eight

eight
8th
presentation
Roman VIII
dual 1000
Octal 10
Duodecimal 8th
Morse code - - - · ·
Arabic ٨
Chinese 八 ， 捌
Greek η
Mathematical properties
sign positive
parity straight
Factorization ${\ displaystyle 2 ^ {3}}$
Divider 1, 2, 4, 8

The eight (8) is the natural number between seven and nine . It's even and a cube number .

Linguistic

The word eight , which developed from the Old High German ahto , comes from an Indo-European root. Originally it may be a dual form, probably “the two tips of four” of the outstretched fingers of the two hands without the thumbs .

Not related to the number word eight in terms of attention, as in be careful (or outdated careful ), eight in the sense of ostracism or aft in shipping.

The Greek word for eight, ὀκτώ (októ) , is found in the foreign words octagon or octopus .

The Latin expression octo with the ordinal number octavus (the eighth) can be found in foreign words such as octet (ensemble), October (originally the 8th month), octave (interval), octant . The German expression today in eight days , with which a period of one week is meant, comes from the Roman counting method , in which the first and last day are also counted. The Latin numerals for 18 28 to 88 are - as in novem (9) - not with octo formed but circumscribed z. B. duo-de-viginti for 18, literally: 2 of 20 (deducted).

In Chinese culture , the eight ( Chinese   , Pinyin ) is considered a lucky number because of the consonance with “ahead” ( Chinese    /  , Pinyin ).

Numeral

Evolution of the character "8"

The original Brahmi character for eight looked like a step leading to the top left. In the further development it initially resembled the 5 and the letter S. The Arabs in the Maghreb used the Ghubar script to connect the ends and thus created the basis for the modern symbol.

In most fonts and manuscripts, the upper loop of the number is shaped smaller than the lower one, which results in a stable image and goes well with fonts that are usually less than half-height ascent. In the case of a flat, oblique view of large digits from relative proximity, for example on a motorway lane or an airplane runway, the view (projection) tends in this direction alone because of the differences in distance.

octahedron

Fractions

• Eighth note is generally the eighth part of a whole in fractions ; the following terms are derived from this:
• Eighth , a measure of the degree of cloudiness in meteorology
• Round of 16 , the fourth from last round with 16 participants in the tournament
• Eighth note , fraction of a whole note, with a black head and a flag on the stem.
• Eighth of a meter , the standard size in construction

Natural sciences

• All arachnids (arachnida) have eight walking legs. The genus Octopus heard as all octopuses to the subordination of the eight-armed squid . The Octocorallia , which used to be called eight-rayed flower animals (Octocorallae), have eight mostly pinnate tentacles and an eight-rayed structure inside.
• There are eight major winds in some ancient Greek scholars; see wind rose .
• The solar system has in astronomical view since 2006 eight planets.
• The octet rule is a simple construction feature for molecules in chemistry, since in most compounds each element aims for a number of valence electrons of eight.
• The chemical element with atomic number 8 is oxygen .
• Eightfold Way , classification of hadrons in the context of quantum chromodynamics.
• One of the magic numbers of atomic nuclei.

symbolism

Floor plan of the Dome of the Rock

The octagon (Greek for octagon) is an important structural form of Christian sacred architecture. It follows the Christian meaning of eight as a sacred number . Following the example of San Vitale in Ravenna and the (Islamic) Dome of the Rock , many important churches were designed around a central octagon, such as the Palatine Chapel of the Aachen Cathedral . Also Baptisteries are often found in an octagonal shape. A special case is the Castel del Monte in Apulia , which was built in the time of Emperor Frederick II and where the eight is interpreted as a symbol for the emperor.

Christianity

Simplified floor plan of the Baptistery of San Giovanni in Florence
• Early Christian Gnostics spoke of eight heavenly spheres.
• In the Christian number symbolism of the Middle Ages, eight is the number of the happy beginning, the new birth, the new beginning, the spiritual rebirth, it is also the number of baptism and resurrection, symbol of the new covenant and symbol of happiness.
• On the 8th day a new week begins , a new time - for the Church Fathers a symbol of the day of the Lord's Resurrection ( resurrectio Domini ) and the new creation in baptism . The octagonal shape of early Christian baptisteries uses this sense of the eighth day.

Judaism

• Eight people are saved in Noah's ark (1 Mos 6:18).
• On the 8th day after the birth, the Jewish circumcision takes place.
• The Jewish Hanukkah festival lasts eight days. Every day another candle is lit on the Hanukkiah , the eight-armed candlestick. The candlestick has nine arms for an additional light, the so-called servant (Hebrew shamash) to light the eight lights.

In Judaism, the number 8 signifies the transition from temporality to timelessness, the connection of immanence (this-worldliness, transience) to transcendence (otherworldliness, over-temporality). It has a connecting, bridge-building character, as it connects the world of the 7 (the world of the 6 working days with the Shabbat day of rest) with the world of the 8 (the divine). There is a perfecting quality inherent in the number eight - it brings two apparently irreconcilable worlds together through the mysterious unifying power of God. "The eight is the number of infinity. ... If we look at the number eight in an upright as well as in a lying form, we recognize a harmonic oscillation in it; it is a movement that, similar to the constant in and out of breathing, defines an inner center in its oscillation between two poles, balances and integrates it. " (Yuval Lapide, "Das Herz der Kabbalah", OWBarth 2011, January 26th) Because of this special meaning of the number eight, the circumcision of the Jewish boy must take place on the eighth day, except in emergencies.

Buddhism

The eight trigrams of the Book of Changes

literature

• Franz Joseph Dölger : The octagon and the symbolism of the figure eight . In: Franz Joseph Dölger: Antiquity and Christianity Vol. 4 . Münster 1934, pp. 153-187
• WE Peuckert: Concise dictionary of the legend. 1961.