another way to locate a photon is to make it go through a small place. knowing when the light source sends out a photon, and knowing the speed of light, we can know when it must be going through a hole in a plate put in the center of its path to the film. we can gradually get closer and closer to finding out exactly where it is in the middle of its flight. however, the path that it will take from there on becomes progressively wild. that is because when a photon goes through a hole like that it experiences diffraction.