Contributions of Muslim Scientists to Physics

Between about the 9th and 14th centuries CE, Muslim scholars in cities such as Baghdad, Cairo, Ghazni, Maragha and Cordoba made real progress in physics. They did not just copy Greek books: they tested ideas with experiments and measurements, which is exactly how physics is done today.

1. Banu Musa brothers (9th century CE)

Field: mechanics · Worked in: Baghdad, Iraq

• Three brothers, Muhammad, Ahmad and Hasan, sons of Musa ibn Shakir.
• Their Kitab al-Hiyal (The Book of Ingenious Devices, about 850 CE) describes about 100 machines, such as fountains, valves and devices that controlled themselves automatically.

2. Al-Kindi (c. 801–873 CE)

Field: optics and sound · Worked in: Basra and Baghdad, Iraq

• Showed that light travels in straight lines, and used this to explain shadows and reflection in mirrors.
• Wrote about musical sounds and how notes are produced. His optics book was translated into Latin as De aspectibus.

3. Ibn al-Haytham (Alhazen) (c. 965–1040 CE)

Field: optics · Worked in: Basra and Cairo, Egypt

• Called the father of optics. Wrote Kitab al-Manazir (The Book of Optics) in seven volumes.
• Studied the reflection and refraction of light with careful experiments.
• Explained the pinhole camera (camera obscura): light through a small hole makes an upside-down image.
• Showed that we see because light from an object enters our eyes.
• Insisted that every idea must be tested by experiment, an early form of the scientific method.

4. Al-Biruni (973–1048 CE)

Field: physics, astronomy and geography · Born in: Khwarazm (Uzbekistan) · Worked in: Ghazni (Afghanistan) and travelled in the subcontinent

• Measured the radius of the Earth from a hill near Nandana Fort, in today's Jhelum district, Pakistan. He measured the height of the hill and how far the horizon dipped below the level when seen from the top, then used trigonometry.
• His answer, about 6,340 km, is very close to the modern average value of about 6,371 km.
• Measured the densities of 18 metals and precious stones very accurately.
• Wrote Kitab al-Hind, a detailed book about the science and culture of the subcontinent.

5. Ibn Sina (Avicenna) (980–1037 CE)

Field: motion and light · Born: near Bukhara (Uzbekistan); died: Hamadan (Iran)

• Explained that a thrown object keeps moving because of a push (mayl) given to it. Air resistance slowly uses it up. In empty space, he said, the motion would not stop.
• This was an early step towards the idea of inertia, which Newton later stated in his first law of motion.
• Argued that light travels at a finite speed, not instantly.

6. Al-Khazini (active c. 1115–1130 CE)

Field: mechanics and density · Worked in: Merv (Turkmenistan)

• Wrote Kitab Mizan al-Hikma (The Book of the Balance of Wisdom, 1121 CE).
• Built a large hydrostatic balance, which weighs objects in air and in water, to find the density of metals and to check whether gold was pure.
• Wrote that the weight of an object is a pull towards the centre of the Earth.

7. Al-Jazari (1136–1206 CE)

Field: mechanical engineering · Worked in: Diyarbakir (Turkey)

• His book, The Book of Knowledge of Ingenious Mechanical Devices (1206 CE), describes 50 machines with drawings and building instructions.
• One of his water pumps used a crank and connecting rod to change turning motion into back-and-forth motion, the same idea used in engines and pumps today.
• Famous for his elephant clock, a water clock that marked the hours.

8. Nasir al-Din al-Tusi (1201–1274 CE)

Field: astronomy · Worked in: Maragha (Iran)

• Set up the Maragha observatory, one of the best observatories of its time.
• His Tusi couple showed that two circular motions can combine to give motion in a straight line.

9. Kamal al-Din al-Farisi (c. 1267–1319 CE)

Field: optics · Worked in: Tabriz (Iran)

• Used a glass ball filled with water as a model of a raindrop.
• Explained correctly that a rainbow forms when sunlight is refracted and reflected inside raindrops. He wrote Tanqih al-Manazir, a revision of Ibn al-Haytham's optics.

A Pakistani Nobel laureate in physics

Dr Abdus Salam (1926–1996) was born in Punjab and became one of the leading physicists of the 20th century.

• In 1979 he shared the Nobel Prize in Physics with Sheldon Glashow and Steven Weinberg, for showing that the electromagnetic force and the weak nuclear force are two sides of one force (the electroweak force).
• He was the first Pakistani to win a Nobel Prize in science.
• In 1964 he founded the International Centre for Theoretical Physics (ICTP) in Trieste, Italy, to help scientists from developing countries.

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