A detector is a device that once it absorbs a minimum amount of energy changes its state and returns data to an observer. The energy in a wave is proportional to the wave number, or momentum, and is continuous. A wave packet of total energy equal to the minimum detection energy could interfere with itself while only being detected when the interference is constructive, as any amount of destructive interference would result in a wave below the minimum detection energy. It could never be detected in more than one location. The constructive energy of two locations, being above the minimum detection energy, would be higher than the initial energy of the packet. Does the double slit experiment for a photon seem so mysterious now?