text:
Time
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For the concept in physics, see Time in physics. For the magazine, see Time (magazine). For other uses, see Time (disambiguation).
Time
Current time (update)
00:34, 23 January 2018 (UTC)
Major concepts[show]
Past
Present
Future
Eternity
arguments for
Fields of study[show]
Archaeology
Chronology
History
Horology
Paleontology
Futurology
Philosophy[show]
Presentism
Eternalism
Event
Fatalism
Religion
Mythology
[show]
Creation
End time
Day of Judgement
Immortality
Afterlife
Reincarnation
Kalachakra
Measurement
Standards
[show]
Metric
Hexadecimal
Science
Naturalism
[show]
Chronobiology
Cosmogony
Evolution
Radiometric dating
Ultimate fate of the universe
Time in physics
Related topics[show]
Motion
Space
Spacetime
Time travel
v
t
e
Classical mechanics
F → = m a → {\displaystyle {\vec {F}}=m{\vec {a}}}
Second law of motion
History
Timeline
Branches[show]
Applied
Celestial
Continuum
Dynamics
Kinematics
Kinetics
Statics
Statistical
Fundamentals[show]
Acceleration
Angular momentum
Couple
D'Alembert's principle
Energy
kinetic
potential
Force
Frame of reference
Impulse
Inertia / Moment of inertia
Mass

Mechanical power
Mechanical work

Moment
Momentum
Space
Speed
Time
Torque
Velocity
Virtual work
Formulations[show]
Newton's laws of motion
Analytical mechanics
Lagrangian mechanics
Hamiltonian mechanics
Routhian mechanics
Hamilton–Jacobi equation
Appell's equation of motion
Udwadia–Kalaba equation
Koopman–von Neumann mechanics
Core topics[show]
Damping (ratio)
Displacement
Equations of motion
Euler's laws of motion
Fictitious force
Friction
Harmonic oscillator
Inertial / Non-inertial reference frame
Mechanics of planar particle motion
Motion (linear)
Newton's law of universal gravitation
Newton's laws of motion
Relative velocity
Rigid body
dynamics
Euler's equations
Simple harmonic motion
Vibration
Rotation[show]
Circular motion
Rotating reference frame
Centripetal force
Centrifugal force
reactive
Coriolis force
Pendulum
Tangential speed
Rotational speed
Angular acceleration / displacement / frequency / velocity
Scientists[show]
Galileo
Newton
Kepler
Horrocks
Halley
Euler
d'Alembert
Clairaut
Lagrange
Laplace
Hamilton
Poisson
Daniel Bernoulli
Johann Bernoulli
Cauchy
v
t
e
The flow of sand in an hourglass can be used to measure the passage of time. It also concretely represents the present as being between the past and the future.
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.[1][2][3] 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.[4][5][6][7] Time is often referred to as a fourth dimension, along with three spatial dimensions.[8]
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.[2][6][7][9][10][11] 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.[12][13][14]
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.[15][16] 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[17] and Immanuel Kant,[18][19] holds that time is neither an event nor a thing, and thus is not itself measurable nor can it be travelled.
Time in physics is unambiguously operationally defined as "what a clock reads".[6][17][20] 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.[21] 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.
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 (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 life spans.
Contents
[hide]
1 Temporal measurement and history
1.1 History of the calendar
1.2 History of time measurement devices
1.3 Units of time
2 Definitions and standards
2.1 World time
2.1.1 History of the development of UTC
2.1.2 The ephemeris second
2.1.3 The SI second
2.1.4 Current application of UTC
2.2 Time conversions
2.3 Sidereal time
2.4 Chronology
2.5 Time-like concepts: terminology
3 Religion
3.1 Linear and cyclical time
3.2 Time in Greek mythology
3.3 Time in Kabbalah
4 Philosophy
4.1 Time as "unreal"
5 Physical definition
5.1 Classical mechanics
5.2 Spacetime
5.3 Time dilation
5.4 Relativistic time versus Newtonian time
5.5 Arrow of time
5.6 Quantized time
6 Time travel
7 Time perception
7.1 Biopsychology
7.2 Development of awareness and understanding of time in children
7.3 Alterations
8 Use of time
9 Spatial conceptualization of time
10 See also
10.1 Books
10.2 Organizations
10.3 Miscellaneous arts and sciences
10.4 Miscellaneous units of time
11 References
12 Further reading
13 External links
Temporal measurement and history
Generally speaking, methods of temporal measurement, or chronometry, take two distinct forms: the calendar, a mathematical tool for organising intervals of time,[22] and the clock, a physical mechanism that counts the passage of time. In day-to-day life, the clock is consulted for periods less than a day whereas the calendar is consulted for periods longer than a day. Increasingly, personal electronic devices display both calendars and clocks simultaneously. The number (as on a clock dial or calendar) that marks the occurrence of a specified event as to hour or date is obtained by counting from a fiducial epoch—a central reference point.
History of the calendar
Main article: Calendar
Artifacts from the Paleolithic suggest that the moon was used to reckon time as early as 6,000 years ago.[23] Lunar calendars were among the first to appear, either 12 or 13 lunar months (either 354 or 384 days). Without intercalation to add days or months to some years, seasons quickly drift in a calendar based solely on twelve lunar months. Lunisolar calendars have a thirteenth month added to some years to make up for the difference between a full year (now known to be about 365.24 days) and a year of just twelve lunar months. The numbers twelve and thirteen came to feature prominently in many cultures, at least partly due to this relationship of months to years. Other early forms of calendars originated in Mesoamerica, particularly in ancient Mayan civilization. These calendars were religiously and astronomically based, with 18 months in a year and 20 days in a month, plus five epagomenal days at the end of the year.[24]
The reforms of Julius Caesar in 45 BC put the Roman world on a solar calendar. This Julian calendar was faulty in that its intercalation still allowed the astronomical solstices and equinoxes to advance against it by about 11 minutes per year. Pope Gregory XIII introduced a correction in 1582; the Gregorian calendar was only slowly adopted by different nations over a period of centuries, but it is now the most commonly used calendar around the world, by far.
During the French Revolution, a new clock and calendar were invented in attempt to de-Christianize time and create a more rational system in order to replace the Gregorian calendar. The French Republican Calendar's days consisted of ten hours of a hundred minutes of a hundred seconds, which marked a deviation from the 12-based duodecimal system used in many other devices by many cultures. The system was later abolished in 1806.[25]
History of time measurement devices
Horizontal sundial in Taganrog
An old kitchen clock
Main article: History of timekeeping devices
See also: Clock
A large variety of devices have been invented to measure time. The study of these devices is called horology.
An Egyptian device that dates to c.1500 BC, similar in shape to a bent T-square, measured the passage of time from the shadow cast by its crossbar on a nonlinear rule. The T was oriented eastward in the mornings. At noon, the device was turned around so that it could cast its shadow in the evening direction.[26]
A sundial uses a gnomon to cast a shadow on a set of markings calibrated to the hour. The position of the shadow marks the hour in local time. The idea to separate the day into smaller parts is credited to Egyptians because of their sundials, which operated on a duodecimal system. The importance of the number 12 is due the number of lunar cycles in a year and the number of stars used to count the passage of night.[27]
The most precise timekeeping device of the ancient world was the water clock, or clepsydra, one of which was found in the tomb of Egyptian pharaoh Amenhotep I (1525–1504 BC). They could be used to measure the hours even at night, but required manual upkeep to replenish the flow of water. The Ancient Greeks and the people from Chaldea (southeastern Mesopotamia) regularly maintained timekeeping records as an essential part of their astronomical observations. Arab inventors and engineers in particular made improvements on the use of water clocks up to the Middle Ages.[28] In the 11th century, Chinese inventors and engineers invented the first mechanical clocks driven by an escapement mechanism.
A contemporary quartz watch, 2007
The hourglass uses the flow of sand to measure the flow of time. They were used in navigation. Ferdinand Magellan used 18 glasses on each ship for his circumnavigation of the globe (1522).[29] Incense sticks and candles were, and are, commonly used to measure time in temples and churches across the globe. Waterclocks, and later, mechanical clocks, were used to mark the events of the abbeys and monasteries of the Middle Ages. Richard of Wallingford (1292–1336), abbot of St. Alban's abbey, famously built a mechanical clock as an astronomical orrery about 1330.[30][31] Great advances in accurate time-keeping were made by Galileo Galilei and especially Christiaan Huygens with the invention of pendulum driven clocks along with the invention of the minute hand by Jost Burgi.[32]
The English word clock probably comes from the Middle Dutch word klocke which, in turn, derives from the medieval Latin word clocca, which ultimately derives from Celtic and is cognate with French, Latin, and German words that mean bell. The passage of the hours at sea were marked by bells, and denoted the time (see ship's bell). The hours were marked by bells in abbeys as well as at sea.
Chip-scale atomic clocks, such as this one unveiled in 2004, are expected to greatly improve GPS location.[33]
Clocks can range from watches, to more exotic varieties such as the Clock of the Long Now. They can be driven by a variety of means, including gravity, springs, and various forms of electrical power, and regulated by a variety of means such as a pendulum.
Alarm clocks first appeared in ancient Greece around 250 BC with a water clock that would set off a whistle. This idea was later mechanized by Levi Hutchins and Seth E. Thomas.[32]
A chronometer is a portable timekeeper that meets certain precision standards. Initially, the term was used to refer to the marine chronometer, a timepiece used to determine longitude by means of celestial navigation, a precision firstly achieved by John Harrison. More recently, the term has also been applied to the chronometer watch, a watch that meets precision standards set by the Swiss agency COSC.
The most accurate timekeeping devices are atomic clocks, which are accurate to seconds in many millions of years,[34] and are used to calibrate other clocks and timekeeping instruments. Atomic clocks use the frequency of electronic transitions in certain atoms to measure the second. One of the most common atoms used is caesium, most modern atomic clocks probe caesium with microwaves to determine the frequency of these electron vibrations.[35] Since 1967, the International System of Measurements bases its unit of time, the second, on the properties of caesium atoms. SI defines the second as 9,192,631,770 cycles of the radiation that corresponds to the transition between two electron spin energy levels of the ground state of the 133Cs atom.
Today, the Global Positioning System in coordination with the Network Time Protocol can be used to synchronize timekeeping systems across the globe.
In medieval philosophical writings, the atom was a unit of time referred to as the smallest possible division of time. The earliest known occurrence in English is in Byrhtferth's Enchiridion (a science text) of 1010–1012,[36] where it was defined as 1/564 of a momentum (1½ minutes),[37] and thus equal to 15/94 of a second. It was used in the computus, the process of calculating the date of Easter.
As of May 2010[update], the smallest time interval uncertainty in direct measurements is on the order of 12 attoseconds (1.2 × 10−17 seconds), about 3.7 × 1026 Planck times.[38]
Units of time
See also: Time (Orders of magnitude) and Unit of time § List
The second (s) is the SI base unit. A minute (min) is 60 seconds in length, and an hour is 60 minutes in length. A day is 24 hours or 86,400 seconds in length.
Definitions and standards
The Mean Solar Time system defines the second as 1/86,400 of the mean solar day, which is the year-average of the solar day. The solar day is the time interval between two successive solar noons, i.e., the time interval between two successive passages of the Sun across the local meridian. The local meridian is an imaginary line that runs from celestial north pole to celestial south pole passing directly over the head of the observer. At the local meridian the Sun reaches its highest point on its daily arc across the sky.
In 1874 the British Association for the Advancement of Science introduced the CGS (centimetre/gramme/second system) combining fundamental units of length, mass and time. The second is "elastic", because tidal friction is slowing the earth's rotation rate. For use in calculating ephemerides of celestial motion, therefore, in 1952 astronomers introduced the "ephemeris second", currently defined as
the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.
[39]
The CGS system has been superseded by the Système international. The SI base unit for time is the SI second. The International System of Quantities, which incorporates the SI, also defines larger units of time equal to fixed integer multiples of one second (1 s), such as the minute, hour and day. These are not part of the SI, but may be used alongside the SI. Other units of time such as the month and the year are not equal to fixed multiples of 1 s, and instead exhibit significant variations in duration.[40]
The official SI definition of the second is as follows:[40][41]
The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
At its 1997 meeting, the CIPM affirmed that this definition refers to a caesium atom in its ground state at a temperature of 0 K.[40]
The current definition of the second, coupled with the current definition of the metre, is based on the special theory of relativity, which affirms our spacetime to be a Minkowski space. The definition of the second in mean solar time, however, is unchanged.
World time
While in theory, the concept of a single worldwide universal time-scale may have been conceived of many centuries ago, in practicality the technical ability to create and maintain such a time-scale did not become possible until the mid-19th century. The timescale adopted was Greenwich Mean Time, created in 1847. A few countries have replaced it with Coordinated Universal Time, UTC.
History of the development of UTC
With the advent of the industrial revolution, a greater understanding and agreement on the nature of time itself became increasingly necessary and helpful. In 1847 in Britain, Greenwich Mean Time (GMT) was first created for use by the British railways, the British navy, and the British shipping industry. Using telescopes, GMT was calibrated to the mean solar time at the Royal Observatory, Greenwich in the UK.
As international commerce continued to increase throughout Europe, in order to achieve a more efficiently functioning modern society, an agreed upon, and highly accurate international standard of time measurement became necessary. In order to find or determine such a time-standard, three steps had to be followed:
An internationally agreed upon time-standard had to be defined.
This new time-standard then had to be consistently and accurately measured.
The new time-standard then had to be freely shared and distributed around the world.
The development of what is now known as UTC time came about historically as an effort which first began as a collaboration between 41 nations, officially agreed to and signed at the International Meridian Conference, in Washington D.C. in 1884. At this conference, the local mean solar time at the Royal Observatory, Greenwich in England was chosen to define the "universal day", counted from 0 hours at Greenwich mean midnight. This agreed with the civil Greenwich Mean Time used on the island of Great Britain since 1847. In contrast astronomical GMT began at mean noon, i.e. astronomical day X began at noon of civil day X. The purpose of this was to keep one night's observations under one date. The civil system was adopted as of 0 hours (civil) 1 January 1925. Nautical GMT began 24 hours before astronomical GMT, at least until 1805 in the Royal Navy, but persisted much later elsewhere because it was mentioned at the 1884 conference. In 1884, the Greenwich meridian was used for two - thirds of all charts and maps as their Prime Meridian.[42]
Among the 41 nations represented at the conference, the advanced time-technologies that had already come into use in Britain were fundamental components of the agreed upon method of arriving at a universal and agreed upon international time. In 1928 Greenwich Mean Time was rebranded for scientific purposes by the International Astronomical Union as Universal Time (UT). This was to avoid confusion with the previous system where the day had begun at noon. As the general public had always begun the day at midnight the timescale continued to be presented to them as Greenwich Mean Time. By 1956, universal time had been split into various versions – UT2, which smoothed for polar motion and seasonal effects, was presented to the public as Greenwich Mean Time. Later, UT1 (which smooths only for polar motion) became the default form of UT used by astronomers and hence the form used in navigation, sunrise and sunset and moonrise and moonset tables where the name Greenwich Mean Time continues to be employed. Greenwich Mean Time is also the preferred method of describing the timescale used by legislators. Even to the present day, UT is still based on an international telescopic system. Observations at the Greenwich Observatory itself ceased in 1954, though the location is still used as the basis for the coordinate system. Because the rotational period of Earth is not perfectly constant, the duration of a second would vary if calibrated to a telescope-based standard like GMT, where the second is defined as 1/86 400 of the mean solar day.
For the better part of the first century following the "International Meridian Conference," until 1960, the methods and definitions of time-keeping that had been laid out at the conference proved to be adequate to meet time tracking needs of science. Still, with the advent of the "electronic revolution" in the latter half of the 20th century, the technologies that had been available at the time of the Convention of the Metre proved to be in need of further refinement in order to meet the needs of the ever-increasing precision that the "electronic revolution" had begun to require.
The ephemeris second
An invariable second (the "ephemeris second") had been defined, use of which removed the errors in ephemerides resulting from the use of the variable mean solar second as the time argument. In 1960 this ephemeris second was made the basis of the "coordinated universal time" which was being derived from atomic clocks. It is a specified fraction of the mean tropical year as at 1900 and, being based on historical telescope observations, corresponds roughly to the mean solar second of the early nineteenth century.[43]
The SI second
In 1967 a further step was taken with the introduction of the SI second, essentially the ephemeris second as measured by atomic clocks and formally defined in atomic terms.[44] The SI second (Standard Internationale second) is based directly on the measurement of the atomic-clock observation of the frequency oscillation of caesium atoms. It is the basis of all atomic timescales, e.g. coordinated universal time, GPS time, International Atomic Time, etc. Atomic clocks do not measure nuclear decay rates, which is a common misconception, but rather measure a certain natural vibrational frequency of caesium-133.[45] Coordinated universal time is subject to one constraint which does not affect the other atomic timescales. As it has been adopted as the civil timescale by some countries (most countries have opted to retain mean solar time) it is not permitted to deviate from GMT by more than 0.9 second. This is achieved by the occasional insertion of a leap second.
Current application of UTC
Most countries use mean solar time. Australia, Canada (Quebec only), Colombia, France, Germany, New Zealand, Papua New Guinea (Bougainville only), Paraguay, Portugal, Switzerland, the United States and Venezuela use UTC. However, UTC is widely used by the scientific community in countries where mean solar time is official. UTC time is based on the SI second, which was first defined in 1967, and is based on the use of atomic clocks. Some other less used but closely related time-standards include International Atomic Time (TAI), Terrestrial Time, and Barycentric Dynamical Time.
Between 1967 and 1971, UTC was periodically adjusted by fractional amounts of a second in order to adjust and refine for variations in mean solar time, with which it is aligned. After 1 January 1972, UTC time has been defined as being offset from atomic time by a whole number of seconds, changing only when a leap second is added to keep radio - controlled clocks synchronized with the rotation of the Earth.
The Global Positioning System also broadcasts a very precise time signal worldwide, along with instructions for converting GPS time to UTC. GPS-time is based on, and regularly synchronized with or from, UTC-time.
Earth is split up into a number of time zones. Most time zones are exactly one hour apart, and by convention compute their local time as an offset from GMT. For example, time zones at sea are based on GMT. In many locations (but not at sea) these offsets vary twice yearly due to daylight saving time transitions.
Time conversions
These conversions are accurate at the millisecond level for time systems involving earth rotation (UT1 & TT). Conversions between atomic time systems (TAI, GPS, and UTC) are accurate at the microsecond level.
System
Description
UT1
UTC
TT
TAI
GPS
UT1 Mean Solar Time UT1 UTC = UT1 - DUT1 TT = UT1 + 32.184 s + LS - DUT1 TAI = UT1 - DUT1 + LS GPS = UT1 - DUT1 + LS - 19 s
UTC Civil Time UT1 = UTC + DUT1 UTC TT = UTC + 32.184 s + LS TAI = UTC + LS GPS = UTC + LS - 19 s
TT Terrestrial (Ephemeris) Time UT1 = TT - 32.184 s - LS + DUT1 UTC = TT - 32.184 s - LS TT TAI = TT - 32.184 s GPS = TT - 51.184 s
TAI Atomic Time UT1 = TAI + DUT1 - LS UTC = TAI - LS TT = TAI + 32.184 s TAI GPS = TAI - 19 s
GPS GPS Time UT1 = GPS + DUT1 - LS + 19 s UTC = GPS - LS + 19 s TT = GPS + 51.184 s TAI = GPS + 19 s GPS
Definitions:
LS = TAI - UTC = Leap Seconds from http://maia.usno.navy.mil/ser7/tai-utc.dat
DUT1 = UT1 - UTC from http://maia.usno.navy.mil/ser7/ser7.dat or http://maia.usno.navy.mil/search/search.html
Sidereal time
Sidereal time is the measurement of time relative to a distant star (instead of solar time that is relative to the sun). It is used in astronomy to predict when a star will be overhead. Due to the orbit of the earth around the sun a sidereal day is about 4 minutes (1/366th) less than a solar day.
Chronology
Main article: Chronology
Another form of time measurement consists of studying the past. Events in the past can be ordered in a sequence (creating a chronology), and can be put into chronological groups (periodization). One of the most important systems of periodization is the geologic time scale, which is a system of periodizing the events that shaped the Earth and its life. Chronology, periodization, and interpretation of the past are together known as the study of history.
Time-like concepts: terminology
The term "time" is generally used for many close but different concepts, including:
instant[46] as an object—one point on the time axes. Being an object, it has no value;
time interval[47] as an object—part of the time axes limited by two instants. Being an object, it has no value;
date[48] as a quantity characterising an instant. As a quantity, it has a value which may be expressed in a variety of ways, for example "2014-04-26T09:42:36,75" in ISO standard format, or more colloquially such as "today, 9:42 a.m.";
duration[49] as a quantity characterizing a time interval.[50] As a quantity, it has a value, such as a number of minutes, or may be described in terms of the quantities (such as times and dates) of its beginning and end.
Religion
Hindu units of time shown logarithmically
Further information: Time and fate deities
Linear and cyclical time
See also: Time cycles and Wheel of time
Ancient cultures such as Incan, Mayan, Hopi, and other Native American Tribes - plus the Babylonians, Ancient Greeks, Hinduism, Buddhism, Jainism, and others - have a concept of a wheel of time: they regard time as cyclical and quantic,[clarification needed] consisting of repeating ages that happen to every being of the Universe between birth and extinction.[citation needed]
In general, the Islamic and Judeo-Christian world-view regards time as linear[51] and directional,[52] beginning with the act of creation by God. The traditional Christian view sees time ending, teleologically,[53] with the eschatological end of the present order of things, the "end time".
In the Old Testament book Ecclesiastes, traditionally ascribed to Solomon (970–928 BC), time (as the Hebrew word עידן, זמן `iddan(age, as in "Ice age") zĕman(time) is often translated) was traditionally regarded[by whom?] as a medium for the passage of predestined events.[citation needed] (Another word, زمان" זמן" zamān, meant time fit for an event, and is used as the modern Arabic, Persian, and Hebrew equivalent to the English word "time".)
Time in Greek mythology
The Greek language denotes two distinct principles, Chronos and Kairos. The former refers to numeric, or chronological, time. The latter, literally "the right or opportune moment", relates specifically to metaphysical or Divine time. In theology, Kairos is qualitative, as opposed to quantitative.[citation needed]
In Greek mythology, Chronos (Ancient Greek: Χρόνος) is identified as the Personification of Time. His name in Greek means "time" and is alternatively spelled Chronus (Latin spelling) or Khronos. Chronos is usually portrayed as an old, wise man with a long, gray beard, such as "Father Time". Some English words whose etymological root is khronos/chronos include chronology, chronometer, chronic, anachronism, synchronise, and chronicle.
Time in Kabbalah
According to Kabbalists, "time" is a paradox[54] and an illusion.[55] Both the future and the past are recognised to be combined and simultaneously present.
Philosophy
Main articles: Philosophy of space and time and Temporal finitism
Two distinct viewpoints on time divide many prominent philosophers. 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.[16] An opposing view is that time does not refer to any kind of actually existing dimension that events and objects "move through", nor to any entity that "flows", but that it is instead an intellectual concept (together with space and number) that enables humans to sequence and compare events.[56] This second view, in the tradition of Gottfried Leibniz[17] and Immanuel Kant,[18][19] holds that space and time "do not exist in and of themselves, but ... are the product of the way we represent things", because we can know objects only as they appear to us.
Furthermore, it may be that there is a subjective component to time, but whether or not time itself is "felt", as a sensation, or is a judgment, is a matter of debate.[2][6][7][57][58]
The Vedas, the earliest texts on Indian philosophy and Hindu philosophy dating back to the late 2nd millennium BC, describe ancient Hindu cosmology, in which the universe goes through repeated cycles of creation, destruction and rebirth, with each cycle lasting 4,320 million years.[59] Ancient Greek philosophers, including Parmenides and Heraclitus, wrote essays on the nature of time.[60] Plato, in the Timaeus, identified time with the period of motion of the heavenly bodies. Aristotle, in Book IV of his Physica defined time as 'number of movement in respect of the before and after'.[61]
In Book 11 of his Confessions, St. Augustine of Hippo ruminates on the nature of time, asking, "What then is time? If no one asks me, I know: if I wish to explain it to one that asketh, I know not." He begins to define time by what it is not rather than what it is,[62] an approach similar to that taken in other negative definitions. However, Augustine ends up calling time a "distention" of the mind (Confessions 11.26) by which we simultaneously grasp the past in memory, the present by attention, and the future by expectation.
In contrast to ancient Greek philosophers who believed that the universe had an infinite past with no beginning, medieval philosophers and theologians developed the concept of the universe having a finite past with a beginning. This view is shared by Abrahamic faiths as they believe time started by creation, therefore the only thing being infinite is God and everything else, including time, is finite.
Isaac Newton believed in absolute space and absolute time; Leibniz believed that time and space are relational.[63] The differences between Leibniz's and Newton's interpretations came to a head in the famous Leibniz–Clarke correspondence.
Time is not an empirical concept. For neither co-existence nor succession would be perceived by us, if the representation of time did not exist as a foundation a priori. Without this presupposition we could not represent to ourselves that things exist together at one and the same time, or at different times, that is, contemporaneously, or in succession.
“
”
Immanuel Kant, Critique of Pure Reason (1781), trans. Vasilis Politis (London: Dent., 1991), p.54.
Immanuel Kant, in the Critique of Pure Reason, described time as an a priori intuition that allows us (together with the other a priori intuition, space) to comprehend sense experience.[64] With Kant, neither space nor time are conceived as substances, but rather both are elements of a systematic mental framework that necessarily structures the experiences of any rational agent, or observing subject. Kant thought of time as a fundamental part of an abstract conceptual framework, together with space and number, within which we sequence events, quantify their duration, and compare the motions of objects. In this view, time does not refer to any kind of entity that "flows," that objects "move through," or that is a "container" for events. Spatial measurements are used to quantify the extent of and distances between objects, and temporal measurements are used to quantify the durations of and between events. Time was designated by Kant as the purest possible schema of a pure concept or category.
Henri Bergson believed that time was neither a real homogeneous medium nor a mental construct, but possesses what he referred to as Duration. Duration, in Bergson's view, was creativity and memory as an essential component of reality.[65]
According to Martin Heidegger we do not exist inside time, we are time. Hence, the relationship to the past is a present awareness of having been, which allows the past to exist in the present. The relationship to the future is the state of anticipating a potential possibility, task, or engagement. It is related to the human propensity for caring and being concerned, which causes "being ahead of oneself" when thinking of a pending occurrence. Therefore, this concern for a potential occurrence also allows the future to exist in the present. The present becomes an experience, which is qualitative instead of quantitative. Heidegger seems to think this is the way that a linear relationship with time, or temporal existence, is broken or transcended.[66] We are not stuck in sequential time. We are able to remember the past and project into the future—we have a kind of random access to our representation of temporal existence; we can, in our thoughts, step out of (ecstasis) sequential time.[67]
Time as "unreal"
In 5th century BC Greece, Antiphon the Sophist, in a fragment preserved from his chief work On Truth, held that: "Time is not a reality (hypostasis), but a concept (noêma) or a measure (metron)." Parmenides went further, maintaining that time, motion, and change were illusions, leading to the paradoxes of his follower Zeno.[68] Time as an illusion is also a common theme in Buddhist thought.[69][70]
J. M. E. McTaggart's 1908 The Unreality of Time argues that, since every event has the characteristic of being both present and not present (i.e., future or past), that time is a self-contradictory idea (see also The flow of time).
These arguments often center on what it means for something to be unreal. Modern physicists generally believe that time is as real as space—though others, such as Julian Barbour in his book The End of Time, argue that quantum equations of the universe take their true form when expressed in the timeless realm containing every possible now or momentary configuration of the universe, called 'platonia' by Barbour.[71]
A modern philosophical theory called presentism views the past and the future as human-mind interpretations of movement instead of real parts of time (or "dimensions") which coexist with the present. This theory rejects the existence of all direct interaction with the past or the future, holding only the present as tangible. This is one of the philosophical arguments against time travel. This contrasts with eternalism (all time: present, past and future, is real) and the growing block theory (the present and the past are real, but the future is not).
Physical definition
Classical mechanics
F → = m a → {\displaystyle {\vec {F}}=m{\vec {a}}}
Second law of motion
History
Timeline
Branches[show]
Applied
Celestial
Continuum
Dynamics
Kinematics
Kinetics
Statics
Statistical
Fundamentals[hide]
Acceleration
Angular momentum
Couple
D'Alembert's principle
Energy
kinetic
potential
Force
Frame of reference
Impulse
Inertia / Moment of inertia
Mass

Mechanical power
Mechanical work

Moment
Momentum
Space
Speed
Time
Torque
Velocity
Virtual work
Formulations[show]
Newton's laws of motion
Analytical mechanics
Lagrangian mechanics
Hamiltonian mechanics
Routhian mechanics
Hamilton–Jacobi equation
Appell's equation of motion
Udwadia–Kalaba equation
Koopman–von Neumann mechanics
Core topics[show]
Damping (ratio)
Displacement
Equations of motion
Euler's laws of motion
Fictitious force
Friction
Harmonic oscillator
Inertial / Non-inertial reference frame
Mechanics of planar particle motion
Motion (linear)
Newton's law of universal gravitation
Newton's laws of motion
Relative velocity
Rigid body
dynamics
Euler's equations
Simple harmonic motion
Vibration
Rotation[show]
Circular motion
Rotating reference frame
Centripetal force
Centrifugal force
reactive
Coriolis force
Pendulum
Tangential speed
Rotational speed
Angular acceleration / displacement / frequency / velocity
Scientists[show]
Galileo
Newton
Kepler
Horrocks
Halley
Euler
d'Alembert
Clairaut
Lagrange
Laplace
Hamilton
Poisson
Daniel Bernoulli
Johann Bernoulli
Cauchy
v
t
e
Main article: Time in physics
Until Einstein's reinterpretation of the physical concepts associated with time and space, time was considered to be the same everywhere in the universe, with all observers measuring the same time interval for any event.[72] Non-relativistic classical mechanics is based on this Newtonian idea of time.
Einstein, in his special theory of relativity,[73] postulated the constancy and finiteness of the speed of light for all observers. He showed that this postulate, together with a reasonable definition for what it means for two events to be simultaneous, requires that distances appear compressed and time intervals appear lengthened for events associated with objects in motion relative to an inertial observer.
The theory of special relativity finds a convenient formulation in Minkowski spacetime, a mathematical structure that combines three dimensions of space with a single dimension of time. In this formalism, distances in space can be measured by how long light takes to travel that distance, e.g., a light-year is a measure of distance, and a meter is now defined in terms of how far light travels in a certain amount of time. Two events in Minkowski spacetime are separated by an invariant interval, which can be either space-like, light-like, or time-like. Events that have a time-like separation cannot be simultaneous in any frame of reference, there must be a temporal component (and possibly a spatial one) to their separation. Events that have a space-like separation will be simultaneous in some frame of reference, and there is no frame of reference in which they do not have a spatial separation. Different observers may calculate different distances and different time intervals between two events, but the invariant interval between the events is independent of the observer (and his or her velocity).
Classical mechanics
In non-relativistic classical mechanics, Newton's concept of "relative, apparent, and common time" can be used in the formulation of a prescription for the synchronization of clocks. Events seen by two different observers in motion relative to each other produce a mathematical concept of time that works sufficiently well for describing the everyday phenomena of most people's experience. In the late nineteenth century, physicists encountered problems with the classical understanding of time, in connection with the behavior of electricity and magnetism. Einstein resolved these problems by invoking a method of synchronizing clocks using the constant, finite speed of light as the maximum signal velocity. This led directly to the result that observers in motion relative to one another measure different elapsed times for the same event.
Two-dimensional space depicted in three-dimensional spacetime. The past and future light cones are absolute, the "present" is a relative concept different for observers in relative motion.
Spacetime
Main article: Spacetime
Time has historically been closely related with space, the two together merging into spacetime in Einstein's special relativity and general relativity. According to these theories, the concept of time depends on the spatial reference frame of the observer, and the human perception as well as the measurement by instruments such as clocks are different for observers in relative motion. For example, if a spaceship carrying a clock flies through space at (very nearly) the speed of light, its crew does not notice a change in the speed of time on board their vessel because everything traveling at the same speed slows down at the same rate (including the clock, the crew's thought processes, and the functions of their bodies). However, to a stationary observer watching the spaceship fly by, the spaceship appears flattened in the direction it is traveling and the clock on board the spaceship appears to move very slowly.
On the other hand, the crew on board the spaceship also perceives the observer as slowed down and flattened along the spaceship's direction of travel, because both are moving at very nearly the speed of light relative to each other. Because the outside universe appears flattened to the spaceship, the crew perceives themselves as quickly traveling between regions of space that (to the stationary observer) are many light years apart. This is reconciled by the fact that the crew's perception of time is different from the stationary observer's; what seems like seconds to the crew might be hundreds of years to the stationary observer. In either case, however, causality remains unchanged: the past is the set of events that can send light signals to an entity and the future is the set of events to which an entity can send light signals.[74][75][76]
Time dilation
Relativity of simultaneity: Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and occurs later in the red frame.
Main article: Time dilation
Einstein showed in his thought experiments that people travelling at different speeds, while agreeing on cause and effect, measure different time separations between events, and can even observe different chronological orderings between non-causally related events. Though these effects are typically minute in the human experience, the effect becomes much more pronounced for objects moving at speeds approaching the speed of light. Subatomic particles exist for a well known average fraction of a second in a lab relatively at rest, but when travelling close to the speed of light they are measured to travel farther and exist for much longer than when at rest. According to the special theory of relativity, in the high-speed particle's frame of reference, it exists, on the average, for a standard amount of time known as its mean lifetime, and the distance it travels in that time is zero, because its velocity is zero. Relative to a frame of reference at rest, time seems to "slow down" for the particle. Relative to the high-speed particle, distances seem to shorten. Einstein showed how both temporal and spatial dimensions can be altered (or "warped") by high-speed motion.
Einstein (The Meaning of Relativity): "Two events taking place at the points A and B of a system K are simultaneous if they appear at the same instant when observed from the middle point, M, of the interval AB. Time is then defined as the ensemble of the indications of similar clocks, at rest relative to K, which register the same simultaneously."
Einstein wrote in his book, Relativity, that simultaneity is also relative, i.e., two events that appear simultaneous to an observer in a particular inertial reference frame need not be judged as simultaneous by a second observer in a different inertial frame of reference.
Relativistic time versus Newtonian time
Views of spacetime along the world line of a rapidly accelerating observer in a relativistic universe. The events ("dots") that pass the two diagonal lines in the bottom half of the image (the past light cone of the observer in the origin) are the events visible to the observer.
The animations visualise the different treatments of time in the Newtonian and the relativistic descriptions. At the heart of these differences are the Galilean and Lorentz transformations applicable in the Newtonian and relativistic theories, respectively.
In the figures, the vertical direction indicates time. The horizontal direction indicates distance (only one spatial dimension is taken into account), and the thick dashed curve is the spacetime trajectory ("world line") of the observer. The small dots indicate specific (past and future) events in spacetime.
The slope of the world line (deviation from being vertical) gives the relative velocity to the observer. Note how in both pictures the view of spacetime changes when the observer accelerates.
In the Newtonian description these changes are such that time is absolute:[77] the movements of the observer do not influence whether an event occurs in the 'now' (i.e., whether an event passes the horizontal line through the observer).
However, in the relativistic description the observability of events is absolute: the movements of the observer do not influence whether an event passes the "light cone" of the observer. Notice that with the change from a Newtonian to a relativistic description, the concept of absolute time is no longer applicable: events move up-and-down in the figure depending on the acceleration of the observer.
Arrow of time
Main article: Arrow of time
Time appears to have a direction—the past lies behind, fixed and immutable, while the future lies ahead and is not necessarily fixed. Yet for the most part the laws of physics do not specify an arrow of time, and allow any process to proceed both forward and in reverse. This is generally a consequence of time being modelled by a parameter in the system being analysed, where there is no "proper time": the direction of the arrow of time is sometimes arbitrary. Examples of this include the cosmological arrow of time, which points away from the Big Bang, CPT symmetry, and the radiative arrow of time, caused by light only travelling forwards in time (see light cone). In particle physics, the violation of CP symmetry implies that there should be a small counterbalancing time asymmetry to preserve CPT symmetry as stated above. The standard description of measurement in quantum mechanics is also time asymmetric (see Measurement in quantum mechanics). The second law of thermodynamics states that entropy must increase over time (see Entropy). This can be in either direction - Brian Greene theorizes that, according to the equations, the change in entropy occurs symmetrically whether going forward or backward in time. So entropy tends to increase in either direction, and our current low-entropy universe is a statistical aberration, in the similar manner as tossing a coin often enough that eventually heads will result ten times in a row. However, this theory is not supported empirically in local experiment.[78]
Quantized time
See also: Chronon
Time quantization is a hypothetical concept. In the modern established physical theories (the Standard Model of Particles and Interactions and General Relativity) time is not quantized.
Planck time (~ 5.4 × 10−44 seconds) is the unit of time in the system of natural units known as Planck units. Current established physical theories are believed to fail at this time scale, and many physicists expect that the Planck time might be the smallest unit of time that could ever be measured, even in principle. Tentative physical theories that describe this time scale exist; see for instance loop quantum gravity.
Time travel
Main article: Time travel
See also: Time travel in fiction, Wormhole, and Twin paradox
Time travel is the concept of moving backwards or forwards to different points in time, in a manner analogous to moving through space, and different from the normal "flow" of time to an earthbound observer. In this view, all points in time (including future times) "persist" in some way. Time travel has been a plot device in fiction since the 19th century. Travelling backwards in time has never been verified, presents many theoretical problems, and may be an impossibility.[79] Any technological device, whether fictional or hypothetical, that is used to achieve time travel is known as a time machine.
A central problem with time travel to the past is the violation of causality; should an effect precede its cause, it would give rise to the possibility of a temporal paradox. Some interpretations of time travel resolve this by accepting the possibility of travel between branch points, parallel realities, or universes.
Another solution to the problem of causality-based temporal paradoxes is that such paradoxes cannot arise simply because they have not arisen. As illustrated in numerous works of fiction, free will either ceases to exist in the past or the outcomes of such decisions are predetermined. As such, it would not be possible to enact the grandfather paradox because it is a historical fact that your grandfather was not killed before his child (your parent) was conceived. This view doesn't simply hold that history is an unchangeable constant, but that any change made by a hypothetical future time traveller would already have happened in his or her past, resulting in the reality that the traveller moves from. More elaboration on this view can be found in the Novikov self-consistency principle.
Time perception
Philosopher and psychologist William James
Main article: Time perception
The specious present refers to the time duration wherein one's perceptions are considered to be in the present. The experienced present is said to be ‘specious’ in that, unlike the objective present, it is an interval and not a durationless instant. The term specious present was first introduced by the psychologist E.R. Clay, and later developed by William James.[80]
Biopsychology
The brain's judgment of time is known to be a highly distributed system, including at least the cerebral cortex, cerebellum and basal ganglia as its components. One particular component, the suprachiasmatic nuclei, is responsible for the circadian (or daily) rhythm, while other cell clusters appear capable of shorter-range (ultradian) timekeeping.
Psychoactive drugs can impair the judgment of time. Stimulants can lead both humans and rats to overestimate time intervals,[81][82] while depressants can have the opposite effect.[83] The level of activity in the brain of neurotransmitters such as dopamine and norepinephrine may be the reason for this.[84] Such chemicals will either excite or inhibit the firing of neurons in the brain, with a greater firing rate allowing the brain to register the occurrence of more events within a given interval (speed up time) and a decreased firing rate reducing the brain's capacity to distinguish events occurring within a given interval (slow down time).[85]
Mental chronometry is the use of response time in perceptual-motor tasks to infer the content, duration, and temporal sequencing of cognitive operations.
Development of awareness and understanding of time in children
Children's expanding cognitive abilities allow them to understand time more clearly. Two- and three-year-olds' understanding of time is mainly limited to "now and not now." Five- and six-year-olds can grasp the ideas of past, present, and future. Seven- to ten-year-olds can use clocks and calendars.[86]
Alterations
In addition to psychoactive drugs, judgments of time can be altered by temporal illusions (like the kappa effect),[87] age,[88] and hypnosis.[89] The sense of time is impaired in some people with neurological diseases such as Parkinson's disease and attention deficit disorder.
Psychologists assert that time seems to go faster with age, but the literature on this age-related perception of time remains controversial.[90] Those who support this notion argue that young people, having more excitatory neurotransmitters, are able to cope with faster external events.[85]
Use of time
See also: Time management and Time discipline
In sociology and anthropology, time discipline is the general name given to social and economic rules, conventions, customs, and expectations governing the measurement of time, the social currency and awareness of time measurements, and people's expectations concerning the observance of these customs by others. Arlie Russell Hochschild[91][92] and Norbert Elias[93] have written on the use of time from a sociological perspective.
The use of time is an important issue in understanding human behavior, education, and travel behavior. Time-use research is a developing field of study. The question concerns how time is allocated across a number of activities (such as time spent at home, at work, shopping, etc.). Time use changes with technology, as the television or the Internet created new opportunities to use time in different ways. However, some aspects of time use are relatively stable over long periods of time, such as the amount of time spent traveling to work, which despite major changes in transport, has been observed to be about 20–30 minutes one-way for a large number of cities over a long period.
Time management is the organization of tasks or events by first estimating how much time a task requires and when it must be completed, and adjusting events that would interfere with its completion so it is done in the appropriate amount of time. Calendars and day planners are common examples of time management tools.
A sequence of events, or series of events, is a sequence of items, facts, events, actions, changes, or procedural steps, arranged in time order (chronological order), often with causality relationships among the items.[94][95][96] Because of causality, cause precedes effect, or cause and effect may appear together in a single item, but effect never precedes cause. A sequence of events can be presented in text, tables, charts, or timelines. The description of the items or events may include a timestamp. A sequence of events that includes the time along with place or location information to describe a sequential path may be referred to as a world line.
Uses of a sequence of events include stories,[97] historical events (chronology), directions and steps in procedures,[98] and timetables for scheduling activities. A sequence of events may also be used to help describe processes in science, technology, and medicine. A sequence of events may be focused on past events (e.g., stories, history, chronology), on future events that must be in a predetermined order (e.g., plans, schedules, procedures, timetables), or focused on the observation of past events with the expectation that the events will occur in the future (e.g., processes, projections). The use of a sequence of events occurs in fields as diverse as machines (cam timer), documentaries (Seconds From Disaster), law (choice of law), computer simulation (discrete event simulation), and electric power transmission[99] (sequence of events recorder). A specific example of a sequence of events is the timeline of the Fukushima Daiichi nuclear disaster.
Spatial conceptualization of time
Although time is regarded as an abstract concept, there is increasing evidence that time is conceptualized in the mind in terms of space.[100] That is, instead of thinking about time in a general, abstract way, humans think about time in a spatial way and mentally organize it as such. Using space to think about time allows humans to mentally organize temporal events in a specific way.
This spatial representation of time is often represented in the mind as a Mental Time Line (MTL).[101] Using space to think about time allows humans to mentally organize temporal order. These origins are shaped by many environmental factors[100]––for example, literacy appears to play a large role in the different types of MTLs, as reading/writing direction provides an everyday temporal orientation that differs from culture to culture.[101] In western cultures, the MTL may unfold rightward (with the past on the left and the future on the right) since people read and write from left to right.[101] Western calendars also continue this trend by placing the past on the left with the future progressing toward the right. Conversely, Arabic, Farsi, Urdu and Israeli-Hebrew speakers read from right to left, and their MTLs unfold leftward (past on the right with future on the left), and evidence suggests these speakers organize time events in their minds like this as well.[101]
This linguistic evidence that abstract concepts are based in spatial concepts also reveals that the way humans mentally organize time events varies across cultures––that is, a certain specific mental organization system is not universal. So, although Western cultures typically associate past events with the left and future events with the right according to a certain MTL, this kind of horizontal, egocentric MTL is not the spatial organization of all cultures. Although most developed nations use an egocentric spatial system, there is recent evidence that some cultures use an allocentric spatialization, often based on environmental features.[100]
A recent study of the indigenous Yupno people of Papua New Guinea focused on the directional gestures used when individuals used time-related words.[100] When speaking of the past (such as "last year" or "past times"), individuals gestured downhill, where the river of the valley flowed into the ocean. When speaking of the future, they gestured uphill, toward the source of the river. This was common regardless of which direction the person faced, revealing that the Yupno people may use an allocentric MTL, in which time flows uphill.[100]
A similar study of the Pormpuraawans, an aboriginal group in Australia, revealed a similar distinction in which when asked to organize photos of a man aging "in order," individuals consistently placed the youngest photos to the east and the oldest photos to the west, regardless of which direction they faced.[102] This directly clashed with an American group which consistently organized the photos from left to right. Therefore, this group also appears to have an allocentric MTL, but based on the cardinal directions instead of geographical features.[102]
The wide array of distinctions in the way different groups think about time leads to the broader question that different groups may also think about other abstract concepts in different ways as well, such as causality and number.[100]
See also
Book: Time
Time's mortal aspect is personified in this bronze statue by Charles van der Stappen
Era
Horology
International System of Quantities
Kairos
List of UTC timing centers
UTC
Term (time)
Books
A Brief History of Time by Stephen Hawking
About Time: Einstein's Unfinished Revolution by Paul Davies
From Eternity to Here: The Quest for the Ultimate Theory of Time by Sean M. Carroll
The Discovery of Time by Stephen Toulmin and June Goodfield
The Physical Basis of The Direction of Time by Heinz-Dieter Zeh
An Experiment with Time by J. W. Dunne
Einstein's Dreams by Alan Lightman
Being and Time by Martin Heidegger
Time Reborn by Lee Smolin
Organizations
Leading scholarly organisations for researchers on the history and technology of time and timekeeping
Antiquarian Horological Society—AHS (United Kingdom)
Chronometrophilia (Switzerland)
Deutsche Gesellschaft für Chronometrie—DGC (Germany)
National Association of Watch and Clock Collectors—NAWCC (United States)
Miscellaneous arts and sciences
Anachronism
Date and time representation by country
List of cycles
Network Time Protocol (NTP)
Nonlinear narrative
Philosophy of physics
Rate (mathematics)
Miscellaneous units of time
Fiscal year
Half-life
Hexadecimal time
Season
Tithi
Unit of time
Unix epoch
References
Jump up ^ "Oxford Dictionaries:Time". Oxford University Press. 2011. Retrieved 18 May 2017. The indefinite continued progress of existence and events in the past, present, and future regarded as a whole
^ Jump up to: a b c
"Webster's New World College Dictionary". 2010. Retrieved 9 April 2011. 1.indefinite, unlimited duration in which things are considered as happening in the past, present, or future; every moment there has ever been or ever will be… a system of measuring duration 2.the period between two events or during which something exists, happens, or acts; measured or measurable interval
"The American Heritage Stedman's Medical Dictionary". 2002. Retrieved 9 April 2011. A duration or relation of events expressed in terms of past, present, and future, and measured in units such as minutes, hours, days, months, or years.
"Collins Language.com". HarperCollins. 2011. Archived from the original on 2 October 2011. Retrieved 18 December 2011. 1. The continuous passage of existence in which events pass from a state of potentiality in the future, through the present, to a state of finality in the past. 2. physics a quantity measuring duration, usually with reference to a periodic process such as the rotation of the earth or the frequency of electromagnetic radiation emitted from certain atoms. In classical mechanics, time is absolute in the sense that the time of an event is independent of the observer. According to the theory of relativity it depends on the observer's frame of reference. Time is considered as a fourth coordinate required, along with three spatial coordinates, to specify an event.
"The American Heritage Science Dictionary @dictionary.com". 2002. Retrieved 9 April 2011. 1. A continuous, measurable quantity in which events occur in a sequence proceeding from the past through the present to the future. 2a. An interval separating two points of this quantity; a duration. 2b. A system or reference frame in which such intervals are measured or such quantities are calculated.
"Eric Weisstein's World of Science". 2007. Retrieved 9 April 2011. A quantity used to specify the order in which events occurred and measure the amount by which one event preceded or followed another. In special relativity, ct (where c is the speed of light and t is time), plays the role of a fourth dimension.
Jump up ^ "Time". The American Heritage Dictionary of the English Language (Fourth ed.). Houghton Mifflin Company. 2011. A nonspatial continuum in which events occur in apparently irreversible succession from the past through the present to the future.
Jump up ^ Merriam-Webster Dictionary the measured or measurable period during which an action, process, or condition exists or continues : duration; a nonspatial continuum which is measured in terms of events that succeed one another from past through present to future
Jump up ^ Compact Oxford English Dictionary A limited stretch or space of continued existence, as the interval between two successive events or acts, or the period through which an action, condition, or state continues. (1971).
^ Jump up to: a b c d
"Internet Encyclopedia of Philosophy". 2010. Retrieved 9 April 2011. Time is what clocks measure. We use time to place events in sequence one after the other, and we use time to compare how long events last... Among philosophers of physics, the most popular short answer to the question "What is physical time?" is that it is not a substance or object but rather a special system of relations among instantaneous events. This working definition is offered by Adolf Grünbaum who applies the contemporary mathematical theory of continuity to physical processes, and he says time is a linear continuum of instants and is a distinguished one-dimensional sub-space of four-dimensional spacetime.
"Dictionary.com Unabridged, based on Random House Dictionary". 2010. Retrieved 9 April 2011. 1. the system of those sequential relations that any event has to any other, as past, present, or future; indefinite and continuous duration regarded as that in which events succeed one another.... 3. (sometimes initial capital letter) a system or method of measuring or reckoning the passage of time: mean time; apparent time; Greenwich Time. 4. a limited period or interval, as between two successive events: a long time.... 14. a particular or definite point in time, as indicated by a clock: What time is it? ... 18. an indefinite, frequently prolonged period or duration in the future: Time will tell if what we have done here today was right.
Ivey, Donald G.; Hume, J.N.P. (1974). Physics. 1. Ronald Press. p. 65. Our operational definition of time is that time is what clocks measure.
^ Jump up to: a b c Le Poidevin, Robin (Winter 2004). "The Experience and Perception of Time". In Edward N. Zalta. The Stanford Encyclopedia of Philosophy. Retrieved 9 April 2011.
Jump up ^ "Newton did for time what the Greek geometers did for space, idealized it into an exactly measurable dimension." About Time: Einstein's Unfinished Revolution, Paul Davies, p. 31, Simon & Schuster, 1996, ISBN 978-0684818221
Jump up ^ Sean M Carroll (2009). From Eternity to Here: The Quest for the Ultimate Theory of Time. Dutton. ISBN 978-0-525-95133-9.
Jump up ^ Adam Frank, Cosmology and Culture at the Twilight of the Big Bang, "the time we imagine for the cosmos and the time we imagined into the human experience turn out to be woven so tightly together that we have lost the ability to see each of them for what it is." p. xv, Free Press, 2011, ISBN 978-1439169599
Jump up ^ St. Augustine, Confessions, Simon & Brown, 2012, ISBN 978-1613823262
Jump up ^ Official Baseball Rules, 2011 Edition (2011). "Rules 8.03 and 8.04" (Free PDF download). Major League Baseball. Retrieved 18 May 2017. Rule 8.03 Such preparatory pitches shall not consume more than one minute of time...Rule 8.04 When the bases are unoccupied, the pitcher shall deliver the ball to the batter within 12 seconds...The 12-second timing starts when the pitcher is in possession of the ball and the batter is in the box, alert to the pitcher. The timing stops when the pitcher releases the ball.
Jump up ^ "Guinness Book of Baseball World Records". Guinness World Records, Ltd. Retrieved 7 July 2012. The record for the fastest time for circling the bases is 13.3 seconds, set by Evar Swanson at Columbus, Ohio in 1932...The greatest reliably recorded speed at which a baseball has been pitched is 100.9 mph by Lynn Nolan Ryan (California Angels) at Anaheim Stadium in California on 20 August 1974.
Jump up ^ Zeigler, Kenneth (2008). Getting organized at work : 24 lessons to set goals, establish priorities, and manage your time. McGraw-Hill. ISBN 9780071591386. 108 pages.
Jump up ^ Rynasiewicz, Robert : Johns Hopkins University (12 August 2004). "Newton's Views on Space, Time, and Motion". Stanford Encyclopedia of Philosophy. Stanford University. Retrieved 5 February 2012. Newton did not regard space and time as genuine substances (as are, paradigmatically, bodies and minds), but rather as real entities with their own manner of existence as necessitated by God's existence ... To paraphrase: Absolute, true, and mathematical time, from its own nature, passes equably without relation to anything external, and thus without reference to any change or way of measuring of time (e.g., the hour, day, month, or year).
^ Jump up to: a b Markosian, Ned. "Time". In Edward N. Zalta. The Stanford Encyclopedia of Philosophy (Winter 2002 Edition). Retrieved 23 September 2011. The opposing view, normally referred to either as “Platonism with Respect to Time” or as “Absolutism with Respect to Time”, has been defended by Plato, Newton, and others. On this view, time is like an empty container into which events may be placed; but it is a container that exists independently of whether or not anything is placed in it.
^ Jump up to: a b c Burnham, Douglas : Staffordshire University (2006). "Gottfried Wilhelm Leibniz (1646–1716) Metaphysics – 7. Space, Time, and Indiscernibles". The Internet Encyclopedia of Philosophy. Retrieved 9 April 2011. First of all, Leibniz finds the idea that space and time might be substances or substance-like absurd (see, for example, "Correspondence with Clarke," Leibniz's Fourth Paper, §8ff). In short, an empty space would be a substance with no properties; it will be a substance that even God cannot modify or destroy.... That is, space and time are internal or intrinsic features of the complete concepts of things, not extrinsic.... Leibniz's view has two major implications. First, there is no absolute location in either space or time; location is always the situation of an object or event relative to other objects and events. Second, space and time are not in themselves real (that is, not substances). Space and time are, rather, ideal. Space and time are just metaphysically illegitimate ways of perceiving certain virtual relations between substances. They are phenomena or, strictly speaking, illusions (although they are illusions that are well-founded upon the internal properties of substances).... It is sometimes convenient to think of space and time as something "out there," over and above the entities and their relations to each other, but this convenience must not be confused with reality. Space is nothing but the order of co-existent objects; time nothing but the order of successive events. This is usually called a relational theory of space and time.
^ Jump up to: a b Mattey, G. J. : UC Davis (22 January 1997). "Critique of Pure Reason, Lecture notes: Philosophy 175 UC Davis". Archived from the original on 14 March 2005. Retrieved 9 April 2011. What is correct in the Leibnizian view was its anti-metaphysical stance. Space and time do not exist in and of themselves, but in some sense are the product of the way we represent things. The[y] are ideal, though not in the sense in which Leibniz thought they are ideal (figments of the imagination). The ideality of space is its mind-dependence: it is only a condition of sensibility.... Kant concluded ... "absolute space is not an object of outer sensation; it is rather a fundamental concept which first of all makes possible all such outer sensation."...Much of the argumentation pertaining to space is applicable, mutatis mutandis, to time, so I will not rehearse the arguments. As space is the form of outer intuition, so time is the form of inner intuition.... Kant claimed that time is real, it is "the real form of inner intuition."
^ Jump up to: a b McCormick, Matt : California State University, Sacramento (2006). "Immanuel Kant (1724–1804) Metaphysics: 4. Kant's Transcendental Idealism". The Internet Encyclopedia of Philosophy. Retrieved 9 April 2011. Time, Kant argues, is also necessary as a form or condition of our intuitions of objects. The idea of time itself cannot be gathered from experience because succession and simultaneity of objects, the phenomena that would indicate the passage of time, would be impossible to represent if we did not already possess the capacity to represent objects in time.... Another way to put the point is to say that the fact that the mind of the knower makes the a priori contribution does not mean that space and time or the categories are mere figments of the imagination. Kant is an empirical realist about the world we experience; we can know objects as they appear to us. He gives a robust defense of science and the study of the natural world from his argument about the mind's role in making nature. All discursive, rational beings must conceive of the physical world as spatially and temporally unified, he argues.
Jump up ^ Considine, Douglas M.; Considine, Glenn D. (1985). Process instruments and controls handbook (3 ed.). McGraw-Hill. pp. 18–61. ISBN 0-07-012436-1.
Jump up ^ Duff, Okun, Veneziano, ibid. p. 3. "There is no well established terminology for the fundamental constants of Nature. ... The absence of accurately defined terms or the uses (i.e., actually misuses) of ill-defined terms lead to confusion and proliferation of wrong statements."
Jump up ^ Richards, E. G. (1998). Mapping Time: The Calendar and its History. Oxford University Press. pp. 3–5.
Jump up ^ Rudgley, Richard (1999). The Lost Civilizations of the Stone Age. New York: Simon & Schuster. pp. 86–105.
Jump up ^ Van Stone, Mark. "The Maya Long Count Calendar: An Introduction." Archaeoastronomy 24.(2011): 8-11. Academic Search Complete. Web. 20 Feb. 2016.
Jump up ^ "French Republican Calendar | Chronology." Encyclopædia Britannica Online. Encyclopædia Britannica, n.d. Web. 21 Feb. 2016.
Jump up ^ Barnett, Jo Ellen Time's Pendulum: The Quest to Capture Time—from Sundials to Atomic Clocks Plenum, 1998 ISBN 0-306-45787-3 p.28
Jump up ^ Lombardi, Michael A. "Why Is a Minute Divided into 60 Seconds, an Hour into 60 Minutes, Yet There Are Only 24 Hours in a Day?" Scientific American. Springer Nature, 5 Mar. 2007. Web. 21 Feb. 2016.
Jump up ^ Barnett, ibid, p. 37
Jump up ^ Laurence Bergreen, Over the Edge of the World: Magellan's Terrifying Circumnavigation of the Globe, HarperCollins Publishers, 2003, hardcover 480 pages, ISBN 0-06-621173-5
Jump up ^ North, J. (2004) God's Clockmaker: Richard of Wallingford and the Invention of Time. Oxbow Books. ISBN 1-85285-451-0
Jump up ^ Watson, E (1979) "The St Albans Clock of Richard of Wallingford". Antiquarian Horology 372–384.
^ Jump up to: a b "History of Clocks." About.com Inventors. About.com, n.d. Web. 21 Feb. 2016.
Jump up ^ "NIST Unveils Chip-Scale Atomic Clock". 27 August 2004. Retrieved 9 June 2011.
Jump up ^ "New atomic clock can keep time for 200 million years: Super-precise instruments vital to deep space navigation". Vancouver Sun. 16 February 2008. Archived from the original on 11 February 2012. Retrieved 9 April 2011.
Jump up ^ "NIST-F1 Cesium Fountain Clock". Retrieved 24 July 2015.
Jump up ^ "Byrhtferth of Ramsey". Encyclopædia Britannica. 2008. Retrieved 15 September 2008.
Jump up ^ "atom", Oxford English Dictionary, Draft Revision September 2008 (contains relevant citations from Byrhtferth's Enchiridion)
Jump up ^ "12 attoseconds is the world record for shortest controllable time". 12 May 2010. Retrieved 19 April 2012.
Jump up ^ Whitaker's Almanac 2013 (ed. Ruth Northey), London 2012, p 1131, ISBN 978-1-4081-7207-0.
^ Jump up to: a b c Organisation Intergouvernementale de la Convention du Métre (1998). The International System of Units (SI), 7th Edition (PDF). Archived from the original (PDF) on 27 April 2004. Retrieved 9 April 2011.
Jump up ^ "Base unit definitions: Second". NIST. Retrieved 9 April 2011.
Jump up ^ Howse, Derek (1997). Greenwich Time and the Longitude. London: Philip Wilson. pp. 133–137. ISBN 0-85667-468-0.
Jump up ^ "Leap Seconds". Time Service Department, United States Naval Observatory. Archived from the original on 12 March 2012. Retrieved 22 November 2015.
Jump up ^ W Markowitz, RG Hall, L Essen, JVL Parry; Hall; Essen; Parry (1958). "Frequency of cesium in terms of ephemeris time" (PDF). Physical Review Letters. 1 (3): 105–107. Bibcode:1958PhRvL...1..105M. doi:10.1103/PhysRevLett.1.105. CS1 maint: Multiple names: authors list (link)
Jump up ^ Cesium Atoms at Work Archived 23 February 2015 at the Wayback Machine. USNO, downloaded 28 June 2016.
Jump up ^ IEC 60050-113:2011, item 113-01-08
Jump up ^ IEC 60050-113:2011, item 113-01-010; ISO 80000-3:2006, item 3-7
Jump up ^ IEC 60050-113:2011, item 113-01-012: "mark attributed to an instant by means of a specified time scale
Jump up ^ IEC 60050-113:2011, item 113-01-013: "range of a time interval (113-01-10)"
Jump up ^ ISO 80000-3:2006, item 3-7
Jump up ^ Rust, Eric Charles (1981). Religion, Revelation and Reason. Mercer University Press. p. 60. ISBN 9780865540583. Retrieved 2015-08-20. Profane time, as Eliade points out, is linear. As man dwelt increasingly in the profane and a sense of history developed, the desire to escape into the sacred began to drop in the background. The myths, tied up with cyclic time, were not so easily operative. [...] So secular man became content with his linear time. He could not return to cyclic time and re-enter sacred space though its myths. [...] Just here, as Eliade sees it, a new religious structure became available. In the Judaeo-Christian religions – Judaism, Christianity, Islam – history is taken seriously, and linear time is accepted. The cyclic time of the primordial mythical consciousness has been transformed into the time of profane man, but the mythical consciousness remains. It has been historicized. The Christian mythos and its accompanying ritual are bound up, for example, with history and center in authentic history, especially the Christ-event. Sacred space, the Transcendent Presence, is thus opened up to secular man because it meets him where he is, in the linear flow of secular time. The Christian myth gives such time a beginning in creation, a center in the Christ-event, and an end in the final consummation.
Jump up ^ Betz, Hans Dieter, ed. (2008). Religion Past & Present: Encyclopedia of Theology and Religion. 4: Dev-Ezr (4 ed.). Brill. p. 101. ISBN 9789004146884. Retrieved 2015-08-20. [...] God produces a creation with a directional time structure [...].
Jump up ^ Lundin, Roger; Thiselton, Anthony C.; Walhout, Clarence (1999). The Promise of Hermeneutics. Wm. B. Eerdmans Publishing. p. 121. ISBN 9780802846358. Retrieved 2015-08-20. We need to note the close ties between teleology, eschatology, and utopia. In Christian theology, the understanding of the teleology of particular actions is ultimately related to the teleology of history in general, which is the concern of eschatology.
Jump up ^ Hus, Boʿaz; Pasi, Marco; Von Stuckrad, Kocku (2011). Kabbalah and Modernity: Interpretations, Transformations, Adaptations. BRILL. ISBN 9004182845.
Jump up ^ Wolfson, Elliot R. (2006). Alef, Mem, Tau: Kabbalistic Musings on Time, Truth, and Death. University of California Press. p. 111. ISBN 0-520-93231-5. Extract of page 111
Jump up ^ Navratil, Gerhard (2009). Research Trends in Geographic Information Science. Springer Japan. p. 217. ISBN 3-540-88243-X. Retrieved 9 April 2011.
Jump up ^ Carrol, Sean, Chapter One, Section Two, Plume, 2010. From Eternity to Here. ISBN 978-0452296541. As human beings we 'feel' the passage of time.
Jump up ^ Lehar, Steve. (2000). The Function of Conscious Experience: An Analogical Paradigm of Perception and Behavior, Consciousness and Cognition.
Jump up ^ Layton, Robert (1994). Who needs the past?: indigenous values and archaeology (2nd ed.). Routledge. p. 7. ISBN 0-415-09558-1. Retrieved 9 April 2011. , Introduction, p. 7
Jump up ^ Dagobert Runes, Dictionary of Philosophy, p. 318
Jump up ^ Hardie, R. P.; Gaye, R. K. "Physics by Aristotle". MIT. Retrieved 4 May 2014. "Time then is a kind of number. (Number, we must note, is used in two senses – both of what is counted or the countable and also of that with which we count. Time obviously is what is counted, not that with which we count: there are different kinds of thing.) [...] It is clear, then, that time is 'number of movement in respect of the before and after', and is continuous since it is an attribute of what is continuous. "
Jump up ^ Augustine of Hippo. Confessions. Retrieved 9 April 2011. Book 11, Chapter 14.
Jump up ^ Gottfried Martin, Kant's Metaphysics and Theory of Science
Jump up ^ Kant, Immanuel (1787). The Critique of Pure Reason, 2nd edition. Retrieved 9 April 2011. translated by J. M. D. Meiklejohn, eBooks@Adelaide, 2004
Jump up ^ Bergson, Henri (1907) Creative Evolution. trans. by Arthur Mitchell. Mineola: Dover, 1998.
Jump up ^ Balslev, Anindita N.; Jitendranath Mohanty (November 1992). Religion and Time. Studies in the History of Religions, 54. The Netherlands: Brill Academic Publishers. pp. 53, 54, 55, 56, 57, 58, and 59. ISBN 978-90-04-09583-0.
Jump up ^ Martin Heidegger (1962). "V". Being and Time. p. 425. ISBN 978-0-631-19770-6.
Jump up ^ Harry Foundalis. "You are about to disappear". Retrieved 9 April 2011.
Jump up ^ Huston, Tom. "Buddhism and the illusion of time". Retrieved 9 April 2011.
Jump up ^ Garfield, Jay L. (1995). The fundamental wisdom of the middle way: Nāgārjuna's Mūlamadhyamakakārikā. New York: Oxford University Press. ISBN 978-0-19-509336-0.
Jump up ^ "Time is an illusion?". Retrieved 9 April 2011.
Jump up ^ Herman M. Schwartz, Introduction to Special Relativity, McGraw-Hill Book Company, 1968, hardcover 442 pages, see ISBN 0-88275-478-5 (1977 edition), pp. 10–13
Jump up ^ A. Einstein, H. A. Lorentz, H. Weyl, H. Minkowski, The Principle of Relativity, Dover Publications, Inc, 2000, softcover 216 pages, ISBN 0-486-60081-5, See pp. 37–65 for an English translation of Einstein's original 1905 paper.
Jump up ^ "Albert Einstein's Theory of Relativity". YouTube. 30 November 2011. Retrieved 24 September 2013.
Jump up ^ "Time Travel: Einstein's big idea (Theory of Relativity)". YouTube. 9 January 2007. Retrieved 24 September 2013.
Jump up ^ Hours, After (11 February 2012). "7 Theories on Time That Would Make Doc Brown's Head Explode". Cracked.com. Retrieved 24 September 2013.
Jump up ^ Knudsen, Jens M.; Hjorth, Poul (2012). Elements of Newtonian Mechanics (illustrated ed.). Springer Science & Business Media. p. 30. ISBN 978-3-642-97599-8. Extract of page 30
Jump up ^ Greene, Brian (2005). The Fabric of the Cosmos - Chapter 6: Chance and the Arrow. London.
Jump up ^ Quznetsov, Gunn (30 March 2010). "Informational Time and Space". 1 (2). Retrieved 30 December 2016 – via Prespacetime Journal.
Jump up ^ Andersen, Holly; Rick Grush (2009). "A brief history of time-consciousness: historical precursors to James and Husserl" (PDF). 47 (2). Journal of the History of Philosophy: 277–307. Archived from the original (PDF) on 16 February 2008. Retrieved 9 April 2011.
Jump up ^ Wittmann, M.; Leland DS; Churan J; Paulus MP. (8 October 2007). "Impaired time perception and motor timing in stimulant-dependent subjects". Drug Alcohol Depend. 90 (2–3): 183–92. doi:10.1016/j.drugalcdep.2007.03.005. PMC 1997301  . PMID 17434690.
Jump up ^ Cheng, Ruey-Kuang; Macdonald, Christopher J.; Meck, Warren H. (2006). "Differential effects of cocaine and ketamine on time estimation: Implications for neurobiological models of interval timing" (online abstract). Pharmacology Biochemistry and Behavior. 85 (1): 114–122. doi:10.1016/j.pbb.2006.07.019. PMID 16920182. Retrieved 9 April 2011.
Jump up ^ Tinklenberg, Jared R.; Walton T. Roth1; Bert S. Kopell (January 1976). "Marijuana and ethanol: Differential effects on time perception, heart rate, and subjective response". Psychopharmacology. 49 (3): 275–279. doi:10.1007/BF00426830. PMID 826945. Retrieved 9 April 2011.
Jump up ^ Arzy, Shahar; Istvan Molnar-Szakacs; Olaf Blanke (18 June 2008). "Self in Time: Imagined Self-Location Influences Neural Activity Related to Mental Time Travel" (Abstract). The Journal of Neuroscience. 28 (25): 6502–6507. doi:10.1523/JNEUROSCI.5712-07.2008. PMID 18562621. Retrieved 9 April 2011.
^ Jump up to: a b Carter, Rita (2009). The Human Brain Book. Dorling Kindersley Publishing. pp. 186–187. ISBN 978-0-7566-5441-2.
Jump up ^ Kennedy-Moore, Eileen (28 March 2014). "Time Management for Kids". Psychology Today. Retrieved 26 April 2014.
Jump up ^ Wada Y, Masuda T, Noguchi K, 2005, "Temporal illusion called 'kappa effect' in event perception" Perception 34 ECVP Abstract Supplement
Jump up ^ Robert, Adler. "Look how time flies." Retrieved 9 April 2011.
Jump up ^ Bowers, Kenneth; Brenneman, HA (January 1979). "Hypnosis and the perception of time". International Journal of Clinical and Experimental Hypnosis. International Journal of Clinical and Experimental Hypnosis. 27 (1): 29–41. doi:10.1080/00207147908407540. PMID 541126.
Jump up ^ Gruber, Ronald P.; Wagner, Lawrence F.; Block, Richard A. (2000). "Subjective Time Versus Proper (Clock) Time". In Buccheri, R.; Di Gesù, V.; Saniga, Metod. Studies on the structure of time: from physics to psycho(patho)logy. Springer. p. 54. ISBN 0-306-46439-X. Retrieved 9 April 2011. Extract of page 54
Jump up ^ Russell Hochschild, Arlie (1997). The time bind: when work becomes home and home becomes work. New York: Metropolitan Books. ISBN 9780805044713
Jump up ^ Russell Hochschild, Arlie (20 April 1997). "There's no place like work". New York Times Magazine. The New York Times.
Jump up ^ Elias, Norbert (1992). Time: an essay. Oxford, UK Cambridge, USA: Blackwell. ISBN 9780631157984.
Jump up ^ "Sequence - Order of Important Events" (PDF). Austin Independent School District. 2009.
Jump up ^ "Sequence of Events Worksheets". Reference.com. Archived from the original on 13 October 2010.
Jump up ^ Compiled by David Luckham & Roy Schulte. "Event Processing Glossary—Version 2.0". Complex Event Processing.
Jump up ^ Richard Nordquist. "narrative". About.com.
Jump up ^ David J. Piasecki. "Inventory Accuracy Glossary". AccuracyBook.com (OPS Publishing).
Jump up ^ "Utility Communications Architecture (UCA) glossary". NettedAutomation.
^ Jump up to: a b c d e f Núñez, Rafael; Cooperrider, Kensy; Doan, D; Wassmann, Jürg (2012-07-01). "Contours of time: Topographic construals of past, present, and future in the Yupno valley of Papua New Guinea". Cognition. 124 (1): 25–35. doi:10.1016/j.cognition.2012.03.007.
^ Jump up to: a b c d Bottini, Roberto; Crepaldi, Davide; Casasanto, Daniel; Crollen, Virgine; Collignon, Olivier (2015-08-01). "Space and time in the sighted and blind". Cognition. 141: 67–72. doi:10.1016/j.cognition.2015.04.004.
^ Jump up to: a b "Remembrances of Times East". Psychological Science. PMID 20959511. Retrieved 2016-12-07.
Further reading
Barbour, Julian (1999). The End of Time: The Next Revolution in Our Understanding of the Universe. Oxford University Press. ISBN 0-19-514592-5.
Landes, David (2000). Revolution in Time. Harvard University Press. ISBN 0-674-00282-2.
Das, Tushar Kanti (1990). The Time Dimension: An Interdisciplinary Guide. New York: Praeger. ISBN 0-275-92681-8. - Research bibliography
Davies, Paul (1996). About Time: Einstein's Unfinished Revolution. New York: Simon & Schuster Paperbacks. ISBN 0-684-81822-1.
Feynman, Richard (1994) [1965]. The Character of Physical Law. Cambridge (Mass): The MIT Press. pp. 108–126. ISBN 0-262-56003-8.
Galison, Peter (1992). Einstein's Clocks and Poincaré's Maps: Empires of Time. New York: W. W. Norton. ISBN 0-393-02001-0.
Highfield, Roger (1992). Arrow of Time: A Voyage through Science to Solve Time's Greatest Mystery. Random House. ISBN 0-449-90723-6.
Mermin, N. David (2005). It's About Time: Understanding Einstein's Relativity. Princeton University Press. ISBN 0-691-12201-6.
Penrose, Roger (1999) [1989]. The Emperor's New Mind: Concerning Computers, Minds, and the Laws of Physics. New York: Oxford University Press. pp. 391–417. ISBN 0-19-286198-0. Retrieved 9 April 2011.
Price, Huw (1996). Time's Arrow and Archimedes' Point. Oxford University Press. ISBN 0-19-511798-0. Retrieved 9 April 2011.
Reichenbach, Hans (1999) [1956]. The Direction of Time. New York: Dover. ISBN 0-486-40926-0.
Stiegler, Bernard, Technics and Time, 1: The Fault of Epimetheus
Quznetsov, Gunn A. (2006). Logical Foundation of Theoretical Physics. Nova Sci. Publ. ISBN 1-59454-948-6.
Whitrow, Gerald J. (1973). The Nature of Time. Holt, Rinehart and Wilson (New York).
Whitrow, Gerald J. (1980). The Natural Philosophy of Time. Clarendon Press (Oxford).
Whitrow, Gerald J. (1988). Time in History. The evolution of our general awareness of time and temporal perspective. Oxford University Press. ISBN 0-19-285211-6.
Rovelli, Carlo (2006). What is time? What is space?. Rome: Di Renzo Editore. ISBN 88-8323-146-5. Archived from the original on 27 January 2007.

Charlie Gere, (2005) Art, Time and Technology: Histories of the Disappearing Body, Berg
Craig Callendar, Introducing Time, Icon Books, 2010, ISBN 978-1848311206
Benjamin Gal-Or, Cosmology, Physics and Philosophy, Springer Verlag, 1981, 1983, 1987, ISBN 0-387-90581-2, ISBN 0-387-96526-2.
Roberto Mangabeira Unger and Lee Smolin, The Singular Universe and the Reality of Time, Cambridge University Press, 2014, ISBN 978-1-107-07406-4.
External links
Find more aboutTimeat Wikipedia's sister projects
Definitions from Wiktionary
Media from Wikimedia Commons
Quotations from Wikiquote
Textbooks from Wikibooks
Accurate time vs. PC Clock Difference
Exploring Time from Planck Time to the lifespan of the universe
Different systems of measuring time
Time on In Our Time at the BBC.
Time in the Internet Encyclopedia of Philosophy, by Bradley Dowden.
Le Poidevin, Robin (Winter 2004). "The Experience and Perception of Time". In Edward N. Zalta. The Stanford Encyclopedia of Philosophy. Retrieved 9 April 2011.
Time at Open Directory
[show]
v
t
e
Elements of nature
Universe
Space
Time
Energy
Matter
Change
Earth
Earth science
History (geological)
Structure
Geology
Plate tectonics
Oceans
Gaia hypothesis
Future
Weather
Meteorology
Atmosphere (Earth)
Climate
Clouds
Sunlight
Tides
Wind
Natural environment
Ecology
Ecosystem
Field
Radiation
Wilderness
Wildfires
Life
Origin (abiogenesis)
Evolutionary history
Biosphere
Hierarchy
Biology (astrobiology)
Organism
Eukaryota
flora
plants
fauna
animals
fungi
protista
Prokaryotes
archaea
bacteria
Viruses
Category:Nature
Portal:Science
[show]
v
t
e
Time
Key concepts
Past
history
deep time
Present
Future
Futures studies
Far future in religion
Far future in science fiction and popular culture
Timeline of the far future
Eternity
Eternity of the world
Measurement and
standards
Chronometry
UTC
UT
TAI
Unit of time
Planck time
Second
Minute
Hour
Day
Week
Month
Season
Year
Decade
Century
Millennium
Tropical year
Sidereal year
Samvatsara
Measurement
systems
Time zone
Six-hour clock
12-hour clock
24-hour clock
Daylight saving time
Solar time
Sidereal time
Metric time
Decimal time
Hexadecimal time
Calendars
Gregorian
Julian
Hebrew
Islamic
Lunar
Solar Hijri
Mayan
Intercalation
Leap second
Leap year
Clocks
Horology
History of timekeeping devices
Main types
astrarium
atomic
quantum
marine
sundial
sundial markup schema
watch
water-based
Chronology
History
Astronomical chronology
Big History
Calendar era
Chronicle
Deep time
Periodization
Regnal year
Timeline
Religion
Mythology
Dreamtime
Kāla
Kalachakra
Prophecy
Time and fate deities
Wheel of time
Immortality
Philosophy of time
A-series and B-series
B-theory of time
Causality
Duration
Endurantism
Eternal return
Eternalism
Event
Multiple time dimensions
Perdurantism
Presentism
Static interpretation of time
Temporal finitism
Temporal parts
The Unreality of Time
Human experience
and use of time
Accounting period
Chronemics
Fiscal year
Generation time
Mental chronometry
Music
Procrastination
Punctuality
Temporal database
Term
Time discipline
Time management
Time perception
Specious present
Time-tracking software
Time-use research
Time-based currency (time banking)
Time value of money
Time clock
Timesheet
Yesterday – Today – Tomorrow
Time in
Geology
Geological time
age
chron
eon
epoch
era
period
Geochronology
Geological history of Earth
Physics
Absolute time and space
Arrow of time
Chronon
Coordinate time
Imaginary time
Planck epoch
Planck time
Proper time
Rate
Spacetime
Theory of relativity
Time dilation
gravitational
Time domain
Time translation symmetry
Time reversal symmetry
other subject
areas
Chronological dating
Chronobiology
Circadian rhythms
Dating methodologies in archaeology
Time geography
Related topics
Carpe diem
Clock position
Space
System time
Tempus fugit
Time capsule
Time complexity
Time signature
Time travel
Time portal
Category
[show]
Time articles: Detailed navigation
[show]
v
t
e
Time measurement and standards
Chronometry
Orders of magnitude
Metrology
International standards
Coordinated Universal Time
offset
UT
ΔT
DUT1
International Earth Rotation and Reference Systems Service
ISO 31-1
ISO 8601
International Atomic Time
6-hour clock
12-hour clock
24-hour clock
Barycentric Coordinate Time
Barycentric Dynamical Time
Civil time
Daylight saving time
Geocentric Coordinate Time
International Date Line
Leap second
Solar time
Terrestrial Time
Time zone
180th meridian
Obsolete standards
Ephemeris time
Greenwich Mean Time
Prime meridian
Time in physics
Absolute time and space
Spacetime
Chronon
Continuous signal
Coordinate time
Cosmological decade
Discrete time and continuous time
Planck time
Proper time
Theory of relativity
Time dilation
Gravitational time dilation
Time domain
Time translation symmetry
T-symmetry
Horology
Clock
Astrarium
Atomic clock
Complication
History of timekeeping devices
Hourglass
Marine chronometer
Marine sandglass
Radio clock
Watch
Water clock
Sundial
Dialing scales
Equation of time
History of sundials
Sundial markup schema
Calendar
Astronomical
Dominical letter
Epact
Equinox
Gregorian
Hebrew
Hindu
Intercalation
Islamic
Julian
Leap year
Lunar
Lunisolar
Solar
Solstice
Tropical year
Weekday determination
Weekday names
Archaeology and geology
Chronological dating
Geologic time scale
International Commission on Stratigraphy
Astronomical chronology
Galactic year
Nuclear timescale
Precession
Sidereal time
Other units of time
Shake
Jiffy
Second
Minute
Moment
Hour
Day
Week
Fortnight
Month
Year
Olympiad
Lustrum
Decade
Century
Saeculum
Millennium
Related topics
Chronology
Duration
music
Mental chronometry
Metric time
System time
Time value of money
Timekeeper
[show]
v
t
e
Chronology
Key topics
Archaeology
Astronomy
Geology
History
Paleontology
Time
Eras
Epochs
Calendar eras
Human Era
Ab urbe condita
Anno Domini / Common Era
Anno Mundi
Byzantine era
Seleucid era
Spanish era
Before Present
Hijri
Egyptian
Sothic cycle
Hindu units of time (Yuga)
Mesoamerican
Long Count
Short Count
Tzolk'in
Haab'
Regnal year
Canon of Kings
Lists of kings
Limmu
Era names
Chinese
Japanese
Korean
Vietnamese
Calendars
Pre-Julian / Julian
Pre-Julian Roman
Original Julian
Proleptic Julian
Revised Julian
Gregorian
Gregorian
Proleptic Gregorian
Old Style and New Style dates
Adoption of the Gregorian calendar
Dual dating
Astronomical
Lunisolar
Solar
Lunar
Astronomical year numbering
Others
Chinese sexagenary cycle
Geologic Calendar
Hebrew
Iranian
Islamic
ISO week date
Mesoamerican
Maya
Aztec
Winter count (Plains Indians)
Astronomic time
Cosmic Calendar
Ephemeris
Galactic year
Metonic cycle
Milankovitch cycles
Geologic time
Concepts
Deep time
Geological history of Earth
Geological time units
Standards
Global Standard Stratigraphic Age (GSSA)
Global Boundary Stratotype Section and Point (GSSP)
Methods
Chronostratigraphy
Geochronology
Isotope geochemistry
Law of superposition
Luminescence dating
Samarium–neodymium dating
Chronological
dating
Absolute dating
Amino acid racemisation
Archaeomagnetic dating
Dendrochronology
Ice core
Incremental dating
Lichenometry
Paleomagnetism
Radiometric dating
Radiocarbon
Uranium–lead
Potassium–argon
Tephrochronology
Luminescence dating
Thermoluminescence dating
Relative dating
Fluorine absorption
Nitrogen dating
Obsidian hydration
Seriation
Stratigraphy
Genetic methods
Molecular clock
Linguistic methods
Glottochronology
Related topics
Chronicle
New Chronology
Periodization
Synchronoptic view
Timeline
Year zero
Circa
Floruit
Terminus post quem
ASPRO chronology
Portal
[show]
v
t
e
Time in religion and mythology
Time and fate deities
Eternity
Eschatology
Golden Age
Divination
Prophecy
Calendar
Fate
[show]
v
t
e
Philosophy of time
Concepts
in time
Time
A priori and a posteriori
A-series and B-series
Action
Deterministic system
Duration
Eternal return
Eternity
Event
Free will
Growing block universe
Imaginary time
Multiple time dimensions
Temporal parts

Time Portal
Theories
of time
B-Theory of time
Compatibilism and incompatibilism
Determinism
Endurantism
Eternalism
Four dimensionalism
Fatalism
Temporal finitism
Indeterminism
Perdurantism
Presentism
Static interpretation of time
Related
articles
Etiology
Metaphysics
Post hoc ergo propter hoc
Teleology
The Unreality of Time
The Singular Universe and the Reality of Time
An Experiment with Time
[show]
v
t
e
Metaphysics
Metaphysicians
Parmenides
Plato
Aristotle
Plotinus
Duns Scotus
Thomas Aquinas
Francisco Suárez
Nicolas Malebranche
René Descartes
John Locke
David Hume
Thomas Reid
Immanuel Kant
Isaac Newton
Arthur Schopenhauer
Baruch Spinoza
Georg W. F. Hegel
George Berkeley
Gottfried Wilhelm Leibniz
Henri Bergson
Friedrich Nietzsche
Charles Sanders Peirce
Joseph Maréchal
Ludwig Wittgenstein
Martin Heidegger
Alfred N. Whitehead
Bertrand Russell
Dorothy Emmet
G. E. Moore
Jean-Paul Sartre
Gilbert Ryle
Hilary Putnam
P. F. Strawson
R. G. Collingwood
Adolph Stöhr
Rudolf Carnap
Saul Kripke
Willard V. O. Quine
G. E. M. Anscombe
Donald Davidson
Michael Dummett
David Malet Armstrong
David Lewis
Alvin Plantinga
Peter van Inwagen
Derek Parfit
more ...
Theories
Abstract object theory
Action theory
Anti-realism
Determinism
Dualism
Enactivism
Essentialism
Existentialism
Free will
Idealism
Libertarianism
Liberty
Materialism
Meaning of life
Monism
Naturalism
Nihilism
Phenomenalism
Realism
Physicalism
Pirsig's metaphysics of Quality
Platonic idealism
Relativism
Scientific realism
Solipsism
Subjectivism
Substance theory
Type theory
Concepts
Abstract object
Anima mundi
Being
Category of being
Causality
Choice
Cogito ergo sum
Concept
Embodied cognition
Entity
Essence
Existence
Experience
Hypostatic abstraction
Idea
Identity
Identity and change
Information
Insight
Intelligence
Intention
Linguistic modality
Matter
Meaning
Memetics
Mental representation
Mind
Motion
Necessity
Notion
Object
Pattern
Perception
Physical body
Principle
Property
Qualia
Quality
Reality
Soul
Subject
Substantial form
Thought
Time
Truth
Type–token distinction
Universal
Unobservable
Value
more ...
Related topics
Axiology
Cosmology
Epistemology
Feminist metaphysics
Interpretations of quantum mechanics
Meta-
Ontology
Philosophy of mind
Philosophy of psychology
Philosophy of self
Philosophy of space and time
Teleology
Theoretical physics
Category
Portal
[show]
v
t
e
SI base quantities
Base quantity
Quantity
SI unit
Name
Symbol
Dimension
symbol
Unit name
(symbol)
Example
length l, x, r, (etc.) L metre (m) r = 10 m
mass m M kilogram (kg) m = 10 kg
time, duration t T second (s) t = 10 s
electric current I , i I  ampere (A) I = 10 A
thermodynamic temperature T Θ kelvin (K) T = 10 K
amount of substance n N mole (mol) n = 10 mol
luminous intensity Iv J candela (cd) Iv = 10 cd
Specification
The quantity (not the unit) can have a specification: Tmax = 300 K
Derived quantity
Definition
A quantity Q is expressed in the base quantities: Q = f ( l , m , t , I , T , n , I v ) {\displaystyle Q=f\left({\mathit {l,m,t,I,T,n,I}}\mathrm {_{v}} \right)}
Derived dimension
dim Q = La · Mb · Tc · Id · Θe · Nf · Jg (Superscripts a–g are algebraic exponents, usually a positive, negative or zero integer.)
Example
Quantity acceleration = l1 · t−2, dim acceleration = L1 · T−2
possible units: m1 · s−2, km1 · Ms−2, etc.
See also
History of the metric system
International System of Quantities
Proposed redefinitions
Systems of measurement
Book
Category
Outline
Authority control
GND: 4067461-7
Time portal
Physics portal
Retrieved from "https://en.wikipedia.org/w/index.php?title=Time&oldid=821694181"
Categories:
Time
Concepts in metaphysics
Concepts in physics
Physical quantities
SI base quantities
Spacetime
Hidden categories:
Articles with inconsistent citation formats
CS1 maint: Multiple names: authors list
Webarchive template wayback links
Wikipedia indefinitely semi-protected pages
Use dmy dates from November 2012
Articles containing potentially dated statements from May 2010
All articles containing potentially dated statements
Wikipedia articles needing clarification from February 2014
All articles with unsourced statements
Articles with unsourced statements from August 2015
Articles with specifically marked weasel-worded phrases from August 2015
Articles with unsourced statements from January 2015
Articles with unsourced statements from May 2017
Pages using div col without cols and colwidth parameters
Wikipedia articles with GND identifiers
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
View source
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Wikiquote
Languages
Afrikaans
Alemannisch
አማርኛ
العربية
Aragonés
অসমীয়া
Asturianu
Atikamekw
Avañe'ẽ
Azərbaycanca
تۆرکجه
বাংলা
Bân-lâm-gú
Башҡортса
Беларуская
Беларуская (тарашкевіца)
Български
Boarisch
བོད་ཡིག
Bosanski
Brezhoneg
Буряад
Català
Чӑвашла
Čeština
ChiShona
Cymraeg
Dansk
Deutsch
Eesti
Ελληνικά
Emiliàn e rumagnòl
Эрзянь
Español
Esperanto
Estremeñu
Euskara
فارسی
Français
Frysk
Furlan
Gaeilge
Galego
客家語/Hak-kâ-ngî
Хальмг
한국어
Հայերեն
हिन्दी
Hrvatski
Ido
Bahasa Indonesia
Interlingua
Íslenska
Italiano
עברית
Basa Jawa
ಕನ್ನಡ
ქართული
Қазақша
Kiswahili
Kreyòl ayisyen
Кыргызча
ລາວ
Latina
Latviešu
Lëtzebuergesch
Lietuvių
Limburgs
Livvinkarjala
Magyar
मैथिली
Македонски
മലയാളം
मराठी
Bahasa Melayu
Mìng-dĕ̤ng-ngṳ̄
Монгол
မြန်မာဘာသာ
Nāhuatl
Nederlands
Nedersaksies
नेपाली
नेपाल भाषा
日本語
Nordfriisk
Norsk
Norsk nynorsk
Novial
Occitan
ଓଡ଼ିଆ
Oʻzbekcha/ўзбекча
ਪੰਜਾਬੀ
پنجابی
پښتو
Patois
Piemontèis
Plattdüütsch
Polski
Português
Qaraqalpaqsha
Română
Runa Simi
Русиньскый
Русский
Саха тыла
Scots
Seeltersk
Sesotho sa Leboa
Shqip
Sicilianu
සිංහල
Simple English
سنڌي
Slovenčina
Slovenščina
Словѣньскъ / ⰔⰎⰑⰂⰡⰐⰠⰔⰍⰟ
Ślůnski
Soomaaliga
کوردی
Српски / srpski
Srpskohrvatski / српскохрватски
Basa Sunda
Suomi
Svenska
Tagalog
தமிழ்
Татарча/tatarça
తెలుగు
ไทย
Тоҷикӣ
ᏣᎳᎩ
Türkçe
Türkmençe
Українська
اردو
Vèneto
Vepsän kel’
Tiếng Việt
Võro
文言
Winaray
吴语
ייִדיש
Yorùbá
粵語
Zazaki
Žemaitėška
中文
Edit links
This page was last edited on 22 January 2018, at 02:03.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

values: mw-page-base noprint

values: mw-head-base noprint

attrs: class id

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

attrs: href class title

values:
/wiki/Time_(disambiguation)
mw-disambig
Time (disambiguation)

attrs: role class

values:
note
hatnote navigation-not-searchable

attrs: class style

value: span

attrs: class href

attrs: id class style

values: font-size: 105%; padding: 0.2em 0px 0.4em; text-align: center; display: none;

values: float:right;clear:right;width:22.0em;margin:0 0 1.0em 1.0em;background:#f9f9f9;border:1px solid #aaa;padding:0.2em;border-spacing:0.4em 0;text-align:center;line-height:1.4em;font-size:88%

values: vertical-align: -0.338ex; width:8.14ex; height:2.843ex;

values:
/wiki/Second_law_of_motion
mw-redirect
Second law of motion

values: font-size: 105%; padding: 0.35em 0px 0.4em; text-align: center; display: none;

values:
/wiki/Fourth_dimension
mw-disambig
Fourth dimension

values:
/wiki/Gottfried_Leibniz
mw-redirect
Gottfried Leibniz

values:
/wiki/Electronic_transition
mw-redirect
Electronic transition

values:
/wiki/Ancient_world
mw-redirect
Ancient world

values: History of science and technology in China

values:
/wiki/Quartz_watch
mw-redirect
Quartz watch

values:
/wiki/Bell_(instrument)
mw-redirect
Bell (instrument)

values: plainlinks noexcerpt noprint asof-tag update

values:
/wiki/Time_(Orders_of_magnitude)
mw-redirect
Time (Orders of magnitude)

values:
/wiki/Special_theory_of_relativity
mw-redirect
Special theory of relativity

values:
/wiki/Industrial_revolution
mw-redirect
Industrial revolution

values:
/wiki/Mean_solar_time
mw-redirect
Mean solar time

values:
/wiki/Prime_Meridian
mw-redirect
Prime Meridian

values:
nofollow
external free
http://maia.usno.navy.mil/ser7/ser7.dat

values:
/wiki/Time_interval
mw-redirect
Time interval

values:
/wiki/Time_cycles
mw-redirect
Time cycles

values:
/wiki/Algebraic_form
mw-redirect
Algebraic form

values: The text near this tag may need clarification or removal of jargon. (February 2014)

values:
noprint Inline-Template
margin-left:0.1em; white-space:nowrap;

values: This claim needs references to reliable sources. (August 2015)

values:
noprint Inline-Template Template-Fact
white-space:nowrap;

values: The material near this tag may use weasel words or too-vague attribution. (August 2015)

values: Wikipedia:Manual of Style/Words to watch

values: This claim needs references to reliable sources. (January 2015)

values: This claim needs references to reliable sources. (May 2017)

values:
/wiki/Sir_Isaac_Newton
mw-redirect
Sir Isaac Newton

values:
/wiki/Absolute_time_and_space
mw-redirect
Absolute time and space

values:
/wiki/Greek_philosophy
mw-redirect
Greek philosophy

values:
/wiki/Confessions_(St._Augustine)
mw-redirect
Confessions (St. Augustine)

values:
/wiki/Negative_theology
mw-redirect
Negative theology

values: position: absolute; left: 0px; top: 0px; text-align: left; font-family:'Times New Roman',serif; font-weight:bold; font-size: large; color: gray;

values: position: absolute; right: 0px; bottom: 0px; text-align: left; font-family:'Times New Roman',serif; font-weight:bold; font-size: large; color: gray;

values: float: right; clear: right; margin: 0.5em 0 0.8em 1.4em; width:35%; padding: 10px; border: 1px solid #aaa; font-size: 88%; background-color: #F9F9F9;

values:
/wiki/Spacetime_interval
mw-redirect
Spacetime interval

values:
/wiki/Mean_lifetime
mw-redirect
Mean lifetime

attrs: alt src width height class data-file-width data-file-height

values:
/wiki/General_Relativity
mw-redirect
General Relativity

values:
/wiki/Temporal_illusion
mw-redirect
Temporal illusion

values:
/wiki/Attention_deficit_disorder
mw-redirect
Attention deficit disorder

values: Timeline of the Fukushima Daiichi nuclear disaster

values:
/wiki/Israeli_Hebrew_language
mw-redirect
Israeli Hebrew language

values: Aboriginal groupings of Western Australia

values:
/wiki/From_Eternity_to_Here
mw-redirect
From Eternity to Here

values:
/wiki/The_Discovery_of_Time
mw-redirect
The Discovery of Time

values: National Association of Watch and Clock Collectors

values: width: 25%;text-align: left; vertical-align: top;

values: border-collapse: collapse; padding: 0; border: 0; background:transparent; width:100%;

values:
nofollow
external text
http://www.yourdictionary.com/time

values:
nofollow
http://www.iep.utm.edu/time/
external text

values:
nofollow
external text
http://www.iep.utm.edu/leib-met/#H7

values:
nofollow
external text
http://www.iep.utm.edu/kantmeta/#H4

values:
nofollow
external text
http://search.eb.com/eb/article-9438957

values:
nofollow
external text
http://tycho.usno.navy.mil/leapsec.html

values:
nofollow
external text
//doi.org/10.1103%2FPhysRevLett.1.105

values: Category:CS1 maint: Multiple names: authors list

values:
nofollow
external text
http://tycho.usno.navy.mil/cesium.html

values:
/wiki/J._M._D._Meiklejohn
mw-redirect
J. M. D. Meiklejohn

attrs: alt src title width height srcset data-file-width data-file-height

values:
/wiki/PubMed_Identifier
mw-redirect
PubMed Identifier

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/17434690

values:
nofollow
external text
//doi.org/10.1016%2Fj.pbb.2006.07.019

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/16920182

values:
nofollow
external text
//doi.org/10.1007%2FBF00426830

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/826945

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/18562621

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/541126

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/20959511

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

values:
/wiki/David_S._Landes
mw-redirect
David S. Landes

values: Technics and Time, 1: The Fault of Epimetheus

values: The Singular Universe and the Reality of Time

values: font-size:90%; -moz-column-count: 2; -webkit-column-count: 2; column-count: 2;

values: div-col columns column-count column-count-2

values: padding-bottom: 0.75em; text-align: center;

attrs: alt src width height style srcset data-file-width data-file-height

values: display: inline-block; width: 31px; line-height: 31px; vertical-align: middle; text-align: center;

values: display: inline-block; margin-left: 4px; width: 182px; vertical-align: middle;

values: border-top:1px solid #aaa; padding-top: 0.75em;

values: metadata plainlinks plainlist mbox-small

values: border:1px solid #aaa; padding:0.75em; background:#f9f9f9;

values:
nofollow
external text
http://exploringtime.org/?page=segments

values:
nofollow
external text
http://tycho.usno.navy.mil/systime.html

values:
nofollow
http://www.dmoz.org/Reference/Time/
external text

values: nowraplinks hlist collapsible autocollapse navbox-inner

values: Far future in science fiction and popular culture

values:
/wiki/K%C4%81la_(time)
mw-redirect
Kāla (time)

values:
/wiki/Eon_(geology)
mw-redirect
Eon (geology)

values:
/wiki/Planck_epoch
mw-redirect
Planck epoch

values: nowraplinks hlist collapsible collapsed navbox-inner

values: background:#e8e8ff;background:#ee9; border:1px solid silver; padding:0.2em 1em 0.2em 6.5em;

values: Template talk:Time measurement and standards

values: International Earth Rotation and Reference Systems Service

values: International Commission on Stratigraphy

values:
/wiki/Chinese_sexagenary_cycle
mw-redirect
Chinese sexagenary cycle

values: Global Boundary Stratotype Section and Point

values: nowraplinks collapsible collapsed navbox-inner

values: navigation navbox Chronology padding:3px

values: Template talk:Time in religion and mythology

values: nowraplinks collapsible autocollapse navbox-inner

values:
navbox-image
3
width:1px;padding:0px 0px 0px 2px

values:
/wiki/B-Theory_of_time
mw-redirect
B-Theory of time

values:
/wiki/Compatibilism_and_incompatibilism
mw-redirect
Compatibilism and incompatibilism

values:
/wiki/Four_dimensionalism
mw-redirect
Four dimensionalism

values:
/wiki/Presentism_(philosophy_of_time)
mw-redirect
Presentism (philosophy of time)

values:
/wiki/Mind-body_dualism
mw-redirect
Mind-body dualism

values:
/wiki/Enactivism_(psychology)
mw-redirect
Enactivism (psychology)

values: navigation navbox Metaphysics padding:3px

values:
text-align:center;
headerSort
0
columnheader button
Sort ascending

values: Uppercase letter i in italic, subscript lowercase letter v

values:
wikitable sortable jquery-tablesorter
text-align:center; margin:0;

values: The seven SI base quantities and their units

values:
navbox-image
4
width:1px;padding:0px 0px 0px 2px

values: {\displaystyle Q=f\left({\mathit {l,m,t,I,T,n,I}}\mathrm {_{v}} \right)}

values: vertical-align: -0.838ex; width:24.155ex; height:2.843ex;

values: Q=f\left({\mathit {l,m,t,I,T,n,I}}\mathrm {_{v}} \right)

values:
/wiki/Dimension_of_a_physical_quantity
mw-redirect
Dimension of a physical quantity

values:
nofollow
external text
https://d-nb.info/gnd/4067461-7

values: Stylised atom with three Bohr model orbits and stylised nucleus.svg

values:
noprint metadata navbox
navigation
Portals
font-weight:bold;padding:0.4em 2em

values: Category:Articles with inconsistent citation formats

values: Category:Webarchive template wayback links

values: Category:Wikipedia indefinitely semi-protected pages

values: Category:Use dmy dates from November 2012

values: Category:Articles containing potentially dated statements from May 2010

values: Category:All articles containing potentially dated statements

values: Category:Wikipedia articles needing clarification from February 2014

values: Category:All articles with unsourced statements

values: Category:Articles with unsourced statements from August 2015

values: Category:Articles with specifically marked weasel-worded phrases from August 2015

values: Category:Articles with unsourced statements from January 2015

values: Category:Articles with unsourced statements from May 2017

values: Category:Pages using div col without cols and colwidth parameters

values: Category:Wikipedia articles with GND identifiers

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values:
/wiki/Time
View the content page [ctrl-alt-c]
c

values:
This page is protected.
You can view its source [ctrl-alt-e]

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values: portal navigation p-wikibase-otherprojects p-wikibase-otherprojects-label

values:
https://af.wikipedia.org/wiki/Tyd
Tyd – Afrikaans
af
af
interlanguage-link-target

values:
https://als.wikipedia.org/wiki/Zeit
Zeit – Alemannisch
als
als
interlanguage-link-target

values:
https://an.wikipedia.org/wiki/Tiempo
Tiempo – Aragonese
an
an
interlanguage-link-target

values:
https://ast.wikipedia.org/wiki/Tiempu
Tiempu – Asturian
ast
ast
interlanguage-link-target

values:
https://gn.wikipedia.org/wiki/%C3%81ra
Ára – Guarani
gn
gn
interlanguage-link-target

values: Час – Belarusian (Taraškievica orthography)

values:
https://bar.wikipedia.org/wiki/Zeid
Zeid – Bavarian
bar
bar
interlanguage-link-target

values: དུས་ཚོད། – Tibetan

values:
https://br.wikipedia.org/wiki/Amzer
Amzer – Breton
br
br
interlanguage-link-target

values:
https://ca.wikipedia.org/wiki/Temps
Temps – Catalan
ca
ca
interlanguage-link-target

values:
https://cs.wikipedia.org/wiki/%C4%8Cas
Čas – Czech
cs
cs
interlanguage-link-target

values:
https://sn.wikipedia.org/wiki/Nguva
Nguva – Shona
sn
sn
interlanguage-link-target

values:
https://cy.wikipedia.org/wiki/Amser
Amser – Welsh
cy
cy
interlanguage-link-target

values:
https://da.wikipedia.org/wiki/Tid
Tid – Danish
da
da
interlanguage-link-target

values:
https://de.wikipedia.org/wiki/Zeit
Zeit – German
de
de
interlanguage-link-target

values:
https://et.wikipedia.org/wiki/Aeg
Aeg – Estonian
et
et
interlanguage-link-target

values: Χρόνος – Greek

values:
https://es.wikipedia.org/wiki/Tiempo
Tiempo – Spanish
es
es
interlanguage-link-target

values:
https://eo.wikipedia.org/wiki/Tempo
Tempo – Esperanto
eo
eo
interlanguage-link-target

values:
https://ext.wikipedia.org/wiki/Tiempu
Tiempu – Extremaduran
ext
ext
interlanguage-link-target

values:
https://eu.wikipedia.org/wiki/Denbora
Denbora – Basque
eu
eu
interlanguage-link-target

values:
https://fr.wikipedia.org/wiki/Temps
Temps – French
fr
fr
interlanguage-link-target

values:
https://fy.wikipedia.org/wiki/Tiid
Tiid – Western Frisian
fy
fy
interlanguage-link-target

values:
https://fur.wikipedia.org/wiki/Timp
Timp – Friulian
fur
fur
interlanguage-link-target

values:
https://ga.wikipedia.org/wiki/Am
Am – Irish
ga
ga
interlanguage-link-target

values:
https://gl.wikipedia.org/wiki/Tempo
Tempo – Galician
gl
gl
interlanguage-link-target

values: Ժամանակ – Armenian

values:
https://io.wikipedia.org/wiki/Tempo
Tempo – Ido
io
io
interlanguage-link-target

values:
https://id.wikipedia.org/wiki/Waktu
Waktu – Indonesian
id
id
interlanguage-link-target

values:
https://ia.wikipedia.org/wiki/Tempore
Tempore – Interlingua
ia
ia
interlanguage-link-target

values:
https://is.wikipedia.org/wiki/T%C3%ADmi
Tími – Icelandic
is
is
interlanguage-link-target

values:
https://it.wikipedia.org/wiki/Tempo
Tempo – Italian
it
it
interlanguage-link-target

values:
https://jv.wikipedia.org/wiki/Wektu
Wektu – Javanese
jv
jv
interlanguage-link-target

values: Уақыт – Kazakh

values:
https://sw.wikipedia.org/wiki/Wakati
Wakati – Swahili
sw
sw
interlanguage-link-target

values:
https://ht.wikipedia.org/wiki/Tan
Tan – Haitian Creole
ht
ht
interlanguage-link-target

values: Убакыт – Kyrgyz

values: ລາຍຊື່ໜ່ວຍນັບເວລາ – Lao

values:
https://la.wikipedia.org/wiki/Tempus
Tempus – Latin
la
la
interlanguage-link-target

values: interlanguage-link interwiki-la badge-Q17437796 badge-featuredarticle

values:
https://lv.wikipedia.org/wiki/Laiks
Laiks – Latvian
lv
lv
interlanguage-link-target

values:
https://lb.wikipedia.org/wiki/Z%C3%A4it
Zäit – Luxembourgish
lb
lb
interlanguage-link-target

values:
https://lt.wikipedia.org/wiki/Laikas
Laikas – Lithuanian
lt
lt
interlanguage-link-target

values:
https://li.wikipedia.org/wiki/Tied
Tied – Limburgish
li
li
interlanguage-link-target

values:
https://olo.wikipedia.org/wiki/Aigu
Aigu – Livvi-Karelian
olo
olo
interlanguage-link-target

values:
https://hu.wikipedia.org/wiki/Id%C5%91
Idő – Hungarian
hu
hu
interlanguage-link-target

values:
https://ms.wikipedia.org/wiki/Masa
Masa – Malay
ms
ms
interlanguage-link-target

values: အချိန် – Burmese

values:
https://nah.wikipedia.org/wiki/Cahuitl
Cahuitl – Nāhuatl
nah
nah
interlanguage-link-target

values:
https://nl.wikipedia.org/wiki/Tijd
Tijd – Dutch
nl
nl
interlanguage-link-target

values:
https://nds-nl.wikipedia.org/wiki/Tied
Tied – Low Saxon
nds-NL
nds-NL
interlanguage-link-target

values:
https://frr.wikipedia.org/wiki/Tidj
Tidj – Northern Frisian
frr
frr
interlanguage-link-target

values:
https://no.wikipedia.org/wiki/Tid
Tid – Norwegian
no
no
interlanguage-link-target

values:
https://nn.wikipedia.org/wiki/Tid
Tid – Norwegian Nynorsk
nn
nn
interlanguage-link-target

values:
https://nov.wikipedia.org/wiki/Tempe
Tempe – Novial
nov
nov
interlanguage-link-target

values:
https://oc.wikipedia.org/wiki/Temps
Temps – Occitan
oc
oc
interlanguage-link-target

values: ସମୟ (କାଳ) – Odia

values:
https://uz.wikipedia.org/wiki/Vaqt
Vaqt – Uzbek
uz
uz
interlanguage-link-target

values:
https://jam.wikipedia.org/wiki/Taim
Taim – Jamaican Creole English
jam
jam
interlanguage-link-target

values:
https://pms.wikipedia.org/wiki/Temp
Temp – Piedmontese
pms
pms
interlanguage-link-target

values:
https://nds.wikipedia.org/wiki/Tiet
Tiet – Low German
nds
nds
interlanguage-link-target

values:
https://pl.wikipedia.org/wiki/Czas
Czas – Polish
pl
pl
interlanguage-link-target

values:
https://pt.wikipedia.org/wiki/Tempo
Tempo – Portuguese
pt
pt
interlanguage-link-target

values:
https://ro.wikipedia.org/wiki/Timp
Timp – Romanian
ro
ro
interlanguage-link-target

values:
https://qu.wikipedia.org/wiki/Mit%27awi
Mit'awi – Quechua
qu
qu
interlanguage-link-target

values:
https://sco.wikipedia.org/wiki/Time
Time – Scots
sco
sco
interlanguage-link-target

values:
https://stq.wikipedia.org/wiki/Tied
Tied – Saterland Frisian
stq
stq
interlanguage-link-target

values:
https://nso.wikipedia.org/wiki/Nako
Nako – Northern Sotho
nso
nso
interlanguage-link-target

values:
https://sq.wikipedia.org/wiki/Koha
Koha – Albanian
sq
sq
interlanguage-link-target

values:
https://scn.wikipedia.org/wiki/Tempu
Tempu – Sicilian
scn
scn
interlanguage-link-target

values:
https://simple.wikipedia.org/wiki/Time
Time – Simple English
simple
simple
interlanguage-link-target

values:
https://sl.wikipedia.org/wiki/%C4%8Cas
Čas – Slovenian
sl
sl
interlanguage-link-target

values:
https://szl.wikipedia.org/wiki/Czas
Czas – Silesian
szl
szl
interlanguage-link-target

values:
https://so.wikipedia.org/wiki/Wakhti
Wakhti – Somali
so
so
interlanguage-link-target

values:
https://sh.wikipedia.org/wiki/Vrijeme
Vrijeme – Serbo-Croatian
sh
sh
interlanguage-link-target

values:
https://su.wikipedia.org/wiki/Waktu
Waktu – Sundanese
su
su
interlanguage-link-target

values:
https://fi.wikipedia.org/wiki/Aika
Aika – Finnish
fi
fi
interlanguage-link-target

values:
https://sv.wikipedia.org/wiki/Tid
Tid – Swedish
sv
sv
interlanguage-link-target

values:
https://tl.wikipedia.org/wiki/Panahon
Panahon – Tagalog
tl
tl
interlanguage-link-target

values: நேரம் – Tamil

values: Вакыт – Tatar

values: Замон – Tajik

values:
https://tr.wikipedia.org/wiki/Zaman
Zaman – Turkish
tr
tr
interlanguage-link-target

values:
https://tk.wikipedia.org/wiki/Wagt
Wagt – Turkmen
tk
tk
interlanguage-link-target

values:
https://vec.wikipedia.org/wiki/Tenpo
Tenpo – Venetian
vec
vec
interlanguage-link-target

values:
https://vep.wikipedia.org/wiki/Aig
Aig – Veps
vep
vep
interlanguage-link-target

values:
https://fiu-vro.wikipedia.org/wiki/Aig
Aig – Võro
fiu-vro
fiu-vro
interlanguage-link-target

values:
https://diq.wikipedia.org/wiki/Zeman
Zeman – Zazaki
diq
diq
interlanguage-link-target

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Time rootpage-Time skin-vector action-view