Editing Alpha (section)

==Uses==

===Greek===
In [[Ancient Greek]], alpha was pronounced {{IPAblink|ä|a}} and could be either [[phoneme|phonemically]] long ([aː]) or short ([a]). Where there is ambiguity, long and short alpha are sometimes written with a [[Macron (diacritic)|macron]] and [[breve]] today: {{Lang|el|Ᾱᾱ, Ᾰᾰ|italic=no}}.
*{{Wikt-lang|grc|ὥρα|italic=no}} = {{Lang|grc|ὥρᾱ|italic=no}} ''{{Lang|grc-latn|hōrā}}'' {{IPA|el|hɔ́ːraː}} "a time"
*{{Wikt-lang|grc|γλῶσσα|italic=no}} = {{Lang|grc|γλῶσσᾰ|italic=no}} ''{{Lang|grc-latn|glôssa}}'' {{IPA|el|ɡlɔ̂ːssa}} "tongue"

In [[Modern Greek]], [[vowel length]] has been lost, and all instances of alpha simply represent the [[open front unrounded vowel]] {{IPA|el|a|IPA}}.

In the [[polytonic Greek|polytonic]] orthography of Greek, alpha, like other vowel letters, can occur with several [[diacritic]] marks: any of three accent symbols ({{lang|grc|ά, ὰ, ᾶ}}), and either of two breathing marks ({{lang|grc|ἁ, ἀ}}), as well as combinations of these. It can also combine with the [[iota subscript]] ({{lang|grc|ᾳ}}).

====Greek grammar====
In the [[Attic Greek|Attic]]–[[Ionic Greek|Ionic]] dialect of Ancient Greek, long alpha {{IPA|[aː]}} fronted to {{IPAblink|ɛː}} ([[eta]]). In Ionic, the shift took place in all positions. In Attic, the shift did not take place after [[epsilon]], [[iota]], and [[rho]] ({{Lang|grc|ε, ι, ρ|italic=no}}; {{Lang|grc-latn|e, i, r}}). In [[Doric Greek|Doric]] and [[Aeolic Greek|Aeolic]], long alpha is preserved in all positions.<ref>[[Herbert Weir Smyth]]. ''Greek grammar for colleges''. [http://www.ccel.org/s/smyth/grammar/html/smyth_1b_uni.htm#30 paragraph 30] {{Webarchive|url=https://web.archive.org/web/20110220092904/http://www.ccel.org/s/smyth/grammar/html/smyth_1b_uni.htm#30 |date=20 February 2011 }} and [http://www.ccel.org/s/smyth/grammar/html/smyth_1b_notes.htm#30D note] {{Webarchive|url=https://web.archive.org/web/20090313050255/http://www.ccel.org/s/smyth/grammar/html/smyth_1b_notes.htm#30D |date=13 March 2009 }}.</ref>
*Doric, Aeolic, Attic {{lang|grc|χώρᾱ}} ''{{Lang|grc-latn|chṓrā}}'' – Ionic {{lang|grc|χώρη}} ''{{Lang|grc-latn|chṓrē}}'', "country"
*Doric, Aeolic {{lang|grc|φᾱ&#769;μᾱ}} ''{{Lang|grc-latn|phā́mā}}'' – Attic, Ionic {{lang|grc|φήμη}} ''{{Lang|grc-latn|phḗmē}}'', "report"

[[Privative a]] is the Ancient Greek prefix {{Lang|grc|ἀ-|italic=no}} or {{Lang|grc|ἀν-|italic=no}} {{Lang|grc-latn|a-, an-}}, added to words to negate them. It originates from the [[Proto-Indo-European language|Proto-Indo-European]] {{lang|ine-x-proto|*n̥-}} ([[syllabic consonant|syllabic]] nasal) and is [[cognate]] with English ''un-''.

[[Copulative a]] is the Greek prefix {{Lang|el|ἁ-|italic=no}} or {{Lang|el|ἀ-|italic=no}} {{Lang|el-latn|ha-, a-}}. It comes from Proto-Indo-European {{lang|ine-x-proto|*sm&#805;}}.

===Mathematics and science===
{{main|Alpha (disambiguation)}}
The letter alpha represents various concepts in [[physics]] and [[chemistry]], including [[alpha radiation]], [[angular acceleration]],<ref>{{Citation |last=Elert |first=Glenn |title=Special Symbols |date=2023 |work=The Physics Hypertextbook|quote= '''α''', α rotational acceleration |url=https://physics.info/symbols/ |access-date=2025-02-01 |publisher=hypertextbook |language=en}}</ref> [[alpha particle]]s, [[alpha carbon]] and strength of [[electromagnetic interaction]] (as [[fine-structure constant]]).<ref>{{Cite web |title=fine-structure constant |url=https://physics.nist.gov/cgi-bin/cuu/Value?eqalph%7Csearch_for=fine |access-date=2025-02-10 |website=physics.nist.gov}}</ref> Alpha also stands for [[thermal expansion coefficient]] of a [[Chemical compound|compound]] in [[physical chemistry]]. In [[ethology]], it is used to name the [[Alpha (ethology)|dominant individual]] in a group of animals. In aerodynamics, the letter is used as a symbol for the [[angle of attack]] of an aircraft and the word "alpha" is used as a synonym for this property.

In astronomy, α is often used to designate the brightest star in a constellation.<ref>{{Cite book |last=Rabinowitz |first=Harold |title=The manual of scientific style: a guide for authors, editors, and researchers |last2=Vogel |first2=Suzanne |date=2009 |publisher=Elsevier/Academic Press |isbn=978-0-12-373980-3 |edition=1st |location=Amsterdam Burlington, MA |pages=363 |quote=The primary designation system for bright stars, called Bayer designations… The Greek letters are assigned in order (α,β, γ,δ  etc.) according to brightness.}}</ref>

In [[mathematics]], the letter alpha is used to denote the area underneath a [[Normal distribution|normal curve]] in [[statistics]] to denote [[statistical significance|significance level]]<ref>{{cite web|url=http://www.une.edu.au/WebStat/unit_materials/c5_inferential_statistics/what_alpha_level.html |work=Research Methods and Statistics PESS202 Lecture and Commentary Notes |title=Chapter 5: Analysing the Data Part II : Inferential Statistics |url-status=dead |archive-url=https://web.archive.org/web/20110822143239/http://www.une.edu.au/WebStat/unit_materials/c5_inferential_statistics/what_alpha_level.html |archive-date=22 August 2011 }}</ref> when proving [[null hypotheses|null]] and [[Alternative hypothesis|alternative hypotheses]]. It is also commonly used in [[algebra|algebraic solutions]] representing quantities such as angles. In [[mathematical logic]], α is sometimes used as a placeholder for [[ordinal number]]s. It is used for [[Stoneham number|Stoneham numbers]].<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Stoneham Number |url=https://mathworld.wolfram.com/StonehamNumber.html |access-date=2025-01-31 |website=mathworld.wolfram.com |language=en}}</ref>

Most occurrences of alpha in science are the lowercase alpha. The uppercase letter alpha is not generally used as a symbol because it tends to be rendered identically to the uppercase [[A|Latin A]].

The proportionality operator "[[∝]]" (in [[Unicode]]: U+221D) is sometimes mistaken for alpha.

===International Phonetic Alphabet===
In the [[International Phonetic Alphabet]], the letter ɑ, which looks similar to the lower-case alpha, represents the [[open back unrounded vowel]].