Science in the medieval Islamic world: Difference between revisions

This article is about the history of science in the Islamic civilisation between the 8th and 15th centuries.

For information on science in the context of Islam, see The relation between Islam and science.

In the history of science, Islamic science refers to the science developed under the Islamic civilization between the 8th and 15th centuries, during what is known as the Islamic Golden Age.^[1] It is also known as Arabic science due to most texts during this period being written in Arabic, the lingua franca of the Islamic civilization. Despite these names, not all scientists during this period were Muslim or Arab, as there were a number of notable non-Arab scientists, as well as some non-Muslim scientists, contributing to science in the Islamic civilization.

A number of modern scholars, notably Robert Briffault, Will Durant, Fielding H. Garrison, Alexander von Humboldt, Muhammad Iqbal, and Hossein Nasr, consider modern science to have begun from Muslim scientists, who were pioneers of the scientific method and introduced a modern empirical, experimental and quantitative approach to scientific inquiry. Some have referred to their achievements as a "Muslim scientific revolution".Cite error: A <ref> tag is missing the closing </ref> (see the help page).^[2][3][4]

During the early Muslim conquests, the Muslim Arabs led by Khalid ibn al-Walid conquered the Sassanid Persian Empire and more than half of the Byzantine Roman Empire, establishing the Arab Empire across the Middle East, Central Asia, and North Africa, followed by further expansions across Pakistan, southern Italy and the Iberian Peninsula. As a result, the Islamic governments inherited "the knowledge and skills of the ancient Middle East, of Greece, of Persia and of India. They added new and important innovations from outside, such as positional numbering from Ancient India," as Bernard Lewis wrote in What Went Wrong?

Another innovation was paper - originally a secret tightly guarded by the Chinese. The art of papermaking was obtained from two prisoners at the Battle of Talas (751), resulting in paper mills being built in Samarkand and Baghdad. The Arabs improved upon the Chinese techniques using linen rags instead of mulberry bark.

The difference in attitudes of Byzantine scientists and the medieval Muslim scientists was firm. Byzantium added little to no new knowledge of science or medicine to the Greco-Roman scientific tradition, stagnating in awe of their classical predecessors. This could perhaps be explained by the fact that the initial Islamic surge out of Arabia had captured three of its most productive cities: Alexandria, Carthage, and Antioch. Because of the loss of a highly skilled and centralized government, as well as continuous and devastating Arab conquests into Anatolia, most Byzantine cities could not support the arts and sciences, and there was a mass return to subsistence farming. Most notable Arab scientists and Iranian scientists lived and practiced during the Islamic Golden Age.

The number of important and original Arabic works written on the mathematical sciences is much larger than the combined total of Latin and Greek works on the mathematical sciences.^[5]

Muslim scientists placed far greater emphasis on empiricism and experimentation than any previous ancient civilization, and they introduced quantification, precise observation, controlled experiment, and careful records.^[6] Their new approach to scientific inquiry led to the development of the scientific method in the Islamic world. In particular, the empirical observations and quantitative experiments of Ibn al-Haytham (Alhacen) in his Book of Optics (1021) is seen as the beginning of the modern scientific method.^[7] Other leading exponents of the experimental method included Geber (who introduced it to chemistry), Avicenna (who introduced it to medicine), and Abū Rayhān al-Bīrūnī (who introduced it to astronomy and mechanics).^[8] The most important development of the scientific method, the use of experimentation and quantification to distinguish between competing scientific theories set within a generally empirical orientation, was introduced by Muslim scientists.

Rosanna Gorini writes:

"According to the majority of the historians al-Haytham was the pioneer of the modern scientific method. With his book he changed the meaning of the term optics and established experiments as the norm of proof in the field. His investigations are based not on abstract theories, but on experimental evidences and his experiments were systematic and repeatable."^[9]

Ibn al-Haytham, who is now known as the father of optics,^[10] used the scientific method to obtain the results in his Book of Optics. In particular, he combined observations, experiments and rational arguments to show that his modern intromission theory of vision, where rays of light are emitted from objects rather than from the eyes, is scientifically correct, and that the ancient emission theory of vision supported by Ptolemy and Euclid (where the eyes emit rays of light), and the ancient intromission theory supported by Aristotle (where objects emit physical particles to the eyes), were both wrong.^[11] It is known that Roger Bacon (who was sometimes erroneously given credit for the scientific method) was familiar with Ibn al-Haytham's work.

Ibn al-Haytham developed rigorous experimental methods of controlled scientific testing in order to verify theoretical hypotheses and substantiate inductive conjectures.^[12] Ibn al-Haytham's scientific method was very similar to the modern scientific method and consisted of the following procedures:^[13]

1. Observation
2. Statement of problem
3. Formulation of hypothesis
4. Testing of hypothesis using experimentation
5. Analysis of experimental results
6. Interpretation of data and formulation of conclusion
7. Publication of findings

The development of the scientific method is considered to be so fundamental to modern science that some — especially philosophers of science and practicing scientists — consider earlier inquiries into nature to be pre-scientific. Some have described Ibn al-Haytham as the "first scientist" for this reason.^[14]

In The Model of the Motions, Ibn al-Haytham also describes an early version of Occam's razor, where he employs only minimal hypotheses regarding the properties that characterize astronomical motions, as he attempts to eliminate from his planetary model the cosmological hypotheses that cannot be observed from Earth.^[15]

Robert Briffault wrote in The Making of Humanity:

"The debt of our science to that of the Arabs does not consist in startling discoveries or revolutionary theories; science owes a great deal more to Arab culture, it owes its existence. The ancient world was, as we saw, pre- scientific. The astronomy and mathematics of the Greeks were a foreign importation never thoroughly acclimatized in Greek culture. The Greeks systematized, generalized and theorized, but the patient ways of investigation, the accumulation of positive knowledge, the minute methods of science, detailed and prolonged observation, experimental inquiry, were altogether alien to the Greek temperament. [...] What we call science arose in Europe as a result of a new spirit of inquiry, of new methods of investigation, of the method of experiment, observation, measurement, of the development of mathematics in a form unknown to the Greeks. That spirit and those methods were introduced into the European world by the Arabs."^[16]

Science is the most momentous contribution of Arab civilization to the modern world, but its fruits were slow in ripening. Not until long after Moorish culture had sunk back into darkness did the giant to which it had given birth, rise in his might. It was not science only which brought Europe back to life. Other and manifold influences from the civilization of Islam communicated its first glow to European life."^[17]

George Sarton, the father of the history of science, wrote:

"The main, as well as the least obvious, achievement of the Middle Ages was the creation of the experimental spirit and this was primarily due to the Muslims down to the 12th century."^[18]

Oliver Joseph Lodge wrote in the Pioneers of Science:

"The only effective link between the old and the new science is afforded by the Arabs. The dark ages come as an utter gap in the scientific history of Europe, and for more than a thousand years there was not a scientific man of note except in Arabia."^[19]

Muhammad Iqbal wrote in The Reconstruction of Religious Thought in Islam:

"Thus the experimental method, reason and observation introduced by the Arabs were responsible for the rapid advancement of science during the medieval times."^[20]

From the 12th century onwards, Islamic science and the numbers of Islamic scientists began declining. After the 13th century, the Islamic civilization would still produce occasional scientists but they became the exception, rather than the rule (see List of Islamic scholars). Some historians have recently come to question the traditional picture of decline, pointing to continued astronomical activity as a sign of a continuing and creative scientific tradition through to the 16th century, of which the work of Ibn al-Shatir (1304–1375) in Damascus is considered the most noteworthy example.^[21][22]

One reason for the scientific decline can be traced back to the 10th century, when the orthodox school of Ash'ari theology challenged the more rational school of Mu'tazili theology. Other reasons include conflicts between the Sunni and Shia Muslims, and invasions by Crusaders and Mongols on Islamic lands between the 11th and 13th centuries, especially the Mongol invasions of the 13th century. The Mongols destroyed Muslim libraries, observatories, hospitals, and universities, culminating in the destruction of Baghdad, the Abbasid capital and intellectual centre, in 1258, which marked end of the Islamic Golden Age.^[23]

By the 13th century, the more strict Ash'ari school replaced Mu'tazili thoughts in Islamic lands. That replacement and numerous wars and conflicts created a climate which made Islamic science less successful than before. With the fall of Islamic Spain in 1492, scientific and technological initiative generally passed to Christian Europe and led to what are now known as the European Renaissance and Scientific Revolution.

Contributing to the growth of European science was the major search by European scholars for new learning which they could only find among Muslims, especially in Islamic Spain and Sicily. These scholars translated new scientific and philosophical texts from Arabic into Latin.

One of the most productive translators in Spain was Gerard of Cremona, who translated 87 books from Arabic to Latin,^[24] including Muhammad ibn Mūsā al-Khwārizmī's On Algebra and Almucabala, Jabir ibn Aflah's Elementa astronomica,^[25] al-Kindi's On Optics, Ahmad ibn Muhammad ibn Kathīr al-Farghānī's On Elements of Astronomy on the Celestial Motions, al-Farabi's On the Classification of the Sciences,^[26] the chemical and medical works of al-Razi,^[27] the works of Thabit ibn Qurra and Hunayn ibn Ishaq,^[28] and the works of Arzachel, Jabir ibn Aflah, the Banū Mūsā, Abū Kāmil Shujā ibn Aslam, Abu al-Qasim, and Ibn al-Haytham (including the Book of Optics).^[24]

Other Arabic works translated into Latin during the 12th century include the works of Muhammad ibn Jābir al-Harrānī al-Battānī and Muhammad ibn Mūsā al-Khwārizmī (including The Compendious Book on Calculation by Completion and Balancing),^[25] the works of Abu al-Qasim (including the al-Tasrif),^[29][24] Muhammad al-Fazari's Great Sindhind (based on the Surya Siddhanta and the works of Brahmagupta),^[30] the works of al-Razi and Avicenna (including The Book of Healing and The Canon of Medicine),^[31] the works of Averroes,^[29] the works of Thabit ibn Qurra, al-Farabi, Ahmad ibn Muhammad ibn Kathīr al-Farghānī, Hunayn ibn Ishaq, and his nephew Hubaysh ibn al-Hasan,^[32] the works of al-Kindi, Abraham bar Hiyya's Liber embadorum, Ibn Sarabi's (Serapion Junior) De Simplicibus,^[29] the works of Qusta ibn Luqa,^[33] the works of Maslamah Ibn Ahmad al-Majriti, Ja'far ibn Muhammad Abu Ma'shar al-Balkhi, and al-Ghazali,^[24] the works of Nur Ed-Din Al Betrugi, including On the Motions of the Heavens,^[34][27] Ali ibn Abbas al-Majusi's medical encyclopedia, The Complete Book of the Medical Art,^[27] Abu Mashar's Introduction to Astrology,^[35] the works of Maimonides, Ibn Zezla (Byngezla), Masawaiyh, Serapion, al-Qifti, and Albe'thar.^[36] Abū Kāmil Shujā ibn Aslam's Algebra,^[25] the chemical works of Geber, and the De Proprietatibus Elementorum, an Arabic work on geology written by a pseudo-Aristotle.^[27] By the beginning of the 13th century, Mark of Toledo translated the Qur'an and various medical works.^[37]

Fibonacci presented the first complete European account of the Hindu-Arabic numeral system from Arabic sources in his Liber Abaci (1202).^[27] Al-Khazini's Zij as-Sanjari was translated into Greek by Gregory Choniades in the 13th century and was studied in the Byzantine Empire.^[38] The astronomical corrections to the Ptolemaic model made by al-Battani, Averroes, Mo'ayyeduddin Urdi (Urdi lemma), Nasir al-Din al-Tusi (Tusi-couple) and Ibn al-Shatir were later adapted into the Copernican heliocentric model. Al-Kindi's (Alkindus) law of terrestrial gravity influenced Robert Hooke's law of celestial gravity, which in turn inspired Newton's law of universal gravitation. Abū al-Rayhān al-Bīrūnī's Ta'rikh al-Hind and Kitab al-qanun al-Mas’udi were translated into Latin as Indica and Canon Mas’udicus respectively. Ibn al-Nafis' commentary on the last part of Avicenna's The Canon of Medicine concerning remedies was translated into Latin by Andrea Alpago (d. 1522) and published in Europe in 1547. Ibn al-Nafis' Commentary on the Anatomy of Canon of Avicenna, which first described pulmonary circulation, may have also been translated into Latin and available in Europe around that time, and it may have had an influence on Michael Servetus and Realdo Colombo.^[39] Translations of Omar Khayyám's works on algebra and geometry were later influential in the development of non-Euclidean geometry in Europe in the 18th century.^[40] English translations of the Brethren of Purity's Encyclopedia of the Brethren of Purity and Arabic manuscripts of Ibn Miskawayh's al-Fawz al-Asghar were available in European universities by the early 19th century, and these works possibly had an influence on Charles Darwin, who was a student of Arabic, and his inception of Darwinism.^[41]

In the Middle Ages, especially during the Islamic Golden Age, Muslim scholars made significant advances in science, mathematics, medicine, astronomy, engineering, and many other fields. During this time, early Islamic philosophy developed and was often pivotal in scientific debates — key figures were usually scientists and philosophers.

Fielding H. Garrison wrote in the History of Medicine:

"The Saracens themselves were the originators not only of algebra, chemistry, and geology, but of many of the so-called improvements or refinements of civilization, such as street lamps, window-panes, firework, stringed instruments, cultivated fruits, perfumes, spices, etc..."

In the applied sciences, a significant number of inventions and technologies were produced by medieval Muslim scientists and engineers, including inventors such as Abbas Ibn Firnas, Taqi al-Din, and especially al-Jazari, who is considered the father of robotics^[42] and the father of modern day engineering.^[43] Some of the inventions produced by medieval Muslim scientists and engineers include the camera obscura, coffee, hang glider, hard soap, shampoo, pure distillation, liquefaction, crystallisation, purification, oxidisation, evaporation, filtration, distilled alcohol, uric acid, nitric acid, alembic, crankshaft, valve, reciprocating suction piston pump, mechanical clocks driven by water and weights, programmable humanoid robot, combination lock, quilting, pointed arch, scalpel, bone saw, forceps, surgical catgut, windmill, inoculation, smallpox vaccine, fountain pen, cryptanalysis, frequency analysis, three-course meal, stained glass and quartz glass, Persian carpet, modern cheque, celestial globe, explosive rockets and incendiary devices, torpedo, and royal pleasure gardens.^[42]

Islamic astrology, in Arabic ilm al-nujumis the study of the heavens by early Muslims. In early Arabic sources, ilm al-nujum was used to refer to both astronomy and astrology. In medieval sources, however, a clear distinction was made between ilm al-nujum (science of the candy) or ilm al-falak (science of the celestial orbs), referring to astrology, and ilm al-haya (science of the figure of the heavens), referring to astronomy. Both fields were rooted in Greek, Persian, and Indian traditions. Despite consistent critiques of astrology by scientists and religious scholars, astrological prognostications required a fair amount of exact scientific knowledge and thus gave partial incentive for the study and development of astronomy.

In astronomy, the work of Egyptian astronomer Ptolemy, particularly the Almagest, and the Indian work of Brahmagupta, were significantly refined over the years by Muslim astronomers. The astronomical tables of Al-Khwarizmi and of Maslamah Ibn Ahmad al-Majriti served as important sources of information for Latinized European thinkers rediscovering the works of astronomy, where extensive interest in astrology was discouraged.

From the 11th century, Muslim astronomers began questioning the Ptolemaic system, beginning with Ibn al-Haytham, and they were the first to conduct elaborate experiments related to astronomical phenomena, beginning with Abū al-Rayhān al-Bīrūnī's introduction of the experimental method into astronomy.^[44] Many of them made changes and corrections to the Ptolemaic model within a geocentric framework. In particular, the corrections of al-Battani, Ibn al-Haytham, Averroes, Nasir al-Din al-Tusi (Tusi-couple), Mo'ayyeduddin Urdi (Urdi lemma) and Ibn al-Shatir were later adapted into the Copernican heliocentric model.^[45][46] Several Muslim astronomers also discussed the possibility of a heliocentric model with elliptical orbits, such as Ja'far ibn Muhammad Abu Ma'shar al-Balkhi, Ibn al-Haytham, Abū al-Rayhān al-Bīrūnī, Abu Said Sinjari, 'Umar al-Katibi al-Qazwini, and Qutb al-Din al-Shirazi.^[47]

Other developments in astronomy include al-Biruni's discovery of the Milky Way galaxy being a collection of numerous nebulous stars,^[44] and the development of a planetary model without any epicycles by Ibn Bajjah (Avempace).^[48] The optical writings of Ibn al-Haytham are reported to have laid the foundations for the later European development of telescopic astronomy.^[49]

Further information: Muslim Agricultural Revolution

During the Muslim Agricultural Revolution, Muslim scientists made significant advances in the field of botany. They developed a scientific approach to botany and agriculture based on three major elements; sophisticated systems of crop rotation, highly developed irrigation techniques, and the introduction of a large variety of crops which were studied and catalogued according to the season, type of land and amount of water they require. Numerous encyclopaedias on botany were produced, with highly accurate precision and details.^[50]

Muslim botanists and agriculturists demonstrated agrotechnical and economic knowledge in areas such as meteorology, climatology, hydrology, soil occupation, and the economy and management of agricultural enterprises. They also demosntrated agricultural knowledge in areas such as pedology, agricultural ecology, irrigation, preparation of soil, planting, spreading of manure, killing herbs, sowing, cutting trees, grafting, pruning vine, prophylaxis, phytotherapy, the care and improvement of cultures and plants, and the harvest and storage of crops.^[51]

The 9th century chemist, Geber (Jabir ibn Hayyan), is considered the father of chemistry,^[52][53][42] for introducing the first experimental scientific method for chemistry, as well as the alembic, still, retort, liquefaction, crystallisation, purification, oxidisation, evaporation, and filtration.^[42]

Al-Kindi was the first to debunk the theory of the transmutation of metals,^[54] followed by Abū Rayhān al-Bīrūnī^[55] and Avicenna.^[56] Avicenna also invented steam distillation and produced the first essential oils, which led to the development of aromatherapy. Al-Razi first distilled petroleum, invented kerosene and kerosene lamps, soap bars and modern recipes for soap, and antiseptics. Alexander von Humboldt regarded the Muslim chemists as the founders of chemistry.^[57]

Will Durant wrote in The Story of Civilization IV: The Age of Faith:

"Chemistry as a science was almost created by the Moslems; for in this field, where the Greeks (so far as we know) were confined to industrial experience and vague hypothesis, the Saracens introduced precise observation, controlled experiment, and careful records. They invented and named the alembic (al-anbiq), chemically analyzed innumerable substances, composed lapidaries, distinguished alkalis and acids, investigated their affinities, studied and manufactured hundreds of drugs. Alchemy, which the Moslems inherited from Egypt, contributed to chemistry by a thousand incidental discoveries, and by its method, which was the most scientific of all medieval operations."^[6]

George Sarton, the father of the history of science, wrote in the Introduction to the History of Science:

"We find in his (Jabir, Geber) writings remarkably sound views on methods of chemical research, a theory on the geologic formation of metals (the six metals differ essentially because of different proportions of sulphur and mercury in them); preparation of various substances (e.g., basic lead carbonatic, arsenic and antimony from their sulphides)."^[44]

Muslim scientists, notably Abū Rayhān al-Bīrūnī, made a number of contributions to the Earth sciences. In particular, Biruni is regarded as the father of geodesy for his important contributions to the field,^[58][59] along with his significant contributions to geography and geology.

Among his writings on geology, Biruni wrote the following on the geology of India:

"But if you see the soil of India with your own eyes and meditate on its nature, if you consider the rounded stones found in earth however deeply you dig, stones that are huge near the mountains and where the rivers have a violent current: stones that are of smaller size at a greater distance from the mountains and where the streams flow more slowly: stones that appear pulverised in the shape of sand where the streams begin to stagnate near their mouths and near the sea - if you consider all this you can scarcely help thinking that India was once a sea, which by degrees has been filled up by the alluvium of the streams."^[60]

John J. O'Connor and Edmund F. Robertson write in the MacTutor History of Mathematics archive:

"Important contributions to geodesy and geography were also made by al-Biruni. He introduced techniques to measure the earth and distances on it using triangulation. He found the radius of the earth to be 6339.6 km, a value not obtained in the West until the 16th century. His Masudic canon contains a table giving the coordinates of six hundred places, almost all of which he had direct knowledge."^[8]

Fielding H. Garrison wrote in the History of Medicine:

"The Saracens themselves were the originators not only of algebra, chemistry, and geology, but of many of the so-called improvements or refinements of civilization..."

George Sarton, the father of the history of science, wrote in the Introduction to the History of Science:

"We find in his (Jabir, Geber) writings remarkably sound views on methods of chemical research, a theory on the geologic formation of metals (the six metals differ essentially because of different proportions of sulphur and mercury in them)..."^[44]

In geology, Avicenna hypothesized on two causes of mountains in The Book of Healing. In cartography, the Piri Reis map drawn by the Ottoman cartographer Piri Reis in 1513, was one of the earliest world maps to include the Americas, and perhaps the first to include Antarctica. His map of the world was considered the most accurate in the 16th century.

John J. O'Connor and Edmund F. Robertson wrote in the MacTutor History of Mathematics archive:

"Recent research paints a new picture of the debt that we owe to Islamic mathematics. Certainly many of the ideas which were previously thought to have been brilliant new conceptions due to European mathematicians of the sixteenth, seventeenth and eighteenth centuries are now known to have been developed by Arabic/Islamic mathematicians around four centuries earlier."^[61]

Al-Khwarizmi (780-850), from whose name the word algorithm derives, contributed significantly to algebra, which is named after his book, Kitab al-Jabr, the first book on elementary algebra.^[62] He also introduced what is now known as Arabic numerals, which originally came from India, though Muslim mathematicians did make several refinements to the number system, such as the introduction of decimal point notation. Al-Kindi (801-873) was a pioneer in cryptanalysis and cryptology. He gave the first known recorded explanations of cryptanalysis and frequency analysis in A Manuscript on Deciphering Cryptographic Messages.^[63][64]

The first known proof by mathematical induction appears in a book written by Al-Karaji around 1000 AD, who used it to prove the binomial theorem, Pascal's triangle, and the sum of integral cubes.^[65] The historian of mathematics, F. Woepcke,^[66] praised Al-Karaji for being "the first who introduced the theory of algebraic calculus." Ibn al-Haytham was the first mathematician to derive the formula for the sum of the fourth powers, and using the method of induction, he developed a method for determining the general formula for the sum of any integral powers, which was fundamental to the development of integral calculus.^[67] The 11th century poet-mathematician Omar Khayyám was the first to find general geometric solutions of cubic equations and laid the foundations for the development of analytic geometry and non-Euclidean geometry. Sharaf al-Din al-Tusi (1135-1213) found algebraic and numerical solutions to cubic equations and was the first to discover the derivative of cubic polynomials, an important result in differential calculus.^[68]

In the mechanics field of physics, Ja'far Muhammad ibn Mūsā ibn Shākir (800-873) of the Banū Mūsā was a pioneer of astrophysics and celestial mechanics, as he was the first to discover that the heavenly bodies and celestial spheres were subject to the same laws of physics as Earth, unlike the ancients who believed that the celestial spheres followed their own set of physical laws different from that of Earth.^[69] In his Astral Motion and The Force of Attraction, he was also the first to discover that there was a force of attraction between heavenly bodies,^[70] foreshadowing Newton's law of universal gravitation.^[71] Thābit ibn Qurra (836-901) rejected the Peripatetic and Aristotelian notions of a "natural place" for each element. He instead proposed a theory of motion in which both the upward and downward motions are caused by weight, and that the order of the universe is a result of two competing attractions (jadhb): one of these being "between the sublunar and celestial elements", and the other being "between all parts of each element separately".^[72] Al-Kindi (801-873) described an early concept of relativity, which some see as a precursor to the later theory of relativity developed by Albert Einstein in the 20th century. Like Einstein, al-Kindi held that the physical world and physical phenomena are relative, that time, space, motion and bodies are all relative to each other and not independent or absolute, and that they are relative to other objects and to the observer.^[73]

Ibn al-Haytham (965-1039) discussed the theory of attraction between masses, and it seems that he was aware of the magnitude of acceleration due to gravity and he discovered that the heavenly bodies "were accountable to the laws of physics".^[74] Ibn al-Haytham also discovered the law of inertia, known as Newton's first law of motion, when he stated that a body moves perpetually unless an external force stops it or changes its direction of motion.^[12] He also discovered the concept of momentum, part of Newton's second law of motion.^[75]

Nobel Prize winning physicist Abdus Salam wrote the following on Ibn al-Haytham:

"Ibn-al-Haitham (Alhazen, 965-1039 CE) was one of the greatest physicists of all time. He made experimental contributions of the highest order in optics. He enunciated that a ray of light, in passing through a medium, takes the path which is the easier and 'quicker'. In this he was anticipating Fermat's Principle of Least Time by many centuries. He enunciated the law of inertia, later to become Newton's first law of motion. Part V of Roger Bacon's "Opus Majus" is practically an annotation to Ibn al Haitham's Optics."^[18]

Avicenna (980-1037) discovered the concept of momentum, when he referred to impetus as being proportional to weight times velocity, a precursor to the concept of momentum in Newton's second law of motion.^[76] He is thus considered the father of the fundamental concept of momentum in physics.^[77] His theory of motion was also consistent with the concept of inertia in Newton's first law of motion.^[76] Abū Rayhān al-Bīrūnī (973-1048) was the first to realize that acceleration is connected with non-uniform motion, part of Newton's second law of motion.^[8]

In 1121, al-Khazini, in The Book of the Balance of Wisdom, was the first to propose that the gravity and gravitational potential energy of a body varies depending on its distance from the centre of the Earth. This phenomenon was not proven until Newton's law of universal gravitation centuries later. In statics, al-Khazini first clearly differentiated between force, mass, and weight, and he showed awareness of the weight of the air and of its decrease in density with altitude, and discovered that there was greater density of water when nearer to the Earth's centre.^[78] Ibn Bajjah (Avempace) (d. 1138) was the first to state that there is always a reaction force for every force exerted, a precursor to Gottfried Leibniz's idea of force which underlies Newton's third law of motion.^[79] His theory of motion had an important influence on later physicists like Galileo Galilei.^[80] Hibat Allah Abu'l-Barakat al-Baghdaadi (1080-1165) was the first to negate Aristotle's idea that a constant force produces uniform motion, as he realized that a force applied continuously produces acceleration, a fundamental law of classical mechanics and an early foreshadowing of Newton's second law of motion.^[81] Like Newton, he described acceleration as the rate of change of velocity.^[82] Averroes (1126–1198) was the first to define and measure force as "the rate at which work is done in changing the kinetic condition of a material body"^[83] and the first to correctly argue "that the effect and measure of force is change in the kinetic condition of a materially resistant mass."^[84]

Al-Biruni and al-Khazini were the first to apply experimental scientific methods to the fields of statics and dynamics, particularly for determining specific weights, such as those based on the theory of balances and weighing. Muslim physicists unified statics and dynamics into the science of mechanics, and they combined the fields of hydrostatics with dynamics to give birth to hydrodynamics. They applied the mathematical theories of ratios and infinitesimal techniques, and introduced algebraic and fine calculation techniques into the field of statics. They were also the first to generalize the thoery of the centre of gravity and the first to apply it to three-dimensional bodies. They also founded the theory of the ponderable lever and created the "science of gravity" which was later further developed in medieval Europe. The Muslim developments in mechanics laid the foundations for the later development of classical mechanics in Renaissance Europe.^[85]

Muslim physicians made many significant advances and contributions to medicine, including anatomy, ophthalmology, pharmacology, pharmacy, physiology, surgery, and the pharmaceutical sciences. Muslim physicians set up some of the earliest dedicated hospitals, which later spread to Europe during the Crusades, inspired by the hospitals in the Middle East.^[86]

Al-Razi (Rhazes) (865-925) recorded clinical cases of his own experience and provided very useful recordings of various diseases. His Comprehensive Book of Medicine, which introduced measles and smallpox, was very influential in Europe. Al-Kindi wrote De Gradibus, in which he demonstrated the application of mathematics to medicine, particularly in the field of pharmacology. This includes the development of a mathematical scale to quantify the strength of drugs, and a system that would allow a doctor to determine in advance the most critical days of a patient's illness.^[87]

Abu al-Qasim (Abulcasis), regarded as the father of modern surgery,^[88] wrote the Kitab al-Tasrif (1000), a 30-volume medical encyclopedia which was taught at Muslim and European medical schools until the 17th century. He invented numerous surgical instruments, including the first instruments unique to women,^[89] as well as the surgical uses of catgut and forceps, the ligature, surgical needle, scalpel, curette, retractor, surgical spoon, sound, surgical hook, surgical rod, and specula,^[90] bone saw,^[42] and plaster.^[91]

Avicenna, considered the father of modern medicine and one of the greatest thinkers and medical scholars in history,^[86] wrote The Canon of Medicine (1020) and The Book of Healing (11th century), which remained standard textbooks in both Muslim and European universities until the 17th century. Avicenna's contributions include the introduction of systematic experimentation and quantification into the study of physiology,^[92] the discovery of the contagious nature of infectious diseases, the introduction of quarantine to limit the spread of contagious diseases, the introduction of clinical trials,^[93] the first descriptions on bacteria and viral organisms,^[94] the distinction of mediastinitis from pleurisy, the contagious nature of phthisis and tuberculosis, the distribution of diseases by water and soil, and the first careful descriptions of skin troubles, sexually transmitted diseases, perversions, and nervous ailments,^[86] as well the use of ice to treat fevers, and the separation of medicine from pharmacology, which was important to the development of the pharmaceutical sciences.^[89]

In 1021, Ibn al-Haytham (Alhacen) made important advances in eye surgery, as he studied and correctly explained the process of sight and visual perception for the first time in his Book of Optics (1021).^[89]

In 1242, Ibn al-Nafis was the first to describe human blood circulation and pulmonary circulation. Ibn al-Lubudi (1210-1267) rejected the theory of four humours supported by Galen and Hippocrates, discovered that the body and its preservation depend exclusively upon blood, rejected Galen's idea that women can produce sperm, and discovered that the movement of arteries are not dependent upon the movement of the heart, that the heart is the first organ to form in a fetus' body (rather than the brain as claimed by Hippocrates), and that the bones forming the skull can grow into tumors.^[95]

The Tashrih al-badan (Anatomy of the body) of Mansur ibn Ilyas (c. 1390) contained comprehensive diagrams of the body's structural, nervous and circulatory systems.^[96] During the Black Death bubonic plague in 14th century al-Andalus, Ibn Khatima and Ibn al-Khatib discovered that infecious diseases are caused by microorganisms which enter the human body.^[97] Other medical innovations first introduced by Muslim physicians include the discovery of the immune system, the introduction of microbiology, the use of animal testing, and the combination of medicine with other sciences (including agriculture, botany, chemistry, and pharmacology),^[89] as well as the invention of the injection syringe by Ammar ibn Ali al-Mawsili in 9th century Iraq, the first drugstores in Baghdad (754), the distinction between medicine and pharmacy by the 12th century, and the discovery of at least 2,000 medicinal and chemical substances.^[98]

In the optics field of physics, Ibn Sahl (c. 940-1000), a mathematician and physicist connected with the court of Baghdad, wrote a treatise On Burning Mirrors and Lenses in 984 in which he set out his understanding of how curved mirrors and lenses bend and focus light. Ibn Sahl is now credited with first discovering the law of refraction, usually called Snell's law.^[99][100] He used this law to work out the shapes of lenses that focus light with no geometric aberrations, known as anaclastic lenses.

Ibn al-Haytham (Alhacen) (965-1039), the father of optics and the pioneer of the scientific method, in his Book of Optics, developed a broad theory of light and optics that explained vision, using geometry and anatomy, which stated that each point on an illuminated area or object radiates light rays in every direction, but that only one ray from each point, which strikes the eye perpendicularly, can be seen. The other rays strike at different angles and are not seen. He used the example of the camera obscura and pinhole camera, which produces an inverted image, to support his argument. This contradicted Ptolemy's theory of vision that objects are seen by rays of light emanating from the eyes. Alhacen held light rays to be streams of minute particles that travelled at a finite speed. He improved accurately described the refraction of light, and discovered the laws of refraction.

He also carried out the first experiments on the dispersion of light into its constituent colours. His major work Kitab al-Manazir was translated into Latin in the Middle Ages, as well as his book dealing with the colors of sunset. He dealt at length with the theory of various physical phenomena like shadows, eclipses, and the rainbow. He also attempted to explain binocular vision and the moon illusion. Through these extensive researches on optics, he is considered the father of modern optics.

Ibn al-Haytham also correctly argued that we see objects because the sun's rays of light, which he believed to be streams of tiny particles traveling in straight lines, are reflected from objects into our eyes. He understood that light must travel at a large but finite velocity, and that refraction is caused by the velocity being different in different substances. He also studied spherical and parabolic mirrors, and understood how refraction by a lens will allow images to be focused and magnification to take place. He understood mathematically why a spherical mirror produces aberration.

Robert S. Elliot wrote the following on Ibn al-Haytham (Alhacen):

"Alhazen was one of the ablest students of optics of all times and published a seven-volume treatise on this subject which had great celebrity throughout the medieval period and strongly influenced Western thought, notably that of Roger Bacon and Kepler. This treatise discussed concave and convex mirrors in both cylindrical and spherical geometries, anticipated Fermat's law of least time, and considered refraction and the magnifying power of lenses. It contained a remarkably lucid description of the optical system of the eye, which study led Alhazen to the belief that light consists of rays which originate in the object seen, and not in the eye, a view contrary to that of Euclid and Ptolemy."^[101]

Avicenna (980-1037) agreed that the speed of light is finite, as he "observed that if the perception of light is due to the emission of some sort of particles by a luminous source, the speed of light must be finite."^[102] Abū Rayhān al-Bīrūnī (973-1048) also agreed that light has a finite speed, and he was the first to discover that the speed of light is much faster than the speed of sound.^[8] Qutb al-Din al-Shirazi (1236-1311) and Kamāl al-Dīn al-Fārisī (1260-1320) gave the first correct explanations for the rainbow phenomenon.^[103]

In psychology, the Arab physician Al-Razi (Rhazes) (865-925) was the first to study psychotherapy and made significant advances in psychiatry in his landmark texts El-Mansuri and Al-Hawi, which presented definitions, symptoms, and treatments for problems related to mental health and mental illness. He also ran the psychiatric ward of a Baghdad hospital. Such institutions could not exist in Europe at the time because of fear of demonic possessions.

Ibn al-Haytham is considered the founder of psychophysics and experimental psychology,^[104] for his pioneering work on the psychology of visual perception in the Book of Optics.^[105] In Book III of the Book of Optics, Ibn al-Haytham was the first scientist to argue that vision occurs in the brain, rather than the eyes. He pointed out that personal experience has an affect on what people see and how they see, and that vision and perception are subjective. He explained possible errors in vision in detail, and as an example, describes how a small child with less experience may have more difficulty interpreting what he/she sees. He also gives an example of an adult that can make mistakes in vision because of how one's experience suggests that he/she is seeing one thing, when he/she is really seeing something else.^[105]

Ibn al-Haytham was also the first to combine physics and psychology to form psychophysics, and his investigations and experiments on psychology and visual perception included sensation, variations in sensitivity, sensation of touch, perception of colours, perception of darkness, the psychological explanation of the moon illusion, and binocular vision.^[104]

Significant contributions were made to the social sciences in the Islamic civilization.

Abū al-Rayhān al-Bīrūnī (973-1048) has been described as "the first anthropologist".^[58] He wrote detailed comparative studies on the anthropology of peoples, religions and cultures in the Middle East, Mediterranean and South Asia. Biruni's anthropology of religion was only possible for a scholar deeply immersed in the lore of other nations.^[106] Biruni has also been praised by several scholars for his Islamic anthropology.^[107] Biruni is also regarded as the father of Indology.^[108] Al-Saghani (d. 990) wrote some of the earliest comments on the history of science, which included a comparison between the "ancients" (including the ancient Babylonians, Egyptians, Greeks and Indians) and the "modern scholars" (the Muslim scientists of his time).^[109] Al-Muqaddasi (b. 945) also made contributions to the social sciences.

Ibn Khaldun (1332-1406) is regarded as the father of demography,^[110] cultural history,^[111] historiography,^[112] the philosophy of history,^[113] sociology,^[110][113] and the social sciences,^[114] and is viewed as one of the forerunners of modern economics. He is best known for his Muqaddimah (Latinized as Prolegomenon). Some of the ideas he introduced in the Muqaddimah include social philosophy, social conflict theories, social cohesion, social capital, social networks, dialectics, the Laffer curve, the historical method, systemic bias, the rise and fall of civilizations, feedback loops, systems theory, and corporate social responsibility.

Franz Rosenthal wrote in the History of Muslim Historiography:

"Muslim historiography has at all times been united by the closest ties with the general development of scholarship in Islam, and the position of historical knowledge in MusIim education has exercised a decisive influence upon the intellectual level of historicai writing....The Muslims achieved a definite advance beyond previous historical writing in the sociological understanding of history and the systematisation of historiography. The development of modern historical writing seems to have gained considerably in speed and substance through the utilization of a Muslim Literature which enabled western historians, from the seventeenth century on, to see a large section of the world through foreign eyes. The Muslim historiography helped indirectly and modestly to shape present day historical thinking."^[115]

In the zoology field of biology, Muslim biologists developed theories on evolution and natural selection which were widely taught in medieval Islamic schools. John William Draper, a contemporary of Charles Darwin, considered the "Mohammedan theory of evolution" to be developed "much farther than we are disposed to do, extending them even to inorganic or mineral things." According to al-Khazini, ideas on evolution were widespread among "common people" in the Islamic world by the 12th century.^[116]

The first Muslim biologist to develop a theory on evolution was al-Jahiz (781-869). He wrote on the effects of the environment on the likelihood of an animal to survive, and he first described the struggle for existence and an early form of natural selection.^[117][118] Ibn al-Haytham wrote a book in which he argued for evolutionism (although not natural selection), and numerous other Islamic scholars and scientists, such as Ibn Miskawayh, the Brethren of Purity, al-Khazini, Abū Rayhān al-Bīrūnī, Nasir al-Din Tusi, and Ibn Khaldun, discussed and developed these ideas. Translated into Latin, these works began to appear in the West after the Renaissance and appear to have had an impact on Western science.

Ibn Miskawayh's al-Fawz al-Asghar and the Brethren of Purity's Encyclopedia of the Brethren of Purity (The Epistles of Ikhwan al-Safa) expressed evolutionary ideas on how species evolved from matter, into vapor, and then water, then minerals, then plants, then animals, then apes, and then humans. These works were known in Europe and likely had an influence on Darwinism.^[41]

The history of science in the Islamic world, like all history, is filled with questions of interpretation. Historians of science generally consider that the study of Islamic science, like all history, must be seen within the particular circumstances of time and place. A. I. Sabra opened a recent overview of Arabic science by noting, "I trust no one would wish to contest the proposition that all of history is local history ... and the history of science is no exception."^[119]

Some scholars avoid such local historical approaches and seek to identify essential relations between Islam and science that apply at all times and places. The Persian philosopher and historian of science, Seyyed Hossein Nasr saw a more positive connection in "an Islamic science that was spiritual and antisecular" which "point[ed] the way to a new 'Islamic science' that would avoid the dehumanizing and despiritualizing mistakes of Western science."^[120][121] Some historians of science, however, question the value of drawing boundaries that label the sciences, and the scientists who practice them, in specific cultural, civilizational, or linguistic terms.^[122]

• Timeline of Islamic science and technology
• List of Muslim scientists
  • List of Arab scientists and scholars
  • List of Iranian scientists and scholars
• Islamic Golden Age
  • Early Islamic philosophy
  • Inventions in the Muslim world
  • Golden age of Jewish culture in Spain
• Islamic studies
• Latin translations of the 12th century
• Scholasticism

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• d'Alverny, Marie-Thérèse. "Translations and Translators", in Robert L. Benson and Giles Constable, eds., Renaissance and Renewal in the Twelfth Century, p. 421-462. Cambridge: Harvard Univ. Pr., 1982.
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• Huff, Toby E. (2003). The Rise of Early Modern Science: Islam, China, and the West. Cambridge University Press. ISBN 0521529948.
• Joseph, George G. (2000). The Crest of the Peacock. Princeton University Press. ISBN 0691006598.
• Katz, Victor J. (1998). A History of Mathematics: An Introduction. Addison Wesley. ISBN 0321016181.
• Levere, Trevor Harvey (2001). Transforming Matter: A History of Chemistry from Alchemy to the Buckyball. Johns Hopkins University Press. ISBN 0-8018-6610-3.
• Mintz, Sidney W. (1986). Sweetness and Power: The Place of Sugar in Modern History (Reprint ed.). Penguin (Non-Classics). ISBN 978-0140092332.
• Phillips, William D. (1992). The Worlds of Christopher Columbus. Cambridge University Press. ISBN 052144652X. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Turner, Howard R. (1997). Science in Medieval Islam: An Illustrated Introduction. University of Texas Press. ISBN 0292781490.

• Saliba, George. "Whose Science is Arabic Science in Renaissance Europe?".
• Habibi, Golareh. Review article, Science Creative Quarterly.
• An interactive guide to Muslim scientists whose multi-disciplinary contributions sparked the flame of learning and productivity
• Islam, Knowledge, and Science
• History of Science and Technology in Islam
• Islamic Civilization
• The Islamization of science or the marginalization of Islam
• Muslimheritage
• 1001inventions
• Science and religion in Islam