Â鶹Éç

Philip Ball tells the story of Ibn al-Haytham, a native of present-day Iraq, who in the early 11th Century, showed how light and the human eye collaborate to produce our sense of vision.

Abu Ali al-Hassan ibn al-Haytham was one of the many Arabic scholars who took the science and philosophy of the ancient world and extended it, not least by finding out if it actually fitted with our everyday experience. At this time in the 1000s the Islamic world of the Middle East was one of the most intellectually advanced civilizations.

Today we know that vision is only partly explained by how light enters the eye – because the eye is not after all really like a camera, passively recording the scene in front of it. The brain has to work harder than that. As far as the brain is concerned, the eye supplies only clues – sometimes imperfect, ambiguous, conflicting. The brain’s job is to use those clues to make a good guess at what is there and what is actually happening in the world that we see.

Philip Ball discusses the life and times of Ibn al Haytham with Jim al-Khalili, professor of physics at University of Surrey and author of Pathfinders, a book about the Golden Age of Arabic Science, who was born in Iraq. Philip meets Harriet Allen of Nottingham University who is trying to understand in detail the complex process of vision, in particular what happens in the brain to give us the sense of vision.