Greek alphabetThe Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as well as consonants. In Archaic and early Classical times, the Greek alphabet existed in many local variants, but, by the end of the 4th century BC, the Euclidean alphabet, with 24 letters, ordered from alpha to omega, had become standard and it is this version that is still used for Greek writing today.
Letter (alphabet)A letter is a segmental symbol of a phonemic writing system. The inventory of all letters forms an alphabet. Letters broadly correspond to phonemes in the spoken form of the language, although there is rarely a consistent and exact correspondence between letters and phonemes. The word letter, borrowed from Old French letre, entered Middle English around 1200 AD, eventually displacing the Old English term bōcstæf (bookstaff). Letter is descended from the Latin littera, which may have descended from the Greek "διφθέρα" (, writing tablet), via Etruscan.
Latin scriptThe Latin script, also known as the Roman script, is an alphabetic writing system based on the letters of the classical Latin alphabet, derived from a form of the Greek alphabet which was in use in the ancient Greek city of Cumae, in southern Italy (Magna Graecia). The Greek alphabet was adopted by the Etruscans, and subsequently their alphabet was adopted by the Romans. Several Latin-script alphabets exist, which differ in graphemes, collation and phonetic values from the classical Latin alphabet.
Mu (letter)Mu ˈm(j)uː (uppercase Μ, lowercase μ; Ancient Greek μῦ mŷː, μι or μυ—both mi) is the twelfth letter of the Greek alphabet, representing the voiced bilabial nasal m. In the system of Greek numerals it has a value of 40. Mu was derived from the Egyptian hieroglyphic symbol for water, which had been simplified by the Phoenicians and named after their word for water, to become 𐤌 (mem). Letters that derive from mu include the Roman M and the Cyrillic М, though the lowercase resembles a small Latin U (μ).
Greek diacriticsGreek orthography has used a variety of diacritics starting in the Hellenistic period. The more complex polytonic orthography (πολυτονικό σύστημα γραφής), which includes five diacritics, notates Ancient Greek phonology. The simpler monotonic orthography (μονοτονικό σύστημα γραφής), introduced in 1982, corresponds to Modern Greek phonology, and requires only two diacritics. Polytonic orthography () is the standard system for Ancient Greek and Medieval Greek.
Planck constantThe Planck constant, or Planck's constant, is a fundamental physical constant of foundational importance in quantum mechanics. The constant gives the relationship between the energy of a photon and its frequency, and by the mass-energy equivalence, the relationship between mass and frequency. Specifically, a photon's energy is equal to its frequency multiplied by the Planck constant. The constant is generally denoted by . The reduced Planck constant, or Dirac constant, equal to divided by , is denoted by .
Matter waveMatter waves are a central part of the theory of quantum mechanics, being half of wave–particle duality. All matter exhibits wave-like behavior. For example, a beam of electrons can be diffracted just like a beam of light or a water wave. The concept that matter behaves like a wave was proposed by French physicist Louis de Broglie (dəˈbrɔɪ) in 1924, and so matter waves are also known as de Broglie waves.
RhoRho 'roʊ (uppercase Ρ, lowercase ρ or ; ρο or ρω) is the seventeenth letter of the Greek alphabet. In the system of Greek numerals it has a value of 100. It is derived from Phoenician letter res . Its uppercase form uses the same glyph, Ρ, as the distinct Latin letter P; the two letters have different Unicode encodings. Rho is classed as a liquid consonant (together with Lambda and sometimes the nasals Mu and Nu), which has important implications for morphology.
