The Islamic mathematician whose work defied the Greeks to prove that light travels in a straight line

Ibn Al Haytham inspired generations of European philosophers, physicists and astronomers - but his road to recognition was a rocky one

The Royal Astronomical Society library in London, a window into the world of Ibn Al Haytham. Photo: Royal Astronomical Society

A set of rare books at a London library shows the impact that one Islamic mathematician had on western physics and astronomy – yet its author has always been more widely read in Europe than in the Middle East.

The Book of Optics by Ibn Al Haytham, written almost 1,000 years ago, argued that light travels in straight lines and that other objects reflect light into the human eye, which allows us to see them.

His conclusions would defy major Greek philosophers but remain fundamental to modern physics, and his methods of experimentation with a camera obscura would inspire generations of European philosophers, physicists and astronomers.

Modern physics

“Ibn al-Haytham is one of most important scientists in the Islamicate world. He was purely focused on the exact sciences and the scientific experimental method. He did not mingle science as such with the cultural dimensions” said Prof Nader El-Bizri, a senior research fellow at the Warburg Institute in London.

Other physicists and philosophers of the era, including Ibn Sinna, known as Avicenna in Latin, and Ibn Rushd, known in Latin at Averroes, often combined their work with readings of the Quran, the Hadith and other literature, Prof El-Bizri told The National.

“Ibn Sinna linked his science of medicine to metaphysics, Ibn Rushd was a faqih (an Islamic jurist) besides being a notable philosopher, but Ibn Al Haitham goes straight to the matter,” Prof El-Bizri said.

The architect and mathematician, who is known as Alhazen in Latin, was born in Basra, and was a vizier in the court of the Buyid Emirate, which stretched from Baghdad to Shiraz at its height.

It is believed he wrote the Book of Optics independently while under house arrest in Egypt, where he had been commissioned by Caliph Al Hakim to build a structure that would regulate flooding of the Nile.

That commission ultimately failed, and Ibn Al Haitham is famously said to have feigned madness while detained in his home to escape the Caliph’s wrath.

Engraving from the title page of Opticae Thesaurus, a latin edition of Ibn al-Haytham's Book of Optics. Among other things it shows how Archimedes allegedly set Roman ships on fire with parabolic mirrors during the Siege of Syracuse. Photo: Wikimedia Commons

Influence in Europe

A Latin translation of the book at the Royal Astronomical Society’s rare books archive in London is a sign of the interest that Renaissance physicists and astronomers took in Ibn Al Haytham’s theories.

It dates back to 1572, the first time that the book was printed, over 100 years after the printing revolution.

Inside the book, an illustration added by the publisher shows a landscape with seven optical illusions: a rainbow, magnified sunlight that sets fire to a ship, and the narrowing width of a bridge at its furthest point.

It shows the legacy that the Book of Optics was credited to have had back then.

His experiments passing light through a glass jar filled with water would inspire Theodoric of Freiburg in the 12th century and French Enlightenment Philosopher Rene Descartes who developed influential theories of the rainbow.

Frontispiece for Johannes Hevelius' Selenographia, a copy of which is held at the Royal Astronomical Society in London. Photo: Wikimedia Commons

Another book in the library – the first comprehensive map of the moon by Dutch astronomer Johannes Hevelius, also credits Ibn Al Haitham.

The frontispiece of Selenographia,sive Lunae descriptio, published in 1647, includes a large drawing of two physicists standing on a pedestal: Ibn Al Haitham and Galileo, the first scientist to observe and draw the moon through a telescope.

The library contains other major works from Islamic mathematicians, such as Abu Ma’shar’ Introduction to Astrology and Al-Qabisi’s Introduction to the Art and Judgement of the Stars.

Although their works were widely circulated in medieval Europe, they were mainly about astrology, which is no longer considered a science.

Dr Sian Prosser, the Society's Head of Libraries, says it is Ibn Al Haitham’s book that remains the most popular among researchers looking at Islamic astronomy today, and it is regularly consulted by fellows of the RAS.

Another popular text from the Islamic age is Ulugh Beg's astronomical tables and star catalogue, translated into Latin and published in London in 1665.

The sultan and astronomer Ulugh Begh, who is the grandson of Mongol conqueror Tamerlane, mapped 1018 stars, many of which were corrections of a similar project by the Greek astronomer Ptolemy.

Members of the public are able to visit the RAS' library to consult the books, by contacting the archival team.

Ibn al-Haytham's theory of vision in the science of optics also influenced Italian Renaissance painters and architects, who pioneered the use of perspective in their drawings and designs.

Among them was the Florentine Lorenzo Ghiberti, who is known for his bronze 'Gates of Paradise' doors of the Florence Baptistery, according to Prof Al Bizri.

The cover page of Book of Optics, 1572. Photo: Wikimedia Commons

Fragile legacy

Despite Ibn Al Haytham’s contributions to western sciences, he was at times overlooked in the Islamic and modern Arab world.

The surviving Arabic manuscripts are incomplete, with large technical fragments missing. His work is also rarely taught in Arabic schools and universities.

Prof El-Bizri is working on editing the unprinted parts of The Book of Optics, based on old Arabic manuscripts, and translating these to English.

But he is also involved in efforts to translate the missing Arabic fragments from the Latin. “The incompleteness of the publication of the Arabic text was a sign of a civilisational gap and neglect that needs to be properly addressed and rectified", he said.

That is not to say that Ibn Al Haitham was ignored entirely. In the Islamic world, Persian scientist Kamal Al Din Farisi, from the Maragh School in Khorasan, wrote a commentary on the Book of Optics in the 12th century.

Ibn Al Haitham also influenced 16th century astronomy and optics of the Ottoman court, namely the Syrian Taqiuddine Ibn Maarouf, Prof El-Bizri explained.

Prof Nader El-Bizri, Senior Research Fellow at the Warburg Institute. Photo: The Warburg Institute.

Prof El-Bizri gave a series of lectures in Kuwait earlier this year about the polymath and his impact on European sciences and arts. There have also been regular celebrations of Ibn Al Haitham in recent years in the UAE and the Gulf.

Historians of science and religion often attribute this neglect to historic clashes between the findings of scientists and the dictates of religious institutions and scripture.

But Prof Nathan Sidoli, a historian of science at Waseda University, believes some of the gaps could also be due to western “selection bias” – whereby Islamic scholars of Ibn Al Haytham were also overlooked.

“Al-Haytham is highly regarded in Arabic, Persian and Hebrew medieval sources, but many of these have not even been edited, let alone discussed in more popular works,” he said.

“Whereas western medievalists have been studying the scholars who read al-Haytham in Latin for more than 100 years, it is only in the last few generations that there has been serious scholarship on the medieval Islamic scholars who read and studied Ibn al-Haytham,” he added.