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Assume a double slit experiment with electrons and no observer (light source). Can the wave-like behavior and resulting interference pattern be explained by the single electron that is being shot, doesn't really travel to the detector, but interacts with other electrons in the medium (e.g. air) between source (electron gun) and target (detector), and this creates the wave? I imagine it as if the shot electron is repelled from other electrons and they again repel other electrons and so forth.

Furthermore, in case of a light source acting as an observer. Could they interact electromagnetically with all these electrons, between the source and target, in a way that the electrons are not moving freely and repel each other. But, acts a contiguous block and the shot electron hits the first electron, that transfers the energy to the second electron, then to the next until the last electron hits the detector. Similarly to Newton's cradle?

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Let me first point out that the double-slit experiment is a Gedankenexperiment, designed to illustrate quantum mechanics - not some puzzling observation requiring explanation. What happens in this experiment is a consequence of the wave-like nature of electrons when described by Schrödinger's equation - the math is nearly exactly the same as for the two-slit experiment in optics (i.e., for waves described by Maxwell equations).

Furthermore, descriptions of the experiment usually resort to language like "electrons are emitted one by one", to stress that we have created all the conditions to avoid that two or more electrons are present at the same time. One could even say that the next electron is emitted after the previous one has been detected on the screen. This is just "classical" interference... applied to electrons.

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    $\begingroup$ But the Davisson-Germer experiment (en.wikipedia.org/wiki/Davisson%E2%80%93Germer_experiment) was not a gedankenexperiment, and was not even intended to discover electron diffraction. They were unaware of DeBroglie's wave hypothesis, and their work preceded and partly motivated Schrödinger's equation. $\endgroup$
    – John Doty
    Jul 4 at 16:36
  • $\begingroup$ @JohnDoty There were several experimental facts that motivated development of quantum mechanics, and any good QM book outlines them. Two-slit experiment is however a pedagogical tool to illustrate a specific point (diffraction on a slit) - it is not make it or break it test for QM. $\endgroup$ Jul 4 at 16:45
  • $\begingroup$ The difference between two-slit diffraction and other forms of diffraction is is theoretically trivial. Same physics, same math. Focusing on the "two slit" aspect of the question misses the point, since the same issues arise in any diffraction experiment. And, as @annav points out, the two-slit version has been performed, too. $\endgroup$
    – John Doty
    Jul 4 at 16:53
  • $\begingroup$ @JohnDoty in a real experiment there are indeed lots of complicated factors - like, e.g., phase rigidity in solid state AB interferometers. The textbook two-slit experiment is however tailored to exclude any such complications - the very text that students usually skip (no offense intended). $\endgroup$ Jul 4 at 19:27
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    $\begingroup$ If you want to call idealizations of real experiments gedankenexperiments, 99% of experiments covered by textbooks are gedanken, and you've drained the term of its meaning. $\endgroup$
    – John Doty
    Jul 4 at 19:57
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No, the experimental evidence does not support the idea that the interference patterns are created in the way you suggest. Aside from the fact that experiments have been performed in a vacuum, which rules out the idea that the incoming electrons are interacting with other particles in their path, diffraction experiments have also been performed with other types of particles, including neutrons, for example, which don't interact in the way that charged particles do and yet the interference effects are still produced. The effects also seem to be largely independent of the material surrounding the slits.

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No not like Newton's cradle. Experiments with electron beams are done in vacuum.

The EM field is responsible for the interaction of the electron with its surroundings (the starting electrode, the slit, the detector, the walls of the chamber, etc). The EM field fills all space! A famous theory is from Richard Feynman, he stated that every photon determines its own path and the same can be said for the electron. Following Feynman's theory for light we realize that photons prefer (higher probability) paths and do not prefer other paths (lower probability). Feynman used his path integral method to calculate the paths and it agrees with the DSE. IN the DSE for photons there are NO photons landing in the dark areas, all photons land in the bright areas .... the same is true for electrons.

The EM field is very dynamic and works at the speed of light, even before the excited electron even leaves the electrode to begin its path many forces are occurring .... these forces influence the path.

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