Talk:Double-slit experiment/Archive 9

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Let's go back to my original question: is there a reference where the detector-before-each-slit is actually done and technically described?DParlevliet (talk) 08:35, 28 December 2013 (UTC)

The experiments I know of are not arranged the way you seem to think they are. The spatial order is:

laser..........double-slits..small detector(s)...........................main detector screen

I am guessing about what "the detector-before-each-slit is actually done" means. There seems to be something missing in your sentence, sorry.P0M (talk) 09:04, 28 December 2013 (UTC)

Most (like Feynman, Brian Greeene, Wikipedia) mention the standard double slit measurement with a detector in front of each slit. This would show through which slit the photon goes, but destroy the interference pattern. DParlevliet (talk) 11:07, 28 December 2013 (UTC)

You are right about Brian Greene. p. 193 of The Fabric of the Cosmos describes your design. (The pictures don't seem to show what he says they show.) The interesting things is that if the detector is one that absorbs a photon, even if it subsequently emits a replacement, then there is no interference because the path of one photon emitted by the laser terminates at the detector, or the path of another photon emitted by the laser goes only through the unblocked slit. Greene's experiment tries to get around this virtual elimination of the double slit by using a non-destructive detector, a polarizing filter. (The same experimental apparatus is presented in a Scientific American article on making your own quantum eraser, and they do it my way.) The problem with the way Greene has diagrammed is that a photon or its wavefunction either goes through the polarizing filter or it goes through the open slit. It is impossible to polarize half of a photon when the apparatus is set up Greene's way. The whole point of the double-slit apparatus is to split the wavefunction of a single photon so that it can interfere with itself. I think Greene's way would work if the right edge of the polarizing detector is aligned exactly with the vertical column between the two slits. So, functionally anyway, it would be like two windows, the left window having a pane of polarizing material in it.

I looked for a long time before finding any simple detector set-up via Google. There is one, prepared by a Princeton University physics teacher Aatish Bhatia. http://www.wired.com/wiredscience/2011/06/why-a-quantum-particle-is-not-like-a-water-drop-a-tale-of-two-slits-part-1/

The physics articles I have studied that show the real apparatus used show the detectors where I said they were. For instance, take a look at this one:

Quantum eraser experiment of Kim et al.

Detectors D₃ and D₄ are so arranged that if a photon shows up in one of them then nothing will show up anywhere else in that one-photon run of the experiment. One wave-function may show up as a photon at the end of the red path or one wave-function may show up as a photon at the end of the blue path. D₁ and D₂ are the termination points for two paths (both a red path and a blue path) so a wave-function and its twin may show up and interfere with each other (i.e. the photon interferes with its self) and show up as a photon that forms part of an interference pattern.

Whatever it is that comes out of the left slit and whatever it is that comes out of the right path can show up at the end of several different paths. Sorting out what has happened in a long series of events is why they have the coincidence counter. The part that is relevant to your original question is what happens after a wave-function and its twin hit the first pair of beam splitters. If a photon shows up in D₃ nothing will show up anywhere else. If a photon shows up in D₄ nothing will show up anywhere else. But we started out with two copies of a wave-function that resulted from the possibility of taking either the left slit or the right slit. The wave-function "collapses" wherever it collapses. A photon shows up where the collapse occurs. However, there are no grounds for asserting that some of the twins or copies are "de-existed" retroactively. There is no need to add such a complication. Wave functions are huge but they collapse to a point. Nobody worries what happens to the rest of the wave function when a photon shows up at some point. In the case where there are two detectors and each has a copy of the same wave-function, the wave-function collapses wherever it collapses. The probabilities are 50-50. Nevertheless, all we can really say is: the photon is emitted by the laser in the upper-left corner, and it will show up in one of the four detectors. We know the paths, and we know that having them or not having them makes a difference. However, one of the basic ideas of the Copenhagen guys is that we are not to make assertions about things we cannot get any evidence on.

See Delayed choice quantum eraser if you need more help following that experiment. The article is linked to the source article with the original diagrams (sometime they got economical and failed to draw in a detector or whatever). P0M (talk) 18:57, 28 December 2013 (UTC)

I found the Scientific American diagram. Use this link and then choose the third item on the slide. http://www.scientificamerican.com/slideshow.cfm?id=a-do-it-yourself-quantum-eraser#1

It says to put the taped-together polarizers "behind" the vertical pin, but I think it would work either way. P0M (talk) 19:16, 28 December 2013 (UTC)

So to conclude: there is no publication of the detectors at the slits, as explained in the Wiki article DParlevliet (talk) 21:29, 28 December 2013 (UTC)

As I've indicated before, I haven't found an article that makes exactly that statement. The experiment is folded into the one with the big diagram above. It the general idea weren't true you would get other results and D₃ and D₄. I have also argued that the statement in the article because it seems to us that if a photon shows up at the end of the path that goes through one detector, then that photon must not have gone through the detector that is on the way toward another detector. That idea makes perfect sense if you are throwing golf balls because we can get Ted Williams to watch the ball all the way along its trajectory. There is one article, by a Nobel Prize winner in physics, who makes the same statement that you object to. It is found by checking out the first footnote for that line of text. There are others who, maybe because they are not writing for poets, are a little more cautions and use "seems to have..." or other such formulations. P0M (talk) 22:08, 28 December 2013 (UTC)

Let's go through what you asserted above:

"Two waves only give an interference pattern if they are coherent." I accept that assertion.

"If the technical working of detector disturbs the coherence of the wave, then the explanation is just technical/physical." I have no idea whatsoever of the meaning of "technical working."

"If one claims the principle that when the experiment distinguish 'which path', there is no inference pattern, then it must show from the description of the detector that it only detects the photon and does not change the wave." I think you have this one exactly wrong. Anything that one does to "detect the photon" must change the wave. That's the whole idea as far as I know. All the attempts to secure "which path" information regarding photons that participate in an interference pattern involve sneaky ways to get "partial" information about the photons, some idea that if you get a tiny bit of information about it you can perhaps determine which slit it went through without doing such a big change to the wavefunction that it will fail to interfere with itself.

The quantum eraser experiment that was published in Scientific American shows that by putting the wavefunction, or rather one of the twin wavefunctions, through a polarizer, then you can tell when a photon reaches the detection screen whether it has been polarized. So you would know which path it went by. But, they demonstrate, by putting in another polarizer you can partially undo the change you made to the copy that was polarized, and get something out that will show interference again, and that is because, they say, you no longer have which-path information. It's a bit tedious to follow through the series of polarizations (vertical or horizontal, and then clockwise or counterclockwise), and you don't end up with what you started with, but what you've demonstrated is that the wave function was not changed in any way other than being polarized, so if you can get the parts that are appropriately polarized together then they will still interfere. That's a different kind of "detector" from a sheet of photographic film because the photon disappears when it shows up on the film.

"Furthermore, versions of the experiment that include particle detectors at the slits find that each photon of light passes through one slit (as would a classical particle), but not through both slits (as would a wave)." I think this is a description of what one will always see plus the common-sense and implicit deduction that says: "If a car ends up at the far end of a bridge from a point on the other side of the river, then it must have come over that bridge."(That's not even reliable "deduction" on the macro scale!) But in the quantum domain the brand of this car is "Mirage," and what started out as one car has hit a double-slit and now we have two somethings that can interfere with each other. If rotate one of the Mirages then it won't be able to interfere with the other Mirage, but we have no grounds for assuming that when we rotate one Mirage either it or its twin must disappear. What happens on the macro scale is that we fire a photon out of a laser, put a double-slit apparatus in its path, add in a detector of some kind, and then a photon shows up that is consistent with a diffraction pattern (which probably looks pretty much like a single spot) diametrically opposite one slit or the other. How did it get there? We don't know. That's why I want to change "passes through one slit" to "seems to pass through one slit," or "invites us to make the simplistic assumption that it has passed through the nearest slit."P0M (talk) 01:07, 29 December 2013 (UTC)

If you will follow the paths drawn in the above diagram, you will find that Detectors 3 and 4 are checking out the output of the two slits. In the physical apparatus described by Kim et al., other parts of the apparatus tend to keep these detectors a little farther away. However, in principle there is no reason they should not be moved right in front of the slits. You would just need to move each beam splitter right against each slit. You could take out the BBO and all the extraneous stuff. All you need is detectors at the ends of the reflected paths and a single detector on which to merge the unreflected paths. Whether longer or shorter, they are all the same paths. Read the Kim article to see what these detectors reveal.P0M (talk) 08:22, 7 January 2014 (UTC)

Alright, but there are no detectors at the slits, and that was the question. I did mention in the Wiki article that there are other ways, like you mention, which are described in other articles.DParlevliet (talk) 13:36, 11 January 2014 (UTC)

"with marking the wave" section

I don't see what this section adds or why it's there. It seems to be saying that interference can be destroyed in polarization experiments, however in both cases this can be explained classically. So why is it in an article on a quantum mechanical phenomenon? If it's to show that not all interference destruction is quantum mechanical, then that should be stated outright, with a reference to that claim. -Jordgette [talk] 19:32, 12 January 2014 (UTC)

Because in the referenced articles it is explained to be a quantum mechanical phenomenon. This are widely used, certainly in education, so these class of wave markers should be mentioned, with their classical explanation. DParlevliet (talk) 20:38, 12 January 2014 (UTC)

@Jordgette: I think this whole thing is based on a misunderstanding of what physicists mean when they say that they have "detected" a photon "at" one or the other double-slit. The double-slit experiment cannot be understood without using a wave interpretation in classical physics or using a quantum-mechanical explanation that speaks in terms of wavefunctions rather than waves.

The most dead simple case of defeating interference would be to build an extension of the center bar between the slits so that the chamber into which the double-slit apparatus leads is divided into two halves. If a photon is detected on the right side of this partition we would, by ordinary intuition, assert that it must have come by way of the right slit. If a photon is detected on the left side of this partition we would, by ordinary intuition, assert that it must have come by way of the left slit. Now the question is, does it matter whether a person puts his eye or other detector right up close to one of the slits and observes what comes out there, or whether that person stands at some distance from the slit. Providing that a dust mote does not take out the photon somewhere in the middle, the distance between the slit and the detector in this set-up is irrelevant.

It doesn't matter to the physicist or to the experiment itself how one determines which slit the photon comes through. Ultimately you have to get it to register on a CCD. Is it isolated from its phantom half by a wall? Is it insulated from interfering with its phantom half by being twisted around by a device that puts it into a different polarity? It doesn't matter. If we detect it with a CCD behind a polarizer we have ended it and replaced that energy with the energy of a boosted electron in the CCD. If we detect it with the new wall in place it ends its life on the left half of the old detection screen or on the right half as a boost in an electron somewhere.

Its really too bad that experimenters ever used the word "erasure" because they have not erased anything. They have not first added something to a photon and later taken it away. They have just done something superficial to the photon and have then done something else equally superficial that takes away the trick that was going to allow the path to be associated with one path or the other.

The Kim et al. article says they are doing quantum erasure. Let's look at what they actually do. They make a sort of pachinko game where a ball falls into the mechanism and come come out in four random but equally likely positions. What happens at D₃ and D₄ is exactly what I described above. They have walled photons from the slit that is higher on the diagram to a path that leads to D₄. So if you stood at the position of that detector and looked back the other way you could see only the top slit. If you stood at D₃ you would look back and see only the bottom slit. That is like standing on one side or the other of the partition in the dead-simple experiment.

So how do their "erase" the effect? They use a beam splitter so that half of the time the path to be followed does not go to either D₃ or D₄. Instead, they go through a series of elements that put them back on the same heading that they would have been on if the prisms and mirrors hadn't been there. They take the paths that they had directed away from each other and bring them back together again. The only kinky part of this trick is that because of some paths going through beam splitters, some paths reflecting off beam splitters, and some paths reflecting off mirrors, the two sets of merging paths are out of phase with each other. They have not scrubbed off anything at all.

For what its worth, putting a plug in one of the slits in the traditional apparatus is a way of detecting a photon at that slit position. A photon either goes through the open split or hits the closed slit (which could have a CCD plugging it if you really wanted to get technical about it). The photon that hits the CCD wedged in a slit or pasted to the far side of it is just as "dead" as a photon that hits a CCD at D₃ or D₄ in the Kim apparatus. Any time one does an experiment with one slit or one small diameter hole one is effectively doing a two-slit experiment with a detector in or behind one slit.

When I first heard about experiments in which photons were detected at one slit or the other, I imagined some kind of translucent material that would light up a bit but let the photon through anyway. I quickly realized that nobody was saying that they could make an apparatus like that.

I hope you can help keep this article on the right track.P0M (talk) 22:59, 12 January 2014 (UTC)

Young's experiment

This experiment is repeatable in the laboratory. There is no need to quibble whether Young used slits or not. The mathematics is simpler for infinite slits. I have removed the merge tags in the respective articles. --Ancheta Wis   (talk | contribs) 10:32, 12 January 2014 (UTC)

This is not a quibble but is based on the discussion in Andrew Robinson's biography (see reference in the main article) of Young. He says that one historian of Science, John Worral says that the double slit experiment was only a 'thought experiment' on Young's part. A second historian, Nahum Kipnis disagrees with this view, but believes that Young did not actually see any interference fringes when he did the two slit experiment, but observed only diffraction effects.

Robinson comments that is surprising that he gives no numerical data about the fringes, and also that he buried the discussion in a mass of data rather than reporting them prominently.

Young gave a lecture to the Royal Society in 1803 where he challenged Newton's corpuscular theory of light. He said that "he had found a simple and demonstrative proof of the general law of the interference of two portions of light". The experiment involved making a small hole in a window shutter which formed a divergent beam of sunlight. He brought a slip of card one thirtieth of an inch in breadth into this sunbeam and observed its shadow on the wall. Beside the fringes of colour on each side of the shadow, the shadow itself was divided by similar parallel fringes. Young says that "these fringes were the joint effects of the portions of light passing on each side of the card". This was not a two slit experiment, and as stated above, Young does not appear to have conducted a two-slit, or a two hole interference experiment. Epzcaw (talk) 18:02, 13 January 2014 (UTC)

Please see A course of lectures on natural philosophy and the mechanical arts, pages 494-495. The experiment described here in this 1807 series of lectures is unmistakably a two-hole/slit experiment. The only question is exactly when he performed the experiment. Stigmatella aurantiaca (talk) 18:32, 13 January 2014 (UTC)

Nowhere in the above article does Young say that he has performed the experiment. Robinson quotes the relevant passage from this article and then says:

"It appears definitive - and there is no question that the double slit experiment does demonstrate the interference of light... But did Young actually perform it? Or was it only a 'thought' experiment like Einstein's notion of catching up with a light ray? A least one current historian of science, John Worrall, thinks the latter is the case: Young's double slit experiment was an intuition of the truth, not a real experiment. Worrall bases his view on the following undoubted facts: Young does not explicitly state that he did the experiment: Young provides no numerical data: Young says nothing about the light source he used and the other experimentla conditions: and Young never again refers to the experment" Epzcaw (talk) 19:32, 13 January 2014 (UTC)

On the other hand, perhaps the lack of detail comes from the fact that the double slit experiment is quite easy to perform, and that Young had previously made very clear what sort of light sources were required to perform the sorts of demonstrations that he outlined. In his lectures, Young tended to present only finished calculations rather than burden the reader with detailed measurement data. Young was very careful to explicitly state the authors of experiments performed by others, but tended to report all of his own work in somewhat of a detached manner.

John Worrall tends to be a bit of an iconoclast. Elsewhere, for example, he has argued persuasively that the famous story of Fresnel, Poisson and the White Spot has been greatly over-dramatized. His interpretations are not to be discounted, but my own readings of the literature surrounding the double-slit experiment fail to corroborate his viewpoint. Stigmatella aurantiaca (talk) 23:26, 13 January 2014 (UTC)

Undent: I've been watching that flag for merging the two accounts for some time now. To me it seems that Young's experiment is of great historical interest regardless of what details can be pinned down about it. The experiment does not need a great deal of attention in this article, however. There seems to be quite enough to talk about to justify keeping it a separate article.P0M (talk) 02:41, 14 January 2014 (UTC)

Here are more citations discussing Young's interference experiment:

1. American Physical Society, This Month in Physics History May 1801: Thomas Young and the Nature of Light accessdate=2014-01-13
2. Max Born (1922) The Restless Universe ISBN 0-486-20412-X page 110: "Young made two narrow slits in a screen and allowed light to pass through these and fall on another screen at some distance. Then he actually saw dark and bright bands (fringes) alternately, just as the wave theory predicts. ..." Born then specializes down to monochromatic light, to show that the phenomenon can be understood from wave theory (figure 49 p. 111) "then it is easy to calculate and mark points on the screen where one wave is exactly a whole wavelength behind the other; there a bright band will be found, and each pair will be separated by a dark band". See also: interferometer
3. Royal Institution, Thomas Young, director p.436 Current Science 67 #6 25 September 1994

The historiography and disputation ought to be given weight appropriate to the article. There is no doubt that the physicists have assigned credit to Young for having actually performed his interference experiment, which has been performed with pinholes (1801), and slits (1807), to produce interference fringes. Whether historiography states A or B is not as important for the article as assigning unblemished credit to Young for his physical insight.

--Ancheta Wis   (talk | contribs) 04:18, 14 January 2014 (UTC)

I agree with both sets of comments.

There is no doubt that Young was one of, if not the most important person, in winning over the scientific community to the wave model of light propagation, and should be credited with that.

However, it is also surely of great interest if it is true that he did not actually ever do a double slit experiment, as this is so widely believed in the physics community. My PhD involved a particular form of a double-hole experiment which I always referred to as "Young's slits", and I was therefore more than somewhat surprised to find the statement in Robinson's book that there is doubt as to whether or not he did actually ever do the experiment. I believe this is of sufficent interest to the wider community to be recorded in Wikipedia.

See also Do the "Double Slit" Experiment the Way it Was Originally Done

As P0M says, the detailed discussion does not belong in the Double slit page. There is already a page entitled Young's interference experiment and the discussion about this should be included here. I will see what I can do. I'm sure Ancheta Wis will also contribute.

I have modified the section about Young in the Double Slit page to ensure that Young's contribution is not downplayed. He was clearly a remarkable man. To do the double slit experiment is his head rather than experimentally could be seen as even more admirable at the time! Epzcaw (talk) 11:25, 14 January 2014 (UTC)

Inconsistency

The statement

A more complicated measurement uses two quarter wave plates at the slits, which transforms linear to circular polarization.[38] However, when two oppositely rotating waves are added (at the detector), the rotation disappears. Also, according to Walborn, the "not interference" pattern is actually the sum of two interference patterns which are shifted 180° to each other.

is inconsistent with what DParlevliet has put on related Wikipedia articles. and it is wrong. P0M (talk) 07:44, 5 February 2014 (UTC)

"Small chunks of matter" in lede

I have removed some wording which indicates that classical particles are "small chunks of matter" as this is inaccurate. Since this was reverted, I've changed to what I hope is a compromise wording (for now) while I explain my rationale. Here's the original text:

The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen—a result that would not be expected if light consisted of classical particles (i.e. small chunks of matter).

I removed the parenthetical section at the end of the sentence. This was then replaced with:

The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen—a result that would not be expected if light consisted of classical particles or small chunks of matter.

Revert message was This description is useful for readers who don't know what a classical particle would be like. The problem I have is that I feel it gives the wrong impression. I wouldn't say that particles are necessarily made of matter, nor must they be particularly small (and the size of a "particle" covers several orders of magnitude, anyway). More importantly, even if it were a small chunk of something, it was not being tested for its size or whether or not it's made of matter - the test is whether light (or charge, or matter, or whatever) is made up of discrete (yes), localized (no) objects. If you're going to clarify what makes something a particle, those are the two criteria that matter and anything else is a distraction. That being said, I think that it's very clear from context what a "classical particle" is, and for those who want further clarification, there is a pipelink to particle earlier in the lede.

For now I've changed it to a compromise wording: ...classical particles (i.e. discrete, localized objects).', but I think it's appropriate to remove the whole aside.0x0077BE (talk) 20:38, 11 February 2014 (UTC)

Actually, looking more closely, it seems to me that the whole lede could use some reworking. The updates about what things exhibit interference patterns should emphatically not be in the lede, and should be moved into some section in the main article (maybe a section in "Variations on the experiment" for large-mass object). I also find the connotation of the word "inexplicable" in the antepenultimate paragraph a bit... hyperbolic. It sets up a dichotomy between modern and classical physics that I don't think really exists. Classical physics today is a subset of modern physics, as relativistic and quantum effects asymptotically approach classical explanations as ensembles and mass grow large and as speed decreases away from c. 0x0077BE (talk) 20:46, 11 February 2014 (UTC)

I'd been wanting to make changes to the lede myself, but haven't had the time. The flowery hyperbole bothered me as well. So go ahead with your edits and best wishes on them! Stigmatella aurantiaca (talk) 20:58, 11 February 2014 (UTC)

Is there a way to make "i.e. discrete, localized objects" more friendly? This is the lede of the article and should be accessible to all readers. I understand the need for accuracy, but these meanings of the words "localized" and "discrete" are not exactly at the end of everyone's tongues, and may be too jargony for some to get a clear understanding. Would "discrete, localized objects or 'chunks of something'" be acceptable? How about "discrete, localized objects -- well-defined 'chunks' of matter or energy"? Or, "discrete, localized objects -- things with a well-defined inside and outside"? I want lay readers to read this sentence and know what is being said, without the sentence being inaccurate. I think it's important. -Jordgette [talk] 01:27, 12 February 2014 (UTC)

Presumably the best way to do this would be to find synonyms for "discrete" and "localized" that are in common parlance. I'm going to re-iterate that I think we can assume that people have a "billiard ball" model of a particle, and an "ocean wave" model of a wave in mind, and leave it to the curious to look in more detail. 0x0077BE (talk) 01:56, 12 February 2014 (UTC)

I think you are right about billiards and the beach. However, I also think this is the point at which we have to direct the learning of the reader a bit to keep him/her from getting lost in a sea of abstractions and technical terms.

If I remember correctly, the term was chosen some time ago because whatever technical term then being used was kicking up questions from readers that indicated that they were missing the intended meaning pretty widely. I write professionally in a field that requires the use of the term "discrete entity," but I am never sure how many readers get the intended meaning. (Maybe, it has occurred to me, they may think that there is a prudish avoidance of discussion of indiscrete entities. ;-). These terms need to be managed closely.

If we begin with what we understand about the photon, electron, or whatever that is a not-wave and a not-particle and is something that manifests some characteristics of a wave and some of a particle, then it will be no trick to explain why we see something analogous to the interference of water waves in the lab and also something analogous to the impact of minute psrticles when those waves intercept a detection screen. However, that leaves the entire discussion over the heads of average well-informed readers. The current discussion is not really ideal for either group of potential readers, but those with a background will glide over the misleading parts of the formulation because they know what it is supposed to mean.

The hitherto unprepared reader needs to be told what they probably would expect is what the early researchers expected when they were in the process of getting beyond Newton's corpuscle model of light. Then they can be shown how the early researchers had to give up on the simple idea of "wave" but also had to give up on the simple idea of "corpuscle," and the really interesting stuff that also came out in the wash.

Our discussion could contrast what one would naively expect light to do if it were actually what people (basing themselves on whatever they understand about the macro world) thought it was to what was later found to be true and how that new understanding permitted researchers to work out a better model of what light actually is. One early idea, wildly wrong but productive of an easy way to get thinking about interference, is that light is analogous to a water wave and that the amplitude of light can be mapped onto the shape (maxima and minima, crest and trough and in between) of a water wave. That kind of model explains Young's observations. Another idea, producing a strong "conflict of notes" (or picturing incompatible qualia to use non-scholastic vocabulary) with the wave idea, is that light comes in units whose analogs could be bullets, marbles, balls from ball bearings, etc. The reader has to be introduced to the experiment by starting from the false expectations that early experimenters must have taken into the lab. What we call these "waves" and "particles," for the sake of the beginning reader, needs to be evocative of the macro-world expectations that we are going to prove turned out in the lab to be wrong. They do not need to be consistent with current understanding of "wave" and "particle" — both of which are now incredibly abstract.

Everyday usage of "particle," for people who aren't interested in physics, might be something like, "Her vision became permanently impaired when she got a particle of carborundum in her eye." "Diamond particles are found to be non-inflammatory." Do we really want to encourage the preconception that electrons will be found to be even smaller versions of a piece of diamond dust? I think not, but I also believe that there will be no harm to explain that early researchers expected the units of light to be something analogous to these motes.

We need a term for something whose qualia are opposite those of a "wave." "Chunk" is a very homely terms. It suggests solidity, resistance to change of shape or change of other characteristics under the influence of most outside forces, relatively low ratio of surface to mass (i.e., not a flat sheet or wildly waving collection of filaments), etc. "Bit" suggests something that might be amorphous and easily malleable, "a bit of raw hamburger on my dog's nose," and most other terms I can think of do not immediately suggest something that would easily be accepted as fitting the description of "a not-wave." "Chunk" is not entirely suitable, not because it is a vernacular term but because its ordinary definition says that it is a large piece of something. "The falling cannon ball took a chunk out of the roof over the fort's well." Maybe somebody has a better thesaurus than I and can find just the right word for "smallest individual constituents of matter." P0M (talk) 04:35, 12 February 2014 (UTC)

I really don't think all this matters. I don't think there needs to be any aside about what a particle is. The relevant concepts inherent to classical particles are obvious from context, especially since it is already in the zeitgeist that particles are billiard balls and waves are undulating water-wave type things. If you're really having trouble with the specific implications of a classical particle, I don't think it'll be resolved with any brief turn of phrase.

As for conjuring up the impression that an electron is a smaller piece of diamond dust - first off, we're defining this by contrast anyway, so we're saying an electron isn't strictly a particle. Second, a particle isn't really the "opposite" of a wave, it just that they are not the same thing. A dog is not the opposite of a cat, nor is a tree the opposite of an ashtray, they're just different. I don't see the need to reinvent the wheel here - I'm fairly confident people know what particles and waves are to a close enough degree that any little parenthetical statement isn't going to make the difference between understanding and not understanding the lede. 0x0077BE (talk) 05:52, 12 February 2014 (UTC)

"Opposite" wasn't the right word. Vocabulary frequently is a problem in these discussions. Maybe "incompatible" would have been better. Anyway, I don't have a big problem with using "particle" and "wave" in the context of the first paragraph — as long as people are not confused when it becomes useful to tighten the definitions of these words as the discussion continues to deepen.P0M (talk) 08:21, 12 February 2014 (UTC)

I agree with 0x0077BE. The classical "particle" and "wave" are mathematical models in physics with a long history and specific behavior. They are used as technical terms in quantum mechanics to encapsulate the two incompatible, complementary aspects of quantum objects. We should avoid "explaining" them in the introduction, via words like "chunks". The terms "wave" and "particle" are adequately visual and self-explanatory for the introduction; "particle" implies "descrete" and "localized". We just need to use them carefully, as technical terms; the present introduction does a fairly adequate job of that. As 0x0077BE said, readers can always refer to Particle and Wave. --Chetvorno^TALK 10:23, 12 February 2014 (UTC)

I also agree with that the paragraphs at the bottom of the intro on recent buckyball and molecule experiments should be moved into the body of the article. --Chetvorno^TALK 10:56, 12 February 2014 (UTC)

Meaning of "particle" across contexts

In the overview, the context of the single word "particle" changes from "classical particle" to "discrete particles" to "individual particles."

Similarly, if light consisted strictly of classical particles and we illuminated two parallel slits, the expected pattern on the screen would simply be the sum of the two single-slit patterns.

However, the later discovery of the photoelectric effect demonstrated that under different circumstances, light can behave as if it is composed of discrete particles. These seemingly contradictory discoveries made it necessary to go beyond classical physics and take the quantum nature of light into account.

The double-slit experiment (and its variations), conducted with individual particles, has become a classic thought experiment for its clarity in expressing the central puzzles of quantum mechanics.

The average well-informed reader may read the word "particle" as meaning the same thing in all three contexts. The second occurrence can be interpreted to mean classical or non-classical particles. It doesn't make any difference since the expression "discrete particles" is appropriately qualified by an "as if" in the sentence. The third sentence, however, is not talking about classical particles. Do we need to flag the change to accommodate to the habits of some readers who may carry the idea of "classical particle" across all three of these contexts? P0M (talk) 15:49, 12 February 2014 (UTC)

Yes, this is indeed confusing. The second one is likely easiest to deal with, because it's just saying that light is quantized, so you can probably replaced "particles" with "quanta" or "units" or some other general term for a discrete-part-of-whole. The third is tougher because it's similar to the way that the Bohr model of the atom was called an "atom" in the same way that the modern conception of an atom is called an atom. I think that if we remove the second reference to "particle" which is an edge case that in some ways bridges the gap between the other two senses of the word "particle", that the emphasis on "classical particle" in the first mention should be enough to make it clear that they are different things. 0x0077BE (talk) 16:00, 12 February 2014 (UTC)

The first two are okay, although I agree the second could be qualified with the word "quanta" or "photons". In the third, the phrase "conducted with individual particles" should probably be deleted, as I assume it is a confused and unnecessary reference to the "single particle at a time" DSE, which hasn't been described yet. --Chetvorno^TALK 16:16, 12 February 2014 (UTC)

Heh, it must be confusing, because that's not how I interpreted the statement at all. I thought it meant "individual particles" as in with individual classes of particle - e.g. electrons, photons, neutrons, protons, etc. I agree that the phrase can be removed. 0x0077BE [^talk/_contrib] 16:24, 12 February 2014 (UTC)

Cheese it. Righter than I thought I was, for once. ;-) P0M (talk) 17:17, 12 February 2014 (UTC)

Done. --Chetvorno^TALK 16:26, 12 February 2014 (UTC)

"Which way" and complementarity

This should be defined more exact. The reference mentions "while at times we may use either", so not "not both at the same time". The same in the Copenhagen wiki article. So it should explain more detailed what is the basic underlying principle. DParlevliet (talk) 15:20, 31 March 2014 (UTC)

This what?

You have removed from the article, without previous discussion, the assertion that something cannot be observed as a wave and a particle at the same time. In the context you removed it from, there is no problem with that assertion. Can you supply any proof to support your action?P0M (talk) 17:25, 31 March 2014 (UTC)

Are you trying to make the implication that because "at some times" somebody may call something a particle and somebody else may call it a wave, it is therefore the fact that they always detected in experiments as both particle and wave? What somebody calls a photon when it is not under observation goes beyond being a construct to being just a term of convenience.

What "Copenhagen" wiki article? You seem to think that Copenhagen is the name of a person. At least you have sometimes reported things that "Copenhagen says." Copenhagen is a city, and the "Copenhagen interpretation" is a general way or attitude about interpreting the math of quantum mechanics that was common among Bohr and his colleagues. So are you talking about something Bohr said somewhere or what?P0M (talk) 17:58, 1 April 2014 (UTC)

Recent spate of reversions

Several changes, back and forth, have recently been made in this article. The only discussion about these changes has been in the edit summaries. Interactions tend to be much smoother if people discuss things first.

I am puzzled by the "1st place" subsection. The heading is entirely nonsensical unless you work backwards from the implications of the quoted material. Readers should not have to guess about what something may be intended to convey.P0M (talk) 13:48, 31 March 2014 (UTC)

Anonymous contributor 76 is relying on a Physics World top 10 overview article which has the "1st Place" item. I quoted it to emphasize the source of 76's edits, from Physics World.

More to the point is De Broglie's physical insight that a particle exists in a medium; apparently this is the reason for his Pilot Wave formulation. This statement is useful for the article, even if other physicists have rejected the formulation. I agree that this should be worked out on the talk page before it shows up in the article, and that we rework the current edits.

The new chapter explains the wave-pilot theory of Broglie-Bohm, which already has its own article, including the double slit explanation. So a reference to this article is sufficient, in stead of repeating all in this article. If the chapter has new information, it should be placed in the Broglie article. DParlevliet (talk) 15:09, 31 March 2014 (UTC)

I have sent messages to recent IP contributors who have been starting their own private edit war. I think they need to be brought into the discussion process. Continued undiscussed major changes will lead to consequences that I'd rather avoid. Maybe others interested in this article could send them messages if they make any further undiscussed changes.P0M (talk) 20:39, 1 April 2014 (UTC)

de Broglie's wave mechanics

de Broglie's "The double solution theory, a new interpretation of Wave Mechanics" is the precursor of de Broglie pilot-wave theory which Bohm picked up on and is now often referred to as de Broglie-Bohm pilot-wave theory.

de Broglie's Wave Mechanics is the foundation of all of this and it is the theory where wave-particle duality is defined as a physical particle having an associated physical wave in a hidden medium.

de Broglie then extended wave mechanics into the double solution theory. The double solution theory describes the connectivity between the physical particle and its physical wave and also describes the wavefunction of quantum mechanics, hence the name "double solution".

Aephraim Steinberg and Yves Couder are two physicists who are actively working in this realm of quantum mechanics, or in the macroscopic version of this realm of wave-particle duality.

de Broglie's "The double solution theory, a new interpretation of Wave Mechanics" is a valid interpretation of quantum mechanics and what occurs physically in nature in a double slit experiment based upon this interpretation belongs in the "Interpretations of the experiment" section of the double slit experiment article.Mpc755 (talk) 21:28, 1 April 2014 (UTC)

Are you possibly referring to "Introduction à la nouvelle théorie des particules de M. Jean-Pierre Vigier et de ses collaborateurs" with your article title(?) above? If it is an article by de Broglie then you need to cite it explicitly. It isn't mentioned in this article or the article on Louis de Broglie.

Have you seen DParlevliet's critique above? P0M (talk) 21:38, 1 April 2014 (UTC)

I see there is indeed an article, available at: http://thehqbooks.com/gb/811718 You need to cite things like that. What is the true date of the paper? He died in 1987 and the article was published in Annales de la Fondation Louis de Broglies in that same year. It looks like the original was published in French in 1972, so it might be worthwhile to point out that this "new" interpretation is now about 40 years old.P0M (talk) 21:51, 1 April 2014 (UTC)

I changed the title to "Interpretation of quantum mechanics by the double solution theory" which is the title of the article associated with the pdf which is referred to at the end of the first de Broglie quote. Let me know if this title is still not accurate.Mpc755 (talk) 21:53, 1 April 2014 (UTC)

Changed title to "Double solution theory"Mpc755 (talk) 21:57, 1 April 2014 (UTC)

Probably "De Broglie's double solution theory" would be even better. Dicklyon (talk) 22:04, 1 April 2014 (UTC)

"Relational interpretation" is not "Carlo Rovelli's relational interpretation". If there is a consensus of what the title should be then it should be changed. Thanks for the feedback. Mpc755 (talk) 22:18, 1 April 2014 (UTC)

I'm making it "Wave mechanics" as that is what de Broglie first refers to in the article the first quote is from. Mpc755 (talk) 22:20, 1 April 2014 (UTC)

I changed it back to your previous choice. "Wave mechanics" is way too broad a concept, not representative of de Broglie's interpretation. Dicklyon (talk) 23:31, 1 April 2014 (UTC)

I changed it to "de Broglie's wave mechanics" as the discussion centers around an explanation as to what is occurring in a double slit experiment which de Broglie's wave mechanics is more suited for as it is focused on the physical particle and the associated physical wave in the hidden medium. Mpc755 (talk) 03:40, 2 April 2014 (UTC)

The section is a bit of mess. Here is a good source to help write it better. Probably "pilot wave" would be a more appropriate name, or part of the name. Dicklyon (talk) 23:35, 1 April 2014 (UTC)

Pilot wave is thought of as de Broglie-Bohm pilot-wave theory and has too much baggage. One of the main problems with de Broglie-Bohm pilot-wave theory is that it is nonlocal where de Broglie wave mechanics is local. A problem with de Broglie's pilot-wave is that it is considered a hidden variable theory. There are no such things as hidden variables. Due to conservation of momentum each of the downconverted photon pair can determine the position and momentum of the other based upon their own position and momentum. Entanglement is not a physical or superluminal connection. Entanglement is each of the pair being able to determine the state of the other. Bohm's concept of the wave piloting the particle was described as the radio waves guiding the plane. This is not what the wave of de Broglie wave mechanics is. de Broglie describes the "energetic contact" between the particle and the hidden medium and describes the particle as occupying a very small region of the wave which is in no way describing anything near analogous to radio waves piloting an airplane. What de Broglie is referring to is more correctly described as the particle moving through and displacing the medium. There is also this associated with de Broglie-Bohm pilot-wave theory "The de Broglie–Bohm theory is explicitly nonlocal: the velocity of any one particle depends on the value of the guiding equation, which depends on the whole configuration of the universe." That is not what de Broglie is referring to in terms of the physical wave. Mpc755 (talk) 00:20, 2 April 2014 (UTC)

It appears this section may have been fraudulently created or modified in order to advance a pseudoscientific argument user Mpc755 was trying to promote on the public science discussion website www.sciforums.com. Here's a link to the specific thread, on which the user Mpc755 is presently posting as "cav755" to evade a previous ban from the site. Hopefully this community is readily on guard against cranks further seeking to modify the content here for purposes of misinformation and self-promotion. 209.89.250.95 (talk) 04:03, 2 April 2014 (UTC)

What I have posted here is an explanation of what occurs physically in nature in a double slit experiment according to de Broglie's wave mechanics. I'm not sure why it causes people who consider themselves knowledgeable about physics to go nuts. Mpc755 (talk) 09:33, 2 April 2014 (UTC)

I have to agree with Dicklyon. Basically what is present so far are a few quotations sort of stuck together. It's hard to know what to do with a quotation when you have to figure out who might have said it by taking a look at a footnote. The reader has to guess why you are putting quotations from several sources in sequence.

I think I answered this by adding information within brackets to the quotes. Mpc755 (talk) 14:54, 4 April 2014 (UTC)

Readers would probably benefit from knowing when de Broglie got started on his ideas, when and why he initially gave up on them, and why (in two steps, I guess) he got interested in them again and has had a renewed influence on discussions since the 1970s. P0M (talk) 06:51, 4 April 2014 (UTC)

Mpc755, if you look to the article De Broglie Bohm theory you will find the same, even more extended. So why repeat it in this article? If you have more information, you can add it to that article. Then all information about this theory is in one article and not spead-out over several articles. That is easier for the reader. DParlevliet (talk) 07:21, 4 April 2014 (UTC)

The article starts off with "When in 1923-1924 I had my first ideas about Wave Mechanics...". I don't think this is the place for a history of de Broglie wave mechanics. This is not de Broglie-Bohm theory. I already explained why I am referring to de Broglie's wave mechanics and not de Broglie-Bohm theory. de Broglie's wave mechanics is by de Broglie. de Broglie-Bohm theory is by Bohm. Bohm mistakes the wave function for a physical wave. They are two very different theories and the name of de Broglie-Bohm theory including the name "de Broglie" is very misleading. Mpc755 (talk) 14:54, 4 April 2014 (UTC)

The problem with Mpc755's article as it's presently written (aside from what I've already argued are questionable intentions about making a case for the aether on a science forum), is that his article is lacking in technical details, contains vague and scattered quotes from multiple sources, and it relies mostly on quoting popular science publications rather than transcribing any original or technical papers. Even in the link to de Broglie's original paper, which could certainly be of great academic value, none of the technical arguments therein are outlined and explained, and instead the only part of it contained in this article amounts to a historical quote. I urge all regular contributors here to carefully consider whether Mpc755's contribution contains accurate and relevant scientific info, and not to hesitate to remove anything they don't feel qualifies, or modify the section into a simple link to the original de Broglie article. zz

I just added a technical paper. Mpc755 (talk) 14:54, 4 April 2014 (UTC)

I especially urge the other contributors here to be on their guard for various claims and implications Mpc755 has placed in this section suggesting that de Broglie's model may explain certain measured phenomena in a way that the Copenhagen Interpretation does not. Last I heard, there hasn't been a serious experimental challenge to the Copenhagen Interpretation in the century since it was first introduced. 209.89.250.95 (talk) 13:29, 4 April 2014 (UTC)

The experiment by Aephraim Steinberg allows for a different way of thinking about quantum mechanics. Mpc755 (talk) 14:54, 4 April 2014 (UTC)

I sent an email to Valeriy Sbitnev asking him if my interpretation of his article is accurate. Mpc755 (talk) 14:58, 4 April 2014 (UTC)

Hmmmm, the whole focus of the article is wrong. The article fails to include the standard quantum mechanical derivation of the result, there is only a classical wave physics derivation and then there is a lot of talk about the different intepretations. This is what really should be fixed. I would want my students to study this subject and then be able to answer questions like why you also get interference fringes when photons from the slits are deflected by freely floating mirrors. So, why doesn't the change in the momentum of the mirrors constitute the "which way information" that should wipe out the interference fringes? A well written article would contain enough information to allow the student to at least in principle be able to address this question using the presented mathematical description. The current explanation falls way short of that. Count Iblis (talk) 16:56, 4 April 2014 (UTC)

You are placing a false constraint on de Broglie's wave mechanics by thinking it has the notion of "which way information". If you want to do your students a favor, have them execute the following experiment.

http://www.quora.com/Mike-Cavedon/Posts/A-de-Broglie-is-correct-experiment

Mpc755 (talk) 17:18, 4 April 2014 (UTC)

User Mpc755, this talk page is for discussing the article, not the subject, and certainly not your own private reasearch. See wp:Talk page guidelines. - DVdm (talk) 17:57, 4 April 2014 (UTC)

I only responded with the experiment I propose to show that "which way information" may just be a misunderstanding of what occurs physically in nature; in response to a comment stating that the de Broglie's wave mechanics section was not dealing with it. I don't think the de Broglie's wave mechanics section of what occurs physically in nature in a double slit experiment is the place to be discussing "which way information", nor do I think we need to be discussing it here. Mpc755 (talk) 19:25, 4 April 2014 (UTC)

Another question: What does "singularity" mean as MPC755 is using it? Is it Singularity (mathematics)? Or is something else possibly intended? How is that different from a soliton?P0M (talk) 00:15, 5 April 2014 (UTC)

de Broglie says a particle is a singularity, in a first approximation. My interpretation of this is that de Broglie isn't exactly sure how the particle exists within its wave. At this time, I don't see how you differentiate it from a nugget. Mpc755 (talk) 02:03, 5 April 2014 (UTC)

I've done some modest cleanup to the section. I make no claims to understanding the material being reported, so I hope others will review and tweak better. Dicklyon (talk) 02:37, 5 April 2014 (UTC)

I'm not sure why the article by Valeriy Sbitnev was removed. It is discussing a particle traveling a Bohmian path through a superfluid physical medium. The wave of Bohmian mechanics is not the wave of de Broglie wave mechanics, however, it is still considered to be a wave which passes through both slits in a double slit experiment while the particle travels through a single slit. Mpc755 (talk) 03:07, 5 April 2014 (UTC)

Thanks for the clean-up. Here are some observations on things that need to be tightened up.

There is still a big problem with the paragraph that starts with: "Aephraim Steinberg's experiments on measuring..." This remark comes out of nowhere. The reader needs to understand that Steinberg was doing measurements that evidently diverged from what standard quantum mechanical theory would predict and found that they were closer to the de Broglie theory-based calculations.

The measurements do not diverge from what standard quantum mechanical theory would predict. From the article, "David Deutsch of the University of Oxford, UK, is not convinced that the experiment has told us anything new about how the universe works. He says that although "it's quite cool to see strange predictions verified", the results could have been obtained simply by "calculating them using a computer and the equations of quantum mechanics"." Simply calculating the equations of quantum mechanics is the problem with quantum mechanics. It's the "shut up and calculate" method of quantum mechanics. It doesn't explain what occurs physically in nature. The experiment performed by Steinberg is showing that you can weakly measure some aspect of the particle and still get an interference pattern.

The part that starts out, "For his part,..." sounds very much like special pleading to me. Who cares what this professor says unless it is well substantiated by experiment and observation. If it is, why do we need his lofty authority to be mentioned?

Because the main interpretation of quantum mechanics, the Copenhagen interpretation, insists you can't ask what occurs physically in nature in physics. You can't ask if the particle travels through one slit or the other. You can't even ask if the particle exists in three dimensional space until it is detected. You have to redefine what a particle is in order to make stuff up. What Steinberg is getting at and what de Broglie insisted was, particles are particles and waves are waves. A particle in a double slit experiment always exists as a particle. It is the hidden medium which waves.

"Steinberg's work stood out because..." strikes me as more of the same. What's worse, it still isn't clear to the average well-informed reader what it is that stood out and why it might be important.

From the article, "The experiment reveals, for example, that a photon detected on the right-hand side of the diffraction pattern is more likely to have emerged from the optical fibre on the right than from the optical fibre on the left. While this knowledge is not forbidden by quantum mechanics, Steinberg says that physicists have been taught that "asking where a photon is before it is detected is somehow immoral". "Little by little, people are asking forbidden questions," says Steinberg, who adds that his team's experiment will "push [physicists] to change how they think about things"." One of the recent popular interpretations of quantum mechanics is Many-worlds. In Many-worlds you can't even say the particle exists in three dimensional space in "our world" until the particle is detected. My interpretation of the point Steinberg is trying to make is that the particle always exists in three dimensional space. To have to state that the particle always exists in three dimensional space in "our world" is nonsense. The particle just exists in three dimensional space. One you understand particles are always particles and waves are always waves and in a double slit experiment the particle travels through a single slit and the associated wave in the hidden medium passes through both most of the nonsense associated with quantum mechanics goes away. Mpc755 (talk) 04:33, 5 April 2014 (UTC)

One of the sources I ran on to was quite refreshingly explicit in saying, basically, "We aren't going to be able to prove anything on a few experiments even if they all go our way. We know that the next experiment may blow us out of the water. But until that happens the results are intriguing enough that we are convinced that we ought to do much more digging in the same place." P0M (talk) 03:32, 5 April 2014 (UTC)

Edit conflict, trying to get back on the track:

O.K., the "double solution theory" paper, p. 3f does have such an assertion. If you are going to provide a section of the double-slit article that does not have the bad effect of mystifying the phenomenon and in so doing put the reader in a confused state, you will need to figure out what this "singularity" is, and also give a clear proof by citation that what you represent in this section is more than your own best guess. To make things a bit more complicated, "singularity" has recently become a buzz word. Who knows what associations the reader will bring to this term?

de Broglie defines "singularity" as a very small region of the wave of high energy concentration. The particle occupies a very small region of the wave.

For me, the particle, precisely located in space at every instant, forms on the v wave a small region of high energy concentration, which may be likened in a first approximation, to a moving singularity. ... This result may be interpreted by noticing that, in the present theory, the particle is defined as a very small region of the wave where the amplitude is very large ... In the double solution theory however, the quantity g is certainly concentrated in a very small region occupied by the particle ... Thusfar, the insertion of the particle in its wave was restrictively defined by stating that the real physical wave must include a small region of very high amplitude, which is the particle. Apart from this singular region, the physical wave is the v wave, of very limited amplitude, and satisfying the usual linear equation. —Louis de Broglie

Does it seem to you that de Broglie offers a wavefunction that is a mathematical model for an entity that has mass, energy, and momentum? Does it seem, further, that some small part of the (probably moving) volume of space characterized by that wavefunction itself shows the characteristic of its own "revolving" that gives it an angular frequency and a wave length? (That de Broglie established the proper frequency of the electron is an earlier part of his research upon which the theory currently under discussion must be an elaboration, so that frequency and wave length characteristics are not likely to be subject to debate.) It is how what you call a "nugget" is related to what is basically a Schrödinger wavefunction that needs to be clear. Then the next question would be how that particular model of what is going on would be used to explain the double-slit experiment.

de Broglie's wave function is purely statistical. The wave function of de Broglie's wave mechanics does not move as it does not physically exist. It is the real wave of de Broglie's wave mechanics which is a wave in the hidden medium. de Broglie's "double solution theory" is referring to the two waves. The physical wave guides the particle and the statistical wave function is for making predictions associated with experimental results. Mpc755 (talk) 10:12, 5 April 2014 (UTC)

This result may be interpretated by stating that the current statistical theory considers as spread out in the entire wave, devoid of singularity, that which in reality is totally concentrated in the singularity. It is on account of the foregoing interpretation that I simultaneously considered two distinct solutions of the wave propagation equation connected by eq. (33), one, v, having physical reality, and the other, ψ, normed, and of statistical character. I therefore named this reinterpretation of wave mechanics the double solution theory. By distinction of the two waves v and ψ, the mystery of the double character, subjective and objective, of the wave in the usual theory, vanishes, and one no longer has to give a simple probability representation the strange property of creating observable phenomena. —Louis de Broglie

To use the water-droplet experiment as an analogy, there seems to be one equation that governs the behavior of the "support apparatus" surrounding the suspended droplet, and another equation that characterizes the droplet itself.

There is one equation representing the connectivity between the particle and the physical wave and another equation giving statistical information. One equation represents what is occurring physically in nature and the other allows for making predictions of expected results from experiments. Mpc755 (talk) 10:12, 5 April 2014 (UTC)

However, since the publication of Schr ̈odinger’s works in 1926, it became customary to only consider the ψ wave, of arbitrarily normed amplitude. But this wave cannot be considered as a physical wave, first because the amplitude of a physical wave has a well determined value, and cannot be arbitrarily normed, and because if ψ 1 and ψ 2 are two particular normed solutions of the linear ψ wave, the ψ 1 + ψ 2 sum of these two solutions is not a normed solution. In other words, the normed ψ wave is not endowed with the superposition property characteristic of the physical wave solutions of a linear propagation equation. One is therefore led to consider the ψ wave as a probability representation, a simple prediction instrument, permitting a forecast of the possible measurement results of physical quantities belonging to a particle or to an ensemble of particles. It is however impossible for a simple probability representation to create physical phenomena such as the local observation of a particle, or to impose definite values to energies of atomic stationary states. Objective reality only, may give such effects, and a probability representation has no such character —Louis de Broglie

Beyond this basic level of understanding, the revived de Broglie explanation will face the difficulty that there are apparently no objective measures possible that would allow one to predict what trajectory an electron would take from the region of the double-slit diaphragm. Will this explanation be able to offer anything other than a "just believe me" substantiation?

The uncertainty principle still applies. The uncertainty is that you can not know where the particle exists within its wave without detecting it.

Right now the section is not clear.It is not good enough to write something that contains only true statements (assuming that the truth of any statement can be established unless it is just something of the sort "Smith said," when Smith or recording of Smith's speech support the assertion). Misunderstandings will surely emerge from an inadequately structured essay, and "You failed to guess what I was really getting at" is not an adequate defense of such an essay. P0M (talk) 03:12, 5 April 2014 (UTC)

I agree, it's not clear. Please do what you can... Dicklyon (talk) 03:51, 5 April 2014 (UTC)

If you are referring to the section discussing the article by Valeriy Sbitnev, it is included because it is the first article I have found which relates the wave of wave-particle duality with the hidden medium, in this case described as the superfluid physical vacuum. I think it is important information as it is stating that it is the "window glass" described by Robert Laughlin which waves. The article does refer to the Bohmian interpretation of the wave which is different than the de Broglie physical wave I have been describing and does cause confusion. Mpc755 (talk) 04:06, 5 April 2014 (UTC)

The article by Valeriy Sbitnev describes the particle as moving through the superfluid physical vacuum causing it to wave. This is the definition of wave-particle duality as defined by de Broglie's wave mechanics. Mpc755 (talk) 05:07, 5 April 2014 (UTC)

This last paragraph you added is not even sensibly formatted. It's hard to see what it is supposed to mean, and the interpretation is unsourced. The referenced paper does not even appear to be peer reviewed. I don't quite see the relation to the two-slit experiment anyway. I expect it will need to be removed. Dicklyon (talk)

In a double slit experiment the particle travels through a single slit and the associated wave in the superfluid physical vacuum passes through both. Mpc755 (talk) 05:08, 5 April 2014 (UTC)

Your idiosyncratic interpretation of the physical reality is of little relevance on this talk page. Dicklyon (talk) 05:14, 5 April 2014 (UTC)

Let me rephrase that... The waves on the oil surface and the interference pattern created by them, are akin to the de Broglie pilot-wave. And the oil in the bath plays the role of the superfluid physical vacuum for the droplet that moves on this surface. Mpc755 (talk) 15:11, 5 April 2014 (UTC)

I have reverted your last bit. See edit summary. - DVdm (talk) 15:29, 5 April 2014 (UTC)

I asked Valeriy Sbitnev to review what I had written and the following is his response.

As for the experiment of Yves Couder and co-workers, the droplets bounce on the oil surface which undergoes to a very small vertical vibration inducing subcritical Faraday waves. What does it mean? Amplitude of the subcritical waves is so small that we can not see visually these waves. But if we increase slightly vibrations of a basin with the oil the waves exhibits themselves visually. That is, the vibrations are supported near the supercritical bifurcation of emergence of the Faraday waves.

The oil surface gets high sensitivity in the vicinity of the supercritical bifurcation on any touching to it. The closer the bifurcation point the higher the sensitivity. It means, that as soon as the droplet touches the surface, it induces on the surface nondecaying Faraday oscillations. These oscillations create the interference with each other. In turn, it provides an optimal path for the droplet that is moving on this surface.

The waves on the oil surface and the interference pattern created by them, are akin to the de Broglie pilot-wave. And the oil in the bath plays a role of aether for the droplet that moves on this surface.

It is my vision of the de Broglie-Bohm theory. As I see, it is in good accordance with your vision.

What Valeriy Sbitnev writes to you is entirely irrelevant.

Also, please have a careful look at wp:BRD. You made a bold edit ([1]), I reverted ([2]) and started discussing here ([3]). The idea is that you discuss and not revert again as you did just now ([4]). - DVdm (talk) 15:46, 5 April 2014 (UTC)

In the revision history of the main Double-slit_experiment page you said, "No evidence that this is directly related to the article". It is directly related to the article as the article is written by Valeriy Sbitnev and he is saying the walking droplets and their associated waves are akin to de Broglie's pilot-wave and he uses the term "aether" to refer to the hidden medium. All I did was replace "aether" with "superfluid physical vacuum" so as not to have people freak out over the use of the word "aether" and switch "a" to "the" for readability. Mpc755 (talk) 16:04, 5 April 2014 (UTC)

Please have a careful look at wp:SYNTH. - DVdm (talk) 17:00, 5 April 2014 (UTC)

Couder discovered a macroscopic pilot wave system in the form of walking droplets. Sbitnev relates that to particles moving through the aether. They are both describing physical phenomenon having to do with pilot-waves. They are both describing the same physical phenomenon. Sbitnev extrapolates the walking droplets behavior to particles having associated pilot waves in the aether. Mpc755 (talk) 17:15, 5 April 2014 (UTC)

Please have a careful look at wp:FRINGE and wp:UNDUE. - DVdm (talk) 17:37, 5 April 2014 (UTC)

The article by Valeriy Sbitnev is under consideration for publication in J. Fluid Mech. Can we wait to see if it is published before removing it? In general, it is a very good explanation of de Broglie's pilot wave. I added "Under consideration for publication in J. Fluid Mech." to the article reference. Mpc755 (talk) 17:55, 5 April 2014 (UTC)

Seems to be putting the cart before the horse there, Mpc755. Anything can be "under consideration for publication" by anything. I could submit a crayon drawing to Nature and it'll be "under consideration for publication" until they turn me down. Why not wait until it actually gets published before making arguments about whether or not it should be included. (I have removed the "under consideration" language, as that inappropriately associated J. Fluid Mech with something that they have not decided to publish.) 0x0077BE [^talk/_contrib] 18:54, 5 April 2014 (UTC)

Again, as I wrote above, Mpc755 specifically added the "info" on de Broglie's outdated theory because he's trying to argue for a classical Newtonian universe that evilly conspires to look random. Mpc755 started a discussion at sciforums.com as user "cav755", where he's promoting himself as a revolutionary genius who's finally bringing back the good old aether theory. Notice how the de Broglie section contains little relevant information other than speculative quotes taken out of context in order to favour the old deterministic point of view? Notice how it doesn't even contain a single equation or anything technical- after all, why would the guy who wrote the section bother to learn mathematics and real science when he's already convinced himself that probabilistic quantum mechanics is fundamentally wrong?

The de Broglie section takes up a vastly disproportionate amount of space, in an otherwise important article that could have been useful to students and laymen who come here to learn about real science, instead of the preachings of a crank who thinks he knows more about reality than all the greats of the past 100 years, and doesn't have any technical background. The section should be deleted outright because of its lack of useful information, its misleading out of context quotes, its disproportionate volume in relation to the rest of the article (in direct violation of Wikipedia's fringe policies, as I understand them), and the fact that it was really just placed here so a layman fringe crank could promote old 19th century notions of aether. The section should be deleted, and if Mpc755 or any other incarnation of his accounts tries once again to put it back or revert it without debate against the spirit of Wikipedia community policies, he should be permanently banned from being able to do so. What he's doing here is equivalent to scribbling notes into library biology textbooks about how creationism must be the only possible explanation for life and who they should listen to in order to understand why.

Oh and Mpc755, if you once again edit my comments in any way so as to stick your response into the middle and mess up my formatting, I'm going to revert your edit. 209.89.250.95 (talk) 19:43, 8 April 2014 (UTC)

I think a two line summary would be just about wp:DUE. The remainder of the section reads like a schoolbook example of extreme wp:SYNTH - DVdm (talk) 20:23, 8 April 2014 (UTC)

The section in its present form violates a whole bunch of Wikipedia policies, on top of being written in terribly poor taste. I agree that it might be nice to make a little mention of de Broglie, especially since his original wave mechanics ideas helped give birth to the Schrodinger approach to quantum mechanics. I agree that a couple of sentences and a link to the main article would be all that's relevant here, and I don't understand why such an important and likely widely-perused article has sat here being repeatedly vandalized by the same user, repeatedly reverted to the way he wants it without discussion, and so on. What are you guys waiting for, exactly? If one crank can cause so much trouble and get away with it for more than a week, just wait until the dozens of others over at sciforums.com alone figure out it's open season on Wikipedia. 209.89.250.95 (talk) 20:48, 8 April 2014 (UTC)

I 'm a bit baffled by this too, and I already mentioned this at Wikipedia talk:WikiProject Physics#Heads up at Double-slit experiment. I am not going to touch the article in this respect because it would get me blocked for edit-warring in no-time. So, frankly, I'm somewhat waiting for someone to use a nine-foot pole and do the job that needs to be done. - DVdm (talk) 21:01, 8 April 2014 (UTC)

Done. I agree with DVdm, it is WP:SYNTH and WP:UNDUE. If someone wants to add back a few lines of appropriate and sourced content on whatever in that mess was relevant to the article, be my guest. --Chetvorno^TALK 21:54, 8 April 2014 (UTC)

This is not a section on weak measurement. This is a section on de Broglie wave mechanics. Steinberg says his results match those of pilot-wave theory. The MIT experiment specifically says, "Whatever the case may be in quantum mechanics, the statistics are an incomplete description of our fluid system and emerge from an underlying pilot-wave dynamics". This is one of the main points of this section. Both Steinberg and the MIT professors are saying quantum mechanics is statistical and incomplete and their experiments are better represented by pilot-wave dynamics. In the video it goes on to say, "This physical picture is remarkably similar to an early model of quantum dynamics proposed by Louis de Broglie..." They are saying they are seeing de Broglie's wave mechanics in the walking droplets. They have evidence of de Broglie's wave mechanics. Mpc755 (talk) 22:24, 8 April 2014 (UTC)

Aaaaaaand it seems some crazy person has put it back once again. 209.89.250.95 (talk) 22:19, 8 April 2014 (UTC)

de Broglie-Bohm Theory was a theory by Bohm where the wave function is the physical wave. This is completely different than de Broglie wave mechanics, double solution theory or de Broglie pilot-wave theory. In de Broglie's theories the wave is physical and in "energetic contact" with the particle. The particle occupies a very small region of the wave. In de Brolglie's double solution theory there is the physical wave and there is the wave function which is purely statistical. In Bohmian mechanics, which is the de Broglie-Bohm theory, the wave function is somehow thought to be physical. de Broglie wave mechanics and de Broglie-Bohm theory are two very different theories. de Broglie-Bohm theory is incorrectly named as it is really Bohmian mechanics which de Broglie did not agree with. Mpc755 (talk) 22:42, 8 April 2014 (UTC)

@Mpc755 - Then you need a reliable, secondary source that describes th de Broglie wave mechanics interpretation of quantum mechanics. It would help if the source also mentions how it relates to the double-slit experiment. As it is right now, the section is a synthesis of a primary source (de Broglie quotes) and a few tangential or loosely connected statements from other secondary sources. For example, connecting Laughlin's glass to de Broglie's pilot wave is pure synthesis on your part - you need a secondary source that draws that connection to include here. Also, only in the first ref to the weak measurement experiment does it mention a pilot-wave theory but even then it doesn't indicate whether it is talking about the de Broglie-Bohm theory or your de Broglie wave mechanics. --FyzixFighter (talk) 23:03, 8 April 2014 (UTC)

From the MIT video, "Whatever the case may be in quantum mechanics, the statistics are an incomplete description of our fluid system and emerge from an underlying pilot-wave dynamics. This physical picture is remarkably similar to an early model of quantum dynamics proposed by Louis de Broglie..." The early model of quantum dynamics proposed by Louis de Broglie is de Broglie's wave mechanics. Also from the video, at the 2:10 mark, the MIT researches refer to what they are seeing as an "Exposed Variable Theory". de Broglie's pilot-wave theory is considered a hidden variables theory. The MIT researches are saying what they witnessed is not a hidden variable theory. The MIT researches are saying we need to go back to the beginning, which is de Broglie's wave mechanics. Mpc755 (talk) 00:09, 9 April 2014 (UTC)

Being "similar" does not mean it confirms the theory, and the video is not peer-reviewed. More importantly, this article is not about recent developments in interpretations of QM. Mpc755, your long entry, with quotes, is not appropriate for this article. Why don't you add it to Interpretations of quantum mechanics? --Chetvorno^TALK 02:56, 9 April 2014 (UTC)

de Broglie's wave mechanics is the only explanation where there is a physical particle which travels through a single slit and an associated physical wave which passes through both. If the de Broglie's wave mechanics section only has a description of de Broglie's wave mechanics it gets removed for not having any supporting evidence. If I then add supporting evidence you remove it for not simply discussing de Broglie's wave mechanics. Mpc755 (talk) 03:08, 9 April 2014 (UTC)

Mpc755, the consensus on this page seems to be against your addition. You need to stop pushing it. --Chetvorno^TALK 03:00, 9 April 2014 (UTC)

The consensus thinks a probability wave function physically exists. The consensus doesn't know the difference between de Broglie's wave mechanics and de Broglie-Bohm pilot-wave theory. The consensus can't explain what occurs physically in nature in a double slit experiment. Mpc755 (talk) 03:08, 9 April 2014 (UTC)

Nevertheless, WP:CONSENSUS is how issues are decided on Wikipedia. You could write your theory on Wikibooks. They have no requirement for sources, you could write a whole book about it. Please read WP:EDIT WAR. If you keep edit-warring, I will report you to an administrator, and you could get blocked. --Chetvorno^TALK 04:53, 9 April 2014 (UTC)

Just FYI - there is already a report at WP:ANEW since he blew past 3RR in less than two hours today. --FyzixFighter (talk) 05:02, 9 April 2014 (UTC)

...aaand he got a 24 hour block. --Chetvorno^TALK 06:16, 9 April 2014 (UTC)

Added a short summary of de Broglie's wave mechanics with a link to where it is described in de Broglie's important theories. Mpc755 (talk) 07:30, 10 April 2014 (UTC)

I have removed your wp:UNSOURCED content, pointing to the same freshly added wp:UNDUE and wp:SYNTH content in another article Louis de Broglie. - DVdm (talk) 07:47, 10 April 2014 (UTC)

I have reduced the de Broglie's wave mechanics interpretation of what occurs physically in nature in a double slit experiment to its most basic description. Mpc755 (talk) 08:34, 10 April 2014 (UTC)

Reverted. User Mpc755 is blocked again, now for 5 days. - DVdm (talk) 08:55, 10 April 2014 (UTC)

I'm making a scientific prediction here that yet more junk science vandalism will occur once the strait jacket comes off again, and the corresponding ban lengths will asymptote to $N^{5/2}$, where $N$ is the number of violations. 209.89.250.95 (talk) 17:12, 10 April 2014 (UTC)

Note that it's not a ban, but a block. Check out the difference. - DVdm (talk) 17:21, 10 April 2014 (UTC)

Unsourced content

User DParlevliet has been adding the same unsourced comment 3 times now:

1. [5] adding unsourced content
2. [6] re-adding same content with a source not backing the content
3. [7] re-adding same content with a source not backing the content, made in logged out mode as 83.160.119.77 (talk · contribs)

I checked the cited source (Brian Greene, The fabric of the cosmos chapter 5 - Propability and laws of physics). In my version (ISBN 0-375-41288-3), chapter 5 is The frozen river and it is about Time. It never mentions anything even remotely related to the added content. Does anyone have another version of this book? - DVdm (talk) 09:39, 21 April 2014 (UTC)

Sorry, my error, it is chapter 4. My page 107, but I have a Dutch version which probably will be different. DParlevliet (talk) 09:57, 21 April 2014 (UTC)

The double-slit experiment is indeed implictly mentioned in chapter 4 (see also figure 4.4). Probability and the Laws of Physics is a section between pages 88 and 92. Can you cite the passage (in Dutch) that you think supports the content you want to add? - DVdm (talk) 10:09, 21 April 2014 (UTC)

Probably the figures has the same numbers. Fig 4-4 shows the double slit with electrons. The propability text is just above figure 4-5. However you still did not tell what you dispute.DParlevliet (talk) 11:31, 21 April 2014 (UTC)

Ok, got it. In my version we do find something that directly supports your text. It's on page 90, a few paragraphs under figure 4.5. I will re-insert your text with this source:

By the way, I have taken the ISBN 0-307-42853-2 version that allows direct verification. - DVdm (talk) 19:11, 21 April 2014 (UTC)