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Has a totally blocking physical partition ever been used in between the slits in order to keep a particle waves to join after having gone through the two slits?

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    What is the question? Also, I don't understand how the thin material is positioned- can you draw it? – Marco Ocram Jul 31 '21 at 18:43
  • If the material is transparent then yes the experiment has been done. If semitransparent then some photons will make the pattern and some will scatter or absorb. – PhysicsDave Jul 31 '21 at 22:48
  • Will this type of experiment help to determine photon path .... no. As Dirac said " every photon interferes with itself" or put more simply by Feynman ... every photon determines its own path ... – PhysicsDave Jul 31 '21 at 23:14
  • Any double slit experiment that "knows" which slit the photon went through produces a particle result and any experiment that doesn't "know" which slit the photon went through produces a wave result, for all conceivable experiments. The double slit experiment has been "done to death", and that is always the answer that the experimenters get. – David White Aug 01 '21 at 01:17
  • Marco Ocram. They shut me down before I could edit. I am new to all of this. I have yet to spend time and find out who can close another person's post. I would think by someone who has earned some status in the computer rating system. Just a guess. Whoever knows how the rating system works gets a footing. I am going to read those fine details what of these days. The system of rating can be manipulated by the clever ones. –  Aug 01 '21 at 02:39
  • PhysicsDave. Do you know how a photon interfers with itself when the path of interference is blocked? Have you done the experiment or are you quoting without respect to context? No the partition blocks but the width can be manipulated from 1/10 mm to whatever distance from slit to see when the interference is blocked. The whole experiment is really to see if a photons goes through both slit and then recombine. If it recombines then at what distance from the slits roughly.... right? –  Aug 01 '21 at 02:46
  • Marco Ocram, the question is, if a particle does go through both slits, the obvious question is at what distance from the slits, it recombine itself. My question to you is this. Is this a reasonable question to ask or not. If it is not, would you mind giving a reason for why the question has no meaning? –  Aug 01 '21 at 02:55
  • "The whole idea behind the experiment is to find out if the particle do indeed separate, go through both slits then combine back after it passes the slits." This is why I hate descriptions of the double slit experiment as "the particle goes through both slits and interferes with itself". – BioPhysicist Aug 01 '21 at 03:22
  • BioPhysicist, I don't understand what are you actually conveing with your statement? I am left to assume that you hate the lingo because it appears as a conclusive, i.e. "the particle goes through both slits and interferes with itself". Or are you hating something else. I myself never thought it to be conclusive.... I have only read and heard that it appears to be so. So what are you hating, are you hating what I am saying as in I still don't believe it to be conclusive or the expert's position as they come across as being conclusive? –  Aug 01 '21 at 03:36
  • Nothing wrong with you. I'm saying that type of description adds more confusion than clarity. As your say, it means at some point the particle would then have to recombine. The issue is conflating the wave function with the particle itself. The wave function in the position basis has interference patterns. That doesn't necessarily mean the actual particle interferes with itself. It's a horrible description that honestly seems to be used just to sound impressive like "hey QM is weird look at me studying a weird thing". But I digress. – BioPhysicist Aug 01 '21 at 03:55
  • I understand wave function is not the same as waves in the sense of what we know of waves in everyday experience. Aside from that, I don't think at any time any of it actually becomes a particle. An electron may have mass but it is not a particle at anytime. It is either more wavy or less wavy. When a signal hits the whereabout of an electron, it makes it viberate more, causing it to have higher frequency and so it is not as wavy as it is in its natural state. The higher the frequency the more particle like the behavior. Same with photons or what have you. –  Aug 01 '21 at 04:04
  • The DSE was observed in 1810, the image was similar to water wave interference, that was the precedent. Einstein and Dirac any many others discussed it during the early years of QM. In the 1950s Feynman use path integral theory and in 1960s Japanese scientists showed that if 1 photon is fired at a time the pattern still emerges. Most of these scientists focused on the nuclear age and the DSE continued to be taught as in 1801 "interference". – PhysicsDave Aug 02 '21 at 19:29
  • Dirac said " every photon interferes with itself" or put more simply by Feynman ... every photon determines its own path. In my opinion (and others) an excited electron in an atom is already emitting many forces (virtual photons) and this is how any real photon determines its path ... thus it is not hard to imagine how a photon arrives anywhere on its own ... no interference required. – PhysicsDave Aug 02 '21 at 19:36
  • But interference will continue to be taught, mathematically it provides a similar result to Feynman path integrals. I.e. the most probable path is one that is integer (n) wavelengths in length, shortest in time ... the second most probable path is n +1 wavelengths .. etc. In a laser for example if the mirrors are not n wavelengths apart no path is possible and the laser does not last. – PhysicsDave Aug 02 '21 at 19:37

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This sounds to me like a ; see this answer for photos of a quick&dirty setup, and the other answer there for advice on constructing a more traditional two-slit system from inexpensive materials. Note that, to understand what you're seeing, you'll need to know how the single-slit diffraction pattern is "convolved" with the double-slit diffraction pattern; this is completely skipped in popular-science descriptions of the double-slit experiment, and it's even elided in some introductory textbooks.

If your partition is absorbing, you would expect to see (half of) the single-slit diffraction pattern on either side of the partition.

If your partition is reflecting (and many smooth surfaces are "glossy," and become effectively reflecting when viewed at small angles), you might recover some double-slit interference. An individual photon might reach the image plane directly, or might come instead from the reflection of the single visible slit. The quality of this reflection-slit interference pattern will depend on the smoothness of your reflecting partition; there is room for confusing non-quantum weirdness here.

If I were going to spend an afternoon trying this with a laser pointer, I would paint a microscope slide black, use two taped-together razor blades to make parallel slits in the paint, and use a piece of cardstock-weight paper as the partition. The first three versions of the setup wouldn't work because that's what building an experiment is like. But it's not immediately clear to me that you would need any expensive optical equipment, or even a partition that extends all the way to your image plane. The end goal would be a setup where you dramatically remove the paper partition downstream of the slits and the much wider double-slit interference pattern suddenly appears on your wall.

(I don't expect to have an afternoon to spend on this for quite a while. But if you do, please come back with pictures!)

rob
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