Talk:Double-slit experiment

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)

I'm a bit curious about the simulation: How is it constructed? (i.e. what equations describe it) ...is the wave packet demonstrated a solution to the Klein-Gordon equation or how does it work? I assume the walls are chosen to be completely reflective? ----ChrisLHC (talk) 14:46, 29 May 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)

When you say bombarding the experiment with interference, I think what you mean is bombarding the experiment with environmental photons. They've already thought of that; it's called decoherence. -Jordgette [talk] 22:33, 2 May 2013 (UTC)

That's a nice long read, I'll get to that eventually but I have a concern with the title of it and the relevance of what you've said to what I've written. Thanks for your points, it is great to know that they may have thought about what I'm talking about but clearly you don't even know exactly what I'm talking about because I said exactly what I was talking about and the assumption that any photons generated from even the process of thinking would actually interfere with this experiment directly are what you are implying and that is not what I am implying at all. There are however, other forms of radiation (after all it must be some form of radiation) that is interacting with the experiment to cause a change. And the source doesn't have to be human thought but could easily be it (and has been proven to be an effector of the double slit phenomenon) and the other obvious candidate is the "observer". There are more than enough sources of interference present in all that can be considered the observer, and one would have to create an observer that doesn't interfere with such a highly sentative experiment before getting close to saying that there is actually a quantum phenomenon taking place here. Afterall, this is a one major hole, and you don't need to be a quantum physicist to see it. Logic, also a science that many are familiar with (said many void here, except myself as far as I can tell), can easily shed photons on this massive hole for all to see.208.97.104.82 (talk) 23:39, 29 May 2013 (UTC)

I think the "change" you speak of is caused simply by the setup of the experiment. Set it up a different way, with a different slit separation for example, and the wave function will "collapse" in a different manner such that the interactions are consistent with the laws of physics. That aspect of QM isn't controversial or interesting. And, there are experiments called weak measurements that do what you describe, and no results have been found that are inconsistent with the predictions of QM. -Jordgette [talk] 18:19, 30 May 2013 (UTC)

I suppose I wasn't clear enough. I will describe what I'm talking about again. There is an experiment in which a beam of "particles" (electrons but usually a laser) is fired from the source emitter at a plate with 2 tiny slits in it. Now the experiment reports 2 different finds when "observed" and not when observed. This is specifically what I am referring to. Yes, I understand weak measurements have been tested but I don't know what theory of quantum mechanics "predicts" that when we observe phenomenons such as this, they will collapse the wave function. It doesn't matter because, and I know it has a name and whatever name it has, it simply does not take into account what I have stated above. That being that if we observe the results of the experiment without "observers" to run tests on the beam mid experiment and then run the test again with the "observers" and see different results after at the collector/deteciton screen behind, then yes we can say that the observer is obviously affecting the experiment.

The quantum leap being made here is that we are assuming there is no interference being caused by the observers, and that what is therefore happening is a quantum collapse of the wave function that is a given property of the particles fired. Anyway, it is perfectly fine that we make these leaps so long as the word "theory" is tagged on. There are still so many possible forms for interference. Even if one were to "unplug" the observer having left it in its position and then the results again show us the wave function having not collapse, then the PROPER assumption would be to see how the ELECTRICAL CURRENT is affecting the experiment. Obviously. As I said earlier, there are many forms of radiation that can be to blame. And it could even be a complex feedback or discharge effect caused by the moving electrons in the area creating magnetic fields. Do you understand what I am saying?Zoele (talk) 15:46, 31 May 2013 (UTC)

I'm sorry, I don't. What is this electrical current or other forms of radiation you are proposing? Sounds like speculation or original research. There's no place in Wikipedia for that. -Jordgette [talk] 18:08, 31 May 2013 (UTC)

You may be misinterpreting the language, Zoele. In QM, "observation" means "interaction". In your double slit example, in order to "observe" the electron to determine which slit it went through, something has to interact (collide) with the electron. For example, ligphoht photons have to scatter off the electron to determine its position. The momentum change caused by the collision destroys the coherence of the wavefunction ("collapsing" it) so the interference pattern is lost. --Chetvorno^TALK 19:59, 31 May 2013 (UTC)

Chetvorno understands. He also clarified it for me. Jordgette you are a bit too defensive of Wikipedia here. Nothing I spoke about was speculation. The only thing I didn't realise was that they consider any observation an interaction in Quantum physics. Light having to impact an electron to figure out where its going. However, there are still many other methods of observation that you yourself Jordgette linked to under weak measurements. These are also observations of a sort and their electromagnetic signatures are almost non existent. We can observe the wavefunction almost as it happens with such methods. Again, the broad issue is the generality of stating that simply observing is enough to collapse a wave function, when in truth, observations are inherently removed from subjects happenings. For example, if you watch a car crash happening before you, your photons shouldn't be affecting the carcrash anymore than the photons reflected off of anything else in the area. Now, at the quantum level, due to Heisenberg, yeah, we can't actually see an electron (well we can see the path it took) or a photon (we can't determine its position), which is infact what this whole experiment is truthfully reminding us. The way that it is still erroneously presented is that general observations, which therefore is a generality and can allude to any observation, including the type that would not have the following effect, collapse wave functions. This is simply invalid to state like this. Thanks for the clarification Chetvorno. Jordgette, open your mind. This isn't speculation, this is questioning scientific report. Something Wikipedians try to assume they're often immune from due to their propietary standards and organization. And just for you Jordgette, the observers they would be using that WOULD affect these experiments often have power supplies running through them which, by nature, being close to the experiment, could affect the experiment near the observation. A magnetic detector that can sense electrons moving through a slit will be proejecting a magnetic field which will have to be altered for it to know something has passed through. This might be a strong enough effect to actually collapse the wave function. Call it speculation, but theory is just as speculative, and its all over Wikipedia. You don't know what you're talking about Jordgette.