing in Bohr's theoretical outlook either. Both Afshar and Bohr use the words "which way" to represent a concept that exists in the imagination of classical thought. That doesn't mean it's not useful or interesting.

The danger here is that both Bohr and Afshar risk being misinterpreted as positing the validity of the which way concept. Afshar misreads Bohr. You and I misread Afshar.

You might think that this is all just "blah blah" and nothing to do with QM but you will be wrong. Have you read Heisenberg's talk on the philosophical background to quantum theory? Do you think that matrix mechanics just fell out of the sky to be forever SHOUTED at people?

Afshar's experiment is a reasonable one. The wires provide a demonstration of how the interference of the wavelets from each pinhole can be inferred without actually recording any interference patterns! I don't know why Afshar says they are "visible" but lets just say he means "inferentially visible".

Now whether or not the "which way" information is "there" depends on whether you choose to look back at the pin holes through both detectors or just one.

This has nothing to do with the wave function. The wave function's interference, either side of the lens, is not expressed in the detector data as the detectors are beyond the reach of any possible interference patterns being recorded. And as you say, the detectors are just 2D so the fourier components are not expressed. And by the way, this throws water on my hologram experiment since such would have been exposed in Afshar's detector data - as interference patterns. (addendum - good grief, what am I saying? There would be no interference patterns in Afshar's data for that very reason!)

But in Afshar's experiment there are pinholes (as distinct from mine) and there is no (visible) hologram in his detector data (nor in mine). The wave function (on the other hand) can be assumed to still possesses it's coherency and a simple but different experiment would demonstrate this. But in Afshar's experiment this is is not expressed.

Now there are two things here.

One is that the interference of the wave function (where the wires are) is inferred, ie. not actually recorded. This is okay. It's clever and it's interesting. But we need to be careful because concessions to classical theory are only possible if the wave function can remain (if only in the imagination of the classical mind) an approximation of where a particle is. In Afshar's experiment, the wave function is demonstrated ex situ.

Ok. On the which way side, where the concession is normally possible, eg. using a single pinhole, it is no longer possible. The which way concept was always an inferred reality, but now it's not possible unless we counter that the equally inferred wave function is somehow disfunctional. But how? It's clever.

Which way information is being annihilated!

And yet strangely, we can restore complementarity at that point where it looked already restored by the annihilation of which way information (if only in virtual reality) by showing how the decision regarding how we infer the pinholes - using one or both detectors, is in actuality, played out.

This leads us back to how we might re-express the pinhole distinguishability criteria. And fortanatly, where some mathematics can be reintroduced. And the principle of complimentarity, albeit enlarged.

That's for another day.

Remember, a rose by any other name smells just as sweet.

Carl

Dear Carl, I am not shouting, I could underline the main point in bold, but you can also misinterprete it like shouting.

Afshar may have disproved some interpretational aspect of Bohr, and even may have quoations proving his thesis. I have said only that Afshar must know that modern complementarity has strict math definition, so complementarity is no more in the scope of popular science. The fact that Afshar cannot understand my argument based on simple writing of density matrices for me is evidence that Afshar's knowledge in physics is quite limited and I feel sorrow for his 18 years of studying. If I have studied for that long physics possibly I would have moved in some advanced topic in brane theory, not try to do "fishing for red herring". Danko Georgiev MD 11:18, 25 January 2006 (UTC)

What about Heisenberg's principle?

Dear Carl, although I do not want to convince you that Afshar's error is not just interpretation, but very deep math problem, I will just note by the way that usually complementarity is linked to non-commutable variables, and Heisenberg's principle. So why Afshar never stated that he has disproved Heisenberg's principle as well. Here is the quotation from the wiki article:

"The principle of complementarity states that two complementary physical observables cannot both be measured for any given quantum particle. For example, a particle's position and momentum cannot be observed at the same time: this is Werner Heisenberg's uncertainty principle."

Well, I suspect that after Afshar gets the Nobel prize for disproving Bohr, he will apply for second Nobel prize disproving Heisenberg. He possibly does not want to shoot everything at once. Danko Georgiev MD 11:26, 25 January 2006 (UTC)

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Dear Danko, my apologies for getting a little defensive. Neither complimentarity nor the uncertainty principle is compromised in Afshar's experiment. For one thing there is no visible interference pattern (physical observable). So if we are to be mathematically and conceptually strict, Afshar is already wrong here. The wave function of quantum theory, with it's due concession to classical theory (ala Copenhagen) is a mathematical model for predicting actual interference patterns. Since no such patterns are there to be predicted, and the wires are invisible to such predictors, one should question what is being demonstrated here. Are we to say that the experiment establishes the wave function as a reality? From a neoclassical point of view - yes. But from a quantum theoretical point of view - no. Quantum theory was developed in response to very strange but very real facts: the measurement of actual particles (not virtual which way ones) and the actual interference patterns they made - not the virtual interference patterns we might use to predict (compute) such patterns.

(addendum)

So since there are no *visible* interference patterns, the visibility of such equals zero. V=0. That is all that's required to knock down the math.

But I like the experiment. It's conceptually interesting. I like what EPR tried to do. And I like Bohr's comeback even more. I like Bell's inequality tests. I like Cramers approach.

Carl

Dear Carl, there is clear interference in Afshar's setup, and I do not understand what changed your mind. There is so-called Reininger negative measurement experiment in which you collapse the wavefunction WHEN you DO NOT observe the particle. So the Afshar's experiment is no which way from the beginning to the end. At the pinholes you have coherence, so you have interference, at the wires you detect ZERO intensity, so you make negative no which way measurement [Reininger!] so you have again interference, and finally at the detectors the photon comes in superposed pure state ${\frac {1}{\sqrt {2}}}(|D_{1}>+|D_{2}>)$, where the photon is both detectors. There is so-called measurement postulate that says IF you measure a superposed state, you irreversibly collapse it to one of the basis states in which the measurement is done. So now if you read the argument in my pdf explaining the measurement postulate - you cannot make difference by measuring a pure state ${\frac {1}{\sqrt {2}}}(|D_{1}>+|D_{2}>)$ in basis $|D_{1}>$, $|D_{2}>$, and measuring a mixed state ${\frac {1}{2}}|D_{1}><D_{1}|+{\frac {1}{2}}|D_{2}><D_{2}|$ in basis $|D_{1}>$, $|D_{2}>$, . In both cases you obtain ${\frac {1}{2}}$ at $D_{1}$ and ${\frac {1}{2}}$ at $D_{2}$. of course you have to use and you can use other types of measurements to distinguish between pure state and mixed state. For example you can NOT measure/detect two photons at the detectors, but you can catch them in an optical fibre. Then after clever arrangement you can let two such captured photons to interfere. If the two photons catched at the detectors are in pure state ${\frac {1}{\sqrt {2}}}(|D_{1}>+|D_{2}>)$ they WILL INTERFERE, because they are coherent. If the catched photons are in mixed state then they will NOT INTERFERE becuase they are not coherent. Please read my pdf at least very very fast looking over the topics, there I present a dozen of proposed alternative methods to test Afshar's claims. I feel that you start to be confused, while I am still absolutely sure in my thesis, because it is based on unshakable mathematical fundament - the difference between mixed state versus pure quantum state. p.s. Please ignore Afshar's comments. He has never heard of interference of quantum momenta and just shows his ignorance in the topic. Danko Georgiev MD 07:50, 26 January 2006 (UTC)

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Dear Danko and Afshar, this, it would seem, must be my last word here in Wikipedia. Since Danko has been excluded from the discussion at the weblog it must be my last word (with Danko) at the weblog as well. And Danko, yes, there is an error in my reversal re. the hologram experiment. The fourier plane in Afshar's detector would not be able to distinguish between a real pinhole and a hologram of one. The interference of the wave functions (from the hologram) vs the non interference (from the real pinhole) would be indistinguishable in the detector data - for the reasons discussed. My error.

-- NB. I make a distinction between 'interference' in the quantum theoretical waves and actual "interference patterns" in the data. The later is physical data, the former is not. I try to keep this distinction running through my discourse but I sometimes slip, on the assumption that this distinction remains understood. But I risk misrepresenting one as the other. To myself as much as anyone else. So while coherency can be quantum theoretically sustained in the fourier plane of Afshar's experiment - this is a different thing from actual interference patterns ie. the data. So when I say there is no interference patterns in Afshar's experiment I am only referring to the data - not the quantum theoretical state. I want to continue this discussion with you ... otherwise, thanks for all the fish! Very much appreciated.

• Dear Carl, I am glad that you have seen your error. Actually your hologram experiment idea was very good one, and after that you were in temporary delusion. Now I see that you have found the right track again. What about the Afshar's blog - I AM NOT BANNED! I could post on the blog from almost any I.P. address that I want, and Afshar cannot do anything to prevent this. However it is my personal will not to post on Afshar's blog. I do not offend Afshar directly as he does offend me because my academic position in the University and my status of medical doctor do not permit me to behave like that. From Afshar I have heard to be crackpot, having brain disorder, etc. .. If you check below his reply you will see that he does not understand momentum in QM, but I will not be his teacher. If you [Carl] want to discuss something with me, check my Wikipedia information for contact. I am quiting this endless discussion. Danko Georgiev MD 04:08, 27 January 2006 (UTC)

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Hi Danko, my email to you bounced so here it is for public scrutiny.

Bohr would say (if I can be so bold), that in Afshar's experiment, one should not misrepresent the meaning of V, eg. using a value close to one. On the contrary one should represent the meaning of V with a value close to zero.

This is somewhat contrary to what a neoclassical theorist might do. But it's what a quantum theorist would/should do. The reason rests on the very important distinction one should make between the quantum theoretical wave function and the information/data rendered in actual experiments. The data is real. The wave function is not.

V represents, or should represent, what is otherwise rendered in the data.

V should not be used to represent some attribute of the quantum theoretical wave function. The reason for this is not mathematical per se but deeply philosophical.

It is a misrepresentation of Bohr's philosophical position (and therefore quantum theory) to say that Bohr erroneously applys destructive measurement schemes. Bohr does no such thing. It is precisely the data that results from so called "destructive measurement schemes" that defines what is being theorised in quantum theory.

But lets not get too hung up here. If V is defined neoclassically then the problem goes away. Bohr can go back to sleep. And so can I.

Carl

E, t uncertainty violation

Dear Carl, I will only repeat that V=1, because all the light intensity passes through the wire grid. You detect with the wires ZERO intensity, so you prove that there is quantum interference. Afshar uses wires that diffract the light around, but you can use silver compund detectors, so they absorb all the light. In the which way scenario, you will absorb with these wire-silver-detectors 6% of the applied light, and this is analogous to case when you have polarization filters on the pinholes. In Afshar's case the putative silver-wire-detectors will absorb ZERO light AS IF they are inside an absolutely dark room. This is so becuase they are in the interference minima, and there is really DARK !!! You make Reininger negative measurement and you collapse the wavefunction in Energy basis, because you precisely measure the photon's wavelength [energy]. K however is ZERO, because you do not have which way info. In view of the E, t Heisenberg uncertainty, you do not know the time needed for arrival of the photon at say detector 1, so you do not know whether it passed through pinhole 1 or pinhole 2 [the distance passed is different, photon's velocity is c]. So you have no which way info, and K=0. If Afshar was right, you can measure both wavelength $\lambda$ by knowing the place of interference minima, and the photon's energy $E={\frac {hc}{\lambda }}$. Then knowing the "which way" as Afshar WRONGLY suggests, by knowing the 5.2 m distance to the image plane, and the photon's which way path, you can simply compute the time arrival, and hence have precize measurement of E and t, VIOLATING WRONGLY HEISENBERG'S PRINCIPLE. No which way, as I said many times, so K=0, and V=1. E, t, uncertainty is simple because you work with scalars !!!! To work with p, x uncertainty is dangerous, because you work with vectors, and momentum IS NOT the classical vector any more. If you know momentum's magnitude [vector length] then you do not know its direction. So dear Carl, I would like to quit this discussion, and please contact me by e-mail. Although you are flip-floping your decisions, I believe that you may benefit from my mini-lectures. Danko Georgiev MD 10:48, 27 January 2006 (UTC)

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Precisely. If we redefine V neoclassically, as you have done, then V=1. The wave function is no longer just a mathematical representation of what might be realised in a measurement (ala Copenhagen) but a neoclassical reality in itself. Within this neoclassical reality the concept of waves on the one hand and particles on the other are in direct mathematical/geometrical conflict with each other. Thus the apparent violation of complimentarity, and by mathematical ellaboration, uncertainty etc. They can only be brought back into "peace" with each other back out in the real world ie. where measurements are actually realised. For example, introducing polarisers, or downstream reinterference of the photons. This is more or less the same sort of strategy Bohr did with EPR. But in EPR the measurements are made *before* being brought back together. But it doesn't matter. The so called measurement problem takes place in virtual reality. It is the data which determines whether we jettison the probability function - not the other way around. I mean, I can still use a probability function to determine the probability of where I might find the trace of a particle in an already recorded interference pattern. I look at the pattern as a whole and zoom in upon the predicted peaks in the data - and viola - a single trace.

If we are to find a balance between the traditional virtual reality of classical thought, and the actual reality (ie. actual measurements) that traditional quantum theory theorises we must recognise that these two "realitys" do not occupy the same space. They face each other. Classical reality is that virtual reality inferred from measurements. The reality of quantum theory are the measurements themselves. Qunatum theory itself is not a reality. But in classical thought (and neoclassical thought) theorys are "realitys" in themselves. Measurements are not regarded as realitys in themselves - they are regarded more like pictures or "side effects" of some otherwise invisible reality. So in neoclassicism, an actual interference pattern would be just a picture or side effect of some "real" quantum wave function. Or, in Afshar's experiment, the small increase in the measured detector intensity would be a side effect of some real wave function.

If we adopt a neoclassical perspective then we will need to rewrite quantum theory from such a perspective. And that is something to do, certainly. In fact, it was just such an exercise I was hinting at when looking back at the pinholes from one detector or both, ie. complimentarity from a neoclassical perspective.

This can be called flip flopping. Indeed, we could use the term "flip flopping" as a technical term for a new expanded neoclassical principle of complimentarity.

We can begin with the Danko formula:

  Afshar does not contradict quantum principles because Afshar contradicts quantum principles.

[NO! This is senseless rumbling. My formula is (i) quantum principles and mathematics is consistent, (ii) Afshar derives some form of inconsistency, (iii) therefore Afshar MADE ERROR in applying the quantum principles and mathematics, (iv) I have tried to show clearly where his mathematical ignorance is. My claim has nothing to do with the above mis-understanding of Carl Looper. Danko Georgiev MD 04:12, 7 February 2006 (UTC)]

This can be mathematicaly expressed as:

  if V=1, then K must be zero. 

And indeed, it is true. Were we to reinterfere photons from both detectors, we would discover that K = 0.

And if we didn't? Then K is somehat undefined. We can set it to 1, as Afshar does and use traditional quantum theory:

  Since V=0 and K is undefined ( or classically 1), then where is the pending cataclysmic upheaval in quantum theory?

But if traditional quantum theory is unsatisfying, and new quantum theory (ala Danko) sounds somewhat circular then perhaps we should rethink the issue in complete neoclassical terms:

 If V=1 and K=1 then ?

Then what?

Someone needs to finish this sentence. Afshar lets Danko do it. We end up back at the Danko formula. Perhaps Afshar should answer this question - not Danko. Danko has done a very good job I think. He has really tried to beat this one, but the onus is not on Danko to finish this expression. It is on Afshar.

Carl.

• Dear Carl, your entry above is non-sense. It disappointed me fully. As I said in every experiment there is MATHEMATICAL OBJECT that CORRECTLY describes what will happen, and this math object is called DENSITY MATRIX. You have two types of density matrices - pure state one, where $\rho =\rho ^{2}$, and mixed state ones in which $\rho \neq \rho ^{2}$. Whether you let interference, or not of the captured photons is not important. You are joking with misinterpretations of my thesis. I DO NOT insist on your imagined wrong co-existence of quantum and classical ontologies. WHAT IS IMPORTANT for me is the NATURE of the DENSITY MATRIX. If you know it, you can predict not only the current experiment, but all possible experiments that you might have done, but you haven't done. This is called COUNTERFACTUAL DEFITENESS. My philosophical position is to think of the mathematical objects of ontologies, and not to try to substitute them with popular interpretation. (I am not into popular interpretations - Carl) In 2002 when I was studying QM basics I saw one very poor from my view interpretation, which now is my leading philosophical position - it is called "shut-up-and-calculate interpretation of QM" (this is a principle for children - Carl)In case of QM it is impossible to substitute the math objects with popular wording (true - Carl) and if you forget about the existence of density matrices, you cannot explain every experiment just by popular principles (true - carl), just because the popular wording does not possess the property of the density matrix, say $\rho =\rho ^{2}$ in pure state. Can you interpret that in popular wording??? (No - but you can derive it philosophically - Carl) Now i understand that you suggested the holographic experiment blindly, without understanding the link with the underlying density matrices of photons. Please repair that, before you introduce personal targeted irony in your posts. Danko Georgiev MD 04:25, 30 January 2006 (UTC)

Dear Danko - I am not at all a proponent of popular wording but I am a proponent of philosophical understanding - and irony is a part of that (it is an ancient philosophical technique). I am opposed to the "shut up and calculate" principle as it simply reinforces whatever the current paradigm happens to be. Imagine if Einstein followed that principle - would he have theorised relativity? No - he'd still be calculating Newtonian mechanics. Quantum theory has it's basis in a radical empericism. The wave function is a rationalisation of emperical data. From a strictly emperical point of view only the emperical data is real. The rationalisation is a representation of the data. The wave function represents the data. It is therefore an *effect* of the data - not the *cause* of the data. Now I understand holographic principles intimately. I write computer software for synthesising holograms from 3D models of medical data. I use wave functions every day. I agree with your position regarding "which way" being absent in Afshar's experiment. Until the wave function "collapses" the particle does not yet possess any emperical reality, ie. there is no data that we might call a "particle" - there is not yet what Bohr called "phenomenon". There is no measurement. But I disagree with the visibility of the wave function (through so called "negative measurement"). The wave function itself is not visible. It is not emperically real. It is, however, a mathematical object. So it can be allowed a kind of theoretical "reality". As I said, I use mathematical wave functions everyday to compute interference patterns. But that is all they are - purely mathematical - not physical data.

Reply to Looper - Negative measurement does not measure q-amplitudes!

Dear Looper, your explanation above is certainly messed, because you misunderstood the meaning of negative measurement. I have NEVER said that I observe the quantum amplitude [q-wave in popular sense] I have ALWAYS said that what you measure is probability distribution. I do not observe at the wires zero quantum amplitude, I observe zero light intensity, which is zero photons [real probability distribution]. But when you observe zero light intensity, you actually measure the photon's wavelength and energy, so you know that all photons that pass nearby but you do not catch with your wire detector have pricesely determined energy. So it is as if you have measured all the photons, so all photons at that point are measured/collapsed in basis energy. Now, since at the wires you make measurement in basis energy, so you get the result of the photons wavelength $\lambda$ but you have not measured in basis time [which is non-commuting with energy], so the photon remains in superposition in basis time! i.e. each photon has passed through both pinholes. At the detectors the photons come already in collapsed energy basis - that is you know its energy - but since you do not know the length of its time travel each photon is at both detectors. The subsequent collapse of the photon at one of the detectors does not tell you through which pinhole the photon has passed, so the probability distribution of photons [light intensity] is such of "no which way" measurement i.e. the photon arrives in coherent state at the detectors. Since at the wires you have "no which way" measurement and at the detecors you have "no which way" measurement then you make twice "no which way" measurement - so no problem. The fact that after you collapse the photon at one of the detectors and you know at which detector the photon now is, does not extract retrospectively the "time travel" - you know that the photon is at detecor X, but you do not know WHEN the photon arrived there! In this sense the second measurement is in "position basis" but again in "energy basis" - you collapse twice - you know the energy of the photon, and you know at which detector it is, but you do not know the photon's direction of momentum, so you do not know from which pinhole it came from, nor you know when it came there, thus actually it remains in superposition of time and direction of momentum. The measurement postulate says "If you make the same measurement sufficiently fast you will get the same result", so you measure in basis energy [at wires] and in basis position [at detectors], but twice you do not have measurements in basis time and momentum [its direction]. So twice you measure in NOT basis time. Afshar believes that there is conservation of momentum and quotes some wrong papers from early times when complementarity and QM was not settled on firm fundament. So he had the chance to show that the image plane is not necessary revealing which way information, but instead of this correct interpretation, he produced the pseudo-scientific "Afshar's interpretation" where he took the Nobel prize of Einstein. Danko Georgiev MD 04:49, 2 March 2006 (UTC)

Here I add a note why the second measurement should be considered again in energy basis? Well, the lens refracts photons with different wavelengths in different way, so there will be slight difference in the images of the pinholes created by say blue light, or red light. In Afshar's setup this effect might be "under cover" [i.e not obvious], but theoretically the second measurement at the detectors should be considered again as measurement in basis energy. Danko Georgiev MD 05:10, 2 March 2006 (UTC)

By-the-way: I whole branch in astrophysics [spectroscopy of stars] is based on the different refraction of light with different wavelength by lenses, prisms, etc. So dear Looper, double measurement in energy basis is giving you the same result. If you and Drezet understand this simple fact, you will see that there is nothing strange in negative Reininger experiment - knowing that something didn't happen is as real information as knowing that its negation has happened. So you may think negatively that you have detected zero light intensity, or think positively that you have measured 100% of the photons in basis energy [so you know now their wavelegnth!]. The same is similar to knowing that you are not happy, or that you are sad - two different ways to same the same fact. In negative measurement you measure probability distribution of photons [light intensity] you do NOT measure quantum amplitudes of photons !!! So at wires you measure energy, at the image plane you measure also energy - blue light will form two narrow peaks of the pinholes, while red light should produce wide peaks with less intensity of the maxima. Actually this is basics of microscopy - use shorther wavelength for better resolution of the image :-)))) Danko Georgiev MD 13:14, 2 March 2006 (UTC)

Apodized functions as CONSCIOUS FRAUD!

One more add to my detailed exposition above - I suggest where Afshar manipulated the data = conscious fraud?! Well, he used apodized functions to pass only the central maximum at the detectors (deleting the higher order Airy disc pattern!). As I said in case where you have which way info the maximum as the higher order Airy disc pattern will produce a picture different from the one where you measure the wavelength directly [like the no which way one]. If you see figure 8 of Afshar's preprint [5] the data of the first which way experiment have different intensity of the central maximum and the case when there are two pinholes open the central maximum is lower and the pinhole intensity seems spread wider. Of course if the higher order Airy disc pattern were there the two pictures would be too different, so Afshar's fraud wouldn't work. But Afshar cleverly removed this "bad result" by apodization. Now for non-experienced reader it may look like that fig 8a is like the fig 8c, but this is not so. If you had the whole picture considering as I explained above that in one of the cases you measure the wavelength precisely [no which way] you will have coherent light and monohromatic image, while in the case with which way info [i.e. one slit closed] you no more be sure of exact coherence of the light [regardless of the fact that it is emitted from laser] so you will have not exact monochromatic light, but wider spectrum of energies [superposition of wavelengths!]. I hope finally you can start to think seriously on the subject, a forget about "popular wordings". Please write down clear statements, not metaphysical rumbling. Danko Georgiev MD 13:47, 2 March 2006 (UTC)

---

There are a *range* of frequencys, each a harmonic of the wire frequency, that would predict the same "measurement" (data) in Afshar's experiment. Therefore, (to speak in classical rationalistic terms), the frequency of the light has not been measured (negatively or otherwise). We can allow that the frequency has been *partially* "measured", ie. that there are a range of wave function frequencys which would *not* yield Afshar's emperical results. By the way - good point about the airy disk. I thought of that too. Afshar keeps the aperture to a certain size, thus thwarting the production of relevant phenomenon (data) - but I don't agree it's fraud. Afshar is attempting, by whatever means possible, to yield an exception to the rule. He does not succeed (as far as I am concerned) but it is still a reasonable attempt - just like EPR is a reasonable attempt.

Carl

Dear Carl, you possibly may expect that I will disagree with you. Yes, and I think that the photons with with different frequencies might for example be adjusted to "pass" the wires with zero absorbtion, but then the different wavelength photons will be refracted in different way by the lens, so you will end up with different image at the detectors - consider my airy disc comment that you liked. So actually you are wrong, and in Afshar's setup is measured only on exact value of the photon's wavelength, which should be the announced in Afshar's preprint of 760 nm. Danko Georgiev MD 05:55, 3 March 2006 (UTC)

• Apodization (as any competent optical physicist knows) is a common technique used in optics and it has absolutely no bearing on loss of which-way information as emplyed in my experiment. One can alternatively use Gaussians slits, which ensures lack of extra diffraction bands, etc. I suggest to Danko to stop using the word "fraud" so liberally. It might land him in a court for libel, not to mention taint his academic record.-- Prof. Afshar 00:44, 3 March 2006 (UTC)

• Dear Afshar, you still did not catch the main point. If you measure which way information you may have greater uncertainty in photon's wavelength, and if you do not measure the which way information, you will measure more precisely the wavelength by the place of the interference fringes. Since the Airy pattern is very sensitive to the wavelength of the photon, see wikipedia entry on airy disc then by deleting the airy disc pattern you ERASE the evidence that in the second case when you open both slits, the experiment has changed from "which way" into "no which way". I suppose you did not like the "little" differences that you possibly observed so you decided to apodize the images just for "fitting" your expectations. If you did not do that, then you have done error, because you overlooked the dependence of the Airy discs pattern on the photon's wavelength, so you cannot say that in both experiments the certainty of photon's wavelength is the same. So this is not just loophole, this is the loophole that unmakes your interpretation. Danko Georgiev MD 05:21, 3 March 2006 (UTC)

Danko, I agree with Prof Afshar about the making of accusations. Also, this WP talk page is not an appropriate forum to debate theory. I very strongly recommend that you find some other place to have these discussions. This all has been going on far far too long. linas 00:54, 3 March 2006 (UTC)

Dear linas, I don't understand what you dislike in the discussion. When Afshar called me "crackpot" you were possibly very pleased with the fact, but when I show evidence for "massage" of the experimental data, you do not like it. In every scientific field if there is "evidence for possible massage of experimental data" nobody cares whether you did it consciously or unconsciously - you are accused as fraud, and the only alternative way is to publically announce "I am not a fraud, but I have done severe error having overlooked the facts". In both cases the evidence goes against Afshar. Danko Georgiev MD 05:21, 3 March 2006 (UTC)

I agree with Linas and Prof. Afshar about this. What is the point in positioning, (ad nauseum), Afshar as a "fraud". There is absolutely no evidence for this whatsoever. Zilch. Indeed Afshar's experiment is consistent with a range of experiments by many people (including Einstein) that attempt to poke holes in quantum theory. That's a good thing. Not a bad thing. Carl.

Yes, good thing is to have discussion, and good thing is to reply to everyone who is interested in the topic. This is scientific behavior. But when somebody poses clear question, and you consciously avoid discussion this is a bad thing. Danko Georgiev MD 05:21, 3 March 2006 (UTC)

---

Regarding my "metaphysical rambling". If you do not understand what I am talking about then "metaphysical rambling" is as good a description as any other. But calling it such won't help to understand it any better. Without an understanding of the "metaphysics" (philosophical framework) out of which quantum theory evolves, the math can't evolve.

In rationalist forensic models "reality" is some hidden world exposed by clues within otherwise emperical data. Thus something like the wave function would be a "reality", exposed by clues such as only a 9% drop in the net intensity, of the detector data.

But in the spirit of the philosophical framework in which quantum theory emerges, one should treat the detector data as the reality under investigation, and the wave function as a way of describing that reality (but only while the data has yet to take place). Once the data takes place the wave function can be replaced by the data itself. The data represents itself better than the wave function. That doesn't mean the wave function should be thrown away.

But note how this is the complete inverse of the rationalist forensic model. The detector data does not describe the wave function. It is the wave function that describes (or predicts) the detector data.

The problem for neo-classical forensic rationalists is that they are philosophically forced to imagine the wave function as some independant reality that somehow "collapses" to produce the clues we otherwise call emperical data.

But the term "collapse", and indeed the entire mathematical framework of quantum theory, is a *concession* to classical rationalism, ie. if we are forced to speak in the language of classical rationality then the only way of describing the wave function, at the moment a particle is detected, is in terms of the wave function "collapsing".

But it is we who decide when the wave function collapses. If we want to be more specific about where a particle is to be detected, we don't even need any wave function - we can just wait for a particle detection to occur.

Carl

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• Dear Carl, very briefly, the photons happen to have linear momentum. Upon detection at the image plane the conservation laws demand that they must have originated from he corresponding pinhole. I did not make up this law, it simply is Nature in action! This reasoning was used both by Bohr and Einstein to establish which-way information. Also, I invite you to continue your discusion in my weblog (as you have) and not here. I will shortly reply to your comments in my weblog. Please heed the statement at the top of this page. Regards. Prof. Afshar 22:31, 25 January 2006 (UTC)

• Dear Afshar, POSSIBLY YOU HAVE NEVER HEARD OF SUPERPOSITION OF QUBIT MOMENTA? If so, it is very bad for you. This elementary error is result of classical thinking, and IF you ask me, I can send you some papers published in Physical Reviews explaining how the idea of momentum in quantum mechanics should be correctly understood. You may have superposition of momenta, and interference of momenta, and for 18 years of studying physics you SHOULD know that simple fact. Danko Georgiev MD 07:37, 26 January 2006 (UTC)

Final Warning to Danko Georgiev

Danko, If you accuse me of Fraud one more time, I will report you to your academic institution and peruse legal actions against you and whoever backs you. If you do not want your future ruined by your stupid actions, cease and desist immediately. I will also initiate a ban request for you from Wikipedia. You must apologies to me or face the consequences. Do not force me to do what I utterly dislike. Whiever wishes to help me with banning Danko from Wikipedia please let me know. -- Prof. Afshar 06:43, 3 March 2006 (UTC)

Momentum in QM

Afshar's wrong thesis: " very briefly, the photons happen to have linear momentum. Upon detection at the image plane the conservation laws demand that they must have originated from he corresponding pinhole. I did not make up this law, it simply is Nature in action! " In classical physics you can denote the momentum by vector - it has magnitude and direction. In QM you cannot measure both these values correctly - if you measure the momentum magnitude, you actually do not measure its direction, and you do not really measure momentum, but you make mesurement of photon's energy. So the popular view that the interference picture is measuring momentum is not fully correct - better say that the interference picture is measuring photon's energy because $E={\frac {hc}{\lambda }}$. The popular view is misleading because you may imagine classical momentum vector, and thus think as Afshar does that you have correspondence with a pinhole. However this is wrong and the uncertainty in the momentum's direction is what erases the which way info, and you cannot be sure whether the photon passed through pinhole 1 or pinhole 2. If you put the two pinholes far from each other, so that the uncertainty is much less than the interpinhole distance, then you will have distinguishable photons [at least by time of their arrival] and you will lose the interference picture. Actually you will not measure Energy [wavelength] anymore, but you will measure time arrival. I think that it is better to interprete the Afshar experiment in terms of Heisenberg's E, t uncertainty, instead of classical p, x uncertainty. The problem in the latter is that momentum in classical physics is vector with magnitude and direction, while in QM these both are subject to Heisenberg's uncertainty. I hope this little lecture will be of help to Afshar also, who for 18 years struggles to see the difference between momentum in classical physics and momentum in QM. Right? Danko Georgiev MD 10:42, 26 January 2006 (UTC)

• Dear Danko, ONCE a photon is absorbed it's momentum is constrained by the geometry of the experimental setup (in accordance with the conservation laws), which in the case of my experiment is well-defined, and different for each image. One does not assign a momentum vector to the photon prior to measurement, but after it's wavefunction collapses we have no other choice, otherwise would have to violate the conservation laws. If you disagree with this analysis, you are essentially diasagreeing with Bohr, Einstein, Wheeler, Greenberger, Englert, Zeilinger, Scully...; not to mention the rest of physicsts in the world! That would be a bigger feat than violating the Principle of Complementarity, but one that I would not support. Also, please understand that Heisenberg's uncertainty Principle is not violated in my experiment and any claim to the contrary is wrong. Assigning such claims to me is disinformation. This is not an educational forum, nor do I have the time to correct the seemingly endless errors you make. For the last time, please heed the statement at the top of the page, and allow the agreed upon process discussed in the voting debate to start. Please respect the outcome of your failed deletion bid. Interference with that process may lead to being blocked from Wikipedia. -- Prof. Afshar 12:49, 26 January 2006 (UTC)

Dear Afshar, your post is non-sense. I have opposed to Unruh, Drezet, Cramer, Zeilinger .. etc., so IF you add some more names that have made the same error like you, you should provide some direct quotations, and then list them in my negative list. Science is science, so anyone who understands mathematics can check and see that you do not understand what is momentum in QM. In order to make retrospective claim you need to have your photon labeled (e.g. by polarization filters at the pinholes), otherwise it is the uncertainty principle that forbids you to make which way propositions. Read some papers in Physical Reviews because I do not have time to teach you. Danko Georgiev MD 04:19, 27 January 2006 (UTC)

Here I present visualisation of how should be understood the momentum in QM, and why conservation laws should NOT be applied. Use the standard double slit experiment. Although the light might be emitted perpendicularly to the double slit, it can be detected also in any point where the probability is not zero in the interference pattern at the screen. You cannot look only the photon in considering Afshar's pseudo-conservation of momentum, because you will see absurd - the photon before the double slit goes in one direction, and the final "kick" at the screen in another direction. So something happens during the photon's flight - it interacts with the double slit.

Now since the two slits $S_{1}$ and $S_{2}$ are not distinguishable, the photon's probability follows no-which-way distribution where $P=|\psi _{1}+\psi _{2}|^{2}$. The MAGNITUDE of the photon's momentum is known, but the DIRECTION of the momentum is superposition of flight through $S_{1}$ and $S_{2}$, so the final "kick" at the screen (if one thinks classically) should be in such direction AS IF the photon comes from between the two slits. Actually I think that to sum the momentum vectors and to have "kick" in some resultant direction is good for showing the inconsistency of classical visualization, and indeed I propose that the reality of superposition remains [otherwise the kicked atom from the screen will be attributed defined x, and p, which will violate Heisenberg's relations]. The illustration is done just to show that you CANNOT THINK in classical way and preserve the momentum. When emitted the photon might have been perpendicular to the double-slit, but when detected the "kick" at the screen is neither perpedicular, nor you are allowed to say through which slit the photon has passed, nor you should be able to know the direction of the momentum. To appeal to conservation laws in QM is equal to suicide - neither the velocity of light is the higher limit (e.g. Hawking radiation), nor the conservation of energy is strictly required (e.g. vacuum zero energy fluctuations), nor you can have precise measurement of both momentums magnitude and direction (e.g. Afshar's error).

Now what happens when you put lens? The same thing - the photon passes through both slits, and interacts with the lens in order to be refracted towards both of the images, and he arrives at both detectors in a pure state ${\frac {1}{\sqrt {2}}}(|D_{1}>+|D_{2}>)$. Since the light is coherent the photon after the double slit will have superposition of directions of the momentum, some of which might be in imaginary space [that accounts for the possibility of tunneling]. The final "kick" at the detectors IF you imagine one, will surely not be in direction defined e.g. by connection slit 1, center of the lens, and detector 1, for detection at detector 1, and this is because you cannot know simultaneously both the momentum's magnitude and direction. If you have polarized light however, the final "kick" e.g. at detector 1 will be exactly as the defined above, so you will have 1:1 correspondence between slit 1 and detector 1, yet you will not be able to say the magnitude of this "kick", because you do not know the photon's wavelength. As summary somewhere in the flight the photon interacts with the medium of the lens in order to be refracted and might have changed either the magnitude [wavelength] or the direction of motion, in a way that you cannot use momentum conservation! The situation resembles the delayed choice experiment - if you want to "trick out" the photon by measuring its direction of propagation, the photon will know already the future decision that you will make, so the photon will interact in a way to lose or gain some energy, precluding you knowing its wavelength. Inversely if you want to measure the wavelength the photon will supercausally know this, so the photon will interact with the lens to make its direction of propagation unknowable for you.

p.s. the same principle apllies even for the emission of photons by the laser of Afshar, where $\lambda$ = 650 nm. In case when you know that the photon is with wavelength $\lambda$ = 650 nm, you actually cannot be sure that it is emitted perpendicularly to the double slit, and in case when you know a photon is emitted perpendicularly to the double slit, you no more know that its wavelength is $\lambda$ = 650 nm. Danko Georgiev MD 07:18, 2 February 2006 (UTC)

Energy conservation in QM

Analogously to the Afshar's proposed conservation of momentum, one might argue that the conservation of energy is "Nature in action" (quoting Afshar), so one might equally well argue that vacuum zero energy fluctuations ARE NOT THERE, and one might argue to have disproven QM. So the solution is simple - either you accept that in QM violation of various conservation laws is possible in the limits precribed by Heisenberg's relations, or you should argue that the whole QM is false.

Danko's point of view

Danko could you summarize here in few sentences your argumentations or put a link to a paper ? regards Drezet 27 /01/06

Dear Aurelien, I do not know why you want my argument clearly, but I will do just because I have formulated my main thesis in a dozen of EQUIVALENT formulations. Most of you think that everything is just rumbling, but IF turn back and investigate all my examples, you will see a single main thesis, that reveals its face in different angle. So below I put the summary of my thesis.

• The Afshar experiment should be understood of terms of E, t uncertainty, where Afshar's claim is incompatible with Heisenberg's principle. It is clear that V=1, because the wires, may be well silver compund detectors of light. Since they detect nothing they are in absolutely dark, hence they record interference minima, and perform Reininger's negative collapse of the wavefunction in basis E (energy). So you know precisely the wavelength $\lambda$ of the photon, by the spacing of the wire-detectors, and $E={\frac {hc}{\lambda }}$. But IF you know the which way [K=1] you can calculate the time for arrival of the photon from its emission to its absorbtions. THIS VIOLATES HEISENBERG. But I say that there is no which way, because the photon goes through both pinholes and each photon is in superposition at each detector. Since he has followed two different trajectories each one by single pinhole, you have two calculate time travel by two different length paths, so you have uncertainty in time - so, no which way!
• Why Afshar makes error? He does not understand the difference between classical and quantum momentum. In classical physics you have vector with defined magnitude and direction. In complementarity this does not happen. [1] Suppose you have Afshar's experiment you have measured the wavelength, so you know the MAGNITUDE of the momentum, but because the photon has passed thorugh both pinholes [no which way] you do not know the DIRECTION of the vector of momentum. [2] Now suppose another example if you put two polarization filters on the pinholes. Photons are not coherent so no interference will occur and the wire detectors will capture 6 % of the photons. But suppose you remove the wire grid - you still have two well resolved pinholes at the image plane. But this image will not be superposition (pure state) but will be mixed state image. You know exactly the pinhole throught which the photon has arrived to the detector, because you can measure his polarization. So you know the DIRECTION of the photon's momentum, but you neither know the photon's energy, nor photon's wavelength $\lambda$, so you do not know the MAGNITUDE p of the momentum vector, because $p={\frac {h}{\lambda }}$

Afshar, Unruh et al. believe in Afshar's claim about which way info, and his argument is in conservation of momentum. There is NO SUCH THING in QM. Quantum momentum cannot have precise magntitude of the vector, and precise direction of the vector at the same time - this is forbidden by Heisenberg's principle and complementarity.Danko Georgiev MD 04:09, 30 January 2006 (UTC)

p.s. Dear Aurelien, I still have not published a paper because currently I work on my Ph.D. thesis and I don't have so much time. Also I stopped uploading of e-prints, before peer-reviewing, and I stopped to produce single authored papers. If someone interested in physics wants to collaborate with me on my argument against Afshar I will be glad to collect and present all my draft papers, and posts. I think that once you see the weirdness of quantum momentum, and K = 0 in Afshar's experiment you will have to withdraw you arXiv entry, so you will enter my company of people who have withdrawn pre-print at least once  :-) Danko Georgiev MD 04:40, 30 January 2006 (UTC)

Link to Drezet's Wiki Entry

Drezet your article just shows what I already advocate since 2004.

I put direct links to your math theory

V - visibility of fringes - in Afshar setup is V=1, because in the minima he detects zero light, or almost zero light. This is Reininger negative measurement. Actually the wires are wide enough to detect 6% of the light intensity if you put polarization filters.

K - which way info - is IDENTICAL to D - distingushability in your math formalism. D = 0, so you cannot distiguish from which pinhole the photon comes, so D = 0. There is no which way information. The photon comes in pure state, so the photon is in superposition and both detectors. No which way - so you have pure state density matrix, so you have non-zero off-diagonal elements, so you have photon being holographically at both detectors at once at the image plane. The fact that after that you collapse the superposed photon in basis D1, D2 is irrelevant. The same is in the Fourier plane - there the photon is in superposition at many fringes at once, but you nevertheless collapse it only somewhere in the Fourier plane, you cannot detect the single photon at pieces spread everywhere, can you?

In order to have which way measurement you should produce somehow mixed state of the photon. This can be done by entanglement with polarization filters, where the reduced density matrix of the whole systems that described the photon only will "look-like" mixed one. So you will have which way information, but not interference. You will be able to diffract 6% of the photons by the wires in Afshar's setup. The fact is that in the entangled state, the photon is not really in mixed state, but the interference info is encoded in the entanglement of the whole system [say photon plus polarization filters]. If you decide to delete the polarization of the photon, in case you have not yet collapsed it [not destructive measurement is done yet], so you can restore back the interference, but this cannot happen without deletion of the which way info.

Best, Danko Georgiev MD 04:31, 31 January 2006 (UTC)

The Emperors New Clothes

The emperor is persuded by his advisor that the beautiful interference patterns in his new clothes are indeed perfectly visible. V=1. The emperor, however, would prefer it if such patterns were also visible in fact.

"Can we not introduce downstream re-interfernce of the photons?" asked the Emperor.

"No your highness," said the advisor, "that is quite unnecessary. Look at how these fine threads have been placed. Do you see how they make the patterns come alive."

"Yes. Of course. You are right. That is brilliant."

The conclusion to this story has become the stuff of legend. But there is a sequel to this story. It is not well known that after the Emperor's defeat at the hands of a mocking crowd, the advisor went on to became the New Emperor. And if you remember the little boy in the crowd who exclaimed V=0, well he had no problem with the Old Emperor. He liked the way the clothes were invisible. He thought it wholly unfair that the Emperor should lose the thrown over such a thing. He hatched a plan. When he grew up he would become advisor to the New Emperor.

"Yes, your highness," the little boy would say to the New Emperor, "that pinhole is indeed a beautiful pinhole. And what's more, it can be demonstrated in new clothes made from just one photon"

"Yes. Of course. You are right. That is brilliant"

You can guess the conclusion to this story. What you wouldn't guess was how the New Emperor's humiliation was far worse than the Old Emperors. For in the laughing crowd was the presence of the Old Emperor, resplendant in a gown of glowing interference patterns laughing louder than everyone else.

But to be fair, the New Emperor would have prefered his new clothes were just satin black with a small hole in them rather than the whole thing made from just one photon.

Carl

Graphics for Theory Section

Dear Drezet, Please bear in mind that the observed interference pattern (IP) is a fully visible one (V=1). The IP you have shown has a low visibility (V<1). If you replace it with an IP in which the dark fringes have zero intensity (V=1), the graphics would be correct. Please let me know what you wish to do. Regards. -- Prof. Afshar 19:54, 31 January 2006 (UTC)

Dear Afshar, yes V=1, but D=0. So without distiguishability you cannot say which way the photon passed. In QM the momentum is complex number (!!!), and exactly because particles may propagate in imaginary direction tunneling is allowed. After collapse of the wavefunction of photon, you measure NOT the quantum vector of momentum that is complex number, but you measure momentum's magnitude only, so it is nothing but measuring the photon's energy and wavelegth. So what conservation of momentum you speak about??? Do you conserve the complex momentum vector??? Please either provide clear answer, or stop disturbing the editing process of your promo-entry, that finally will be turned into manifest of your failure to understand QM. If you do not have access to the following article "Peter Bowcock & Ruth Gregory (1991) Multidimensional tunneling and complex momentum. Phys. Rev. D 44: 1774–1785." I will be glad to send you pdf. Danko Georgiev MD 07:38, 1 February 2006 (UTC)

Dear Drezet, the inserted lens in the figure of the main article is not needed. Either you produce Fraunhoffer diffraction without lens in the far-field approximation, or you may use lens with focal length f, and then the double slit must be located in the focal plane at one site, and the far-field Fraunhoffer image will be produced at the other focal plane. In both directions you will have Fourier and inverse Fourier transform of the corresponding images. So your picture is wrong [not equal distance f between the double slit and the Fraunhoffer image], and also introducing a lens IS OF NO PURPOSE in discussing the double slit. Danko Georgiev MD 10:01, 1 February 2006 (UTC)

IMPORTANT NOTE!

Please if somebody wants to improve the entry on complementarity let he/she edit the complementarity (physics) article. To put the entry of complementarity in encyclopedia, as a sub-entry of Afshar's article is ridiculous! At least here you must have some respect to science! (even if you do not like my comments as a whole) Danko Georgiev MD 07:00, 5 February 2006 (UTC)

Danko has moved this section to the article on complementarity. linas 14:19, 6 February 2006 (UTC)

Specifically, to Complementarity (physics). I just took some time to polish this up, and make it look nice (i.e. follow te WP style guidelines, etc). I think its quite good. Thank you, Drezet for creating this section! linas 01:46, 7 February 2006 (UTC)

I was surprise when Danko moved the page but finally it was my initial intention too so I agree like that. Drezet 7 February 2006 (PS: I am adding an other reference to the list since even if I dont believe what it is claimed in it the paper is mathematically correct and written by a physicist).

Another sockpuppet?

I am wondering if Carl Looper is not indeed another sockpuppet of Afshar, and whether it is not Afshar itself? Crazy, isn't it? But not surprizing! Danko Georgiev MD 04:15, 7 February 2006 (UTC)

SO FAR NO REPLY!!! Carl Looper's entries above belong to Afshar suckpuppeting! The dear Afshar does not value the scientific honesty so much?! Danko Georgiev MD 08:55, 20 February 2006 (UTC)

No, actually, I do not value your opinion! Why so paranoid?!--Prof. Afshar 12:50, 20 February 2006 (UTC)

It is a compliment (of sorts) to be confused with Afshar, (or even Danko) but I am not he. But why should it matter? Is the content of what I am saying any different if I were Afshar? - Carl Looper.

Afshar already has some experience in sockpuppeting, so I decided that he plays another game. But my suggestion to Looper is if he opens an account. If somebody is not ashamed of what he is posting online, he can boldly put his name below his notes. To be wrong sometimes means nothing, it happens to all of us all the time in different situations in life. Danko Georgiev MD 03:00, 2 March 2006 (UTC)

On References vs. Proponents section

I don't know, what most of all may think, but to leave the section titled as References will be even more funny - in the section remains Science fiction column, New Scientist yellow press, and Afshar's unpublished paper, except in Conference bulletin.

My change reflects the repetition of Motl's work and web link to the same resource at two places - as critique ans then as reference, and the other paper link was added personally by me, but it has nothing to do with Afshar's pseudoscience, but should be listed in possible section on wheeler's delayed choice experiment. So what remained as references is just a bunch of sci fi popular writings, and I decided to rename it into Proponents section. To leave it as References will be just a joke. Danko Georgiev MD 05:45, 11 February 2006 (UTC)

Q&A

As per discussions with CSTAR I added a link to the archived Q&A section of my weblog where some of the critics have been addressed.--Afshar 18:00, 18 February 2006 (UTC)

STOP with this parody, dear Afshar! If you want create a FAQ to all those critiques, but do not post links to archived web postings. This is encyclopedia, and one needs the information as fast as possible. If you believe you are right, summarize neatly in your FAQ your opinion. Do NOT post excessive linking to internal pages from your web site. Nobody needs this, and I don't see somebody to have asked you for more information so far.

I think the non-sense you have produced up to this point is enough! Danko Georgiev MD 08:51, 20 February 2006 (UTC)

The link is a useful source of information on response to critics. The issue was fully discussed (see CSTAR's talk page.)-- Prof.Afshar 12:41, 20 February 2006 (UTC)

This should be an answer for DG.

KEY policy of Wikipedia : Avoid bias. Articles should be written from a neutral point of view, representing all differing views on a subject, factually and objectively, in an order which is agreeable to a common consensus.Drezet 16:24, 20 February 2006 (UTC)

Drezet, encyclopedia entry is NOT TALK PAGE !!! For objectivity should I post various links to different web discussions where I have criticized Afshar? If someone wants to browse in Afshar's web site, he is wellcome to do it. But Wikipedia should not be "guide" for Afshar's web. If he feels that there is something importa in his QA talks, he is well advised to put the especially important info in his FAQ. One link to all his replies is best. Please delete this QA link. Regards, Danko 08:04, 21 February 2006 (UTC) p.s. by the way all this non-sense if enough for me - I am not the gatekeeper of Wikipedia, if you all like this parody go on - do commercial entries, do advertisements, etc. The wikipedia idea starts to look stupid, if there are no peer-reviewers of the entries. Afshar calls him "professor", so let it be - I vote that Afshar is promoted into "academician" soon. Bye!

Dates added

I added the dates for the intital work at IRIMS and later at Harvard.--Afshar 18:50, 2 March 2006 (UTC)

comment from a roving mathematician

I don't see the experiment as disproving complementarity. Let's talk somewhere after I get back from vacation. (And I think John G. Cramer has less physical intuition than a WP:CIVIL violation removed. I had an E-mail exchange with him on the apparent gravitational position of the sun -- he sees an anomaly of ${\frac {8.3\ \mathbf {min} }{365.25\ \mathbf {solar\ days} }}$, and I do not. — Arthur Rubin | (talk) 01:02, 3 March 2006 (UTC)