Abraham bar Chija

from Wikipedia, the free encyclopedia

Abraham bar Chija (Abraham bar Ḥiyya ha-Nasi), also Abraham Judaeus or Savasorda (* around 1070 in Barcelona , † around 1136 possibly in Provence or Narbonne ), was a Jewish mathematician, moral philosopher ( Neoplatonist ), who worked in Spanish Catalonia , Astrologer and astronomer of the 12th century. He was the first researcher to write scientific and mathematical treatises in Hebrew .

life and work

His Latinized name Savasorda comes from the Arabic (guard leader, Ṣāḥib al-Shurṭa) and indicates an official position (for example with the Count of Barcelona or the King of Aragon) in his home town of Barcelona, ​​which was under Christian rule, but where then Names derived from Arabic were also in use. His precise knowledge of Arabic mathematics and astronomy, however, indicate a longer stay in an Islamic scholarly center such as Saragossa , which was also the center of Jewish scholarship. References in his works also suggest a connection to Jewish circles in Provence .

He is known for his Hebrew textbook on Islamic mathematics (Ḥibbūr ha-meshīḥah we-ha-tishboret, treatise on measuring and arithmetic), which Plato of Tivoli translated into Latin in 1145 as Liber Embadorum . This contains the first complete treatment of the quadratic equation in the West, roughly at the same time as the algebra by al-Chwarizmi, which was also translated into Latin in 1145 (by Robert von Chester ) . The book influenced Fibonacci . Abraham bar Chija studied the ancient Greek mathematicians through Arabic texts, as did Abraham ibn Esra (1092–1167), and both are considered the founders of Jewish studies of mathematics in the Middle Ages. The ancient mathematicians he studied include a. Euclid , Apollonios of Perge , Theodosius of Bithynia , Autolycus of Pitane , Menelaus of Alexandria , Heron of Alexandria , Eudemos of Rhodes and among the Arabs al-Khwarizmi and al-Karaji . He worked as a translator with Plato von Tivoli, who also worked in Barcelona, ​​but wrote all of his own works in Hebrew.

He also published the first Hebrew encyclopedia (Yesod ha-Tebunah u-Migdal ha-Emunah, The Foundations of Knowledge and the Tower of Faith), which covers mathematics, optics, astronomy and music, astronomical texts, a book on moral philosophy (Hegyon ha -Nefesh ha-Azuva, Meditations of the Sad Soul), a book with astrological, historical -theological- eschatological interpretations of history (Megillat ha-Megalleh, scroll of the Revelator), in which he describes the coming of the Messiah for the year 1358 (5118 years after creation) and a book on Jewish calendar calculation (Sefer ha-Ibbur, 1122/23) (the oldest known Hebrew work on the subject), especially for calculating Jewish holidays.

Determination of the content of a circular area

Equation in circle proved by the method of indivisibles.gif

With the geometrical-mechanical method shown on the right, an anticipation of Cavalieri's principle, he proved that the equation S = L⋅½R holds for every circle. (Where S is the area, L is the circumference, and R is the radius.) This proof was published in his book on the measurement of the earth and its division in the 12th century. Abraham bar Chija looks at the circular area made up of concentric circles and cuts it open along the radius. The result is a triangle (since the circumference and diameter of the circle are proportional) with the circumference L as the base and the radius R as the height. The area of ​​the circular area is then the same as that of the triangle and the above formula results.

Illustration of the evidence in the Commentary on the Talmud, Talmud, Succa 8A, Tosfot

literature

  • Leon D. Stitskin, Judaism as philosophy, the philosophy of Abraham bar Hiyya , New York 1960
  • Jose Millas Vallicrosa, The beginnings of science among the jews in spain , Westport 1994
  • Moritz Steinschneider , Abraham Judaeus: Savasorda and Ibn Esra. On the history of mathematical sciences in the 12th century , in Zeitschrift für Mathematik und Physik, Volume 12, 1867, pp. 1-44, online
  • Martin Levey, Abraham Savasorda and his algorism: a study in early European logistic , Osiris, Volume 11, 1954, pp. 50-64
  • the same, The encyclopedia of Abraham Savasorda: a departure of mathematical methodology , Isis, Volume 43, 1952, pp. 257-264
  • GB Sarfatti, Mathematical terminology in Hebrew scientific literature of the Middle Ages , Jerusalem 1968
  • Yitzhak Baer (Fritz Baer), A history of the jews in christian spain , Philadelphia 1992 (German The Jews in Christian Spain , Berlin, Akademie Verlag 1929)
  • Jakob Freimann, article ABRAHAM ben CHIJA HANASSI , in: Jüdisches Lexikon , Berlin 1927, Vol. I
  • Angel Sáenz-Badillos; Judit Targarona Borrás: Abraham bar Ḥiyya '. In: Diccionario de autores judios (Sefarad. Siglos X-XV). El Almendro, Córdoba 1988 (Estudios de Cultura Hebrea, Volume 10), pp. 13-14. ISBN 84-86077-69-9 .

Web links

Individual evidence

  1. ↑ According to McTutor (see web links) born 1070, died 1136. According to the Encyclopedia Britannica he was born around 1065 and died around 1136
  2. ↑ Personal entry in Norman Roth (Ed.): Routledge Revivals - Medieval Jewish Civilization - An Encyclopedia , 2003, ISBN 9781351676977
  3. ↑ The Hebrew suffix Nasi also indicates a leading position
  4. ^ Editions by Baldassare Boncompagni , Millas-Vallicrosa (Catalan translation Llibre de geometria , Barcelona 1931), Michael Guttman (Berlin 1931)
  5. ↑ Possibly a student of Savasorda.
  6. ↑ The work is only partially preserved, as well as Jose M. Millas Vallicrosa La obra enciclopedica Yesode ha-tevuna u-migdal haemunah de R. Abraham bar Hiyya ha-Bargeloni , Madrid, Barcelona 1952
  7. ↑ Heshbon Mahalekhot ha-Kokhavim, a manual on the movement of stars and calendar calculations. Tsurat ha-Aretz ve-Tavnit Kaddurei ha Raki`a (Shape of the Earth), an overview of geography and astronomy, partly in Latin published by Sebastian Münster 1546 (Reprint Jerusalem)
  8. ^ Meditations of the sad soul, New York 1969, translation by Geoffrey Wigoder. A Hebrew edition appeared in Leipzig in 1860 (editor E. Freimann, with a contribution by JL Rapoport) and was reprinted in Jerusalem.
  9. ^ Scroll of the Revelator , J. Guttmann edition, A. Poznanski, Berlin 1924. In Catalan translation, Llibre revelador , Millas-Vallicrosa, Barcelona 1929
  10. ↑ Published in 1851 by Filipowski in London
  11. ↑ Boaz Tsaban and David Garber: The proof of Rabbi Abraham Bar Hiya Hanasi . Archived from the original on August 25, 2011. Retrieved March 28, 2011.
  12. ↑ David Garber, Boaz Tsaban, A mechanical derivation of the area of ​​the sphere, The American Mathematical Monthly, Volume 108, 2001, pp. 10-15, discussion of the evidence from today's mathematical perspective.
personal data
SURNAME Abraham bar Chija
ALTERNATIVE NAMES Abraham bar Hiyya; Abraham bar Chijja; Savasorda; Abraham Judaeus
BRIEF DESCRIPTION Mathematician, astronomer, philosopher and translator
DATE OF BIRTH around 1070
PLACE OF BIRTH Barcelona
DATE OF DEATH around 1136