Concept
Time
Overview
Time is the continuous progression of existence that occurs in an apparently irreversible succession from the past, through the present, and into the future. Time dictates all forms of action, age, and causality, being 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 conscious experience. Time is often referred to as the fourth dimension and the temporal dimension, in addition to the three spatial dimensions.
Time is primarily measured in linear spans or periods, ordered from shortest to longest. Practical, human-scale measurements of time are performed using clocks and calendars, reflecting a 24-hour day collected into a 365-day year linked to the astronomical motion of the Earth. Scientific measurements of time instead vary from Planck time at the shortest to billions of years at the longest. Measurable time is believed to have effectively begun with the Big Bang 13.8 billion years ago, encompassed by the chronology of the universe. Modern physics understands time to be inextricable from space within the concept of spacetime described by general relativity. Time can therefore be dilated by velocity and matter to pass faster or slower for an external observer, though this is considered negligible outside of extreme conditions, namely relativistic speeds or the gravitational pulls of black holes.
Throughout history, time has been an important subject of study in religion, philosophy, and science. Temporal measurement has occupied scientists and technologists, and has been a prime motivation in navigation and astronomy. 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 ("carpe diem") and in human life spans.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
In the original texts
Passages from public-domain books where Time is discussed.
As it is from the disposition of visible and tangible objects we receive the idea of space, so from the succession of ideas and impressions we form the idea of time, nor is it possible for time alone ever to make its appearance, or be taken notice of by the mind. A man in a sound sleep, or strongly occupyed with one thought, is insensible of time; and according as his perceptions succeed each other with greater or…
David Hume, A Treatise of Human Nature
names the idea; a chapter is titled for it; states what it is; author linked in the graph; opens on it
4. Time is not a discursive, or as it is called, general conception, but a pure form of the sensuous intuition. Different times are merely parts of one and the same time. But the representation which can only be given by a single object is an intuition. Besides, the proposition that different times cannot be coexistent could not be derived from a general conception.
Immanuel Kant, The Critique of Pure Reason
names the idea; a chapter is titled for it; states what it is; author linked in the graph; opens on it
If, then, one of these two supposed forms of the homogeneous, namely time and space, is derived from the other, we can surmise _a priori_ that the idea of space is the fundamental datum. But, misled by the apparent simplicity of the idea of time, the philosophers who have tried to reduce one of these ideas to the other have thought that they could make extensity out of duration. While showing how they have been…
Henri Bergson, Time and Free Will
names the idea; states what it is; the book is about it; author linked in the graph; opens on it
The question is important, for, if the experience be what it roughly seems, we have a sort of special sense for pure time--a sense to which empty duration is an adequate stimulus; while if it be an illusion, it must be that our perception of time's flight, in the experiences quoted, is due to the _filling_ of the time, and to our _memory_ of a content which it had a moment previous, and which we feel to agree or…
William James, The Principles of Psychology, Volume 1
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For the same reason that the year 1737 cannot concur with the present year 1738, every moment must be distinct from, and posterior or antecedent to another. 'Tis certain then, that time, as it exists, must be composed of indivisible moments. For if in time we could never arrive at an end of division, and if each moment, as it succeeds another, were not perfectly single and indivisible, there would be an infinite…
David Hume, Philosophical Works, v. 1
names the idea; a chapter is titled for it; author linked in the graph; opens on it
Philosophers who discussed Time
- Gottfried Wilhelm Leibniz
- Zeno of Elea
- Immanuel Kant
- Hans Reichenbach
- Nagarjuna
- Numenius of Apamea
- Thomas Reid
- Chrysippus
- Plotinus
- Paul Tillich
- Ludwig Boltzmann
- Rudolf Carnap
- Eduard von Hartmann
- Strato of Lampsacus
- Pherecydes of Syros
- Ted Honderich
- Theophrastus
- J. L. Schellenberg
- Duration (philosophy)
- Tlön, Uqbar, Orbis Tertius
- Ibn Malka al-Baghdadi
- Achille Varzi (philosopher)
- Robin Le Poidevin
- Apollodorus of Seleucia
Related ideas
- B-theory of time
- French Revolution
- Ancient philosophy
- General relativity
- Greece
- Gottfried Wilhelm Leibniz
- Philosophical realism
- Second law of thermodynamics
- Henri Bergson
- Heraclitus
- Zeno of Elea
- Isaac Newton
- Immanuel Kant
- The Unreality of Time
- Loop quantum gravity
- Vedas
- Mircea Eliade
- Judaism
- Julius Caesar
- John Locke
- Future
- Judeo-Christian
- Kabbalah
- Physics (Aristotle)
Opposing perspectives
Place in the tradition
Part of Existence.