Instant

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[update], the smallest time interval certified in regulated measurements is on the order of 397 zeptoseconds (397 × 10−21 seconds).[3]

## In correspondence

In correspondence, particularly before the twentieth century, instant (usually abbreviated to inst.) can be used to indicate "of the current month". For example, "the 11th inst." means the 11th day of the current month.[4][5] Its use is consistent with the Latin proximo (prox.) for the following month, and ultimo (ult.) for the month just past.[6]

## See also

| Look up instant in Wiktionary, the free dictionary.

|

* Infinitesimal
* Planck time
* Present

## References

1. ↑ Webster's New World College Dictionary, 4th ed. (1999), p. 740.
2. ↑ W. Newton-Smith (1984), "The Russellian construction of instants", The structure of time, Routledge, p. 129, ISBN 978-0-7102-0389-2, https://books.google.com/books?id=29E9AAAAIAAJ&pg=PA129
3. ↑ "Zeptoseconds: New state record in short time measurement". Science Daily. 2020-10-16. https://www.sciencedaily.com/releases/2020/10/201016090209.htm.
4. ↑ "instant". Oxford University Press. https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100005710.
5. ↑ Chambers, Alfred B. (1900) (in en-US). The New Century Standard Letter-Writer. Chicago: Laird & Lee. pp. 258. https://www.gutenberg.org/cache/epub/56911/.
6. ↑ Crowther, Mary Owens (1922) (in en-US). How to Write Letters. New York: Garden City Publishing Co.. pp. 41. https://www.gutenberg.org/cache/epub/22222/pg22222-images.html.

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