# Abu Rayhan ibn al-Biruni

May 15, 2008 by TMO

**Muslim Scientists and Thinkers**

**By Syed Aslam**

Abu Rayhan al-Biruni was born in Kath, Uzbekistan in 973 CE a region adjoining the Aral Sea. He began his studies at a very young age under the famous mathematician Abu Nasr Mansur. In 1017 Sultan Mahmud Ghazni extend his kingdom to Kath area and he took al Biruni with him to his capital. Later on Mahmud ventured into the northern part of India and al Biruni went with him to India. He lived there for thirteen years where he managed to learn Sanskrit from the pundits and translated several Sanskrit texts into Arabic. He also wrote several treatises devoted to Indian astronomy, mathematics, medicine, philosophy and religion. Mahmud died in 1030 CE and he was succeeded by his son Masud who treated al-Biruni with great respect, now al-Biruni was free to travel any where he wanted. He moved back to Ghazni, Afghanistan and died in the year 1048 CE at the age of 75 after spending 40 years gathering and adding knowledge.

Al-Biruni was one of the greatest geniuses ever born; he was a physicist, an anthropologist, an astronomer, a historian, a geographer, a geodesist, a geologist, a mathematician, a physician, a philosopher a scholar and a traveller, who contributed greatly to all of these fields. Along with Geber and al-Haytham, al-Biruni was one of the earliest leading exponents of the experimental scientific method. He was responsible for introducing the experimental method into mechanics, and astronomy.

Al-Biruni mathematical contributions were immense which include: theoretical and practical arithmetic, summation of series, combinatorial analysis, the rule of three, irrational numbers, ratio theory and method of solving algebraic equations. He also did original work on Archimedesâ€™ theorems, trisection of the angle, conic sections, stereographic projection, trigonometry, the sine theorem and spherical triangles.

Al-Biruni is regarded as the father of geodesy and made numerous contribution to earth science, cartography, geography and geology. He introduced techniques to measure the distances on earth using triangulation. He solved complex geodesic equation and accurately calculated the circumference of the earth which is very close to the present value. His calculated value of earthâ€™s radius is 6339 km, which differs from the modern value by 16 km. This value was not obtained by the Europeans until the middle of 16th century. While he was very young he accurately calculated the latitude of various places. After studying soil of India he came to conclusion that Indus valley must be considered as ancient sea basin filled with alluvial soil.

Al-Biruni was the first to conduct experiment related to astronomy, though most people would think that it was Galileo or Copernicus. At a time when people believed in the geocentric theory (earth as the center of the universe) he clearly knew, 600 years before Galileo, that earth rotates on its axis on daily basis and moves yearly around the sun. He argued that heliocentric model of the earth fits very well with his astronomical parameters. He made a scientific explanation of why the sun never sets in the north or south pole at certain months of year. His famous diagram showing different phases of moon clearly indicates the moon revolving around earth and the earth revolving around the sun. Al-Biruni invented a Three Point Observation method which was used by Copernicus to calculate the eccentricity of earthâ€™s orbit around the sun. He discussed about the gravity of the earth by saying that every thing attracts toward the center of the earth which we now know is true.

Al-Biruni started experimental methods in mechanics, specially in the determination of the specific weights. He was the first to realize that acceleration is connected to non-uniform motion. Al-Biruni gave the precise method to determine the specific gravity of a substance which is still in use to this day. He accurately determined the specific gravity of eighteen gemstones. Discovered the finite nature of matter, and gave the idea that it may change forms but the total mass remained the same. This law of conservation of mass was rediscovered by Lavoisier seven century later. Al-Biruni was the first to discover that the speed of light is finite and that it is far greater than the speed of sound. He was a pioneer in experimental psychology as he was the first to describe the concept of reaction time.

At the age of 27 al-Biruni wrote many books which include one book on decimal system, two books on history, one on astrolabe and four about astrology. As he matured he authored many books and treaties: Kitab al-Hind gives a graphic account of the historical and social condition of India. His famous book Oanun al-Masudi discusses several theories of astronomy, trigonometry, solar, lunar, planetary motions and relative topics. In another well-known book al-Athar al-Baqia, he has discussed the rotation of the earth and has given correct values of latitudes and longitudes of various places. He also wrote the Kitab-al-Saidana, which is an extensive medical encyclopedia that combines the then existing Arabic knowledge on medicine with the Indian medicine. His book the Kitab-al-Jamahir delt with the properties of various precious stones.

Al-Biruni was contemporary to ibn Sina and they knew each other. He later engaged in a written debate with ibn Sina regarding Aristotelian natural philosophy and Peripatetic school of thought. He discussed with him eighteen questions about the natural philosophy in which ten were criticisms of Aristotleâ€™s reasons for denying the existence of gravity in the celestial spheres, innate property of the heavenly bodies etc. The other eight questions were on different topics on science. This is regarded as the highly intellectual discourse between the two intellectual giants of the middle ages. In linguistics he could read and write at least five different languages: namely; Persian, Arabic, Greek, Hebrew, and Sanskrit and could understand Syriac, Hindi and Latin. It is impossible to highlight all the achievements of one of the greatest universal scientist of all times in this limited space.

*Aslamsyed1@yahoo.com *

10-21

01.19.2011

I enjoyed reading this article re my country-man abu rayhan biruni. I would greatly appreciate if some-one could guide me to the exact text in which abu rayhan talks about reaction time and its measurement. thank you very much. id