Alpha

Alpha /ˈælfə/ⓘ ALF-ə (uppercase Α, lowercase α) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph ⟨𐤀⟩, whose name comes from the West Semitic word for 'ox'. Letters that arose from alpha include the Latin letter ⟨A⟩ and the Cyrillic letter ⟨А⟩.

Uses

Greek

In Ancient Greek, alpha was pronounced [a] and could be either phonemically long ([aː]) or short ([a]). Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: Ᾱᾱ, Ᾰᾰ.

ὥρα = ὥρᾱ hōrā Greek pronunciation:[hɔ́ːraː] "a time"
γλῶσσα = γλῶσσᾰ glôssa Greek pronunciation:[ɡlɔ̂ːssa] "tongue"

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

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

Greek grammar

In the Attic–Ionic dialect of Ancient Greek, long alpha [aː] fronted to [ɛː] (eta). In Ionic, the shift took place in all positions. In Attic, the shift did not take place after epsilon, iota, and rho (ε, ι, ρ; e, i, r). In Doric and Aeolic, long alpha is preserved in all positions.

Doric, Aeolic, Attic χώρᾱ chṓrā – Ionic χώρη chṓrē, "country"
Doric, Aeolic φᾱ́μᾱ phā́mā – Attic, Ionic φήμη phḗmē, "report"

Privative a is the Ancient Greek prefix ἀ- or ἀν- a-, an-, added to words to negate them. It originates from the Proto-Indo-European *n̥- (syllabic nasal) and is cognate with English un-.

Copulative a is the Greek prefix ἁ- or ἀ- ha-, a-. It comes from Proto-Indo-European *sm̥.

Mathematics and science

The letter alpha represents various concepts in physics and chemistry, including alpha radiation, angular acceleration, alpha particles, alpha carbon and strength of electromagnetic interaction (as fine-structure constant). Alpha also stands for thermal expansion coefficient of a compound in physical chemistry. In ethology, it is used to name the 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.

In mathematics, the letter alpha is used to denote the area underneath a normal curve in statistics to denote significance level when proving null and alternative hypotheses. It is also commonly used in algebraic solutions representing quantities such as angles. In mathematical logic, α is sometimes used as a placeholder for ordinal numbers. It is used for Stoneham numbers.

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 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.

History and symbolism

Origin

The Phoenician alphabet was adopted for Greek in the early 8th century BC, perhaps in Euboea. The majority of the letters of the Phoenician alphabet were adopted into Greek with much the same sounds as they had had in Phoenician, but ʼāleph, the Phoenician letter representing the glottal stop [ʔ], was adopted as representing the vowel [a]; similarly, hē [h] and ʽayin [ʕ] are Phoenician consonants that became Greek vowels, epsilon [e] and omicron [o], respectively.

Alpha and Omega

As the first letter of the alphabet, Alpha as a Greek numeral came to represent the number 1. Therefore, Alpha, both as a symbol and term, is used to refer to the "first", or "primary", or "principal" (most significant) occurrence or status of a thing.

The New Testament has God declaring himself to be the "Alpha and Omega, the beginning and the end, the first and the last." (Revelation 22:13, KJV, and see also 1:8).

Consequently, the term "alpha" has also come to be used to denote "primary" position in social hierarchy, examples being the concept of dominant "alpha" members in groups of animals.

Unicode

All code points with ALPHA or ALFA but without WITH (for accented Greek characters, see Greek diacritics: Computer encoding):

U+0251ɑLATIN SMALL LETTER ALPHA
U+0252ɒLATIN SMALL LETTER TURNED ALPHA
U+0386ΆGREEK CAPITAL LETTER ALPHA WITH TONOS
U+0391ΑGREEK CAPITAL LETTER ALPHA(Α)
U+03ACάGREEK SMALL LETTER ALPHA WITH TONOS
U+03B1αGREEK SMALL LETTER ALPHA(α)
U+1D45ᵅMODIFIER LETTER SMALL ALPHA
U+1D90ᶐLATIN SMALL LETTER ALPHA WITH RETROFLEX HOOK
U+1D9BᶛMODIFIER LETTER SMALL TURNED ALPHA
U+1DE7◌ᷧCOMBINING LATIN SMALL LETTER ALPHA
U+2376⍶APL FUNCTIONAL SYMBOL ALPHA UNDERBAR
U+237A⍺APL FUNCTIONAL SYMBOL ALPHA
U+2C6DⱭLATIN CAPITAL LETTER ALPHA
U+2C70ⱰLATIN CAPITAL LETTER TURNED ALPHA
U+2C80ⲀCOPTIC CAPITAL LETTER ALFA
U+2C81ⲁCOPTIC SMALL LETTER ALFA
U+AB30ꬰLATIN SMALL LETTER BARRED ALPHA
U+AB64ꭤLATIN SMALL LETTER INVERTED ALPHA
U+1D6A8𝚨MATHEMATICAL BOLD CAPITAL ALPHA
U+1D6C2𝛂MATHEMATICAL BOLD SMALL ALPHA
U+1D6E2𝛢MATHEMATICAL ITALIC CAPITAL ALPHA
U+1D6FC𝛼MATHEMATICAL ITALIC SMALL ALPHA
U+1D71C𝜜MATHEMATICAL BOLD ITALIC CAPITAL ALPHA
U+1D736𝜶MATHEMATICAL BOLD ITALIC SMALL ALPHA
U+1D756𝝖MATHEMATICAL SANS-SERIF BOLD CAPITAL ALPHA
U+1D770𝝰MATHEMATICAL SANS-SERIF BOLD SMALL ALPHA
U+1D790𝞐MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL ALPHA
U+1D7AA𝞪MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL ALPHA