Epsilon
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224544437
2008-07-09T09:51:01Z
121.72.160.97
/* Fictional names */
{{otheruses4|Greek epsilon|Latin epsilon|ɛ}}
{{wiktionarypar2|Ε|ε}}
{{Table_Greekletters|letter=epsilon}}
'''Epsilon''' (uppercase '''Ε''', lowercase '''ε'''; {{lang-el|Έψιλον}}) is the fifth letter of the [[Greek alphabet]], corresponding phonetically to a [[close-mid front unrounded vowel]] /e/. In the system of [[Greek numerals]] it has a value of 5. It was derived from the [[Phoenician alphabet|Phoenician letter]] [[He (letter)|He]] [[Image:phoenician he.png|20px|He]]. Letters that arose from Epsilon include the Roman [[E]] and Cyrillic [[Ye (Cyrillic)|Ye]].
"Epsilon" ({{polytonic|ἒ ψιλόν}}, "simple e") was coined in the Middle Ages to distinguish the letter from the [[Greek orthography|diphthong αι]], which started being pronounced the same way during the period of [[New Testament Greek]].
The standard symbol for lowercase epsilon is the '''lunate epsilon [[ϵ]]''' (\epsilon, <math>\epsilon\,</math>, in [[LaTeX]]), which has its origins in Medieval Greek.
In mathematical notation, the minuscule '''open e''' symbol '''[[ɛ]]''' (\varepsilon, <math>\varepsilon</math>, in LaTeX) from the extended [[Latin alphabet]] is often used interchangeably with the '''lunate epsilon.'''
The lunate epsilon ϵ is not to be confused with the set symbol <math>\in</math> or falsely recognized as the lunate version [[Σ]].
==Symbol==
The upper-case Epsilon is not a commonly-used symbol outside of the Greek language because of its similarity to the Roman letter [[E]].
The lower-case epsilon, '''[[ε]]'''/'''[[ϵ]]''', or open e, '''[[ɛ]]''', (see above) is used as the symbol for:
* In mathematics (particularly [[calculus]]), an arbitrarily (or nearly so) small positive quantity is commonly denoted ε; see [[limit (mathematics)|limit]].
** By analogy with this, the late mathematician [[Paul Erdős]] also used the term "epsilons" to refer to children ([[Paul Hoffman|Hoffman]] 1998, p. 4).
* In mathematics, the [[Levi-Civita symbol]].
* In mathematics, to represent the [[dual number]]s: a + bε, with ε<sup>2</sup>=0 and ε≠0.
* In mathematics, sometimes used to denote the [[Heaviside step function]]
* In [[set theory]], the [[epsilon nought|limit ordinal]] of the sequence <math>\omega,\omega^{\omega},\omega^{\omega^{\omega}},\dots</math>.
* In computing, the [[precision]] of a numeric data type and floating-point [[machine epsilon]].
* In [[computer science]], the [[String (computer science)|empty string]], though different writers use a variety of other symbols for the empty string as well, including the lower case Greek letter [[lambda]].
* In physics, the [[permittivity]] of a medium.
* In physics/electronics, the [[Electromotive force|EMF]] of a circuit
* In physics, the [[Strain (materials science)|strain]] of a material (A ratio of extensions).
* In [[automata theory]], a transition that involves no shifting of an input symbol.
* In [[astronomy]], the fifth brightest (usually) star in a [[constellation]]. ''See'' [[Bayer designation]].
* In the [[International Phonetic Alphabet]], the [[open-mid front unrounded vowel]], (but generally written ɛ instead of ε) as in the English word "pet" (/pɛt/)
* In [[astronomy]], Epsilon is the name for Uranus' most distant and most visible ring.
* In [[chemistry]], the [[molar extinction coefficient]] of a [[chromophore]].
* In [[economics]], ε refers to [[elasticity (economics)|elasticity]].
===Fictional names===
* In the popular web series "[[Red vs. blue]]", Epsilon is the name of the AI assigned to freelancer Washington.
* ''Epsilon in Malaysian Pale'' is the name of the second solo album released by [[Tangerine Dream]] leader [[Edgar Froese]] in [[1975]].
* Epsilon is also an [[Australian]] light-powered female-looking [[robot]] that fought [[Pluto (manga)|Pluto]] in an episode of [[Astro Boy (2003)|Astro Boy]].
* ''Epsilon Eridani III'' is the planet that the spacestation [[Babylon 5]] orbited in the eponymous [[science fiction|sci-fi]] television series.
* [[E-104 Epsilon]] is also the name of a robot in [[Sonic Adventure]].
* "Epsilon 9" is the name of the Federation space station consumed by the V'ger cloud in [[Star Trek: The Motion Picture]].
* Epsilon is the name of an unlockable creature in the game [[Monster Rancher 2]]
* In Greek it is used for [[Epsilon Team]].
* "Epsilon Mirror" is the name of one of Aika's moves in the video game [[Skies of Arcadia]].
* ''Epsilon'' is the leader of the Rebellion in [[Mega Man X: Command Mission]]
* "The Epsilon Program" is a mysterious [[cult]] in the video game [[Grand Theft Auto: San Andreas]] by Game Developer [[Rockstar North]]. This cult is thought to be based on [[Scientology]].
* The Epsilon Project is a fictional experiment mentioned in the [[Dreamcast]] and [[Xbox]] versions of [[Dead or Alive 2]] and is based around cloning.
* Epsilon is the lowest of five social [[caste]]s in the [[Aldous Huxley]] novel ''[[Brave New World]]''.
* "Plan Epsilon" was one of many plans to restore [[Doctor Doom]] to life in the event of his death, as shown in [[Fantastic Four]] issue no. 246, written by [[Stan Lee]].
* Epsilon-Eagle is the name of the protagonist in the [[Sega Mega Drive]] game [[Alien Soldier]].
* Epsilon was the name given to one of the ground support teams in the [[Sony Playstation]] game [[G-Police]]
* Epsilon is the name of the newly resurrected Yuri Faction in the [[Yuri's Revenge]] mod [[Mental Omega]]
===Other uses===
*"Epsilon" is the name used by [[General Motors]] for the post-[[2003]] [[GM Epsilon platform|Epsilon platform]].
* [[EpsilonEuskadi]] carmaker <ref>[http://www.epsiloneuskadi.com/ EPSILON EUSKADI==JOAN VILLADELPRAT & SERGIO RINLAND & JORDI CATON==AZKOITIA (43º 10' 22'' N - 2º 19' 26'' O)<!-- Bot generated title -->]</ref> and [[EpsilonEuskadi LMP1]] car.
*[[Hurricane Epsilon (2005)|Hurricane Epsilon]], a storm of the [[2005 Atlantic hurricane season]].
*"Epsilon Concepts" is the name of a national digital agency.
== References ==
*[[Paul Hoffman|Hoffman, Paul]]; ''[[The man who loved only numbers]]''. Hyperion, 1998. ISBN 0-7868-6362-5.
<References/>
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[[Category:Greek letters]]
[[Category:Vowel letters]]
[[als:Ε]]
[[ar:إبسيلون (حرف إغريقي)]]
[[arc:Ε]]
[[ast:Epsilon]]
[[br:Epsilon (lizherenn)]]
[[bg:Епсилон]]
[[ca:Èpsilon]]
[[cy:Epsilon]]
[[da:Epsilon]]
[[de:Epsilon]]
[[el:Έψιλον]]
[[es:Ε]]
[[eo:Epsilono]]
[[ext:Éssilun]]
[[eu:Epsilon (greko)]]
[[fr:Epsilon]]
[[ga:Eipsealón]]
[[gd:Epsilon]]
[[gl:Epsilon]]
[[ko:Ε]]
[[hr:Epsilon]]
[[id:Epsilon]]
[[is:Epsílon]]
[[it:Epsilon (lettera)]]
[[he:אפסילון]]
[[ka:ეფსილონი (ასო)]]
[[sw:Epsilon]]
[[ht:Ε]]
[[ku:Epsilon]]
[[la:Epsilon]]
[[lt:Epsilon (raidė)]]
[[hu:Epszilon]]
[[ms:Epsilon]]
[[nah:Ε]]
[[nl:Epsilon]]
[[ja:Ε]]
[[no:Epsilon]]
[[nn:Epsilon]]
[[nds:Epsilon]]
[[pl:Epsilon]]
[[pt:Ε]]
[[ru:Эпсилон (буква)]]
[[simple:Epsilon]]
[[sk:Epsilon]]
[[sl:Epsilon]]
[[sh:Epsilon]]
[[fi:Epsilon]]
[[sv:Epsilon]]
[[th:เอปไซลอน]]
[[tr:Ε]]
[[uk:Епсилон (літера)]]
[[zh:Ε]]