Muḥammad ibn Muḥammad ibn al-Ḥasan al-Ṭūsī(Persian: محمد بن محمد بن الحسن الطوسی )(born February 1201 in Tus, Khorasan – 26 June 1274 in Kadhimain near Baghdad), better known as Naṣīr al-Dīn al-Ṭūsī (or Tusi in the West), was a Persian[1][2] of the Twelver Shi'a Islamic belief. He was a prolific polymath writer: an astronomer, biologist, chemist, mathematician, philosopher, physician, physicist, scientist, theologian, and Marja Taqleed. A 60-km diameter lunar crater located on the southern hemisphere of the moon is named after him as "Nasireddin". A minor planet 10269 Tusi discovered by Soviet astronomer Nikolai Stepanovich Chernykh in 1979 is named after him.[3][4] The K. N. Toosi University of Technology in Iran is also named after him.
BiographyNasir al-Din Tusi was born in Tus east of Iran in the year 1201 and began his studies at an early age. In Tus he studied the Qur'an, Hadith, Shi'a jurisprudence, logic, philosophy, mathematics, medicine and astronomy.[5] He was apparently born into a shia ismaili family and lost his father at a young age. Fulfilling the wish of his father, the young Muhammad took learning and scholarship very seriously and travelled far and wide to attend the lectures of renowned scholars and ‘acquire the knowledge which guides people to the happiness of the next world. At a young age he moved to Nishapur to study philosophy under Farid al-Din Damad and mathematics under Muhammad Hasib.[6] He met also Farid al-Din al-'Attar, the legendary Sufi master who was later killed in the hand of Mongol invaders and attended the lectures of Qutb al-Din al-Misri. In Mawsil he studied mathematics and astronomy with Kamal al-Din Yunus (d. 639/1242). Later on he corresponded with al-Qaysari, the son-in-law of Ibn al-‘Arabi, and it seems that mysticism, as propagated by Sufi masters of his time, was not appealing to his mind and once the occasion was suitable, he composed his own manual of philosophical Sufism in the form of a small booklet entitled "Awsaf al-ashraf" (The Attributes of the Illustrious). As the armies of Genghis Khan swept his homeland, he fled to join the Ismailis and made his most important contributions in science during this time when he was moving from one stronghold to another. He finally joined Hulagu Khan's ranks, after the invasion of the Alamut castle by the Mongol forces. Works
AchievementsDuring his stay in Nishapur, Tusi established a reputation as an exceptional scholar. Astronomy
Tusi convinced Hulegu Khan to construct an observatory for establishing accurate astronomical tables for better astrological predictions. Beginning in 1259, the Rasad Khaneh observatory was constructed west of Maragheh, the capital of the Ilkhanate Empire. Based on the observations in this for the time being most advanced observatory, Tusi made very accurate tables of planetary movements as depicted in his book Zij-i ilkhani (Ilkhanic Tables). This book contains astronomical tables for calculating the positions of the planets and the names of the stars. His model for the planetary system is believed to be the most advanced of his time, and was used extensively until the development of the heliocentric model in the time of Nicolaus Copernicus. Between Ptolemy and Copernicus, he is considered by many to be one of the most eminent astronomers of his time, and his work and theory in astronomy can also be compared to that of the Chinese scientist Shen Kuo (1031-1095 AD). For his planetary models, he invented a geometrical technique called a Tusi-couple, which generates linear motion from the sum of two circular motions. He used this technique to replace Ptolemy's problematic equant, and it was later employed in Ibn al-Shatir's geocentric model and Nicolaus Copernicus' heliocentric Copernican model. He also calculated the value for the annual precession of the equinoxes and contributed to the construction and usage of some astronomical instruments including the astrolabe. Tusi was also the first to present empirical observational evidence of the Earth's rotation, using the location of comets relevant to the Earth as evidence, which Ali al-Qushji elaborated on with further empirical observations. The arguments of Tusi were similar to the arguments later used by Copernicus in 1543 to explain the Earth's rotation.[7] BiologyTusi wrote extensively on biology and is one of the early pioneers of biological evolution in scientific thought. He begins his theory of evolution with the universe once consisting of equal and similar elements, which themselves consist of elementary particles. According to Tusi, internal contradictions began appearing, and as a result, some substances began developing faster and differently from other substances. He then explains how the elements evolved into minerals, then plants, then animals, and then humans. Tusi then goes on to explain how hereditary variability was an important factor for biological evolution of living things:[8]
Tusi discusses how organisms are able to adapt to their environments:[8]
Tusi recognized three types of living things: plants, animals, and humans. He wrote:[8]
Tusi then explains how humans evolved from advanced animals:[8]
Chemistry and PhysicsIn chemistry and physics, Tusi stated an early version of the law of conservation of mass. He wrote that a body of matter is able to change, but is not able to disappear:[8]
MathematicsTusi was perhaps the first to treat trigonometry as a separate mathematical discipline, and in his Treatise on the Quadrilateral, he gave the first extensive exposition of spherical trigonometry, as he was the first to list the six distinct cases of a right triangle in spherical trigonometry. He also created the famous sine formula for plane triangles, which was one of his main mathematical contributions:
In 1265, Tusi wrote a manuscript regarding the calculation for nth roots of an integer. Moreover, he revealed the coefficients of the expansion of a binomial to any power giving the binomial formula and the Pascal triangle relations between binomial coefficients. He also wrote a famous work on theory of colour, based on mixtures of black and white, and included sections on jewels and perfumes. See also
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