Question I cannot seem to understand regarding the light shot through a slit. Changing when observed. How does anyone know what the light does when it's not observed... If they aren't observing it? "Oh the light passes through both when not observed but when we so observe it, it acts like a single photon." Well if we can't see it being in two places at one time, how did anyone know it was in two places at once? Unless someone observed it?