Science in the medieval Islamic world

Context

Through the Umayyad and, in particular, the succeeding Abbasid Caliphate's early phase, lies the period of Islamic history known as the Islamic Golden Age, between 692 and 945, with stable political structures and flourishing trade. Major religious and cultural works of the empire were translated into Arabic. The culture inherited Greek, Indic, Assyrian and Persian influences, and a new common civilisation formed, based on Islam. An era of high culture and innovation ensued.

Fields of inquiry

Islamic scientific achievements encompass a wide range of subject areas, especially mathematics, astronomy, and medicine. Other subjects of scientific inquiry included physics, alchemy and chemistry, ophthalmology, and geography and cartography.

Alchemy and chemistry

Alchemy was already well established before the rise of Islam, based on the belief that substances were made up of the four Aristotelian elements, fire, earth, air, and water in different proportions. Alchemists supposed that gold was the noblest metal, and that other metals formed a series down to the basest, such as lead. They believed, too, that a fifth element, the elixir, could transform a base metal into gold. Jabir ibn Hayyan (8th–9th centuries) wrote on alchemy, based on his own experiments. He described laboratory techniques and experimental methods that would continue to be used when alchemy had transformed into chemistry. Ibn Hayyan identified many substances including sulfuric and nitric acids. He described processes including sublimation, reduction and distillation. He utilized equipment such as the alembic and the retort stand. There is considerable uncertainty as to the actual provenance of many works that are ascribed to him.

Astronomy and cosmology

Astronomy was one of the major disciplines within Islamic science. The effort was devoted both towards understanding the nature of the cosmos and to practical purposes, including determining the Qibla, the direction in which to pray, and to astrology, predicting events affecting human life and selecting suitable times for actions such as going to war or founding a city. Al-Battani (850–922) accurately determined the length of the solar year. He contributed to numeric tables, such as the Tables of Toledo, used by astronomers to predict the movements of the sun, moon and planets across the sky. Some of his astronomic tables were later used by Copernicus. Al-Zarqali (1028–1087) developed a more accurate astrolabe, used for centuries afterwards. He constructed a water clock in Toledo. He discovered that the Sun's apogee moves slowly relative to the fixed stars, and obtained a good estimate of its motion. for its rate of change. Nasir al-Din al-Tusi (1201–1274) wrote an important revision to Ptolemy's celestial model. When he became Helagu's astrologer, he was given an observatory and gained access to Chinese techniques and observations. He developed trigonometry as a separate field, and compiled the most accurate astronomical tables available up to that time.

Botany

The study of the natural world extended to a detailed examination of plants. The work done was directly useful in the unprecedented growth of pharmacology across the Islamic world. Al-Dinawari is considered the founder of Arabic botany for his six-volume Kitab al-Nabat (Book of Plants). Only volumes 3 and 5 have survived, with part of volume 6 reconstructed from quoted passages. In what survives, 637 plants are described in alphabetical order from the letters sin to ya, so the whole book must have covered several thousand kinds of plant. Al-Dinawari describes the phases of plant growth and the production of flowers and fruit. Zakariya al-Qazwini's thirteenth century encyclopedia ʿAjā'ib al-makhlūqāt (The Wonders of Creation) contained among many other topics both realistic botany and fantastic trees which grew birds on their twigs in place of leaves, but which could only be found in the far-distant British Isles.

Geography and cartography

The swift spread of Islam across West Asia and North Africa encouraged and involved an unprecedented growth in trade and travel by land and sea as far away as Southeast Asia, China, much of Africa, Scandinavia and even Iceland. Geographers worked to create and fill in increasingly accurate maps of the known world, starting from many existing but fragmentary sources.al-Idrisi (1100–1166) created a map of the world for Roger, the Norman King of Sicily, and wrote the Book of Roger, a geographic study of the peoples, climates, resources and industries of all the world known at that time. Piri Reis (c. 1470–1553) made a map of the New World and West Africa in 1513, making use of maps from Greece, Portugal, Muslim sources, and perhaps one made by Christopher Columbus.

Mathematics

Islamic mathematicians gathered, organised and clarified the mathematics they inherited from ancient Egypt, Greece, India, Mesopotamia and Persia, and went on to make innovations of their own. Islamic mathematics can be divided into algebra, geometry and arithmetic. Algebra was mainly used for recreation and had few practical applications. Geometry was studied at different levels. Some texts contain practical geometrical rules for surveying and for measuring figures. Theoretical geometry was a necessary prerequisite for understanding astronomy and optics, and it required years of concentrated work. Soon after the establishment of the Abbasid caliphate and the founding of Baghdad in the mid-eighth century, some mathematical knowledge must have been assimilated from the pre-Islamic Persian tradition in astronomy. Astronomers from India were invited to the court of the caliph in the late eighth century, and they explained the rudimentary trigonometrical techniques used in Indian astronomy. Ancient Greek works such as Ptolemy's Almagest and Euclid's Elements were translated into Arabic. During the second half of the ninth century, Islamic mathematicians were already making contributions to the most sophisticated parts of Greek geometry. Islamic mathematics reached its apogee in the Eastern part of the Islamic world between the tenth and twelfth centuries CE, though little support was provided for it. Most mathematical works were written in Arabic, others in Persian.

al-Khwarizmi (8th–9th centuries), considered the greatest mathematician of Islamic civilization, was instrumental in the adoption of the Indian numbering system, later known as Arabic numerals. He developed algebra, which also had Indian antecedents, introducing methods of simplifying equations, and used Euclidean geometry in his proofs. Ibn Ishaq al-Kindi (801–873) worked on cryptography for the caliphate. Avicenna (ca. 980–1037) contributed to the development of mathematical techniques such as Casting out nines. Thabit ibn Qurra (835–901) calculated the solution to a chessboard problem involving an exponential series. al-Farabi (ca. 870–950) attempted to describe, geometrically, the repeating patterns popular in Islamic decorative motifs. His book on the subject is titled Spiritual Crafts and Natural Secrets in the Details of Geometrical Figures. Omar Khayyam (1048–1131), known in the West as a poet, calculated the length of the year to within 5 decimal places. He found geometric solutions to all 13 forms of cubic equations. He developed some quadratic equations still in use. Jamshid al-Kashi (ca. 1380–1429) is credited with several theorems of trigonometry including the Law of Cosines, also known as Al-Kashi's Theorem. He is often credited with the invention of decimal fractions, and a method like Horner's to calculate roots. He calculated π correct to 17 significant figures.

Medicine

Islamic society paid careful attention to medicine, following a hadith enjoining the preservation of good health. Its physicians inherited knowledge and traditional medical beliefs from the civilisations of classical Greece, Rome, Syria, Persia and India. These included the writings of Hippocrates, including the theory of the four humours, and the theories of Galen. al-Razi (ca. 854–925/935) identified smallpox and measles, and recognized that fever was a part of the body's defenses. He wrote a 23-volume compendium of Chinese, Indian, Persian, Syriac and Greek medicine. al-Razi questioned the classical Greek medical theory of how the four humors regulate life processes. He challenged Galen's work on several fronts, including the treatment of bloodletting, arguing that it was effective. al-Zahrawi (936–1013) was a surgeon whose most important surviving work is referred to as al-Tasrif (Medical Knowledge). It is a 30 volume set mainly discussing medical symptoms, treatments, and pharmacology, but the last volume, on surgery, describes surgical instruments, supplies, and pioneering procedures. Avicenna (ca. 980–1037) wrote the major medical textbook, The Canon of Medicine. ibn al-Nafis (1213–1288) wrote an influential book on medicine, believed to have replaced Avicenna's Canon in the Islamic world. He wrote commentaries on Galen and Avicenna's works. One of these commentaries was discovered in 1924, and yielded a description of pulmonary transit, the circulation of blood through the lungs.

Optics and ophthalmology

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. Hunayn ibn Ishaq (809–873) wrote the book Ten Treatises on the Eye, influential in the West until the 17th century. Abbas ibn Firnas (810–887) developed lenses for magnification and the improvement of vision. Ibn Sahl (ca. 940–1000) discovered the law of refraction known as Snell's law. He used the law to produce the first Aspheric lenses that focused light without geometric aberrations. In the eleventh century, Ibn al-Haytham (Alhazen, 965–1040) rejected Greek ideas about vision, and argued in his "Book of Optics" that light was reflected upon different surfaces in different directions, thus causing different light signatures of objects seen. He also studied the effects of light refraction, and suggested that the mathematics of reflection and refraction needed to be consistent with the anatomy of the eye.

Pharmacology

Advances in botany and chemistry in the Islamic world encouraged developments in pharmacology. Muhammad ibn Zakarīya Rāzi (Rhazes) (865-915) promoted the medical uses of chemical compounds. Abu al-Qasim al-Zahrawi (Abulcasis) (936-1013) pioneered the preparation of medicines by sublimation and distillation. His Liber servitoris provides recipes and instructions for preparing "simples" from which were compounded the complex drugs then used. Sabur Ibn Sahl (d 869), was the first physician to describe a large variety of drugs and remedies for ailments. Al-Biruni (973-1050) wrote the Kitab al-Saydalah (The Book of Drugs), describing in detail the properties of drugs, the role of pharmacy and the duties of the pharmacist. Ibn Sina (Avicenna) described 700 preparations, their properties, mode of action and their indications, devoting a whole volume to simple drugs in The Canon of Medicine. Works by Masawaih al-Mardini (c. 925–1015) and Ibn al-Wafid (1008–1074) were both printed in Latin more than fifty times, appearing as De Medicinis universalibus et particularibus by Masawaiyh (Mesue) the younger, and the Medicamentis simplicibus by Ibn al-Wafid (Abenguefit). Peter of Abano (1250–1316) translated and added a supplement to the work of al-Mardini under the title De Veneris. Al-Muwaffaq, in the 10th century, wrote The foundations of the true properties of Remedies, describing chemicals such as arsenious oxide and silicic acid. He made clear distinction between sodium carbonate and potassium carbonate, and drew attention to the poisonous nature of copper compounds, especially copper vitriol, and also lead compounds.

Physics

The fields of physics studied in this period, apart from optics and astronomy which are described separately, are aspects of mechanics: statics, dynamics, kinematics and motion. In the sixth century John Philoponus had rejected the Aristotelian view of motion, and argued that an object acquires an inclination to move when it has a motive power impressed on it. In the eleventh century Ibn Sina adopted roughly the same idea, that a moving object has force which is dissipated by external agents like air resistance. Ibn Sina distinguished between 'force' and 'inclination' (mayl); he claimed that an object gained mayl when the object is in opposition to its natural motion. 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. However, he also claimed that a projectile in a vacuum would not stop unless it is acted upon, a view consistent with Newton's first law of motion, inertia; but as a non-Aristotelian suggestion, it was essentially abandoned until it was described as "impetus" by Jean Buridan (c. 1295–1363), who was influenced by Ibn Sina's Book of Healing.

In Abū Rayḥān al-Bīrūnī's (973–1048) Shadows, non-uniform motion is described as the result of acceleration. Ibn-Sina's theory of mayl tried to relate the velocity and weight of a moving object, a precursor of the concept of momentum. Aristotle's theory of motion stated that a constant force produces a uniform motion; Abu'l-Barakāt al-Baghdādī (c. 1080 – 1164/5) contradicted this, arguing that velocity and acceleration are two different things, and and that force is proportional to acceleration and not velocity.

Ibn Bajjah (Avempace, c. 1085–1138) proposed that for every force there is a reaction force. While he did not specify that these forces be equal, it was still an early version of Newton's third law of motion.

The Banu Musa brothers, Jafar-Muhammad, Ahmad and al-Hasan (ca. early 9th century) created automated devices described in their Book of Ingenious Devices.

Zoology

Many classical works including those of Aristotle were transmitted from Greek to Syriac, then to Arabic, then to Latin in the Middle Ages. Aristotle's zoology remained dominant in its field for the next two thousand years. The Kitāb al-Hayawān (كتاب الحيوان, English: Book of Animals) is a 9th-century Arabic translation of History of Animals: 1–10, On the Parts of Animals: 11–14, and Generation of Animals: 15–19.

The book was mentioned by Al-Kindī (d. 850), and commented on by Avicenna (Ibn Sīnā) in his The Book of Healing. Avempace (Ibn Bājja) and Averroes (Ibn Rushd) commented on On the Parts of Animals and Generation of Animals, Averroes criticising Avempace's interpretations.

Significance

Historians of science differ in their views of the significance of the scientific accomplishments in the medieval Islamic world. The traditionalist view, exemplified by Bertrand Russell, holds that Islamic science, while admirable in many technical ways, lacked the intellectual energy required for innovation and was chiefly important for preserving ancient knowledge, and handing it on to medieval Europe. The revisionist view, exemplified by Abdus Salam, George Saliba and John M. Hobson holds that a Muslim scientific revolution occurred during the Middle Ages. Scholars such as Donald Routledge Hill and Ahmad Y Hassan argue that Islam was the driving force behind these scientific achievements.

According to Ahmed Dallal, science in medieval Islam was "practiced on a scale unprecedented in earlier human history or even contemporary human history". Toby E. Huff takes the view that, although science in the Islamic world did produce innovations, it did not lead to a Scientific Revolution, which in his view required an ethos which existed in Europe in the twelfth and thirteenth centuries but not elsewhere in the world. Will Durant, Fielding H. Garrison, Hossein Nasr and Bernard Lewis held that Muslim scientists helped in laying the foundations for an experimental science with their contributions to the scientific method and their empirical, experimental and quantitative approach to scientific inquiry.