Ibn Al-Haytham and the Legacy of Arabic Optics

The year 2015 marks the 1000th anniversary since the appearance of the remarkable seven volume treatise on optics Kitab al-Manazir written by the Arab scientist Ibn al-Haytham. Born around a thousand years ago in present day Iraq, Al-Hasan Ibn al-Haytham (known in the West by the Latinised form of his first name, initially “Alhacen” and later “Alhazen”) was a pioneering scientific thinker who made important contributions to the understanding of vision, optics and light.

His methodology of investigation, in particular using experiment to verify theory, shows certain similarities to what later became  known as the modern scientific method. Through his Book of Optics (Kitab al-Manazir) and its Latin translation (De Aspectibus), his ideas influenced European scholars including those of the European Renaissance. Today, many consider him a pivotal figure in the history of optics and the “Father of modern Optics”.

Ibn al-Haytham was born during a creative period known as the golden age of Muslim civilisation that saw many fascinating advances in science, technology and medicine. In an area that spread from Spain to China, inspirational men and women, of different faiths and cultures, built upon knowledge of ancient civilisations, making discoveries that had a huge and often underappreciated impact on our world. 

UNESCO and the 2015 International Year of Light have partnered with the UK based organisation 1001 Inventions to launch a high-profile international educational campaign celebrating Ibn al-Haytham called '1001 Inventions and the World of Ibn al-Haytham'.

1001 Inventions and the King Abdulaziz Center for World culture in partnership with UNESCO and the International Year of Light 2015 will produce a short film on the work of 11th century scientist Ibn Al-Haytham: "1001 Inventions and the World of Ibn Al Haytham".

To find out more visit: http://www.ibnalhaytham.com

Other initiatives to celebrate Ibn Al-Haytham include educational actions coordinated by a high-level Ibn-Al Haytham Working Group, and a dedicated conference an exhibition at UNESCO HQ starting on 14 September 2015 entitled The Islamic Golden Age of Science for the Knowledge-Based Society.  This conference will see experts in science, history and culture engage world leaders and the public with fascinating insights into the era of ground-breaking discoveries and innovations by scientists of different cultures and faiths who lived during that period of Muslim Civilisation over 1,000 years ago.

To find out more visit:
http://www.unesco.org/new/en/media-services/single-view/news/1000_years_of_arabic_optics_to_be_a_focus_of_the_international_year_of_light_in_2015/ - .VLgvHktt1uY

Ibn al-Haytham, pioneering scientist

Ibn al-Haytham's work was remarkable for its emphasis on proof and evidence. He is known to have said: “If learning the truth is the scientist’s goal… then he must make himself the enemy of all that he reads.” By this he meant it was essential to conduct experiments to test what is written rather than blindly accepting it as true.

Ibn al-Haytham was born in the year 965 in Basra, and died in about 1040 in Cairo. He was one of the earliest scientists to study the characteristics of light and the mechanism/process of vision. He sought experimental proof of his theories and ideas. During many years living in Egypt, ten of which were spent underwhat we may now call protective custody (house arrest), he composed one of his most celebrated works, the Kitab al-Manazir, whose title is commonly translated into English as Book of Optics but more properly has the broader meaning Book of Vision.

Ibn al-Haytham made significant advances in optics, mathematics and astronomy. His work on optics was characterised by a strong emphasis on carefully designedexperiments to test theories and hypotheses. In that regard he was following a procedure somewhat similar to the one modern scientists adhere to in their investigative research.

Different views about how the process of vision could be explained had been in circulation for centuries mainly among classical Greek thinkers.   Some said rays came out of the eyes, while others thought something entered the eyes to represent an object.  But it was the 11th-century scientist Ibn al-Haytham who undertook a systematic critique of these ideas about vision in order to demonstrate by both reason and experiment that light was a crucial, and independent, part of the visual process. He thus concluded that vision would only take place when a light ray issued from a luminous source or wasreflected from such a source before it entered the eye.

Ibn al-Haytham is credited with explaining the nature of light and vision, through using a dark chamber he called “Albeit Almuzlim”, which has the Latin translation as the “camera obscura”; the device that forms the basis of photography.

Out of the 96 books he is recorded to have written; only 55 are known to have survived. Those related to the subject of light included: The Light of the Moon, The Light of the Stars, The Rainbow and the Halo, Spherical Burning Mirrors, Parabolic Burning Mirrors, The Burning Sphere, The Shape of the Eclipse, The Formation of Shadows, Discourse on Light, as well as his masterpiece, Book of Optics.  Latin translations of some of his works are known to have influenced important Medieval and European Renaissance thinkers like Roger Bacon, René Descartes and Christian Huygens, who knew him as “Alhazen”. The crater Alhazen on the Moon is named in his honour, as is the asteroid 59239Alhazen.

  • Born in 965 in Basra, during the intellectual heyday of Muslim civilisation.
  • Invited to Egypt to help build a dam on the Nile.  After a field visit, he declined to proceed with the project causing him to end up in what we now call -protective custody for 10 years.
  • From his observations of light entering a dark room, he made major breakthroughs in understanding light and vision.
  • His discoveries led him to make significant revision to ancient views about how our eyes see.
  • Through his studies of earlier work by Galen and others, he gave names to several parts of the eye, such as the lens, the retina and the cornea.
  • He set new standards in experimental science and completed his great Book of Optics sometime around 1027.
  • He died at the age of 74 in around the year 1040.
  • His Book of Optics was translated into Latin and had a significant influence on many scientists of the Middle Ages, Renaissance and Enlightenment.  For example, the optics book Perspectiva was authored around 1275 by Erazmus Witelo, who later was called "Alhazen's Ape" when people realised he had largely copied al-Haytham’s Book of Optics. 

What modern Scientists and Historians say about Ibn al-Haytham

The late Abdelhamid Sabra, Professor Emeritus of the History of Arabic Science, Harvard University, and an authority on Ibn al-Haytham, said the following about Ibn al-Haytham in The Harvard Magazine, September-October 2003:

Relatively late in his life, apparently stimulated by controversies with contemporaries about truth and authority and the role of criticism in scientific research, Ibn al-Haytham articulated some remarkably sophisticated statements on the practice of science and the growth of scientific knowledge. In a critical treatise, Aporias (doubts) against Ptolemy, he asserts that "Truth is sought for itself"—but "the truths," he warns, "are immersed in uncertainties" and the scientific authorities (such as Ptolemy, whom he greatly respected) are "not immune from error…." Nor, he said, is human nature itself: "Therefore, the seekerafter the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and deficiency. Thus the duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.

In an article entitled “A Polymath in the 10th Century”, Professor Roshdi Rashed, an authority on Ibn al-Haytham, concludes that:

Ibn al-Haytham, therefore, started not only the traditional theme of optical research but also others, new ones, to cover finally the following areas: optics, meteorological optics, catoptrics, burning mirrors, dioptrics, the burning sphere and physical optics

Speaking to 1001 Inventions, Professor George Saliba of Columbia University, New York City, USA 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.

George Saliba has been a Professor of Arabic Science at the Department of Middle East and Asian Languages and Cultures, Columbia University, New York, United States, since 1979. For some Saliba’s lectures see:  http://www.1001inventions.com/media/video/salibalectures
In the Encyclopedia Britannica, Professor Richard Lorch comments on Ibn al-Haytham’s work:

The work (The Book of Optics) contains a complete formulation of the laws of reflection and a detailed investigation of refraction, including experiments involving angles of incidence and deviation. Refraction is correctly explained by light’s moving slower in denser mediums. The work also contains “Alhazen’s problem”—to determine the point of reflection from a plane or curved surface, given the centre of the eye and the observed point—which is stated and solved by means of conic sections. Other optical works include Ḍawʾ al-qamar (‘On the Light of the Moon’), al-Hāla wa-qaws quzaḥ (‘On the Halo and the Rainbow’), Ṣūrat al-kusūf (‘On the Shape of the Eclipse’; which includes a discussion of the camera obscura), and al-Ḍawʾ (‘A Discourse on Light’).

Speaking to 1001 Inventions, Mohamed El-Gomati, OBE, Professor of Electron Optics and Nanotechnology at the University of York, UK says:

Ibn al-Haytham's contribution to the field of optics is nothing short of immense. And there are several good reasons for this: his contribution in developing a model which describes the mechanism of vision; his identification of the occurrence of spherical aberration in optical lenses - a difficulty which continues to confound designers of the most complex modern electron and ionmicroscopes today as well as in telescope mirrors; and last but not least and perhaps his most significant contribution, is his early systematic use of the scientific method of enquiry which secures his place in history as one of the great scientists in human history.

Speaking to 1001 Inventions, Professor Mark A Smith of the University of Missouri, USA said about Ibn al-Haytham:

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.

The renowned historian of science, the late George Sarton in his ‘Introduction to the History of Science, p721, Krieger, 31 Dec 1975’ remarked on Ibn al-Haytham:

The greatest Muslim physicist and one of the greatest students of optics of all times.

Speaking to 1001 Inventions, Historian of Science Professor Glen M. Cooper of Claremont McKenna College, Claremont, said about Ibn al-Haytham:

Ibn al-Haytham was one of the truly great men of science. 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. His famous critique of Ptolemaic astronomy led to a fruitful tradition in theoretical astronomy. However, it was through his research in optics that he made an even greater impact. Ibn al-Haytham and his followers in the West laid the groundwork for the Renaissance rediscovery of linear perspective and its inestimably important consequences, namely, the mathematicization of space on the one hand, and the exaltation of the observer, on the other, without which the Scientific Revolution might not have been possible.

In his book Theories of Vision (University of Chicago Press, 1976) noted science historian David C. Lindberg wrote:

Alhazen was undoubtedly the most significant figure in the history of optics between antiquity and the seventeenth century.

Speaking to 1001 Inventions, on Ibn al-Haytham's Contributions to Optics, Art, and Visual Literacy, Professor Charles Falco of Optical Sciences at the University of Arizona, an expert on the optics of Ibn al-Haytham said:

Visual literacy is not limited to the narrative and symbolic qualities of pictures and images, but it is also rooted in the scientific and cultural study of optics and the visual system... [T]he genesis of this concept can be traced to the work of the 11th century Arab polymath, Ibn al-Haytham...

Of the many sources describing Ibn al-Haytham as the father of modern Optics, the UNESCO in Impact of Science on Society - Volumes 26-27 – (1976) Page 140, 1st Edition 1950 said:

One name stands out as that of a rare genius in physical research: Abu 'Ali Al-Hasan Ibn Al-Haytham (965-1039) of Basrah (Iraq), without question the father of modern optics.