To check my understanding, imagine this scenario: You have a very small surface rigged as a light detector (the contact surface is let's say a single atom). You then fire off single photons towards it. As soon as you get a read on the detector, you know very precisely where the light is/was, and you could also know the energy of the photon very precisely because the atom would only accept a certain energy level. One might also imagine that the path the light took was a straight line between the emitter and receiver, but I suppose it wouldn't necessary have to be, therefore an uncertainty in momentum. So would the uncertainty principle in this case come down to just the direction the photon comes from?