For example, sound travels at 331 m/sec at STP( standard temp. (0 degrees C.) and pressure (1 atm). So at STP if you are 331 m. away from a car and someone shuts the car door, the sound takes 1 second to reach you. So the interval of time between the door closing and the sound reaching you is 1 second. My question to all of you is: What is the shortest interval of time known to man between any two occurrences? I'll give you a few days to come up with the answer before I tell you what it is. Frankie