Physics is a science that covers a very wide area of the material world, ranging from research on subatomic particles to studying galaxies. In Physics, what’s most important is the composition and behavior of matter and all of its fundamental laws. The most fascinating works on Physics that have been created by Islamic scientists, are about a subdomain of physics: optics.
This post discusses the contributions of Ibn al-Haytham.
Ibn al-Haytham: Early Life
Ibn al-Haytham, in Europe more commonly called by his Latinized name “Alhazen”, was born in the city of Basra in 965 CE. He went to neighborhood schools and moved to Baghdad to study science on a higher level, like many Arab scientists did at that time. However, he may have had some issues with the Fatimid Caliph Al-Hakim bi-amr-Allah, which resulted in him being grounded in 1011. He would be grounded for a couple of years, until the Caliph died in 1021.
Afterwards he moved to Spain to focus on science once again. At the end of his life, he returned to his home country, Egypt, where he died in 1039.
Ibn al-Haytham And His “Books of Optics”
Ibn al-Haytham is mainly known from his work in optics, which didn’t go by unnoticed in Europe. In his seven-piece book “Kitab al-Manazir”, he began with some very harsh criticism towards several theories from the past. One of these theories was the theory of vision.
One of the things he examined was: what happens when someone is exposed to bright light? He discovered that light going from an external source into the eye has a certain influence on one’s vision. In order to expand knowledge, he began with a series of experiments in which he investigated the relation between light fraction and image distortion. He learned that the mathematical aspect of optics, in this case being the reflection and fraction, had to correspond with the knowledge of the anatomy of the eye. It was for that reason that he drafted an eye with all its components in his book, as shown below:
In his book, Ibn Al-Haytham elaborated on the fact that light that reaches the eye comes from the visible object. In David C. Lindberg’s (a recently deceased American science historian) chronological book “Theories of Vision: From al-Kindi to Kepler”, the author gives Ibn al-Haytham’s definition of the theory of vision:
Light illuminates all visible objects and this light later reaches the eye surface, allowing humans to perceive the object in question.
Because Ibn al-Haytham clearly questioned the theory of vision and supported his own assumptions with proof through his experiments, he was able to harvest ample appreciation from the West.
George Sarton, a Belgian-American science historian, honored Ibn al-Haytham’s contributions to science in his book “History of Science”:
He, Ibn al-Haytham, was the greatest Islamic physicist and student of optics the world has ever known. Whether his successors lived in England or in the far Persia, each and every one of them drank from the same fountain. He had a tremendous influence on the European idea from Bacon to Kepler.
Ibn al-Haytham And His Camera Obscura
Ibn al-Haytham often used the term “al Bayt al-Muthlim” in his experiments, which translates into “the dark room”. With that, he also developed his camera obscura, which is a camera that sends an image through a small hole. None of his predecessors who (Aristotle, Euclides or al-Kindi), just like Ibn al-Haytham, studied the effects of light which goes through a camera obscura, were able to prove that everything which is projected on the screen came from the other side of the hole.
With that, Ibn al-Haytham became the first to prove this by means of an experiment using a lamp with which several light sources were spread and arranged throughout a large surface. He was also the first scientist to successfully project an image onto a screen using a camera obscura.
As such, Ibn al-Haytham was the first scientist in history to develop a working camera.