Science & Islam (Full) | by Jim Al-Khalili | BBC Documentary (EN)

Summary

The documentary follows physicist and presenter Jim Al-Khalili through the history of science in the medieval Islamic world. Across three connected parts, it argues that scholars working in Islamic-ruled societies helped preserve and combine knowledge from many cultures, made important advances in mathematics, medicine, chemistry, and astronomy, and developed practices central to modern science. Its broader message is that science is a shared human enterprise, not the possession of one religion or civilization.

1. Baghdad, translation, and the growth of learning

• Baghdad became a major centre of scholarship. Founded as the Abbasid capital, it stood at the heart of a large, diverse empire connected to regions including Persia, India, North Africa, and Spain. Rulers supported learning for practical reasons—administration, medicine, engineering, and military affairs—as well as for religious and political reasons.
• Arabic provided a common language for scholarship. The documentary describes the decision to use Arabic across the empire as a way to make administration more consistent. It also enabled scholars from different regions to communicate, debate, and share technical ideas.
• The translation movement gathered and translated texts from Greek, Syriac, Persian, Sanskrit, and other traditions. The documentary emphasizes both the scale of this work and the importance of preserving knowledge that might otherwise have been lost. Patronage, including substantial rewards for translators, helped attract scholars and manuscripts.
• Knowledge was adapted, not merely copied. A central example is mathematics. The scholar al-Khwarizmi helped introduce the Indian place-value numeral system to a wider audience, including the use of zero. The documentary explains that this system made calculation far more practical than Roman numerals. It also describes the development of decimal fractions and the creation of algebra as a general method for solving problems.
• The word “algorithm” is linked to the Latinized form of al-Khwarizmi’s name. As presented in the programme, algebra’s power lies in manipulating general quantities and following reusable rules rather than solving every numerical problem from scratch.

2. Medicine: collecting knowledge and caring for patients

• Medieval Islamic medicine drew on Greek, Indian, Chinese, and local healing traditions, as well as religiously informed medical writings. The documentary discusses the Greek physician Galen’s theory of the four humors—blood, yellow bile, black bile, and phlegm—and the treatments that followed from it. It notes that many of these ideas are now known to be mistaken.
• The Canon of Medicine by Ibn Sina (Avicenna) is presented as a landmark because it gathered and organized medical knowledge from many sources into an accessible reference work. It remained influential for centuries, though its medical explanations were eventually superseded, especially as knowledge of microbes transformed medicine.
• The programme stresses that Islamic medicine’s importance lay not only in particular remedies but also in its institutions and ethos of care. Hospitals treated people from different religious communities, and physicians and patients could come from different faiths. Hospitals also incorporated pharmacies and organized medical practice.
• The documentary describes developments in eye care, including couching, an older operation for cataracts. Physicians understood that the lens lay behind the pupil and attempted to move the cloudy lens out of the visual path. The procedure could improve the entry of light, although it did not restore the eye’s ability to focus as a modern replacement lens would.

3. Measurement, mathematics, and the scientific method

The second part presents the rise of scientific practice as a combination of mathematical reasoning, careful measurement, and experimentation.

Measuring the Earth

The documentary describes two approaches:

• An earlier method, used by scholars under Caliph al-Ma’mun, compared the Sun’s angle at two locations and measured the distance between them. It produced a reasonable estimate, but determining the distance by counting paces across difficult terrain made the method unreliable.
• Al-Biruni’s mountain method offered a more precise approach. The programme outlines it as follows:
  1. Choose a mountain with a visible, level horizon, such as the sea.
  2. Measure the mountain’s height indirectly from two points at sea level, a known distance apart, using the angles from each point to the summit.
  3. Use trigonometry to calculate the mountain’s height.
  4. From the summit, measure the angle between the horizontal and the line of sight to the horizon.
  5. Treat the summit, horizon, and Earth’s centre as a large right-angled triangle.
  6. Use the measured height and angle to calculate the Earth’s radius and circumference.

Al-Biruni’s result, as presented in the documentary, was within about one percent of the modern value. The example illustrates how mathematical models can extend what can be learned from direct observation.

Alchemy, chemistry, and classification

• The documentary traces how practical demands from trade and craft industries helped turn alchemy toward experimental chemistry. Metalworking, currency production, glassmaking, soapmaking, perfumery, and weaponry all required reliable knowledge of materials and processes.
• It describes the use of alkalis in soapmaking, chemical additives to alter glass colours, and distillation to extract fragrances. The account emphasizes careful procedures and the use of equipment to control and reproduce results.
• Al-Razi’s classification of substances is presented as an important step toward chemistry. Instead of grouping materials solely through philosophical ideas, he classified them according to observed properties and behaviour—for example, flammability, malleability, or solubility. The documentary treats this as an early move toward systematic experimental classification.

Ibn al-Haytham and optics

• Ibn al-Haytham is presented as a key figure in the development of a scientific method that joined mathematical explanations to tests of the physical world. He challenged explanations of vision that he considered unsatisfactory and argued that light travels into the eye rather than being emitted from it.
• The programme describes his approach as a repeatable process:
  1. Start with a clear question about a physical phenomenon.
  2. Formulate a mathematical or geometrical explanation.
  3. Design an experiment to test a specific part of that explanation.
  4. Record the procedure in enough detail that others can repeat it.
  5. Compare the results with the theory and revise or extend the explanation.
• To test whether light travels in straight lines, Ibn al-Haytham used a straight tube to view a candle, then blocked the tube to check that light could not reach the eye by another route.
• He also used a dark enclosure with a small opening—now known as a camera obscura—to study how an image forms. The inverted image helped demonstrate how rays from different points on an object produce corresponding points in the image.
• The programme further describes his use of observations of twilight to estimate the thickness of the atmosphere. Its central lesson is that mathematics and experiment work together: mathematics gives a theory structure, while experiments test whether that structure describes reality.

4. Astronomy, doubt, and the transmission of ideas

• Astronomy was important for practical and religious reasons. Muslims needed to determine prayer times and the direction of Mecca. The documentary shows how sundials and other instruments helped make timekeeping and observation more precise.
• Al-Battani’s long-term observations are highlighted for their accuracy. Using instruments such as an armillary sphere and astrolabe, he measured the length of the year and other astronomical quantities. The documentary presents his data as a source later used by Copernicus.
• Islamic astronomers also examined the dominant Ptolemaic geocentric model, in which the Sun, planets, and stars revolve around Earth. Ptolemy’s system used devices such as epicycles and deferents to explain irregular planetary motions. The documentary argues that increasingly precise observations exposed tensions between the model’s mathematical machinery and its claim that the heavens revolved around Earth.
• The Arabic term shakk, meaning “doubt,” is presented as a valuable scientific attitude: inherited ideas should be questioned when evidence or reasoning fails to support them. Ibn al-Haytham criticized contradictions in Ptolemy’s model and challenged later astronomers to create an account that was both mathematically consistent and compatible with observation.
• Nasir al-Din al-Tusi and the Maragha Observatory are presented as central to the next stage. The “Tusi couple,” a geometric device involving two rotating circles, offered a way to address a problem in Ptolemy’s system. At Maragha, scholars used improved instruments, large observational programmes, and mathematical models to refine astronomy.
• The documentary argues that Copernicus’s work did not arise in isolation. It points to his use of earlier Islamic observations and mathematical ideas, including diagrams and methods associated with al-Tusi and Ibn al-Shatir. In this account, Copernicus was part of a long chain of scholarship linking the Islamic world and Europe.

5. How knowledge moved west—and why scientific leadership shifted

• Trade, travel, and translation helped transmit scientific and technical knowledge between the Islamic world and Europe. The programme describes Arabic works on algebra, astronomy, and medicine being translated into Latin and circulated in Europe.
• Venice serves as an example of the close, complicated connections between European and Muslim societies through trade. The documentary also discusses an early printed edition of the Qur’an produced in Venice. It argues that printing did not spread as quickly in Arabic-speaking societies because Arabic script posed technical challenges for movable type and the edition contained errors that made it unacceptable to many Muslim readers.
• The programme attributes the later decline of scientific activity in parts of the Islamic world to several interacting forces, rather than a single cause: political fragmentation, wars and invasions, the Mongol destruction of Baghdad, the Christian reconquest of Islamic Spain, the loss of trade and wealth, and the movement of economic power toward European Atlantic empires.
• It also argues that colonial-era accounts often portrayed Islamic societies as having once been advanced but then fallen into decline, helping obscure their continuing historical contributions.
• The documentary ends by noting that scientific research continues in Muslim-majority societies, including contemporary biomedical research in Iran. It returns to its central lesson: scientific findings and methods are not limited by national or religious boundaries. Nature’s laws apply universally, and knowledge can be learned from any source.

Speakers and sources featured

Presenter

• Jim Al-Khalili — physicist, presenter, and narrator.

Named interviewees and contributors

• Dr Peter Pormann — expert on Islamic medicine.
• Naif Scaf — calligrapher.
• Dr Okasha al-Daly — scholar of Egyptian history and hieroglyphs.
• Professor Ian Stewart — mathematician.
• Mr Vic Shah — eye surgeon.
• Dr Nader/Nardo al-Bizri — scholar of Islamic philosophy and science; the subtitles render his name inconsistently.
• Professor Sami Ubi/Chalbi — expert on early Islamic science; the subtitles render his name inconsistently.
• Dr Andrea Sella — chemist.
• Dr Rima Turkmani — astrophysicist and medieval astronomy expert.
• Dr Luisa Piotti — astronomer.
• Vera Costantini — Venice historian.
• Professor Angela Nuovo — scholar who discusses the early printed Qur’an.
• Unnamed researchers and staff at the Royan Institute in Tehran, including a scientific researcher and an Imam involved in medical ethics discussions.

Historical figures and texts used as sources

• Al-Khwarizmi — arithmetic, algebra, and methods associated with algorithms.
• Al-Uqlidisi — decimal fractions, as identified in the documentary.
• Fibonacci (Leonardo of Pisa) and Liber Abaci.
• Galen and the theory of the four humors.
• Ibn Sina (Avicenna) and the Canon of Medicine.
• Ibn Wahshiyya — work on Egyptian hieroglyphs, as discussed in the programme.
• Al-Razi — medical and chemical writings, including classification of substances.
• Al-Biruni — writings on measuring the Earth and astronomical observations.
• Ibn al-Haytham — the Book of Optics.
• Ptolemy and the Almagest.
• Al-Battani — astronomical tables and observations.
• Nasir al-Din al-Tusi — the Tusi couple and Maragha astronomy.
• Ibn al-Shatir — astronomical models discussed in relation to Copernicus.
• Nicolaus Copernicus and De revolutionibus orbium coelestium.
• Al-Kindi — quoted on accepting truth from any source.
• The Qur’an, the Hadith, and The Prophet’s Medicine are also discussed as religious and medical sources.