Born : 1265
Died: 12 January 1318
Main interests : Optics, Physics, Mathematics, Science.
According to Encyclopædia Iranica, Kamal al-Din was the most prominent Persian author
on optics.
Kamal al-Din al-Farisi's autograph manuscript in Optics, Tanqih al-Manazir,
1309 A.D., Adilnor Collection.
Optics
The colophone of Al-Basa'ir fi 'ilm al-Basa'ir, copied in 731 H.E. from
Kamal al-Din's original manuscript, states that Kamal al-Din's real name is
al-Hasan ibn Ali ibn al-Hasan and he has completed the work in 708 H.E. The
scribe states also that Kamal al-Din died on 19 Dhu al-Qa'dah 718 H.E. (12
January 1319)
His work on optics was prompted by a question put to him concerning the
refraction of light. Shirazi advised him to consult the Book of Optics of Ibn
al-Haytham (Alhacen), and Farisi made such a deep study of this treatise
that Shirazi suggested that he write what is essentially a revision of that
major work, which came to be called the Tanqih. Qutb al-Din
Al-Shirazi himself was writing a commentary on works of Avicenna at
the time.
Farisi is known for giving the first mathematically satisfactory
explanation of the rainbow, and an explication of the nature of colours
that reformed the theory of Ibn al-Haytham Alhazen. Farisi also
"proposed a model where the ray of light from the sun was refracted twice
by a water droplet, one or more reflections occurring between the two
refractions." He verified this through extensive experimentation using a
transparent sphere filled with water and a camera obscura.
His research in this regard was based on theoretical investigations in
dioptrics conducted on the so-called Burning Sphere (al-Kura
al-muhriqa) in the tradition of Ibn Sahl (d. ca. 1000)
and Ibn al-Haytham (d. ca. 1041) after him. As he noted in his Kitab
Tanqih al-Manazir (The Revision of the Optics), Farisi used a
large clear vessel of glass in the shape of a sphere, which was filled with
water, in order to have an experimental large-scale model of a rain drop. He
then placed this model within a camera obscura that has a controlled
aperture for the introduction of light. He projected light unto the sphere and
ultimately deducted through several trials and detailed observations of
reflections and refractions of light that the colors of the rainbow are
phenomena of the decomposition of light. His research had resonances with the
studies of his contemporary Theodoric of Freiberg (without any
contacts between them; even though they both relied on Ibn al-Haytham's
legacy), and later with the experiments
of Descartes and Newton in dioptrics (for instance, Newton
conducted a similar experiment at Trinity College, though using a prism rather
than a sphere).
Number theory
Farisi made a number of important contributions to number theory. His most
impressive work in number theory is on amicable numbers. In Tadhkira
al-ahbab fi bayan al-tahabb ("Memorandum for friends on the proof
of amicability") introduced a major new approach to a whole area of number
theory, introducing ideas concerning factorization and combinatorial methods.
In fact Farisi's approach is based on the unique factorization of
an integer into powers of prime numbers. While the Greek
mathematician Euclid took the first step on the way to the existence
of prime factorization, al-Farisi took the final step and stated for the
first time the fundamental theorem of arithmetic.
Works
1. Asas al-qawa'id fi usul
al-fawa'id (The base of the rules in the principles of uses) which comprises an
introduction and five chapters dealing with arithmetic, notarial and sales
rules, the areas of surfaces and solids, and the last two essays are on algebra.
The book is a commentary on the treatise of Al-Baha'i uses in the arithmetic
rules of Al-Khawam al-Baghdadi.
2. Tanqih al-Manazir (Arabic: تنقيح المناظر ; The Revision of Ibn al-Haytham's
Optics). He completed the writing of this book in Ramadan 708 H.E. (Feb-Mar
1309 A.D.). The autograph manuscript of this work has newly discovered.
Before the discovery, the completion date of the Tanqih had been controversial,
placed from sometime before 1290 (M. Nazif) to after 1302, but before Quṭb
al-Dīn Shīrāzī’s death in 710/1311 (Wiedemann).
3. Tadhkira al-ahbab fi bayan
al-tahabb (Memorandum for friends on the proof of amicability)
4. Al-Basa'ir fi 'ilm al-manazir
(Insights Into the Sciences of Optics), a text book for students of optics,
presenting the conclusion of the Tanqih without the proofs or experiments. He
completed the writing of this book in 708 H.E. (1309 A.D.).
Sumber
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Mathematician
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