Islamic Thinkers In Physics
Al-Biruni
Al-Biruni was an influential researcher in many fields, raging from physics and astronomy, to geodesy and geography, and he is often considered the father of comparative religion. His work on the density of metals was useful to the metallurgic industry, his work in astronomy would provide key backing for a move away from Aristotle, and his division of hours sexagesimally, into minutes and seconds, is a revolutionary step in time measurement.
Biography
Abu Arrayhan Muhammad ibn Ahmad al-Biruni was born in Kath, Khwarazm in 973CE. He was educated in a multitude of topics from a very young age, studying under Abu Nasr Mansur, a prince and scholar. He faced much hardship in his life, due to the unstable politics of the region. With invasions from the north and collapses throughout Persia, he spent portions of his life in poverty due to a lack of patronage. He would, however, go on to do much work in astronomy, working out latitudes based on the position of the sun in the sky. He would collaborate with many other key figures, including Ibn Sina (Avicenna) and his mentor Abu Nasr Mansur, and developed the field of mechanics in his work on shadows when he discussed the connections between acceleration and non uniform motion. He died around the year 1050CE, and much of his work was forgotten until the British arrived in the region around the 17th century, who used his work for astronomical measurements.
The Earth's Circumference
Contrary to popular belief, humans have known that the earth was round for a very long time. In fact, dating back to the Greeks of the late centuries BCE, beginning with a man named Eratosthenes. He had used two poles in two cities a known distance apart, and had measured the shadows of each at noon, to calculate the angle of the suns rays and how they vary, thus using the angle geometry to calculate the total circumference of the earth. This method was valid, but filled with mildly incorrect assumptions, such as the location of each city in relation to each other, and as such was not a perfect estimate.
Al Biruni, having studied this method, used a new one. He used a mountain in modern day Pakistan that overlooked a body of water. He walked a known distance, and measured the angle between the top of the mountain and the point at which he stood. He then used trigonometric ratios (sin, cos, tan) to calculate the height of the mountain. He then calculated the angle between the top of the mountain and the horizon, and used this to calculate the radius, and thus circumference, of the earth.
whilst his method had flaws, like slight measurement inaccuracies, and not accounting for atmospheric refraction, his value of 3928.77 miles is just 2% higher than the real value in use today, a very impressive feat for the time.
This diagram shows in brief the method used by al-Biruni.
My Introduction to astrophysics at university was an introduction to the history of these kinds of measurements, including work on Eratosthenes. Despite the improvement of the measurement, we never once covered al-Biruni's method, nor any astronomy outside of Greek, and then European, tradition. This, to me, is unreasonable, as it shows a clear lack of variety in the curricula, despite valid and relevant science.
Other works
Al-Biruni, unlike some of the other people on this website, would have less of an active impact than his peers, as much of his work in physics was data based. This included making large amounts of measurements about eclipses, which would later be used by Dunthorne, a Cambridge astronomer, to calculate the acceleration of the moon, as well as calculating and recording the latitudes of many different cities, mainly in Persia.
his wide areas of interest, wider than many of his contemporaries, gave al-Biruni a greater pool of knowledge to work from, and as such, he made advancements in other fields that would have long lasting consequences. The most notable of these is that he is the first person to divide time into minutes and seconds sexagesimally (in 60ths) when discussing the Hebrew calendar. The second is, of course, the standard unit of time in physics, and has much larger consequences for the world as a whole. His wide interests also stretched to India, and he is considered the founder of Indology as an area of study, and this would give him greater access to their knowledge. For example, the Taḥqīq mā li-l-Hind is a large translation of the Indian astronomer Aryabhata, and includes commentary.
Another key work of his was the Al-Qānūn al-Masʿūdi, a large work based on the astronomy of Ptolemy. He corrects Ptolemy in some ways, such as suggesting that the suns apogee is not fixed, and explores techniques to give much higher precision when taking astronomical data.
It seems that, like many of his Islamic predecessors, peers and contemporaries, al-Biruni's work has been clearly left out of the curriculum, even in cases where the history of science is discussed, such as at my university. This is not in any way due to his lack of relevance, as his data with regards to astronomy and geodesy is still quite valuable in teaching data collection, as well as teaching the evolution of science. So why is it that all of these figures are left out of the curriculum.