So I read that in double slit systems the intensity of the "particle" source does not matter. If it is known that only one particle is in the system at a time, the interference pattern will be the same as observed when there are multiple particles in the system. From this we can conclude that the particle is interfering with itself. What puzzles me is this. Let;s say we have multiple electrons in the system. Shouldn't they repel one another and hence blur the interference pattern? Even if they didn't repel one another, wouldn't the phase of one electron be random with respect to the phase of any other, and this would eliminate the interference pattern except for the case of the electron interfering with itself. So I have something wrong here. What is it?