by Pamela Toler
Islamic scholar Abu Ali al-Hassan Ibn al-Haytham (ca. 965-1041), known in the West as Alhazen, began his career as just another Islamic polymath. He soon got himself in trouble with the ruler of Cairo by boasting that he could regulate the flow of the Nile with a series of dams and dikes. At first glance, it had looked like such a simple problem. But the more he studied it, the more impossible it seemed. Al-Hakim, known to his subjects as the Mad Caliph with good reason, was getting impatient. Alhazen only saw one way out: he pretended to be crazy. Safely confined as a madman until the caliph’s death ten years later, Alhazen continued to work.
Time and isolation? It was the perfect situation for a man with a book to write.
While confined in his home, Alhazen revolutionized the study of optics and laid the foundation for the scientific method. (Move over, Sir Isaac Newton.) Before Alhazen, vision and light were questions of philosophy. Alhazen considered vision and light in terms of mathematics, physics, physiology, and even psychology. In his Book of Optics, he discussed the nature of light and color. He accurately described the mechanism of sight and the anatomy of the eye. He was concerned with reflection and refraction. He experimented with mirrors and lenses. He discovered that rainbows are caused by refraction and calculated the height of earth’s atmosphere. In his spare time, he built the first camera obscura.
Modern physicist Jim al-Khalili, in his excellent The House of Wisdom: How Arabic Science Saved Ancient Knowledge and Gave Us the Renaissance, calls Alhazen the greatest physicist of the medieval world, and possibly the greatest in the 2000 years between Archimedes and Sir Isaac Newton. His Book of Optics was first translated into Latin in the late twelfth or early thirteen century. It had an enormous impact on the work of western scientists from Roger Bacon (c. 1214-1292) to Isaac Newton (1642-1727).
About the author: Pamela Toler is a freelance writer with a PhD in history and a large bump of curiosity. She is particularly interested in the times and places where two cultures meet and change.