ABSTRACT
In search of natural laws that govern a phenomenon, science often faces “events” that may or may not occur. The event of disintegration of a given atom of radium is one such example because, in any given time interval, such an atom may or may not disintegrate. The event of finding no defect during inspection of a microwave oven is another example, since an inspector may or may not find defects in the microwave oven. The event that an orbital satellite in space is at a certain position is a third example. In any experiment, an event that may or may not occur is called random. If the occurrence of an event is inevitable, it is called certain, and if it can never occur, it is called impossible. For example, the event that an object travels faster than light is impossible, and the event that in a thunderstorm flashes of lightning precede any thunder echoes is certain.
