Ibn al-Haytham

Full name: 
Abū ‘Alī Al-Hassan Ibn al-Haytham
Arabic name: 
أبو علي الحسن ابن الهيثم
Latin name: 
Alhazen, Alhacen
Date of birth: 
965
Date of death: 
1039

Iraqi polymath scientist, who lived in Egypt (965 – 1039-40), called al-Basri, after his birthplace in the city of Basra, he died in Cairo, where he spent a splendid scientific career. He made significant contributions to the principles of optics, as well as to anatomy, astronomy, engineering, mathematics, medicine, ophthalmology, philosophy, physics, psychology, visual perception, and to science in general with his reflexions on the scientific method.

Ibn al-Haytham's most important work is Kitab al-manazir (Book of Optics) which contains the correct model of vision: the passive reception by the eyes of light rays reflected from objects, not an active emanation of light rays from the eyes. It combines experiment with mathematical reasoning. The work contains a complete formulation of the laws of reflection and a detailed investigation of refraction, including experiments involving angles of incidence and deviation. Refraction is correctly explained by light's moving slower in denser mediums. The work also contains "Alhazen's problem"—to determine the point of reflection from a plane or curved surface, given the centre of the eye and the observed point—which is stated and solved by means of conic sections.

A Latin translation of Ibn al-Haytham's greatest work Optics was made by an unknown scholar, probably early in the 13th century. The work had a major influence not only on 13th-century thinkers such as Roger Bacon but also on later scientists such as Kepler (1571–1630).

See Roshdi Rashed, "A Polymath in the 10th Century", Science Magazine, 2 August 2002, p. 773; and A. I. Sabra, "Ibn al-Haytham: Brief life of an Arab mathematician", Harvard Magazine, September-October 2003; Richard Lorch, "Ibn al-Haytham", Encyclopædia Britannica Online, 2007. See also "Ibn Al-Haitham the Muslim Physicist".