Would someone help me to understand what would happen in this situation. w→ x→ (y)→ z Photon emitter is at point w emitting photons one at a time. Double slit is at point x. Screen is at point z. There is a detector at point y (after photon has already passed through slits) which is capable of recording which slit the photon passed through. The detector marks this on a piece of paper within a closed box that is inaccessible to any human. What would be seen on the screen, an interference pattern, or not? The question has to do with whether it is the actual instrument (detector at point y) that causes collapse of the wave function, or the observation by a sentient being (human). If the human does not see the results, and cannot ever see the result (let's say the paper is burned by the recording instrument after recording before anyone can see the result) would it still result in interference. Thanks for your help.