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What is an event?

An event might be defined simply as whatever is temporally before or after anything else. In ordinary discourse, an event is a happening during which some object changes its properties. The event of the buttering of the toast involves the toast's changing from having the property of being unbuttered to having the property of being buttered. In ordinary discourse, an event has more than an infinitesimal duration, but in the technical discourse of physics, all events are composed of point events. A point event is a spacetime point's having some property other than those it has just by being a location in spacetime. The point event is the having of some property at some point in space for an instant, with no change required. For example, there is the event of a certain point in spacetime having butter. The macroscopic event of a buttering of toast is composed of an infinite number of point events involving the butter and toast. Although point events can be defined in terms of objects and properties and times in this way, point events and spacetime points actually are more basic in physics than are objects and properties. Point events are what all objects and events are made of, and spacetime points are what have the properties. The later Einstein moved away from the relational theory of time to the position that material objects are 'funny' places in the field, with the field itself being spacetime as characterized by the metric and stress-energy tensors. These metaphysical assumptions of modern science are not part of common sense, the shared background beliefs of most people. They also are not acceptable metaphysical assumptions for many philosophers. In 1936, Bertrand Russell and A. N. Whitehead developed a theory of time based on the assumption that all events in spacetime have a finite duration. However, they had to assume that any finite part of an event is an event, and this assumption is no closer to common sense than the physicist's assumption that all events are composed of point events.

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