Zeno \'ze-no\ orig. Tarasicodissa (b. Isauria, Diocese of the East—d. April 9, ad 491) Eastern Roman emperor (474-491). A military leader, he married the daughter of Emperor Leo I (c. 466), and their son reigned briefly as Leo II (474). On the boy’s early death, Zeno became emperor. Obliged to flee to Isauria to escape a coup d’etat, he returned to Con¬ stantinople in 476. He made peace with the Vandals in Africa, put down a rebellion in Asia Minor (484), and persuaded the Ostrogoths to leave the Eastern Empire by making Theodoric king of Italy (489). Seeking to reconcile orthodox Christians and Monophysites, he caused a schism with Rome (484-519).
Zeno of Citium Vze- l no... , si-sh(e-)3m\ (b. c. 335, Citium, Cyprus—d. c. 263 bc, Athens) Greek philosopher, founder of Stoicism. He went to Athens c. 312 bc and attended lectures by the Cynics Crates of Thebes (fl. late 4th century bc) and Stilpon of Megara (c. 380-300 bc), as well as lectures at the Academy. He began to teach in the Stoa Poikile (“Painted Colonnade”), whence the name of his philosophy. His system included logic, epistemology, physics, and ethics. He taught that happiness lies in conforming the will to the divine reason, which governs the universe. In
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2106 I Zeno of Elea ► Zeuxis
logic and epistemology he was influenced by Antisthenes (c. 445-365 bc) and Diodorus Cronus (fl. 4th century bc), in physics by Heracleitus. Only fragmentary quotations from his many treatises have survived.
Zeno of Elea \'e-le-o\ (b. c. 495—d. c. 430 bc) Greek philosopher and mathematician. He was called by Aristotle the inventor of dialectic. He is best known for his paradoxes (see paradoxes of Zeno). As a pupil and friend of Parmenides, he took it upon himself to reply to those who asserted that his master’s doctrine of “the one” (i.e., indivisible reality) was incon¬ sistent (see monism); he tried to show that the assumption of the existence of “the many” (i.e., a plurality of things in time and space) carried with it more serious inconsistencies.
Zenobia \z9-'no-be-3\ in full Sepfimia Zenobia (d. ad after 274) Queen of the Roman colony of Palmyra (267/268-272). Her hus¬ band, a Roman client ruler of Palmyra, was assassinated after recapturing several of Rome’s east¬ ern provinces from the Persians. She became her son’s regent but called herself queen. In 269 she seized Egypt and much of Asia Minor and declared her independence from Rome. Aurelian defeated her armies and besieged Palmyra; she and her son were captured and taken to Rome (272), where she was paraded in Aurelian’s triumph.
zeolite Vze-o-.lflA Any member of a family of hydrated aluminosilicate minerals that have a framework structure enclosing interconnected cavities occupied by large metal cat¬ ions (positively charged ions)— generally sodium, potassium, magnesium, calcium, and barium— and water molecules. The ease of movement of ions and water within the framework allows reversible dehy¬ dration and cation exchange, properties that are exploited in water soft¬ eners and molecular sieves for pollution control, among other uses.
zeolitic facies y.ze-o-'li-tik-'fa-shezV One of the major divisions of the mineral facies classification of metamorphic rocks, encompassing rocks that formed at the lowest temperatures and pressures associated with regional metamorphism. Typical minerals in these facies include the zeolites, albite, and quartz.
Zephaniah (fl. 7th century bc) One of the 12 Minor Prophets of the Hebrew scriptures, traditional author of the book of Zephaniah. (The work is part of a larger book, The Twelve, in the Jewish canon.) He prophesied in the reign of JosiAH, denouncing the worship of foreign gods, which suggests that he preached before the reforms instituted by Josiah. His dominant theme is the coming “day of the Lord,” a time of divine judg¬ ment for Judah’s sins.
zeppelin Rigid airship of a type designed by the German builder Fer¬ dinand, Graf (count) von Zeppelin (1838-1917). It was a cigar-shaped, trussed, and covered frame supported by internal gas cells, below which hung two external cars with an engine geared to two propellers. The first zeppelin flew in 1900. In World War I zeppelins were used as bombers by Germany. In 1928 the Graf Zeppelin inaugurated transatlantic flight service; it had completed 590 flights by 1937, when the Hindenburg disas¬ ter halted such flights.
zero Number and numeral of critical importance in mathematics. Zero is known as the additive identity because adding it to any number does not change the number’s identity, or value. The product of zero and any number is zero; for most number systems the converse is true—that is, if the prod¬ uct of two numbers is zero, at least one of them must equal zero. The latter property is fundamental to the solution of nearly every problem in math¬ ematics. Division by zero is undefined; efforts to deal with such divisions led to calculus. Various punctuation marks were first used in Mesopotamia beginning about 700 bc to indicate an empty space in positional notation, but never at the end of a number—the difference between, say, 78 and 780 had to be understood from the context. Ptolemy first used 0, or the Greek
letter omicron “o,” as an empty placeholder, including at the end of a num¬ ber, to express data in the Babylonian sexagesimal system in his astronomi¬ cal treatise Almagest (c. 130 ad). The Hindu-Arabic numerals and treatment of zero as a number developed between the 6th and 9th centuries in India. Zero soon followed trade routes to China, the Islamic world, and Europe.
Zero in full Mitsubishi A6M Zero Japanese fighter aircraft of World War II. A single-seat, low-wing monoplane made by Mitsubishi, it was introduced in 1940, the 2,600th anniversary of the crowning of Japan’s legendary first emperor, Jimmu, and named for the “zero-year” celebration. It had a top speed of 350 mph (565 kph) at nearly 20,000 ft (6,000 m). When it first appeared, it could outmaneuver every plane it encountered; Allied fighters could not defeat it until 1943. Many Zeros became kami¬ kaze craft in the war’s closing months.
zero-point energy Vibrational energy retained by molecules even at a temperature of absolute zero. Since temperature is a measure of the intensity of molecular motion, molecules would be expected to come to rest at absolute zero. However, if molecular motion were to cease alto¬ gether, the atoms would each have a precisely known location and veloc¬ ity (zero), and the uncertainty principle states that this cannot occur, since precise values of both position and velocity of an object cannot be known simultaneously. Thus, even molecules at absolute zero must have some zero-point energy.
Zeroual \zer-'wal\, Liamine (b. July 3, 1941, Batna, Alg.) President of Algeria (1994-99). After a military education, he rose through the ranks to become chief of land forces in 1989 and defense minister in 1993. In 1994 he was appointed transitional president by the military-dominated High Council of State, which had taken over the government after elec¬ tions were canceled in 1992 and Pres. Mohamed Boudiaf was assassinated. Elected for a full term in 1995, he was replaced in 1999 by Abdelaziz Bouteflika.
Zetkin Vtset-konV Clara orig. Clara Eissner (b. July 5, 1857, Wied- erau, Saxony—d. June 20, 1933, Arkhangelskoye, Russia, U.S.S.R.) Ger¬ man communist leader. She joined the Social Democratic Party in 1881, and she later married a Russian revolutionary exile, Ossip Zetkin (1848— 89). From 1892 she edited the Socialist women’s newspaper Die Gleich- heit (“Equality”) in Stuttgart. A friend of Vladimir Lenin and Rosa Luxemburg, Zetkin was a cofounder of the Spartacists (1916) and later joined the new Communist Party of Germany (1919). In 1921 she was elected to the presidium of the Third International (see Comintern). Her influence waned after Lenin’s death in 1924.