From Academic Kids

Alhazen Abu Ali al-Hasan Ibn Al-Haitham (also: Ibn al Haythen), (965-1040), was an Arab mathematician; he is sometimes called al-Basri, after his birthplace.

He was born at Basra, then part of Buwayhid Persia, now part of Iraq (See [1] ( [2] (, and probably died in Cairo, Egypt. There is another Alhazen who translated Ptolemy's Almagest in the 10th century.

One version of his career has him summoned to Egypt by the mercurial caliph Hakim to regulate the flooding of the Nile. After his field work made him aware of the impracticability of his scheme, and fearing the caliph's anger, he feigned madness. He was kept under house arrest until Hakim's death in 1021. During this time he wrote scores of important mathematical treatises.

Alhazen was a pioneer in optics, engineering and astronomy. According to Giambattista della Porta, he first explained the apparent increase in the size of the moon and sun near the horizon, although Roger Bacon gives the credit of this discovery to Ptolemy. He taught that vision does not result from the emission of rays from the eye, and wrote on the refraction of light, especially on atmospheric refraction, for example, the cause of morning and evening twilight. He solved the problem of finding the point on a convex mirror at which a ray coming from one point is reflected to another point.

His seven volume treatise on optics Kitab al-Manazir (Optics) was translated into Latin by Witelo in 1270. It was published by Friedrich Risner in 1572, with the title Oticae thesaurus Alhazeni libri VII., cum ejusdem libro de crepusculis et nubium ascensionibus. This work enjoyed a great reputation during the Middle Ages. Works by Alhazen on geometrical subjects were found in the Bibliothque nationale in Paris in 1834 by E. A. Sedillot. Other manuscripts are preserved in the Bodleian Library at Oxford and in the library of Leiden.

His Optics made a profound impression, among others, on Roger Bacon, John Pecham, and Witelo.

Alhazen's "Optics" (written from 1015 to 1021) is possibly the earliest work to use the scientific method. The ancient Greeks believed that truth was determined by the logic and beauty of reasoning; experiment was used as a demonstration. Alhazen used the results of experiments to test theories. The "emission" theory of light had been supported by Euclid and Ptolemy. This theory postulated that sight worked by the eye emitting light.

The second or "intromission" theory, supported by Aristotle had light entering the eye. Alhazen performed experiments to determine that the "intromission" theory was scientifically correct.

Alhazen's influenced Westerners such as Bacon and Kepler through his extensive writings.


Ibn al-Haytham's Optics: A Study of the Origins of Experimental Science, by Saleh Beshara Omar (Bibliotheca Islamica, 1977)

External links

See also

de:Alhazen gl:Alhazen nl:Ibn al-Haytham no:Al-Haitham pl:Ibn al-Hajsam pt:Alhazen sl:Ibn al-Haitam


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