Perfect. Why? If effects from causes occurred immediately, versus with a distinct delay, everything would occur at once (or loop forever, that's a bug). Henc

Perfect. Why? If effects from causes occurred immediately, versus with a distinct delay, everything would occur at once (or loop forever, that's a bug). Hence, because we can observe that things happen "in sequence", there is a "propagation delay". That's what time is: "Time: the process whereby effects occur after causes, in a step by step manner".