Watching the daily news stories of never-ending troubles, hardship, misery and violence across the Arab world and central Asia, it is not surprising that many in the west view the culture of these countries as backward, and their religion as at best conservative and often as violent and extremist.

I am on a mission to dismiss a crude and inaccurate historical hegemony and present the positive face of Islam. It has never been more timely or more resonant to explore the extent to which western cultural and scientific thought is indebted to the work, a thousand years ago, of Arab and Muslim thinkers.

What is remarkable, for instance, is that for over 700 years the international language of science was Arabic (which is why I describe it as "Arabic science"). More surprising, maybe, is the fact that one of the most fertile periods of scholarship and scientific progress in history would not have taken place without the spread of Islam across the Middle East, Persia, north Africa and Spain. I have no religious or political axe to grind. As the son of a Protestant Christian mother and a Shia Muslim father, I have nevertheless ended up without a religious bone in my body. However, having spent a happy and comfortable childhood in Iraq in the 60s and 70s, I confess to strong nostalgic motives for my fascination in the history of Arabic science.

If there is anything I truly believe, it is that progress through reason and rationality is a good thing - knowledge and enlightenment are always better than ignorance. I proudly share my worldview with one of the greatest rulers the Islamic world has ever seen: the ninth-century Abbasid caliph of Baghdad, Abu Ja'far Abdullah al-Ma'mun. Many in the west will know something of Ma'mun's more illustrious father, Harun al-Rashid, the caliph who is a central character in so many of the stories of the Arabian Nights. But it was Ma'mun, who came to power in AD813, who was to truly launch the golden age of Arabic science. His lifelong thirst for knowledge was such an obsession that he was to create in Baghdad the greatest centre of learning the world has ever seen, known throughout history simply as Bayt al-Hikma: the House of Wisdom.

We read in most accounts of the history of science that the contribution of the ancient Greeks would not be matched until the European Renaissance and the arrival of the likes of Copernicus and Galileo in the 16th century. The 1,000-year period sandwiched between the two is dismissed as the dark ages. But the scientists and philosophers whom Ma'mun brought together, and whom he entrusted with his dreams of scholarship and wisdom, sparked a period of scientific achievement that was just as important as the Greeks or Renaissance, and we cannot simply project the European dark ages on to the rest of the world.

Of course some Islamic scholars are well known in the west. The Persian philosopher Avicenna - born in AD980 - is famous as the greatest physician of the middle ages. His Canon of Medicine was to remain the standard medical text in the Islamic world and across Europe until the 17th century, a period of more than 600 years. But Avicenna was also undoubtedly the greatest philosopher of Islam and one of the most important of all time. Avicenna's work stands as the pinnacle of medieval philosophy.

But Avicenna was not the greatest scientist in Islam. For he did not have the encyclopedic mind or make the breadth of impact across so many fields as a less famous Persian who seems to have lived in his shadow: Abu Rayhan al-Biruni. Not only did Biruni make significant breakthroughs as a brilliant philosopher, mathematician and astronomer, but he also left his mark as a theologian, encyclopedist, linguist, historian, geographer, pharmacist and physician. He is also considered to be the father of geology and anthropology. The only other figure in history whose legacy rivals the scope of his scholarship would be Leonardo da Vinci. And yet Biruni is hardly known in the western world.

Many of the achievements of Arabic science often come as a surprise. For instance, while no one can doubt the genius of Copernicus and his heliocentric model of the solar system in heralding the age of modern astronomy, it is not commonly known that he relied on work carried out by Arab astronomers many centuries earlier. Many of his diagrams and calculations were taken from manuscripts of the 14th-century Syrian astronomer Ibn al-Shatir. Why is he never mentioned in our textbooks? Likewise, we are taught that English physician William Harvey was the first to correctly describe blood circulation in 1616. He was not. The first to give the correct description was the 13th-century Andalucian physician Ibn al-Nafees.

And we are reliably informed at school that Newton is the undisputed father of modern optics. School science books abound with his famous experiments with lenses and prisms, his study of the nature of light and its reflection, and the refraction and decomposition of light into the colours of the rainbow. But Newton stood on the shoulders of a giant who lived 700 years earlier. For without doubt one of the greatest of the Abbasid scientists was the Iraqi Ibn al-Haytham (born in AD965), who is regarded as the world's first physicist and as the father of the modern scientific method - long before Renaissance scholars such as Bacon and Descartes.

But what surprises many even more is that a ninth-century Iraqi zoologist by the name of al-Jahith developed a rudimentary theory of natural selection a thousand years before Darwin. In his Book of Animals, Jahith speculates on how environmental factors can affect the characteristics of species, forcing them to adapt and then pass on those new traits to future generations.

Clearly, the scientific revolution of the Abbasids would not have taken place if not for Islam - in contrast to the spread of Christianity over the preceding centuries, which had nothing like the same effect in stimulating and encouraging original scientific thinking. The brand of Islam between the beginning of the ninth and the end of the 11th century was one that promoted a spirit of free thinking, tolerance and rationalism. The comfortable compatibility between science and religion in medieval Baghdad contrasts starkly with the contradictions and conflict between rational science and many religious faiths in the world today.

The golden age of Arabic science slowed down after the 11th century. Many have speculated on the reason for this. Some blame the Mongols' destruction of Baghdad in 1258, others the change in attitude in Islamic theology towards science, and the lasting damage inflicted by religious conservatism upon the spirit of intellectual inquiry. But the real reason was simply the gradual fragmentation of the Abbasid empire and the indifference shown by weaker rulers towards science.

Why should this matter today? I would argue that, at a time of increased cultural and religious tensions , misunderstandings and intolerance, the west needs to see the Islamic world through new eyes. And, possibly more important, the Islamic world needs to see itself through new eyes and take pride in its rich and impressive heritage.

· Jim Al-Khalili is a professor of physics at the University of Surrey; he is the 2007 recipient of the Royal Society's Michael Faraday Prize and delivers the Faraday lecture at the Royal Society in London tonight



j.al-khalili@surrey.ac.uk