When working in spacetime the focus shifts from consideration of objects to consideration of events. An event is something that takes place, an occurrence. An event might be a collision between two objects for example. Such an event is not point-like either in space or time but we normally consider its extent in space and its duration to be small enough in the context that the event may be located in spacetime by four coordinates (x,y,z,t). Usually we associate events with active state changes. A more subtle event might be "object found here". That particular event allows us to track the motion of an object in spacetime.

Events may be broken down into a series of state changes in the system involved in the event . Just as events may be considered to be made up of state changes, state changes may consist of a number of events. The shift in viewpoint accompanies a change in the spacetime scale used to examine the event or state change. For example at a large scale, a bat striking a baseball may be an event. At a smaller scale the event consist of changes in state of a number of bat and ball atoms. At still smaller scales the rules of quantum mechanics require a different way of looking events and state changes.

There is usually an implicit assumption about events that they are not causeless. Events thought to be causeless used to be called miracles. An acceptable explanation for an apparently causeless event was that it was "the will of God". With the advance of science it was found that many previously "causeless" events in fact had perfectly natural causes so it became the custom, when faced with an apparently causeless event, to label it "cause unknown" rather than "the will of God". We have not as of this date explained all events but we have quit thinking of them as causeless. I wonder if that is a mistake.

Remember that events are just human conveniences to help us organize out thinking. As far as I know, nature takes no notice of the beginning or end of events. Time appears to just flows along in a continuum of infinitesimal instants.