Now, I heard this example from one of my professor 4 years ago when I first entered university, and at that I had some objections (and I still do), because, I think, if we flick our wrist fast enough, the spot on the moon will not be a continuous spot, but that spot will be like "$. \quad .\quad . \quad . \quad .$", as if we as turning on and off the light while moving it, and these ideas led me to the following question:
Lets shoot a two photon onto a reflective surface, and observe where the photons hit the surface;
What conditions should be satisfied so that we can differentiate the points where the photons collided with the surface ?