In physics and the philosophy of science, instant refers to an infinitesimal interval in time, whose passage is instantaneous. In ordinary speech, an instant has been defined as "a point or very short space of time," a notion deriving from its etymological source, the Latin verb instare, from in- + stare ('to stand'), meaning 'to stand upon or near.'[1]
The continuous nature of time and its infinite divisibility was addressed by Aristotle in his Physics, where he wrote on Zeno's paradoxes. The philosopher and mathematician Bertrand Russell was still seeking to define the exact nature of an instant thousands of years later.[2]
As of October 2020, the smallest time interval certified in regulated measurements is on the order of 397 zeptoseconds (397 × 10−21 seconds).[3]
18th and 19th century usage
Instant (usually abbreviated in print to inst.) can be used to indicate "Of the current month". For example, "the 11th inst." means the 11th day of the current month, whether that date is in the past, or the future, from the date of publication.[4][5][6]
See also
Look up
instant in Wiktionary, the free dictionary.
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Key concepts | |
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Measurement and standards | Chronometry | |
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Measurement systems |
- Italian six-hour clock
- Thai six-hour clock
- 12-hour clock
- 24-hour clock
- Relative hour
- Daylight saving time
- Chinese
- Decimal
- Hexadecimal
- Hindu
- Metric
- Roman
- Sidereal
- Solar
- Time zone
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Calendars |
- Main types
- Gregorian
- Julian
- Hebrew
- Islamic
- Solar Hijri
- Chinese
- Hindu Panchang
- Maya
- List
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Clocks |
- Main types
- astronomical
- atomic
- hourglass
- marine
- sundial
- watch
- 24-hour wristwatch
- mechanical
- stopwatch
- water-based
- Cuckoo clock
- Digital clock
- Grandfather clock
- History
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- Astronomical chronology
- Big History
- Calendar era
- Deep time
- Periodization
- Regnal year
- Timeline
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Philosophy of time |
- A series and B series
- B-theory of time
- Chronocentrism
- Duration
- Endurantism
- Eternal return
- Eternalism
- Event
- Moving spotlight theory
- Perdurantism
- Presentism
- Temporal finitism
- Temporal parts
- The Unreality of Time
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- Ages of Man
- Destiny
- Immortality
- Dreamtime
- Kāla
- Time and fate deities
- Wheel of time
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Human experience and use of time |
- Chronemics
- Generation time
- Mental chronometry
- Music
- Rosy retrospection
- Tense–aspect–mood
- Time management
- Yesterday – Today – Tomorrow
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Time in science | Geology |
- Geological time
- age
- chron
- eon
- epoch
- era
- period
- Geochronology
- Geological history of Earth
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Physics | |
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Other fields |
- Chronological dating
- Chronobiology
- Clock reaction
- Glottochronology
- Time geography
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Related |
- Leap year
- Memory
- Moment
- Six-hour day
- Space
- System time
- Tempus fugit
- Time capsule
- Time immemorial
- Time travel
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International standards |
- Coordinated Universal Time
- UT
- ΔT
- DUT1
- International Earth Rotation and Reference Systems Service
- ISO 31-1
- ISO 8601
- International Atomic Time
- 12-hour clock
- 24-hour clock
- Barycentric Coordinate Time
- Barycentric Dynamical Time
- Civil time
- Daylight saving time
- Geocentric Coordinate Time
- International Date Line
- IERS Reference Meridian
- Leap second
- Solar time
- Terrestrial Time
- Time zone
- 180th meridian
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Obsolete standards |
- Ephemeris time
- Greenwich Mean Time
- Prime meridian
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Time in physics | |
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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
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Calendar |
- Gregorian
- Hebrew
- Hindu
- Holocene
- Islamic (lunar Hijri)
- Julian
- Solar Hijri
- Astronomical
- Dominical letter
- Epact
- Equinox
- Intercalation
- Julian day
- Leap year
- Lunar
- Lunisolar
- Solar
- Solstice
- Tropical year
- Weekday determination
- Weekday names
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Archaeology and geology |
- Chronological dating
- Geologic time scale
- International Commission on Stratigraphy
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Astronomical chronology | |
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Other units of time |
- Flick
- Shake
- Jiffy
- Second
- Minute
- Moment
- Hour
- Day
- Week
- Fortnight
- Month
- Year
- Olympiad
- Lustrum
- Decade
- Century
- Saeculum
- Millennium
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Related topics |
- Chronology
- Duration
- Mental chronometry
- Decimal time
- Metric time
- System time
- Time metrology
- Time value of money
- Timekeeper
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