My question is about the famous double slit experiment used in Quantum physics. In this experiment, even a single electron is behaving as a wave until hitting the phosphorus plane. It seems that Hitachi have conducted this experiment by firing electron-by-electron.
My question is what would happen if the electron gun is displaced from the middle line so electrons paths get slightly different in length. in this case, electrons passing through different paths should require different time to arrive to the Phosphorus plane. Then by measuring the time difference we can know which path the electron has selected. I know that is is not allowed by Quantum physics, but the question is why?