If you consider the photon (particle), a single photon does not go through both slits at once. It takes the path of least action. It's only when the experiment

If you consider the photon (particle), a single photon does not go through both slits at once. It takes the path of least action. It's only when the experiment is repeated that the wave-like behavior emerges. The wave function is simply a probability approximation of the least action required for any set of start and end position. So the question in the title doesn't make much sense.