The reason your heart beats properly is due to a beautiful design and perfect timing. Imagine you could design a spark plug with a built in timer that emits an electrical spark at a set rate. Let's say this plug's timer is set for one second. So every second, this spark plug will emit a spark unless another plug nearby does so first. If a neighboring plug sparks first, the original spark plug will simply carry the electrical impulse to the next plug and restart it's own timer. We'll call the...