User:Yamara/Time
From Wikipedia, the free encyclopedia
Time is a basic component of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects. Time has been a major subject of religion, philosophy, and science, but defining time in a non-controversial manner applicable to all fields of study has consistently eluded the greatest scholars.
In physics and other sciences, time is considered one of the few fundamental quantities.[2] Time is used to define other quantites – such as velocity – and defining time in terms of such quantities would result in circularity of definition.[3] Within science, the only definition needed or possible is an operational one, in which a procedure is given for defining the base unit of time (the second).
Among philosophers, there are two distinct viewpoints on time. One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence. Sir Isaac Newton subscribed to this realist view, and hence it is sometimes referred to as Newtonian time.[4][5] The opposing view is that time does not refer to any kind of "container" that events and objects "move through", nor to any entity that "flows", but that it is instead part of a fundamental intellectual structure (together with space and number) within which humans sequence and compare events. This second view, in the tradition of Gottfried Leibniz[6] and Immanuel Kant,[7][8] holds that time cannot itself be measured.
Temporal measurement has occupied scientists and technologists, and was a prime motivation in astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart. Currently, the international unit of time, the second, is defined as a certain number of hyperfine transitions in caesium atoms (see below). Time is also of significant social importance, having economic value ("time is money") as well as personal value, due to an awareness of the limited time in each day and in human lifespans.