Thābit ibn Qurra


Al-Ṣābiʾ Thābit ibn Qurrah al-Ḥarrānī was an Arab Sabian mathematician, physician, astronomer, and translator who lived in Baghdad in the second half of the ninth century during the time of the Abbasid Caliphate.
Thābit ibn Qurrah made important discoveries in algebra, geometry, and astronomy. In astronomy, Thābit is considered one of the first reformers of the Ptolemaic system, and in mechanics he was a founder of statics.

Biography

Thābit was born in Harran in Upper Mesopotamia, which at the time was part of the Diyar Mudar subdivision of the al-Jazira region of the Abbasid Caliphate. The city of Harran was never fully Christianized. By the early Muslim conquests, the people of Harran were still adhering to the cult of Sin.
Thābit and his pupils lived in the midst of the most intellectually vibrant, and probably the largest, city of the time, Baghdad. He occupied himself with mathematics, astronomy, astrology, magic, mechanics, medicine, and philosophy. Later in his life, Thābit's patron was the Abbasid Caliph al-Mu'tadid. Thābit became the Caliph's personal friend and courtier. Thābit died in Baghdad.

Translation

Thābit's native language was Syriac, which was the eastern Aramaic variety from Edessa, and he was fluent in both Greek and Arabic.
Thābit translated from Greek into Arabic works by Apollonius of Perga, Archimedes, Euclid and Ptolemy. He revised the translation of Euclid's Elements of Hunayn ibn Ishaq. He also rewrote Hunayn's translation of Ptolemy's Almagest and translated Ptolemy's Geography. Thābit's translation of a work by Archimedes which gave a construction of a regular heptagon was discovered in the 20th century, the original having been lost.

Astronomy

The medieval astronomical theory of the trepidation of the equinoxes is often attributed to Thābit. But it had already been described by Theon of Alexandria in his comments of the Handy Tables of Ptolemy. According to Copernicus, Thābit determined the length of the sidereal year as 365 days, 6 hours, 9 minutes and 12 seconds. Copernicus based his claim on the Latin text attributed to Thābit. Thābit published his observations of the Sun.

Mathematics

In mathematics, Thābit discovered an equation for determining amicable numbers. He also wrote on the theory of numbers, and extended their use to describe the ratios between geometrical quantities, a step which the Greeks did not take.
He is known for having calculated the solution to a chessboard problem involving an exponential series.
He computed the volume of the paraboloid.
He also described a generalization of Pythagoras' theorem.

Physics

In physics, Thābit rejected the Peripatetic and Aristotelian notions of a "natural place" for each element. He instead proposed a theory of motion in which both the upward and downward motions are caused by weight, and that the order of the universe is a result of two competing attractions : one of these being "between the and celestial elements", and the other being "between all parts of each element separately". and in mechanics he was a founder of statics.

Works

Only a few of Thābit's works are preserved in their original form.