This post will discuss quantum mechanics, or more specifically, the so called double-slit experiment performed on particles such as electrons. For the reader who feels a need to refresh their quantum mechanics, I suggest first browsing through the following articles:
There seems to be ample experimental evidence to show that certain quantities such as energy and angular momentum are quantized at the microscopic scale. For example, Planck's quantized energy packets of light managed to explain the blackbody radiation formula plus the photoelectric effect, and Bohr's quantization of the angular momentum of the electron orbits around the atomic nucleus did a good first job at explaining the observed energy levels of the hydrogen atom. However, what has been most contentious are the various meta-physical extrapolations that people have made out of the various quantum mechanical concepts. Most famous is the seemingly endless discussion about the interpretation of the particle wave-function surrounding the "measurement problem" and its resolution in a hypothetical multiverse. Experimental evidence for the "action-on-distance", as implied by the Copenhagen interpretation, seem to be anecdotal with the possible exception of the so called double-slit experiment carried out on electrons:
The interference pattern seems to indicate that the "electron-wave" passes through both slits simultaneously with a resulting constructive and destructive interference similar to that of light. As a first critical observation on the above illustration, there doesn't seem to be any limit as to large the distance D between the slits is allowed to be. Is it plausible to believe that the interference would still show up if we allowed D to be, say, 1 meter large? If not, should we not at least try to find some more local explanation?
After having thought about this for a while, a purely "classical" explanation seems far fetched, and why should we necessarily seek such an explanation? Quantized phenomena are abundant on the atomic scale, but can we perhaps find a more "local" or "realist" quantum-mechanical explanation? What about the Stern-Gerlach experiment?
The only thing necessary for the electron beams to diverge according to their quantized spin seems to be a non-homogeneous magnetic field. But where does this magnetic field come from in the double-slit experiment? Well, maybe the magnetic field produced to the electron itself according to Biot-Savartz law. If we have an opening in the wall in close proximity to where the electron passes, that ought to be sufficient to produce an asymmetric magnetic field, would it not?
