Talk:Double-slit experiment

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Please discuss changes[edit]

Dparlevliet, I disagree with your latest change. The way you have phrased it is correct only for a monochromatic source. Your previous change, while not incorrect, just deleted some careful phrasing. I recognize that English is not your primary language, but if you need help with grammar, then let's work on it here.

OK? --Ancheta Wis   (talk | contribs) 13:06, 24 April 2014 (UTC)

The first change is correct too, I think, but shorter so more clear. Too much detailed, formal text is confusing for the average reader, for which Wikipedia is intended. What do you miss in the first change?. The second change: the double slit always uses a monochromatic source, also the former text. Edits of my English are always appreciated. DParlevliet (talk) 13:24, 24 April 2014 (UTC)
Re "the average reader, for which Wikipedia is intended": I don't think that's entirely correct—see WP:TECHNICAL. In a nutshell: "Strive to make each part of every article as understandable as possible to the widest audience of readers who are likely to be interested in that material." Arguably the average reader is not interested in this subject. See also WP:EXPLAINLEAD, from the same guideline, explaining that in the lead—i.e. before the first section—broad readership can indeed benefit from less technical jargon.

Also note that making back/forth changes to the article before consensus is reached on the talk page might be a bad idea. It's better to discuss possibly problematic changes before making them, specially if someone proposed to "work on it here." - DVdm (talk) 13:46, 24 April 2014 (UTC)

I just changed it to be more clear for "the widest audience of readers" and did not made any problematic change. My text explains the same as the former (my first change). Please be more specific what could be wrong. DParlevliet (talk) 14:37, 24 April 2014 (UTC)
I was talking in general, reacting to that average reader comment. I'll leave the specifics for Ancheta Wis. - DVdm (talk) 14:40, 24 April 2014 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── " So this experiment shows that photons has wave-particle duality." This sentence could be a summary, but does not follow from the preceding text, and the verb is ungrammatical. It would be better to simply strike the sentence as gratuitous commentary. But that's not the end of it. I call the cooperative nature of the wiki the wiki-action, where the sum of the changes produces an amazing result. It helps wiki-action to 'go along with the flow'. Instead, I see semi-combative responses, which slows down the wiki-action, as it elicits defensive behavior all the way around, rather than encouragement.

The term 'photon' ... I could go on, but this is a lot of work for one sentence that needs to go. --Ancheta Wis   (talk | contribs) 15:11, 24 April 2014 (UTC)

I will look to it. But the second part I don't understand. What is the striped text? Which sentence needs to go? DParlevliet (talk) 17:14, 24 April 2014 (UTC)
The striped text is due to markup. Perhaps you might simply ignore it.
I fixed the omission of 'monochromatic light' already. How about sitting back a bit (i.e., take a rest). There are many editors who might contribute as well. --Ancheta Wis   (talk | contribs) 17:25, 24 April 2014 (UTC)
I had not yet seen you changes. They are fine for me. The wave-particle is also mentioned later on. I just wanted to make clear that not only the double slit, but also the single slit shows the wave properties. The double slit is just another, more visible interference.DParlevliet (talk) 08:48, 25 April 2014 (UTC)


I must reiterate the above request that DParlevliet discuss his changes here before making changes in the article. I just had a look at the latest change, and the syntax is not correct. The level of DParlevliet's English writing has been a constant problem since he began his editing here. Even knowing how Feynman set his explanation up, I can't really follow the English. When I correct it to what should have been written to make proper English out of it, I see that it makes some statements that are only dogmatic in form, and that stand as isolated utterances. The reader has to guess how one get to sentence n+1 from sentence n. There must be some connection, one would expect, but what is it?

Spirit of collegiality issues aside, the way the article stands now it has a block of incomprehensible text to stymie the progress of any reader. That result, regardless of whether DParlevliet has yet been led to understand what his syntax problems are, is not one that serves the interests of Wikipedia or its readership.

A more colleague-friendly way to take up a change you think is needed would be to state on the discussion page first what you think is wrong with the present text and see whether other people can understand and accept your critique.

I think it must also be kept in mind that this spinning arrow "clock" that Feynman used in his presentation to non-physicists is a huge simplification. On top of that, if I remember correctly, he posits a detector in or near one of the slits that could detect a photon but let it pass on through. Unless I've missed something, there is no such detector. The fact is that how a photon is judged to have passed through the double-slit apparatus always involves a human construction, placed on observables, that pretends to tell us about unobservables. Also we need to remember that the whole discussion is a huge simplification of [quantum electrodynamics]. So if we use the Feynman model to discuss the double-slit experiment, we must be careful not to claim too much for it. P0M (talk) 02:03, 21 May 2014 (UTC)

You need to source your work also, DParlevliet. You have been warned about this on this page before. You replaced a version which had 5 sources with your own completely unsourced version, and then you reverted when I removed it for lack of sources. Please read WP:VERIFIABILITY. "Any material lacking a reliable source directly supporting it may be removed and should not be replaced without an inline citation to a reliable source." You can be blocked for edit-warring. --ChetvornoTALK 03:11, 21 May 2014 (UTC)
First of all, only part of the text is mine. All essential was there before. I only added how Feynman started with the idea of placing detectors at the slits which would remove the interference, with the explanation from his well known lectures. If language is not right, then improve. If something is wrong, then improve or explain here. If there is lack of references, then place "citations needed" where needed. That is wiki-principle, in stead of deleting all.DParlevliet (talk) 08:32, 21 May 2014 (UTC)
I have reverted again ([1]) and gave an edit warring warning on your talk page ([2]). - DVdm (talk) 10:47, 21 May 2014 (UTC)
DParlevliet, besides your English, which is bad enough to make your argument incomprehensible to many readers, your discussion of Feynman's path integral formulation is not really relevant to the issue. The argument you are trying to make is that to create an interference pattern, you need a contribution from both slits; the particle (or wavefunction) needs to be able to reach the screen from both slits. And any detector capable of giving "which path" information will prevent the particle from reaching the screen from that slit. The last statement is not necessarily true. Neither the DParlevliet version nor the old version really addresses the issue of "which path" information. --ChetvornoTALK 13:33, 21 May 2014 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── DParlevliet, it's time to propose your changes on the talk page first, and not in the article. It's more respectful to the other editors. If the formal English that is needed for the article is getting in your way, then please put your version on the talk page or in a draft. But please work it out by yourself, or with others, before posting it to the article page, using the consensus of the community of editors of this article. Coöperation is no small thing. The small things add up to a larger impression that gets in the way of a better article. --Ancheta Wis   (talk | contribs) 14:16, 21 May 2014 (UTC)

Edits must be discussed first when they are controversial, but what I wrote was just the standard explanation of Feynman's detectors, which was already mentioned in the article. See above, there is no explanation in detail about what is wrong, anyway nothing which according Wiki-rules justify deleting. I have written a lot in Wikipedia and only get small adjustments of language, so that cannot be that bad. DParlevliet (talk) 14:44, 21 May 2014 (UTC)

Note - blocked for a week. Meanwhile DParlevliet reverted again to the faulty version. I guess that this edit can safely be undone. - DVdm (talk) 17:51, 21 May 2014 (UTC)

David Deutsch[edit]

David Deutsch says in his book The Fabric of Reality that the Double-slit experiment is a proof for those who argue that Multiverse is real.

The article says nothing regarding the Many-worlds interpretation. May I inquiry why not?

Kartasto (talk) 14:51, 14 July 2014 (UTC)

Please give a page number and a quote to back this up. --Ancheta Wis   (talk | contribs) 15:56, 14 July 2014 (UTC)
The Fabric of the reality, whole chapter 2. Here:[3] is more I suppose...

Kartasto (talk) 16:05, 14 July 2014 (UTC)

The one-line writeup for MWI is making it look fringe, and giving Copenhagen first place and starting its writeup with the word "consensus" is making it look favored. (talk) 10:44, 13 April 2015 (UTC)

Single photon experiments[edit]

An article on Single photon experiments[1] gives a critique of a proposed experiment, to revisit whether a linearly polarized photon state must be a superposition of a pair of circularly polarized photons or not. --Ancheta Wis   (talk | contribs) 02:33, 27 July 2014 (UTC)

  1. ^ Chris Lee (July 26, 2014) Ars Technica

New image in lead[edit]

I'm not crazy about the image that has been added to the lead, and its caption. Over the years the lead has been crafted to avoid stating that particles go through the slits. But the image clearly shows particles at the slits, which is probably only a minority interpretation. For anyone trying to understand wave–particle duality and the significance of the experiment, I feel that the image adds more confusion than clarification. -Jordgette [talk] 03:59, 13 January 2015 (UTC)

I agree. I'm sure the editor who added it meant well, but because there is so much confusion about this experiment, it is important to avoid showing a diagram that might give readers the wrong idea. --ChetvornoTALK 06:32, 13 January 2015 (UTC)
Still it is a very common image which you can find everywhere on the internet, I think also on university sites. An image below shows electons, which is based on the same. Therefore it is better to explain then to remove. Even if it would be a minority, then it is a large one.DParlevliet (talk) 08:25, 13 January 2015 (UTC)
Just because it is common does not change the fact that it is bad. There are lots of other double-slit diagrams on Commons. For example [4] shows only a single electron as both a particle and a wave. Or one that just shows waves [5]. If the diagram shows an interference pattern, it shouldn't show particles between the emitter and screen, to avoid giving readers the erroneous notion that the electron follows a "trajectory". --ChetvornoTALK 09:17, 13 January 2015 (UTC)
@Jordgette: I'm the one who added the image. Yes, maybe you are right. Feel free to modify it, or wait until I find a better one myself. I just think that there must be some kind of illustration in the lead. Tetra quark (don't be shy) 15:47, 13 January 2015 (UTC)

Time to step away from the keyboard[edit]

@Kpvats: It's time to stop, please. The encyclopedia has well-known rules, such as the three-revert rule, which you should defer to, or risk being reverted and blocked. --Ancheta Wis   (talk | contribs) 19:42, 18 October 2015 (UTC)

For what it's worth, 'rm' is the Unix command for 'remove'. In the early days (2001), every editor on the encyclopedia was Unix-literate, typically knowing HTML, etc., and the customary edit summary messages stem from this history of tech-speak. --Ancheta Wis   (talk | contribs) 19:46, 18 October 2015 (UTC)

@Kpvats:, Ancheta Wis is right. Your addition doesn't make any sense to me either, and has no sources. See WP:Verfiability:"Any material lacking a reliable source directly supporting it may be removed and should not be restored without an inline citation to a reliable source." Wikipedia works by WP:CONSENSUS; if material you add is controversial you should discuss it first here on the Talk page, rather than just reverting. The electrons do not distinguish between the screen and any other method of observation. Your unsourced addition looks to me like WP:ORIGINAL RESEARCH i.e. your own private opinions. Where are you getting this from? Please read WP:EDIT WARRING. If you don't stop edit warring, I will report you and you could be blocked. --ChetvornoTALK 22:56, 18 October 2015 (UTC)
Given the user's edits on Dark matter, I think they're trying to make a WP:POINT of some sort. I already explained on their talk page that unsourced additions are unsuitable for Wikipedia so it's concerning that they continued to do it on another article. clpo13(talk) 23:34, 18 October 2015 (UTC)


As someone who studied the Double-slit experiment as an undergrad who now works with the invisible sort of electromagnetic radiation a daily basis as an Engineer, I'm now very seriously questioning the results of this experiment. It seems the detector equipment was simply operating near its signal-to-noise ratio detection limit, and thus sometimes detecting a "photon" on one side and not the other. In this explanation the wave is present in both slits and not registering with the detection equipment on both sides at the same time due to lack of signal strength. Can someone please provide a reference that would put my mind at ease? — Preceding unsigned comment added by Einslaten (talkcontribs) 21:16, 3 December 2015 (UTC)

At very low intensity, firing one photon at a time, detectors at both slits never both fire. It's always one or the other. Or, take the slits away -- any time you have particles and detectors, only one detector ever fires per particle; that's uncontroversial in quantum mechanics. Does that help? Perhaps you can be more specific about what claim in the article you're questioning. -Jordgette [talk] 21:35, 3 December 2015 (UTC)
If you believe you are able to fire a single photon as sensed by your detectors, then you should be able to setup an experiment such that detectors are setup at varying distances from the source of the single photon. The amplitude of electromagnetic radiation decreases according to the inverse square law, so you should be able to show that more than one "photon" arrives at detectors closer to the signal source, and prove the "photon" theory is false. Einslaten (talk) 22:19, 3 December 2015 (UTC)
The double slit experiment is extremely well studied and the statements in this article are fairly well sourced. Which specific statements in the article do you question, Einslaten? BTW, it helps readers if you sign your posts by typing ~~~~ after them. --ChetvornoTALK 22:07, 3 December 2015 (UTC)
I question the circular link between the signal source and signal detector, and would like to see a reference to an article that proves a single photon can be emitted by a signal source. Einslaten (talk) 22:19, 3 December 2015 (UTC)
Emission of photons is of course a random process, but basically all you have to do is turn down the intensity of your light source until it is emitting on average one photon a second, or one photon a minute, or whatever rate you want, at which rate only one photon is present in the experimental apparatus at a time. As you mentioned it's not all that easy an experiment because noise due to black body radiation has to be carefully excluded. Here are some sources confirming that the single-photon double slit experiment has been done: [6], [7], [8], [9], [10] I'll add them to the article since that section may not be well-enough sourced. --ChetvornoTALK 22:56, 3 December 2015 (UTC)
None of these references address the explanation that the detection is simply a result of momentarily exceeding the signal-to-noise ratio requirement of the receiver. All electromagnetic wave receivers exhibit a signal to noise ratio requirement. Go buy one and look at the specs, but I guess it's asking to much to look at the Engineering details. (talk) 00:15, 6 December 2015 (UTC)
Yes, it really is. This Talk page is for discussion of the article, not for discussion of the experiment. The article seems to be based on WP:reliable sources which represent the present understanding of the physics profession, traceable to articles in peer-reviewed journals. If you feel we are using bogus sources, or misrepresenting what the sources say, that would be something to discuss here. If you disagree with the sources themselves, that would be something to take up with the authors. --ChetvornoTALK 00:48, 6 December 2015 (UTC)