I found some very entertaining presentations of the Double-Slit Experiments at ... University of Colorado ... and it made me start thinking. The "professor" presents an example of someone shooting a machine gun through the two slits and the "student" asks why the interference can't come from the bullets hitting each other as they travel through the slits. The professor responds by reminding the student that only a single bullet can come out of the machine gun at a time preventing the bullets from interacting with one another as they travel through the slits. But what about bullets bouncing off the slit apparatus and interfering with incoming bullets. Another website ... Influence of Measurement ... explains that, if the distance between the slits is further than the distance to the machine gun, the bullets near Slit A should not be able to travel fast enough over to interfere with incoming bullets at Slit B. However, what wasn't discussed was what prevents the bullets from bouncing off the detector wall and "interfering" with incoming bullets from the other slit. Can't the interference pattern come from photons (or something similar) bouncing off the detector and interfering with the incoming photons?