Talk:Double-slit experiment

At or on the screen

The "on the screen" .... "at the screen" language in the first paragraph is confusing (at least to me). It seems impossible that the two different patterns are occurring simultaneously "on" the screen; and yet, what could "at" mean if not "on" ?

Greg P. Hodes, Ph.D. ghodesQjuno.com — Preceding unsigned comment added by 69.76.228.125 (talk) 22:34, 26 April 2012 (UTC)

I've changed "at the screen" to "on the screen" -- meaning "on" in the sense of "spilled coffee on the table," i.e., it's a real physical position.

There are two patterns superimposed on the screen (as well as elsewhere), but they are patterns of probabilities, so they are not visible. They produce a single visible patern as a result of their interaction.P0M (talk) 00:42, 27 April 2012 (UTC)

Slits to blame for interference pattern.

There is no mention of the possibility of the slit device it's self causing the interference. It is possible, and highly probable that the particles are bouncing off the edges of the inner walls of the slit, and so mathematically according to the size, shape and depth of the slits, causing the pattern to show up. If you toss a ball towards a double slit repeatedly, some balls will bounce off the inner walls of the slit, and be sent flying to the left, some to the right, and some to the central area. It is my theory that the slit it's self is causing the interference and that a particle is not in two places at once, and that it is not interfering with it's self. If someone credible could confirm what I am talking about, or refute it then please do. Freegen (talk) 05:44, 20 June 2012 (UTC)

If what you suggest were happening, then people would have noticed that the interference patterns were changing depending on how thick the barrier was made. If you have straight-line "bullets" bouncing off the sort of window frame, you have to imagine a "rifle" that shoots inaccurately, sometimes veering left, sometimes veering right, sometimes managing to go straight and then hitting the middle ground between slits. Then you would get some bullets going straight through and some being reflected in one direction (e.g., going from heading left into the left slit to going right coming out of it). So you ought to get something like this: ||| ||||||| |||.

I'm sure that people have been aware of the possibility you suggest going all the way back to Young and the people who were discussing his experiments in his own time. The math would not support the regular bands and predictable distances that depend on slit width and slit spearation, anyway.P0M (talk) 16:21, 20 June 2012 (UTC)

Another demonstration that that is not the explanation: if you block one slit, eliminating the interference pattern, the intensity of light (number of bullets) reaching the screen will decrease in some areas and increase in others. This is the proof that the light waves from the two slits are interacting. If it was only "bullets" bouncing off the edges of the slits, closing one slit could only decrease the number of bullets reaching a given area of screen, not increase it. --Chetvorno^TALK 20:00, 20 June 2012 (UTC)

You don't have to have slits to get two beam interference - a single light beam can be split into two beams travelling in different directions by beam-splitters - they will then produce interference fringes if they overlap, e.g. Michelson, Mach Zender interferometers, Fresnel Biprism etc etc. If you block off one path, the interference fringes disappear just as when you block off one of the double-slits. The geometry of the fringes follows the same rules as two overlapping beams generated by a double slit. This sort of interferometer can be set up so that there is only one photon travelling through it at any time, and fringes will still be observed. This cannot be explained by slit edge effects. Epzcaw (talk) 19:55, 15 August 2012 (UTC)

Interpretations

Shouldn't a mention be made of Everett and DeWitt's "many worlds interpretation?" — Preceding unsigned comment added by 98.170.215.104 (talk) 03:54, 1 August 2012 (UTC)

I'm not sure how useful it would be, as many worlds doesn't offer a unique elucidation of wave–particle duality, as far as I know. The only thing I can think of is that in other worlds, one or both slits may be closed, and in those worlds there is no interference. -Jordgette [talk] 22:20, 1 August 2012 (UTC)

Figure showing double slit fringes

Double slit fringes with sodium light illumination

I suggest that this would illustrate (maybe even illuminate) double slit interference a lot more clearly than the current figure which shows a combination of interference and diffraction.

Or this one,, which is a modified version of the existing one. Epzcaw (talk) 19:40, 15 August 2012 (UTC)

The original purpose of the double image was to head off the frequent confusion between "diffraction pattern" and "interference pattern" by making the difference concrete. I would therefore prefer the modified version of the existing one. Originally I used a picture of a cruder pair of patterns made the traditional way, and in a way I preferred that pair because it showed readers a pattern that they could reproduce for themselves. The first new photo is so artifact free that it begins to look manufactured in Inkscape or something. It's too beautiful. P0M (talk) 15:45, 18 August 2012 (UTC)

Substituted second figure. I have modified the text to take the change into account Epzcaw (talk) 19:45, 23 August 2012 (UTC)

Slow GIF animation

There's a big and slow GIF animation of a double slit simulation, causing longer load time and a bit laggy when scrolling pass. Weaktofu (talk) 03:22, 16 February 2013 (UTC)

The GIF animantionn is my own work an it is no very performant. If it would be accepted I can publish two static PNGs and a hyperlink to a YOUTUBE or a WIKI video source. 88.68.119.120 (talk) 23:16, 22 February 2013 (UTC)

Dropping "s/he" construct

When this block quote was added to the article, the pronouns were modified to "he/she". Later on, another editor changed them to "s/he". But as this passage is a direct quote, I am changing the pronouns back to their original masculine form, as originally published by Časlav Brukner and Anton Zeilinger in their 2002 paper. Link to the full paper. The quoted passage is on page 3, second paragraph starting "Just to follow our example". — Preceding unsigned comment added by Ryanrs (talk • contribs) 08:53, 16 April 2013 (UTC)

No-one else sees the obvious invalidities presented by observations from these experiments?

I mean come on. It's very clear that the observer, which in these cases always does something to truthfully interact with the experiment, doesn't collapse the wave functions "just by observing" as the leaps in logic presented by the scientists running these experiments would have us believe. This is a major issue with scientists. They get stumped by often very obvious things, like the fact that the interaction of physical (electromagnetism included) properties of the so called "observers" themselves could very easily cancel a wave function property just by bombarding the experiment with interference. Where's my nobel prize? No thanks. Could scientists just stop overlooking these simple things in an attempt to, oh I dunno, try and look cool?

And no, I'm not even saying that there are cases where the simple act of observing without interference (you let me know when thats truly possible) might actually cause completely different outcomes from when the experiment is not observed. All I'm really saying is that for the most part, from what I know, this kind of true experiment hasn't happened yet. And when it does, all these people who believe that the simple act of observing was just a simple act of observing will realise that there was probably no way to even do this kind of experiment truthfully until that point in time. I would look forward to the results of that experiment there. As our understanding increases however, the double slit experiment, atleast, will be one of the first supposed quantum mechanical demonstrations to show, via true interfernceless observation, a wave pattern not collapsing so easily.

Our brains alone amplify our computer logic rendered thoughts to do things like cause our body to move. There's obviously alot of detection going on here. And at somepoint there's an electromagnetic charge generated. So its no wonder, even focused thoughts have shown interference on double slits. Essentially double slits are just our most sensitive detectors. Quantum unexplainable collapse of wave function my foot! Get back to work! (previously unsigned) Zoele (talk) 20:37, 2 May 2013 (UTC) (edited) Zoele (talk) 20:54, 2 May 2013 (UTC)