Dalo

I am afraid this is a very simplistic view of science. Mathematics are an indispensable tool. We still need the scientists to think about how to use them.

I have no idea where you got the idea from that I don't not believe in mathematics. You are the one refusing to address my claim, hiding behind general opinion and orthodox interpretation. Apparently, it is not a matter of defending an unorthodox claim, which I have been doing all along. No, as far as you are concerned, any unorthodox claim is a wrong claim and should therefore be rejected without hesitation or analysis.

My interpretation is unorthodox. That in itself does not make it wrong. You will have to prove it. And not only refer to the general opinion or the orthodox interpretation. That is not how a scientific debate works.

I wonder how I have gotten through university with high grades. It is nothing short of a miracle.

You blind reference to authority is certainly not an argument either. Show me where my defense of my claim has gone wrong instead of simply referring to what is now considered as the right interpretation. Science is a living enterprise and constantly changing. The most important changes in history did not come from better calculations but from different interpretations.

That is exactly my claim, and I have defended it. You have not brought a single argument against it. The results of my analysis, considering my claim: - Particles take each time, and whatever the setting, one path and one path only. - there is therefore no superposition of the particles. - the reason why is that there is always an external force present, the length of the difference between the paths in one case (Scariani), the polarization filter in the second case (the pdf file) - You were talking about Bell's theorem, well, here are two perfect examples of not so hidden variables that could account for the results.

please do. And explain at the same time what you have made of it. Apparently your interpretation is quite different from what I have chosen as subject of this thread.

But they are not the subject of this tread. Face my claim or let it rest. You are wasting both our time.

Then you have a very strange definition of which-path experiments. please check p.21 of your first link and explain to me what the differences are between the setting shown there and the setting presented by Scariani. Another one of his quotes: "it is impossible for us to know by which path the particle has traveled, without modifying the result." p.15. If somehow you have changed the subject to the particle-wave duality of light, which seems to be the aim of the first link, then it is an illegal move on your part. It probably does not make any difference since in last instance the problems look very much alike, but that is certainly not the subject of this thread. I can only conclude that you are unwilling to address my claim and are bringing extraneous elements into the discussion in the hope of confusing the issue. It is more than obvious that your interpretation of Scariani, backed by none other than Alain Aspect, is erroneous. Once again read the 15 first pages of the book. The first lines of the second link read: "Light, as we know it, can behave like particles or like waves under different physical conditions. This is what is called the wave-particle duality of light. The particle nature of light is explained by considering light as massless energetic particles called photons." Talking about straw-man argument.

Only Fig.1.3 and Fig.1.4 represent MZI's. The others are there to explain why the results given by the two MZI's are strange and need explanation. They build up the case as it were. Where did the author say that they are not which-path devices? edit: if you do not trust the quotes I am giving of the text, then it will remain a difficult discussion. Maybe you should check it for yourself. "how does it work, that in changing only one of the two paths, we manage to change the behaviour of all of the particles? How is it that the particles that travel by the path that we have not modified can know about the modification?" p.9 I do not know how many quotes will convince you, so let me say it plainly and then you can decide for yourself: Fig1.3 and 1.4 represent MZI's, and which-path devices. The whole set up of the book is to show the effect of which-path information on the results of the experiments done with those two devices. Scarani is trying to prove that the photons somehow know which path they have taken and behave accordingly. An explanation that all supporters of orthodox quantum theory support. So either you accept that and look at my own analysis to criticize it, or you keep doubting what the author is saying and with whom I expect that you will be in complete agreement. Please read at least the first 15 pages of the book and form your own opinion on whether I have presented the author's views correctly, and whether you agree with him. Then you can look at my own analysis and present valid arguments why you do not agree with me. I have until now only defended the author with whom, and I cannot stress it enough, I expect you will be in perfect accordance!

In case my edit goes unnoticed ******************************** I find it interesting that in the case of Scariani's experiments, the external factor that could rationally explain the different percentages was the difference in length of the two main paths, while in this second case, it is the presence, or absence, of a polarizing filter. In both cases, an external factor can be put forward to explain the change of behavior of the photons. A model I can certainly live with, even though I have no idea how both factors work.

Should it be Bohrean? Anyway, Niels Bohr.

Yes, I can understand that. I also prefer to stick to one path. That is why I did not want to discuss MZI's in the other thread, and preferred to stick to double slit experiments. In this case though, both versions were completely separate. You started denying that Scariani was talking about which-path experiments right away. And you refused to bulge from your position. I hope it is behind us now. ************************************************************ In the case of the use of an extra polarizer the whole set up becomes equivalent to a much simpler one: one light source, a polarizer, and then a screen + camera. We can leave out all the rest, that is, the polarizing and non-polarizing beam splitters, and the two mirrors. There would be then no which-path information involved, simply because there is for all practical purposes only one path. But since there is no ambiguity as to where the photons came from, there should be no interference patterns present. And still there is. One way that we could explain the difference between the complex and simple form is accepting the mystical idea that the photons somehow know where they are coming from and choose not to interfere with each other, as they would if we used the simpler form, or the other form with no extra polarizer. It would be interesting to see if the simpler form would be equivalent to the first (no extra polarizer) or the other setup (an extra polarizer). If it gives a similar result to the second form, then we will know for sure that it is not the presence or absence of which-path information that determines the presence or absence of interference patterns. The only factor then eligible for a rational explanation would be the presence or absence of an extra polarizer. If my analysis is correct, then so is my claim that there is no superposition of particles, and that observation does not change the outcome of an experiment. Which also means that particles do not change their behavior unless there is an external cause, in this case a polarizer in the path of the beam.

It is if you insist that his drawing does not represent a which-path experiment while he explicitly states that knowing which path the photon has taken changes the outcome of an experiment. you have not yet given me a single reason to take your objection seriously. Scariani does the same, but instead of using interference patterns and polarization, he uses percentages. There are many forms of MZI's, and many forms of which-path experiments. Apparently you have fixated on the form given by the pdf file and refuse to acknowledge any alternative given by other authors. Here are some quotes from Scariani: "Interference appears when a particle can take several paths in order to arrive at the same detector, and the paths are indistinguishable after detection." Let’s put the principle to work on the phenomena we have already described. In apparatus 1 and 2, there is only one path leading to each detector; consequently, when a particle is detected we know exactly which path it must have taken. It is a situation of distinguishability and no interference effect is apparent. In apparatus 3 and 4, on the other hand, when a particle is detected after the second beam splitter, we have no way of knowing by which path it arrived, since two paths are possible. These two paths are therefore indistinguishable, and the effects of interference are present." p.10-11

You have convinced me that you have not read Scariani. His main argument, which by the way you would subscribe to because it is the orthodox Bohrian interpretation, is that knowing the path (isn't that what which-path information is about?) changes the percentages of photons detected by the different detectors. ****************************************************** The pdf file can be summarized as follows: Which-path information preserved - no polarizer - no interference pattern Which-path information destroyed - polarizer - interference pattern The important question in the interpretation of Fig.5 of the pdf file, is how the interference patterns are related to the which-path information. The quote of p.6 might contain the answer. Here it is again: "We observed that without a polarizer no interference pattern was observed because light exiting the interferometer contained which-path information." If we look at the the second simplified drawing, the one with no polarizer, we immediately understand the meaning of this assertion. The polarizing beam splitter divides the photons in two groups, one is vertically polarized, the other horizontally. In other words, even though no human could distinguish between them, the information is there. In principle, and in a very abstract way, we could know of each photon, whether it is vertically or horizontally polarized. And that in itself would be, according to the authors, sufficient to destroy the interference patterns. When using an extra polarizer at the end of the MZI, we scramble the information contained in each photon in the form of vertical or horizontal polarization. All photons acquire the same polarization before hitting the screen and being registered by the camera. They become therefore indistinguishable from each other, and there is no way anymore of knowing through which path they reached the screen. Which means that the interference patterns are present. The question now is, what is the value of this argumentation? edit: here is another quote that confirms my analysis. "As long as no polarizer is present the path that a photon took is encoded into its polarization state. Thus, it is not free to take both paths and cannot interfere with itself. As soon as another polarizer is introduced at the exit of the system, the information about which path the photon took is destroyed because it has a new polarization." p.4

Fine. Now, tell me why.

I am listening all right. But he is not saying anything except that it is not a which-path experiment, talking about Scarani: which is flagrantly false. Maybe he should read the book and find out. For the pdf file, I am supposed to have done everything wrong, but what exactly? I can do nothing with this kind of criticism. You are welcome to be more specific.

repeating the same thing over and over again does not make anything clearer. What is wrong with the drawings? Specifically.

I will wait until you answer my last post. Because I still have no idea what you mean exactly. Please be precise: "only one which-path...." is not helping me any. I still do not know what is wrong with with I have presented because you have not said anything except damning the whole thread.

This seems quite obvious to me. It wouldn't help to use a Michelson interferometer to discuss of the role of observation in an experiment. But the MZI is used in trying to determine how finding out through which path photons are passing can create ambiguity as to where they came from I agree with you that it is not a matter of interference pattern disappearing but of which-path information. That is exactly what I was discussing in the first posts when dealing with Scariani. Concerning the pdf file you suggested, the trouble I have is to relate it to the first part of the thread, dealing with Scariani. I have not in any way drawn any conclusion regarding the relationship between interference patterns and which-path information. All I have been doing is trying to clarify the meaning of the drawings used in the pdf file, and the explanations of the authors. I therefore do not understand why you are objecting to my analysis at this stage. I have not expressed any opinion yet about the pdf file If you do not agree with my analysis of Scariani's own presentation, then you should make that explicit, and distinct from the second part concerning the pdf file.

Let us try and clear up any misunderstanding. Which drawings are you considering as not which-path experiments, and therefore not relevant to the discussion of the pdf file you suggested. What makes them not acceptable for the discussion at hand.

You should really consult the book and tell me if I am wrong. The drawingsI have presented are taken directly from the book, and the appellation of MZI comes from the author, not from me. As to whether this can be counted as a which-path experiment, I wonder how relevant that is for the subject of the thread which is still: does observation change the results of the experiment? *********************************************** I am simply repeating what's in the text of the pdf file you have linked in the other thread: "We observed that without a polarizer no interference pattern was observed because light exiting the interferometer contained which-path information." p.6

Well, I suggest you get a copy of Scarani's book. Unless you already have it and know the author for being a crackpot. The problem is that would make of Alain Aspect, who wrote the introduction, also a crackpot. **************************************************** getliffe_lab_2_final.pdf as promised

Let us keep on analyzing the information given. The information given in Fig.5 can be represented by two drawing. As you can see, the second drawing is equivalent to a simple drawing of a MZI without any additions. In such a case, we have therefore NO INTERFERENCE PATTERN.