Abu Ja'far al-Khazin

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Abu Dscha'far al-Khazin ( Persian ابوجعفر خازن خراسانی Abudschafar Chazin Khorasani ) was a Persian astronomer and mathematician of the 10th century.

After the Fihrist, he came from Khorasan and he worked at the court of the Bujid ruler Adud ad-Daula , who ruled from 949 to 983. Al-Khazin was commissioned to measure the skewness of the ecliptic in 959/960 .

His book Zij al Safa'ih (Tables of the Discs of the Astrolab) was praised by Ibn al-Qiftī as the best work in this field. It deals with a special astrolabe. A copy of this instrument from Munich's private collection disappeared in Germany during World War II, only photos have survived. Various works by al-Khazin that have not survived are mentioned by al-Biruni . Below is a commentary on the Almagest by Claudius Ptolemy , of which only a fragment has survived, which contains 19 propositions on isoperimetric questions mentioned by Archimedes (sphere and cylinder) and in the Almagest . This includes proof that with the same circumference, the equilateral triangle has the largest area compared to isosceles triangles or triangles with different side lengths.

According to al-Chayyami , he gave the first solution to Archimedes' problem (On Sphere and Cylinder, Book 2, Chapter 4) of dividing a sphere by a plane in volumes of a given ratio. A century earlier, al-Mahani had failed. Al-Khazin used conic sections for the solution. According to al-Chayyami, he is also said to have given an incorrect proof of the parallel postulate . Al-Khazin wrote a commentary on Book 10 of the Elements of Euclid .

Nasir ad-Din at-Tusi mentions a proof of the sine law for spherical right triangles and Heron's theorem from al-Khazin's lost works.

He dealt with number theory and criticized a proof of the case of the power 3 of the Fermat conjecture of al-Khujandi as false.

After Ibn al-Qiftī he was an expert in arithmetic, geometry and planetary astrology.

Al-Chazin developed a model of the sun's orbit that deviated from Ptolemy's (in the geocentric view of the world at that time). Instead of the sun on a circular orbit around a center different from the earth, like Ptolemy, he assumed a circular orbit around the earth as the center, albeit with a uniform speed with respect to an eccentric .

literature

  • Yvonne Dold-Samplonius : Al-Khazin Abu Ja'far Muhammad ibn al-Hasan al-Khurasani , in: Dictionary of Scientific Biography , Volume 7, pp. 334-335
  • J. Samsó Moya : al-Khazin , in: Encyclopedia of Islam, Leiden, from 1960
  • J. Samsó Moya: A homocentric solar model by Abu Ja'far al Khazin , J. Hist. Arabic Sci., Vol. 1, 1977, pp. 268-275.
  • Roshdi Rashed : Les Mathématiques Infinitésimales du IXe au XIe Siècle 1: Fondateurs et commentateurs: Banū Mūsā, Ibn Qurra, Ibn Sīnān, al-Khāzin, al-Qūhī, Ibn al-Samḥ, Ibn Hūd , London 1996
  • Roshdi Rashed: L'analysis diophantienne au Xe siècle: l'exemple d'al-Khazin , Rev. Histoire Sci. Appl., Vol. 32, 1979, pp. 193-222.
  • R. Lorch: Abu Ja'far al-Khazin on isoperimetry and the Archimedean tradition , Z. Gesch. Arab-Islam. Wiss., Vol. 3, 1986, pp. 150-229.

Web links

Individual evidence

  1. ↑ DA King, New light on the Zij al-Safa'ih of Abu Ja'far al-Khazin, Centaurus, Volume 23, 1979/80, pp. 105-117
personal data
SURNAME Chazin, Abu Ja'far al-
ALTERNATIVE NAMES al-Khazin, Abu Jaf'ar
BRIEF DESCRIPTION Persian astronomer and mathematician
DATE OF BIRTH 10th century
PLACE OF BIRTH Khorasan
DATE OF DEATH 10th century