First of all, I am new to this forum but I already appreciate the great efforts invested here and the quality of many of the discussions!! This is all pretty neat! My mind has just been blown by reading about the "Quantum Eraser" experiment.. It shows that it is the availability of the "which-path" information (which slit has the particle gone through?) that makes the particle wave collapse, and not the existence of the detectors.. How far can we push this? Or (metaphorically) how far is nature ready to go to prevent us from accessing both the position and the momentum information at the same time. So if we do the double slit experiment in the version where there is a detector that tells you which slit each particle went though.. We do the experiment in a closed room where no-one is inside. And we record the outcome of the detector in the RAM of a PC.. We also record whatever shows on the screen in a video footage. Then, before getting into the room, we unplug the PC so that all the detector information is irreversibly lost.. and we finally play the video footage. What will we see on the recorded video? A two band pattern? Or an interference pattern? If it is the former, then where do we draw the line between this RAM experiment and the Quantum Eraser experiment?