An event is an observed change of significant status within the immeasurably vast chaos of energy reconfigurations. Events are happenings which have been perceived, noted and tagged with whatever significance is appropriate. A drop of water falling into a container or a single leaf sinking below the surface need not be thought of as events at all unless the fall of that specific drop of water, or the sinking of that specific leaf, has been identified as being a happening of noteworthy importance. Until some awareness determines to partition a time-bite of an activity with some sort of observational significance, then no event of any sort need to be deemed as having occurred.

It is observationally impossible to detect an instantaneous event. A light does not come on instantly...even in the brain. Plants do not grow instantly...although certain weeds appear to do so. Miracles always require an intense period of whining invocation. Rumours are constrained to spread at the speed of light.

Since an event has a duration it must have a beginning and an end which are themselves events having beginnings and ends. Consider the event of a drop of water impacting a fluid surface. Such an event is of sufficiently small duration, compared to the everyday passage of time for a human, that it would usually be treated as if it were instantaneous. By comparison the sinking of a leaf might take some hours or even days. As a consequence the allocation of a beginning event and an end event to the sinking process is more easily carried out. We are generally quite comfortable in assuming that the beginning and end events of a process are instantaneous, but on a smaller time-scale this is clearly not the case. The beginning of the drop impacting the fluid surface might be designated to be when the first deflections of the fluid surfaces had been detected, but it might just as easily be chosen to be when the surface tension of one or the other had been disrupted. The end of the event might be selected to be when the rebound droplet had collapsed back into the body of the fluid, but would be just as reasonable to require all the ripple perturbations to have attenuated away into the background chaos. Whichsoever of these events were to be chosen as the actual start event, technology would need to be developed to measure time on a much briefer scale. Shifting attention from the macro event of a raindrop being the beginning of a thunderstorm, to the micro events which were the beginning and end of the raindrop event, merely increases the level of technological expertise required to determine the beginning and end of a much briefer event.

An event has a duration, marked by the choice of a beginning event and an end event.