Islamic heritage series: Ibn Al-Haytham: The pioneer optician
To explore the nature of light and vision, 11th century physicist Ibn al-Haytham used a dark chamber he called “Albeit Almuzlim,” translated into Latin as “camera obscura” – the device that forms the basis of photography. He observed that light coming through a tiny hole travelled in straight lines and projected an image onto the […]
To explore the nature of light and vision, 11th century physicist Ibn al-Haytham used a dark chamber he called “Albeit Almuzlim,” translated into Latin as “camera obscura” – the device that forms the basis of photography. He observed that light coming through a tiny hole travelled in straight lines and projected an image onto the opposite wall.
Based on such experimentation, Ibn al-Haytham concluded that vision is accomplished by rays coming from external luminous sources and entering the eye, rather than through rays emitted from the eye as was commonly believed.
This was just one of the ways this pioneer of optical sciences, who lived during the Golden Age of Muslim Civilisation, would cast light into our modern world.
Our knowledge of science today is built upon thousands of years of work accumulated throughout ancient civilizations. The historical “collective learning” by people of different languages, faiths and cultures has laid the foundation for modern science. In today’s tension-ridden world, insights from our past can highlight how civilisations have been historically interdependent, providing inspiration to further promote harmony between cultures.
This is especially important in the 21st century, where challenges are not confined to a single nation or region. As we aim to address global challenges, we realise they necessitate collective solutions. Science plays a pivotal role in improving living conditions and catering to social needs, from food security and health to energy sufficiency, supporting the path towards sustainable development.
For the International Year of Light and Light-Based Technologies (IYL2015), UNESCO has been celebrating the achievements of pioneering scientists through the ages, including Ibn al-Haytham, who made lasting contributions to the understanding of vision, optics and light. With light being a subject that unifies humanity, following the development of vision and light theories through Ibn al-Haytham’s contributions offers a highly relevant narrative to the process of historical collective learning. The legacy of the remarkable polymath demonstrates how knowledge was developed through the ages and across civilisations.
Al-Hasan Ibn al-Haytham (known in the West by the Latinised form of his first name, initially “Alhacen” and later “Alhazen”) was born about 1,000 years ago in Basra, which is now in Iraq. This was the height of the Golden Age of Muslim Civilisation – a creative era that spanned a thousand years from the 7th century onwards, from Spain to China, bringing forth many far-reaching advances in science, technology and medicine by men and women of different faiths and cultures. Building upon knowledge of ancient civilisations, their contributions added significant and crucial value to the accumulation of scientific knowledge shaping our homes, schools, hospitals, towns and the way we trade, travel and understand the universe today.
Ibn al-Haytham was “the greatest Muslim physicist and one of the greatest students of optics of all times,” in the words of the renowned historian of science, the late George Sarton, in his Introduction to the History of Science.
Making his mark in the shadow of Aristotle, Euclid, Al-Kindi, Banu Musa, Ibrahim ibn Sinan …
Ibn al-Haytham was born after centuries of intense activity in mathematics, astronomy, optics, and other physical sciences by pioneers such as Aristotle, Euclid, Ptolemy, Al-Kindi, Banu Musa, Thabit ibn Qurra, Ibrahim ibn Sinan, Al-Quhi and Ibn Sahl. He greatly benefited from being able to use the direct translation of many scientific works from Greek, Syriac and Persian thinkers, who in their turn were the heirs to the great scientific traditions of Ancient Egypt, Babylonia, India and China.
Ibn al-Haytham based his theories on the work of the Greek physician Galen, who had provided a detailed description of the eye and the optic pathways. However, Ibn al-Haytham subscribed to a method of empirical analysis to accompany theoretical postulates that is similar in certain ways to the scientific method we know today. Realizing that the senses were prone to error, he devised methods of verification, testing and experimentation to uncover the truth of the natural phenomena he examined. Up until this time, the study of physical phenomena had been an abstract activity with occasional experiments. In his 7-volume Book of Optics, Ibn al-Haytham wrote:
If learning the truth is the scientist’s goal … then he must make himself the enemy of all that he reads.
Ibn al-Haytham’s sketch of the human optical system. The oldest known drawing of the nervous system from Kitab al-Manazir of Ibn al-Haytham (from a manuscript held in the Süleymaniye Library, Istanbul), in which the eyes and optic nerves are illustrated. It shows a large nose at the bottom, eyes on both side and a hollow optic nerve that flows out of each one towards the back of the brain. (Source: Reflections on the Optics of Time © Muslim Heritage)
Ultimately, he was equally recognized for his approach to experimentation as for his discoveries.
“Ibn al-Haytham was one of the truly great men of science,” wrote historian of science Professor Glen M. Cooper of Claremont McKenna College in California. “It is both through his clever use of thought experiments and in his emphasis on performing actual and careful experiments that Ibn al-Haytham must be considered as one of a handful of scientists whose contributions were pivotal to the development of the modern world.”
Indeed, Ibn al-Haytham’s discoveries in optics and vision overturned long periods of misunderstanding. Dr. George Saliba, Professor of Arabic Science at the Department of Middle East and Asian Languages and Cultures at Columbia University, said:
Ibn al-Haytham is universally acknowledged to be one of, if not, the most creative scientist Islamic civilization had ever known. He did not only critique the inherited Greek theories of light and vision, in his Book On Optics, and managed to create his own experimentally tested theories to replace them, thereby ushering the first building blocks for the modern understanding of how human vision takes place, but also subjected Greek cosmological doctrines in his other book, Doubts Against Ptolemy, to a most devastating criticism that managed to undermine the very foundations of those doctrines, thereby initiating a sustained program of research to replace them; a program that lasted for centuries after him and culminated with the ultimate overthrow of the Aristotelian universe and the birth of the modern astronomy of the European Renaissance.
Why his influence lingers
The Polish astronomer Johannes Hevelius chose to honor Ibn al-Haytham, alongside Galileo, in his most famous work on the Moon, Selenographia, published in 1647. Image is from his book’s title page (Source: Houghton Library, Harvard University)
Today, the oldest-known drawing of the nervous system is from Ibn al-Haytham’s Book of Optics, in which the eyes and optic nerves are illustrated. When Ibn al-Haytham’s Book of Optics (Kitab al-Manazir) was translated into Latin (De Aspectibus), its impact rippled out across the whole world. Both his optical discoveries, and the fact that they had been validated using hands-on experiments, would influence those who came after him for centuries.
From Elsevier website