How an ancient Muslim scientist cast his light into the 21st century

Celebrating optics pioneer Ibn al-Haytham — and promoting intercultural collaboration for the International Year of Light

By Hanan Dowidar and Ahmed Salim | Posted on 24 March 2015

Creative illustration depicting Ibn al-Haytham experimenting in Cairo to prove that we see because light from objects travels in a straight line into our eyes (Source: 1001 Inventions: The Enduring Legacy of Muslim Civilization © 1001 Inventions)

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.

Photograph of a creative representation bust of Ibn al-Haytham made by artist Ali Amro for 1001 Inventions to celebrate the UNESCO International Year of Light 2015 (© 1001 Inventions)

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 …

An image of Ibn al-Haytham appears on Iraqi 10 dinar bills.

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.

So how did that influence shine its light on subsequent generations? In the early 12th century, the Spanish town of Toledo was the focus of a huge effort to translate Arabic books into Latin. Christian, Jewish and Muslim scholars flocked there, where they lived alongside one another and worked together to translate the old knowledge into Latin and then into other European languages. Ibn al-Haytham's Book of Optics as well as some of his other scientific works were translated into Latin. Having his work available in Latin proved influential on scholars writing during the Middle Ages and Renaissance, including Roger Bacon, Johannes Kepler and even Leonardo da Vinci, thus significantly contributing to the intellectual legacy that Latin scholars derived from Muslim civilization.

Professor A. Mark Smith of the University of Missouri, who specialises in Medieval history and the history of science, described the significance of Ibn al-Haytham's contributions:

Ibn al-Haytham’s primary contribution to the development of modern optics was the creation of a brilliant optical synthesis from various earlier theories, as well as his own. So elegant, coherent, and logically compelling was that synthesis, in fact, that it informed optical thought in Europe for hundreds of years before it was finally undermined by Kepler. The very fact that it persisted for so long and that it finally took a thinker of Kepler’s exceptional acuity to offer a viable alternative in the theory of retinal imaging is a testament to its elegance and logical power.

Ibn al-Haytham’s seminal work on optics and light is evidence of  the accumulation of scientific knowledge which built on the contributions of different civilisations, helping to this day shape our understanding of the universe and impacting our day-to-day lives. 

A global educational campaign

Ahmed Salim, 1001 Inventions Managing Director, with Prof. Maciej Nalecz, Director of UNESCO's Division of Science Policy & Capacity Building, after unveiling the statue of Ibn al-Haytham at the International Year of Light Opening Ceremony at UNESCO headquarters in Paris.

In today’s information age, distance and language are no longer barriers to the transfer of knowledge. Collective learning no longer requires time spans of thousands of years. With the power of technology and advancements in science, collaboration across cultures could bring massive leaps and rapid advances towards solving shared global challenges and achieving mutual benefits, while also contributing to intercultural understanding.

At a time of mounting political pressures, it is imperative to create platforms for collaboration and an environment conducive to partnerships enabling scientists, across borders, to find common solutions for global challenges.  

Creative illustration and poster for the global campaign "1001 Inventions and the World of Ibn Al-Haytham" (Source: 1001inventions.com © 1001 Inventions)

Inspired by Ibn al-Haytham, 1001 Inventions launched a global educational campaign produced with the King Abdulaziz Center for World Culture in Saudi Arabia and in partnership withUNESCO and the International Year of Light. Titled “1001 Inventions and the World of Ibn Al-Haytham,” the initiative uses the scientist’s extraordinary life to raise awareness of the importance of intercultural dialogue through science diplomacy. It also aims to further instill pride in science heritage, promote social cohesion and encourage mutual understanding and respect through engaging under-represented communities.

What is most important about the campaign is that it aims to inspire young people to study science, technology, engineering and math (STEM) and pursue careers in science. While it celebrates stories from the past, the initiative is highly relevant to our world today. In a world where science is crucial to our wellbeing, harnessing the potential of young people and building their scientific capacity is an indisputable necessity. 

The campaigns of 1001 Inventions and other informal science education initiatives can be considered tools of science diplomacy, building bridges between scientists, academics and societies at large. These initiatives are of utmost importance as they contribute to finding collective solutions for shared challenges, while also resolving political, economic and social tensions. A new generation equipped with a mindset of intercultural collaboration and empowered by tools to become science and technology leaders provides a unique opportunity to build our future constructively.

A giant fully functioning 360-degree camera obscura created by 1001 Inventions as a tribute to Ibn al-Haytham. The interactive exhibit offers audiences the chance to step inside the mind and world of Ibn al-Haytham and experience how we see and learn about the fundamentals of light science. (Photo courtesy of 1001 Inventions)

1001 Inventions

With its motto of “Discovering the Past, Inspiring a Better Future,”1001 Inventions is an award-winning international science and cultural heritage organization based in the UK.

A nonprofit organization, 1001 Inventions has uncovered a thousand years of scientific and cultural achievements from Muslim Civilization from the 7th century onwards, showing how these contributions helped create the foundations of our modern world. Through its educational programs, books, exhibitions, live shows, films and learning products, 1001 Inventions showcases the contributions of inspirational men and women of different faiths and cultures in a civilization that spread from Spain to China.

International Year of Light

Fuelled by UNESCO and a large consortium of scientific bodies, the International Year of Light and Light-Based Technologies (#IYL2015) brings together many different members of the scientific community. This global initiative aims to raise awareness about how light-based technologies promote sustainable development and provide solutions to global challenges in energy, education, agriculture and health. Its goal is to highlight the importance of light and optical technologies in our lives and for the development of society.