Second
SI unit of time, defined as 9 192 631 770 periods of the ground-state hyperfine transitions of caesium-133
Concept
The second (symbol: s) is a unit of time derived from the division of the day, first into 24 hours, then into 60 minutes, and lastly into 60 seconds, for a total of 24 × 60 × 60 = 86400 seconds per day. That definition, based on 1⁄86400 of a rotation of the Earth, is still used by the Universal Time 1 (UT1) system. The current and formal definition in the International System of Units (SI) is more precise:The second [...] is defined by taking the fixed numerical value of the caesium (Cs) frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the Cs-133 atom, to be 9192631770 when expressed in the unit hertz, which is equal to s−1. This current definition was adopted in 1967 when it became feasible to define the second based on fundamental properties of nature with caesium clocks. As the speed of Earth's rotation varies and is slowing ever so slightly, a leap second is added at irregular intervals to civil time to keep clocks in sync with Earth's rotation.
CardsHistory
Second
SI unit of time, defined as 9 192 631 770 periods of the ground-state hyperfine transitions of caesium-133
The second (symbol: s) is a unit of time derived from the division of the day, first into 24 hours, then into 60 minutes, and lastly into 60 seconds, for a total of 24 × 60 × 60 = 86400 seconds per day. That definition, based on 1⁄86400 of a rotation of the Earth, is still used by the Universal Time 1 (UT1) system. The current and formal definition in the International System of Units (SI) is more precise:The second [...] is defined by taking the fixed numerical value of the caesium (Cs) frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the Cs-133 atom, to be 9192631770 when expressed in the unit hertz, which is equal to s−1. This current definition was adopted in 1967 when it became feasible to define the second based on fundamental properties of nature with caesium clocks. As the speed of Earth's rotation varies and is slowing ever so slightly, a leap second is added at irregular intervals to civil time to keep clocks in sync with Earth's rotation.
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Concept — Alters a rule of the game for as long as it stays in play.
Reach
Article length
81 / 120
Rigour
Reference density and count
58 / 120
Anchorage
Age and revision count
341 / 400
Currency
Recent edit activity and view trend
15 / 30
Diffusion
Language editions and incoming links
90 / 100
Article size
35 kB
Sources cited
28
Sections
18
Revisions
2,066
Revisions in 90 days
13
Incoming links
3,006
Language editions
169
Views over 12 months
209,733
Created on
April 5, 2001
Wikidata statements
114
Epic — 99.9th percentile of notability
Rarity ranks cards by how famous their subject is: readership, number of languages and incoming links. This tier appears in 4.50% of cards pulled from packs. It says nothing about the card’s power, which is 663 out of 1000 here.
Effect
This card does not fight on its own: it carries a single effect, chosen by its dominant measure.
History — type matchups
Strong against
Weak against
The source article
This card maps to the Wikidata item Q11574, present in 169 Wikipedia editions.
Illustration : file on Wikimedia Commons — ЮК — licence Public domain. Article text licensed under CC BY-SA 4.0.
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