Ibn al-Haytham: Arab mathematician, astronomer, and physicist

Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham or Ibn al-Haytham in brief, commonly known as Alhazen (also spelled Alhacen) was born in Basra of Old Persia (now southern Iraq) in about 965 AD.

He spent most of his time in Cairo, under the reign of Fatimid Caliph al-Hakim, who showed strong interest in science and philosophy.

Ibn al-Haytham was trained for a civil service job and was appointed as a judge for Basra. Due to the presence of various religious movements with diverse and conflicting views at that time, he became disillusioned with religious studies and decided to dedicate his time and effort for the study of science. His knowledge in mathematics and physics became legendary and he was well known in Iraq, Syria and Egypt.

He was involved in an engineering project that proposed new ways of regulating the annual flood of the river Nile, on which Egypt’s economy depended in its entirety during this period.

Upon viewing the Nile River, nearby monumental, pharaonic works and his available resources he realized his plan wasn’t feasible, and allegedly feigned madness to avoid the wrath of the labile al-Hakim. He remained under house arrest for ten years until the Caliph’s death.

During his period of incarceration, he wrote his influential “Kitab Al Manazer” or the Book of Optic, in addition to several significant books and chapters on physics, mathematics, engineering, astronomy, medicine, psychology, anatomy, visual perception and ophthalmology. He wrote his introduction of the scientific methods.

Kitab Al Manazir is the first real science textbook, combining experiments with mathematical validation. In writing Kitab al-Manazir, Ibn al-Haytham succinctly summarized previous knowledge on vision and also on the basis of his own experimental observations, presented new opinions and scientific information including his famous theory of vision. From a scientific point of view, the Kitab al-Manazir presents a new approach to the studies and theories about vision in the Middle Ages by integrating Aristotelian intromission theories into the analysis of vision, with a thorough analysis of its physiological components.

Intromission theories, whose most prominent advocate was Aristotle (384-322, BC), postulated that objects continuously send-off microscopic replicas of themselves that travel to the eye.

After an exuberant life devoted to different branches of science, Ibn al-Haytham passed away in Cairo, in about 1039 AD.
Ibn al-Haytham: Arab mathematician, astronomer, and physicist