Abstract
Abu Ali Hasan Ibn al-Haitham was one of the most eminent of all physicists, whose contributions to sciences, in particularly optics, were outstanding. Known in the West as Alhazen, he is considered the ‘father of modern optics’. Iranian by birth, Alhazen received his education in both Basra and Baghdad, before travelling to Egypt, where on commission to Caliph al-Hakim, then ruler of Egypt, he attempted to find a way of controlling the flooding of the Nile River. However, upon arriving at the proposed site, Alhazen realised that he had insufficient money and materials to successfully complete the project. Wishing to escape the wrath of Caliph he feigned madness, a pretence he maintained until Caliph’s death 12 years later. By this time, Alhazen was living and pursuing science in Spain. Of his many works, the most distinguished was Kitab-al-Manadhir. Translated into Latin in 1270, Opticae Thesaurus was the first real contribution to the science of optics in the first millennium and had a great influence on both Bacon and Kepler. He also studied the phenomena of eclipses, shadows, and rainbows and the role of the dispersion light in the determination of colours. Alhazen deduced that vision was the product of light being reflected into the eye rather than rays from the eye scanning objects. This overturned a thousand years of Aristotelian scientific thought. His book, Mizan al-Hikmah, examines the density of the atmosphere, atmospheric refraction, and why twilight begins or ends only when the sun is 19 degrees below the horizon. Ultimately, his desire was to use all of these aspects to determine the height of the atmosphere. Alhazen also made significant contributions to both mathematics and physics. In mathematics, he established the link between algebra and geometry that led to his development of analytical geometry. In physics, he devised one of the first laws of motion, stating that a body moves perpetually until stopped by an external force or it changes direction.
