Reference: Disturbance Theory
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Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future. Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions.
Time is the experience of change. Such changes are from ephemeral to enduring. Continual changes have the characteristics of sequence. The sequence may reverse but from the viewpoint of experience the direction of change is always “forward”. Real time always refers to changes in physical extensions. Therefore, in the absence of matter and field there are no extensions and no time.
Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars. Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems.
Time has always been measured relative to changes in material aspects, whether in religion, philosophy, or science.
Two contrasting viewpoints on time divide prominent philosophers. One view is that time is part of the fundamental structure of the universe—a dimension independent of events, in which events occur in sequence. Isaac Newton subscribed to this realist view, and hence it is sometimes referred to as Newtonian time. 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 and Immanuel Kant, holds that time is neither an event nor a thing, and thus is not itself measurable nor can it be travelled.
Newtonian time is measured objectively with respect to changes in matter. But Leibniz and Kant view time subjectively as an abstraction.
Time in physics is unambiguously operationally defined as “what a clock reads”. See Units of Time. Time is one of the seven fundamental physical quantities in both the International System of Units and International System of Quantities. Time is used to define other quantities—such as velocity—so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life. The operational definition leaves aside the question whether there is something called time, apart from the counting activity just mentioned, that flows and that can be measured. Investigations of a single continuum called spacetime bring questions about space into questions about time, questions that have their roots in the works of early students of natural philosophy.
The clock time is Newtonian time because a clock is made up of matter. When we consider field that underlies matter, the changes in the extension of the field appear as time, such that the extension and its change maintain a constant ratio ‘c’. In other words, the extensions of the field can change only at a certain rate determined by ‘c’. In abstract terms, neither space nor time can be considered independently of each other, as they occur in a fixed relationship.
Temporal measurement has occupied scientists and technologists, and was a prime motivation in navigation and 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 by measuring the electronic transition frequency of caesium atoms. 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 life spans.
The objectivity of time has improved with the discovery of the field. The subjectivity of time is felt very strongly as always.
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