Ala al-Dīn Ali ibn Muhammed | |
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| Personal life | |
| Born | 1403 CE |
| Died | 1474 CE |
| Era | Ottoman era |
| Main interest(s) | Kalam (Islamictheology),Fiqh (Islamicjurisprudence),Falkiat,Mathematics |
| Notable work(s) | Concerning the Supposed Dependence of Astronomy upon Philosophy |
| Religious life | |
| Religion | Islam |
| Denomination | Sunni |
| Jurisprudence | Hanafi |
| Creed | Maturidi |
| Muslim leader | |
Influenced by | |
Influenced | |
Ala al-Dīn Ali ibn Muhammed (1403 – 18 December 1474[1]),Persian:علاءالدین علی بن محمد سمرقندی known asAli Qushji (Ottoman Turkish : علی قوشچی,kuşçu –falconer inTurkish;Latin:Ali Kushgii) was aTimuridtheologian,jurist,astronomer,mathematician andphysicist, who settled in theOttoman Empire some time before 1472.[2] As a disciple ofUlugh Beg, he is best known for the development ofastronomical physics independent fromnatural philosophy, and for providingempirical evidence for theEarth's rotation in his treatise,Concerning the Supposed Dependence of Astronomy upon Philosophy. In addition to his contributions toUlugh Beg's famous workZij-i-Sultani and to the founding ofSahn-ı Seman Medrese, one of the first centers for the study of various traditional Islamic sciences in the Ottoman Empire, Ali Kuşçu was also the author of several scientific works and textbooks on astronomy.[3]
Ali Kuşçu was born in 1403 in the city ofSamarkand, in present-dayUzbekistan. His full name at birth wasAla al-Dīn Ali ibn Muhammed al-Qushji. The last nameQushji derived from the Turkish termkuşçu—"falconer"[4]—due to the fact that Ali's father Muhammad was the royalfalconer ofUlugh Beg.[3] Sources consider himTurkic[5] orPersian.[6]
He attended the courses ofQazi zadeh Rumi,Ghiyāth al-Dīn Jamshīd Kāshānī andMuin al-Dīn Kashi. He moved toKerman, Iran (Persia), where he conducted some research on storms in theOman sea. He completedHall-e Eshkal-i Ghammar (Explanations of the Periods of the Moon) andSharh-e Tajrid in Kirman. He moved to Herat and taughtMolla Cami about astronomy (1423). After professing in Herat for a while, he returned to Samarkand. There he presented his work on the Moon to Ulugh Beg, who found it so fascinating that he read the entire work while standing up. Ulugh Beg assigned him toUlugh Beg Observatory, which was called Samarkand Observatory at that time. Qushji worked there until Ulugh Beg was assassinated.[7]
After Ulugh Beg's death, Ali Kuşçu went to Herat,Tashkent, and finallyTabriz where, around 1470, theAk Koyunlu rulerUzun Hasan sent him as a delegate to the Ottoman SultanMehmed II. At that timeHusayn Bayqarah had come to reign in Herat but Qushji preferred Constantinople over Herat because of Sultan Mehmed's attitude toward scientists and intellectuals.
When he came to Constantinople (present-dayIstanbul), his grandson Ghutb al-Dīn Muhammed had a sonMirim Çelebi who would be a great mathematician and astronomer in the future.[8] Ali Kuşçu composed "risalah dar hay’at" inPersian forMehmed II at Constantinople in 1470.[9] Also he wrote "Sharh e resalye Fathiyeh",[10] "resalye Mohammadiye" in Constantinople, which are inArabic on the topic of mathematics. He then finished "Sharh e tejrid" onNasir al-Din al-Tusi's "Tejrid al-kalam". That work is called "Sharh e Jadid" in scientific community.
Qushji improved onNasir al-Din al-Tusi's planetary model and presented an alternative planetary model forMercury.[11] He was also one of the astronomers that were part ofUlugh Beg's team of researchers working at theSamarqandobservatory and contributed towards theZij-i-Sultani compiled there. In addition to his contributions to Zij, Ali Kuşçu wrote nine works in astronomy, two of them inPersian and seven inArabic.[3] ALatin translation of two of Qushji's works, theTract on Arithmetic andTract on Astronomy, was published byJohn Greaves in 1650.
Qushji's most important astronomical work isConcerning the Supposed Dependence of Astronomy upon Philosophy. Under the influence ofIslamic theologians who opposed the interference ofAristotelianism in astronomy, Qushji rejectedAristotelian physics and completely separatednatural philosophy fromIslamic astronomy, allowing astronomy to become a purelyempirical and mathematical science. This allowed him to explore alternatives to the Aristotelian notion of a stationary Earth, as he explored the idea of a moving Earth instead (thoughEmilie Savage-Smith asserts that no Islamic astronomers proposed a heliocentric universe[12]). He foundempirical evidence for theEarth's rotation through his observation oncomets and concluded, on the basis of empirical evidence rather than speculative philosophy, that the moving Earth theory is just as likely to be true as the stationary Earth theory.[13][14][15]
His predecessor al-Tusi had previously realized that "the monoformity of falling bodies, and the uniformity of celestial motions," both moved "in a single way", though he still relied on Aristotelian physics to provide "certain principles that only the natural philosophers could provide the astronomer." Qushji took this concept further and proposed that "the astronomer had no need for Aristotelian physics and in fact should establish his own physical principles independently of the natural philosophers." Alongside his rejection of Aristotle's concept of a stationary Earth,[16] Qushji suggested that there was no need for astronomers to follow the Aristotelian notion of the heavenly bodies moving inuniform circular motion.[12]
Qushji's work was an important step away from Aristotelian physics and towards an independentastronomical physics.[17] This is considered to be a "conceptual revolution"[12][17] that had no precedent in European astronomy prior to theCopernican Revolution in the 16th century.[18] Qushji's view on the Earth's motion was similar to the later views ofNicolaus Copernicus on this issue, though it is uncertain whether the former had any influence on the latter. However, it is likely that they both may have arrived at similar conclusions due to using the earlier work ofNasir al-Din al-Tusi as a basis. This is more of a possibility considering "the remarkable coincidence between a passage inDe revolutionibus (I.8) and one in Ṭūsī’sTadhkira (II.1[6]) in which Copernicus follows Ṭūsī’s objection to Ptolemy’s "proofs" of the Earth's immobility."[19]
Clearly there is more to the Copernican revolution than some clever astronomical models that arose in the context of a criticism of Ptolemy. There also needed to be a new conceptualization of astronomy that could allow for an astronomically-based physics. But there is hardly anything like this in the European tradition before Copernicus. The fact that we can find a long, vigorous discussion in Islam of this issue intricately-tied to the question of the Earth's movement should indicate that such a conceptual foundation was there for the borrowing.
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