Physics in medieval Islam
Physics in medieval Islam began with understanding metaphysics and physics of the Greeks during the expansion of the Islamic empire and slowly developed into the many fields associated with modern physics. It is a sub field of Islam and Science Many of the figures associated with physics in the Golden Age of Islam, between 750-1258 A.D., were familiar with the Greek thinkers and the Near East thinkers that followed these Greek thinkers, such as Aristotle, Ptolemy, Euclid, Neoplatonism, among others.1 During this period, Islam was encouraging thinkers to find knowledge because the spirit of science did not come into contradiction with the religious aspect of their lives.2 Many thinkers from this period, such as Al-Farabi, Abu Bishr Matta, Ibn Sina, al-Hassan Ibn al-Haytham and Ibn Bajjah, had written their own books on metaphysics or written interpretations of Aristotle's Metaphysics.3 These works and the important commentaries on them were the wellspring of science during the Medieval period. They were translated into Arabic, the lingua franca of this period. Islamic scholarship had inherited Aristotelian physics from the Greeks and during the Islamic Golden Age developed it further. However the Islamic world had a greater respect for knowledge gained from empirical observation, and believed that the universe is governed by a single set of laws. Unlike the Greeks who did not trust their senses and would develop knowledge through reason, and believed that different sets of laws could exist. Their use of empirical observation led to the formation of crude forms of the scientific method.4 The study of physics in the Islamic world started in Iraq and Egypt.5 Fields of physics studied in this period include optics, mechanics (including statics, dynamics, kinematics and motion), and astronomy.
Islamic scholarship had inherited Aristotelian physics from the Greeks and during the Islamic Golden Age developed it further, especially placing emphasis on observation and a priori reasoning, developing early forms of the scientific method. With Aristotelian physics, physics was seen as lower than demonstrative mathematical sciences, but in terms of a larger theory of knowledge, physics was higher than astronomy; many of whose principles derive from physics and metaphysics.6 The primary subject of physics, according to Aristotle, was motion or change; there were three factors involved with this change, underlying thing, privation, and form. In his Metaphysics, Aristotle believed that the Unmoved Mover was responsible for the movement of the cosmos, which Neoplatonists later generalized as the cosmos were eternal.1 Al-Kindi argued against the idea of the cosmos being eternal by claiming that the eternality of the world lands one in a different sort of absurdity involving the infinite; Al-Kindi asserted that the cosmos must have a temporal origin because traversing an infinite was impossible.
One of the first commentaries of Aristotle's Metaphysics is by Al-Farabi. In "'The Aims of Aristotle's Metaphysics", Al-Farabi argues that metaphysics is not specific to natural beings, but at the same time, metaphysics is higher in universality than natural beings.1
One field in physics, optics, developed rapidly in this period. By the ninth century, there were works on physiological optics as well as mirror reflections, and geometrical and physical optics.7 In the eleventh century, Ibn al-Haytham not only rejected the Greek idea about vision, he came up with a new theory.8 ibn al-Haytham postulated in his "Book of Optics" that light was reflected upon different surfaces in different directions, thus causing different light signatures for a certain object that we see.9 It was certainly a different approach than what was previously thought by Greek scientist such as Euclid or Aristotle, who believed light was emitted by either our eyes or by the object to our eyes. Al-Haytham, with this new theory of optics, was able to study the geometric aspects of the visual cone theories without explaining the physiology of perception.7 Also in his Book of Optics, Ibn al-Haytham uses mechanics to try and understand optics. Using projectiles he observed that objects that hit a target perpendicularly exerts much more force than a projectile that hits at an angle. Al-Haytham used this discovery to optics by trying to explain why direct light hurts the eye, because direct light approaches perpendicularly and not at an oblique angle.9 Taqī al-Dīn tried to disproved the wide held belief that light is emitted by the eye and not the object that is being observed. He explains that if light came from our eyes at a constant velocity it would take much to long to illuminate the stars for us to see them while we are still looking at them because they are so far away. Therefore the illumination must be coming from the star so we can see it as soon as we open our eyes.10
The Islamic understanding of the astronomical model around 1000 B.C. was based on the Greek Ptolemaic system. However many early astronomers had started to question the model. It was not always accurate in its predictions and was over complicated because astronomers were trying to mathematically describe the movement of the heavenly bodies. Ibn al-Haytham published Al-Shukuk ala Batiamyus ("Doubts on Ptolemy"), which outlined his many criticisms of the Ptolemaic paradigm. This book encouraged other astronomers to develop new models to explain celestial movement better than Ptolemy.11 In al-Haytham's Book of Optics he argues that the celestial spheres were not made of solid matter, and that the heavens are less dense that air. 12 Al-Haytham eventually concludes that heavenly bodies follow the same laws of physics as Earthly bodies.13 Some astronomers theorized about gravity too, al-Khazini suggests that the gravity an object contains varies depending on its distance from the center of the universe. The center of the universe in this case refers to the center of the Earth.14
The greek philosopher John Philoponus had rejected the Aristotelian view of motion, and argued that an object aquires an inclination to move when it has a motive power impressed on it. In the eleventh century Ibn Sina had roughly adopted this idea, believing that a moving object has force which is dissipated by external agents like air resistance.15 Ibn Sina made distinction between 'force' and 'inclination' (called "mayl"), he claimed that an objected gained mayl when the object is in opposition to its natural motion. So he concluded that continuation of motion is attributed to the inclination that is transferred to the object, and that object will be in motion until the mayl is spent. He also claimed that projectile in a vacuum would not stop unless it is acted upon. This conception of motion is consistent Newton's first law of motion, inertia. Which states that an object in motion will stay in motion unless it is acted on by an external force.16 This idea which dissented from the Aristotelean view was basically abandoned until it was described as "impetus" by John Buridan, who was influenced by Ibn Sina's book Book of Healing.15
In Abū Rayḥān al-Bīrūnī text Shadows, he recognizes that non-uniform motion is the result of acceleration.17 Ibn-Sina's theory of mayl tried to relate the velocity and weight of a moving object, this idea closely resembled the concept of momentum18 Aristotle's theory of motion stated that a constant force produces a uniform motion, Abu'l-Barakāt al-Baghdādī contradicted this and developed his own theory of motion. In his theory he showed that velocity and acceleration are two different things and force is proportional to acceleration and not velocity. 19
Ibn Bajjah proposed that for every force there is always a reaction force. While he did not specify that these forces be equal it is still an early version of the third law of motion which states that for every action there is an equal and opposite reaction.20
- Astronomy in medieval Islam
- History of optics
- History of physics
- History of scientific method
- Islamic contributions to Medieval Europe
- Islamic Golden Age
- Science in medieval Islam
- Science in the Middle Ages
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- I.A., Ahmad (1995). "The Impact of the Qur’anic Conception of Astronomical Phenomena on Islamic Civilization". Vistas in Astronomy 39 (4). pp. 395–403.
- Thiele, Rüdiger (August 2005), "In Memoriam: Matthias Schramm, 1928–2005", Historia Mathematica 32 (3): 271–274, doi:10.1016/j.hm.2005.05.002
- . Islam, Science, and the Challenge of History. New Haven:Yale University Press. pg 57
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- Dallal, Ahmad. Islam, Science, and the Challenge of History. New Haven:Yale University Press. pg 39
- Lindberg, David C. (1976). Theories of Vision from al-Kindi to Kepler. University of Chicago Press, Chicago. ISBN 0-226-48234-0. OCLC 1676198 185636643.
- Taqī al-Dīn. Kitāb Nūr, Book I, Chapter 5, MS ‘O', folio 14b; MS ‘S', folio 12a-b
- Dallal, Ahmad (1999), "Science, Medicine and Technology", in Esposito, John, The Oxford History of Islam, Oxford University Press, New York
- Rosen, Edward. (1985). "The Dissolution of the Solid Celestial Spheres". Journal of the History of Ideas. Vol 46(1):13-31.
- Duhem, Pierre. (1969). "To Save the Phenomena: An Essay on the Idea of Physical Theory from Plato to Galileo". University of Chicago Press, Chicago.
- Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", in Roshdi Rashed, ed., Encyclopedia of the History of Arabic Science, Vol. 2, p. 614-642 Routledge, London and New York
- Sayili, Aydin. "Ibn Sina and Buridan on the Motion the Projectile". Annals of the New York Academy of Sciences vol. 500(1). p.477-482.
- Espinoza, Fernando. "An Analysis of the Historical Development of Ideas About Motion and its Implications for Teaching". Physics Education. Vol. 40(2).
- "Biography of Al-Biruni". University of St. Andrews, Scotland.
- Nasr S.H., Razavi M.A.. "The islamic Intellectual Tradition in Persia" (1996). Routledge
- Pines, Shlomo (1986), Studies in Arabic versions of Greek texts and in mediaeval science 2, Brill Publishers, p. 203, ISBN 965-223-626-8
- Franco, Abel B.. "Avempace, Projectile Motion, and Impetus Theory". Journal of the History of Ideas. Vol. 64(4): 543.