Person: Qushji, Ali
Ali Qushji was an Islamic astronomer and mathematician, born in what is now Uzbekistan, who worked at observatories in Samarkand and Constantinople and whose results influenced Copernicus to produce his heliocentric system.
Mathematical Profile (Excerpt):
- Although his name was Ala al-Din Ali ibn Muhammed, he is always known as Ali Qushji.
- Samarkand, the city where Ali Qushji was born, had been conquered by Tamerlane in 1370 and it became the capital of the Timurid Empire.
- He became one of Ali Qushji's teachers and Ulugh Beg, who also taught at the Madrasa, became another.
- Ali Qushji was also taught by Jamshid al-Kashi who had been invited to the Madrasa by Ulugh Beg.
- It was in this atmosphere that the young Ali Qushji was raised, and this seems to have had a profound effect upon his intellectual outlook.
- After his studies in Samarkand, Ali Qushji went to Kerman in Persia (now in Iran), where he conducted some research on storms in the Oman sea and wrote a work on this topic.
- There Ali Qushji taught astronomy, wrote a work about the Moon (Explanations on the Periods of the Moon) and another on mathematics.
- He was certainly impressed with Ali Qushji's work and appointed him as an astronomer at the Samarkand Observatory, a vast observatory which was nearing completion at this time.
- Ulugh Beg appointed around sixty astronomers to the observatory including Ali Qushji, Qadi Zada al-Rumi and Jamshid al-Kashi.
- Ali Qushji worked at the Samarkand Observatory until 1449 when, following a civil war, Ulugh Beg was assassinated.
- Ali Qushji left Samarkand and went to Herat where he had been working before he was employed at the Samarkand Observatory.
- In 1469, however, Abu Said was defeated by Uzun Hasan and Ali Qushji moved to Tabriz, the capital of the Qara Qoyunlu state in Azerbaijan.
- The position in Constantinople looked very attractive to Ali Qushji but he had promised Uzun Hasan that he would carry out his duty as a good will ambassador and return to Tabriz to report on his mission.
- This was agreed and Ali Qushji returned to Tabriz and reported the success of his mission to Uzun Hasan.
- When Ali Qushji and his entourage approached Constantinople, Sultan Mehmed sent a group of scholars to welcome them.
- Upon arrival in Constantinople, Ali Qushji presented his mathematical work 'al-Muhammadiyya fi al-hisab' to the sultan, which was named in his honour.
- Once in Constantinople, Ali Qushji taught at the Sahn-i Thaman Madrasa.
- Let us now mention some of the many contributions to mathematics and astronomy that Ali Qushji made while working at the Samarkand Observatory and at the Constantinople Madrasas.
- We give information first about what must be considered his most important contribution, namely the belief that it was Ali Qushji's results that, indirectly, influenced Copernicus allowing him to put forward his heliocentric theory.
- Indeed, it would seem, based on evidence presented in the sequel, that an older contemporary of Regiomontanus named Ali Qushji may well have been the discoverer of this crucial proposition and that Regiomontanus learned of it either while in Italy or through the intermediation of Cardinal Bessarion , who had originally suggested to Regiomontanus and his collaborator Georg Peurbach that they write the 'Epitome'.
- Most readers of this journal will be acquainted with Regiomontanus and Peurbach, and perhaps even Bessarion, but Ali Qushji is most likely an unknown figure.
- The work by Ali Qushji which contains these vital propositions is Treatise on the Eccentric Model Being Possible for the Two Lower Planets Just as for the Others.
- We must now look to see why Ali Qushji is prepared to contradict Ptolemy.
- As for the mathematical sciences, Ali Qushji in general tried to free them from Hermetic-Pythagorean mysticism and to provide an alternative to Aristotelian physics as the basis for astronomy and optics.
- Although what we have described above may be the most important of Ali Qushji's contributions, we note that he was in fact a prolific author with interests in a wide range of topics.
- Latin translations of Ali Qushji's Tract on Arithmetic and his Tract on Astronomy were made by John Greaves and published in 1650.
- There is some doubt about the extent of Ali Qushji's contributions to the star catalogue, however, since he published Sharh-i Zij Ulugh Beg which was a commentary on Ulugh Beg's Zij-i Sultani in which Ali Qushji made criticisms of it and pointed out some mistakes.
Born 1403, Samarkand, Timurid Empire, now Uzbekistan. Died 16 December 1474, Constantinople, now Istanbul, Turkey.
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Thank you to the contributors under CC BY-SA 4.0!
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive