Islam, Scientific Method and Heritage (02:35)

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The scientific method, the revolutionary idea that the world operates according to rules that humans can work out, was born in the medieval Islamic world. This is of personal interest to the Iraqi-born scientist narrating.

Islamic Empire (02:50)

Science flourished under the Islamic Empire 1000 years ago, as in most wealthy cultures. We visit the ruins of a once-great city in Iran, one of many in the vast Empire, and a stadium named for a ruling family.

Funding Quest for Knowledge (01:28)

The Empire's size allowed it to raise tax revenues to send scholars around the world to translate books into Arab. Science was crucial to governing the Empire.

Islamic Architectural Achievements (01:19)

The Islamic Empire's legacy includes great mosque architecture and ruins of palaces.

Measurement and the Nile (02:51)

Egypt's Muslim rulers built a device to measure the height of the Nile, whose floods had long determined the country's fate. It is not obvious that measurement can make sense of the world, which can appear chaotic.

Maps and the Religious Motivation for Science (02:29)

A ninth century Islamic ruler commissioned a map of the known world, a vast improvement on previous maps, and sought to measure earth's size. If a being like us made the world, scholars thought, we can make sense of it.

Mecca and Geographic Knowledge (01:37)

Muslims need to know the direction of Mecca- the shortest curve, not a straight line on a flat map. This required determining how steeply earth curves and, therefore, how big it is.

Measuring Earth (02:08)

To measure earth, scholars took the distance between two points and sun's angle at each. Measuring the distance between two cities required pacing, an inexact science.

Al-Biruni and Earth's Size (01:41)

By the 900s, Arabs had translated much of the world's mathematical knowledge. Al-Biruni combined algebra and geometry to create a method to calculate earth's size.

Mountain and Horizon (03:09)

Al-Biruni determined a mountain's height by measuring angles to its top from two points at sea, using a giant protractor. He then measured the angle from the peak to the line-of-sight of the horizon.

Al-Biruni's Right Triangle (01:02)

The mountaintop, horizon and earth's center are corners of a right triangle. He derived lengths from the angle of peak to horizon, subtracting mountain height to derive earth's radius, and thus its circumference.

Geometry and Science (00:59)

Al-Biruni's experiment is an early example of using abstract geometry to comprehend the real world. Einstein used the same approach to develop the General Theory of Relativity.

Craftsmen and Science (02:04)

Craftsmen thrived in the Empire as trade boomed. Their experimentation joined forces with scholars' abstract ideas to create a scientific explosion.

Caravansaries, Carrier Pigeons and Trade (02:32)

Caravansaries, still-standing resting places, went up as a result of the medieval trade boom. Traders used carrier pigeons

Industry, Currency and Alchemy (03:29)

Industrial expansion made, knowledge of material important, leading to pursuit of alchemy and eventually chemistry. The ruler who created a common currency turned to alchemists to adjust proportions in coins.

Chemistry, Alkali and Soap (01:16)

Manufacture of solid soap in the Islamic world flourished due to applied chemistry. A twelfth century document has the first detailed description of soap-making, with alkali a crucial ingredient.

Chemistry and Glass Making (01:10)

Chemists discovered that newly discovered chemicals could change the color of glass and metals.

Chemistry, Distillation and Perfumes (02:56)

Responding to perfume makers' needs, chemists refined the technique of distillation to extract more subtle fragrances from plants. A device (demonstrated) condenses a gas to distill scents.

Chemistry and Weaponry (01:19)

European records of the Crusades mention Muslim attacks using burning missiles. They used distilled petroleum. The idea of laboratories for chemical and industrial processes took hold at this time.

Islamic Chemistry and the Periodic Table (03:29)

Al-Razi overthrew the Greek theory of four elements in favor of an experiment-based classification system whose principles led to the Periodic Table of the Elements.

Mathematics, Physics and Aristotle (02:15)

Aristotle's rejection of mathematical explanations of nature dominated science until the ninth century. Physics was about change, while mathematics is unchanging.

Ibn al-Haytham (01:13)

Ibn al-Haytham, born in 965, led the way in turning mathematics from abstract thought to practical science.

Legend About Ibn al-Haytham (01:59)

Under Egyptian house arrest for failure in his assigned task to control the Nile, Ibn al-Haytham, contemplated a geometric basis for sight, which led him to create modern optics.

Aristotle, Ibn al-Haytham and Sight (02:33)

Aristotle's theory of forms flowing to our eyes was insufficiently mathematical, but alternate Greek theory that eyes emit linear light was problematic. Al-Haytham held that light travels in straight lines into the eyes.

Subjecting First Principles to Experiment (01:52)

Al-Haytham applied geometric principles to the world, then tested his theories with verifiable experiments. He established the first principle that light travels straight by blocking his view of a candle.

Al-Haytham's Explanations in Optics (02:26)

Al-Haytham explains mirrors based on ray angles and refraction based on bending rays. To explain how light makes an image, he built the "camera obscura" as a simplified eye. He pioneered the scientific method.

Atmosphere's Finite Thickness (01:18)

Al-Haytham applied his theories to generate additional knowledge. Realizing sun rays bend entering the atmosphere, he used the length of twilight to determine the atmosphere's thickness.

Greatness of Science (01:47)

Medieval Islamic scientific ambition is overwhelming. We should remember Al-Haytham above all the rest for contributions to the scientific method, the most important idea in human history.

Additional Resources & Credits: The Empire of Reason: Science and Islam--The Golden Age (01:30)

Additional Resources & Credits: The Empire of Reason: Science and Islam--The Golden Age