> Duane’s Law says that if a body is periodic in space in a given direction then momentum exchanges in that direction are quantized. That means that the emergin

> Duane’s Law says that if a body is periodic in space in a given direction then momentum exchanges in that direction are quantized. That means that the emerging electron is more likely to go in certain directions than in others, depending on how many quanta of sideways momentum are exchanged. Guess what? When a stream of electrons is sent through, a ‘diffraction’ pattern results. If this "direction preferentiality" were all that were needed to cause a diffraction pattern, then we should see it if we run the experiment with one slit closed for a while, and then the other slit closed for a while. But that's not what happens! If you send particles through only one slit, you do not get a diffraction pattern! (Actually you do, but the valleys are spaced far wider than those with both slits open.) No diffraction pattern = no valleys. Running the experiment again with the other slit closed can't add those valleys in. This is logically no different than individual electrons simply "randomly" entering alternate slits, so that can't make a diffraction pattern either. What am I missing? It seems like the author is trying to explain double-slit purely in terms of statistical ensembles of quantum-ish particles rather than exploiting the full generality of quantum fields, which makes no sense simply by looking at the results of a single- vs. double-slit setup. (e.g. https://en.wikipedia.org/wiki/Double-slit_experiment#/media/File:Single_slit_and_double_slit2.jpg https://en.wikipedia.org/wiki/Double-slit_experiment#/media/...)