Suppose that one put all the apparatus for the double-slit experiment in a room, with a detector at one of the slits. Then, you record the the "which path" information that the detector makes in the computer. After however many min. it takes to make a pattern, the computer deletes the which path information. It is vital that through all this time there are no people looking at the computer, or the double-slit apparatus. After the computer deletes the the which path information, a person checks if there is an interference pattern or not. If there is interference, then the computer must have changed the past by deleting the which path information. In fact, it would have to change the pattern that had already been created. But if there is no interference, then the photons have been "fooled". But I feel certain that if the detector made a buzzer go off whenever a photon went through the left slit, then there would've been interference. I believe that this could have huge repercussions.