Islamic physics included experimental physics, mathematical physics, and theoretical physics. The fields of physics that were studied by Muslim scientists during this time also included optics and magnetism (which are both now part of electromagnetism), mechanics (including statics, dynamics, kinematics, fluid dynamics, and motion), and astrophysics (see Islamic astronomy). These studies flourished in the Islamic world during the Islamic Golden age and ilsamis
- See also: Islamic science and technology
In medieval Islam, experimental physics began in Iraq and Egypt, with the work of the Muslim physicist, Ibn al-Haytham (known as Alhazen in the West), who is considered the "father of modern optics" and the most important physicist of the Middle Ages, for having developed the earliest experimental scientific method in his Book of Optics.
[Ibn al-Haytham] was not only the greatest Muslim physicist, but by all means the greatest of mediaeval times.
Ibn Haytham's writings reveal his fine development of the experimental faculty. His tables of corresponding angles of incidence and refraction of light passing from one medium to another show how closely he had approached discovering the law of constancy of ratio of sines, later attributed to Snell. He accounted correctly for twilight as due to atmospheric refraction, estimating the sun's depression to be 19 degrees below the horizon, at the commencement of the phenomenon in the mornings or at its termination in the evenings.
Matthias Schramm wrote in his Ibn al-Haythams Weg zur Physik:
Through a closer examination of Ibn al-Haytham's conceptions of mathematical models and of the role they play in his theory of sense perception, it becomes evident that he was the true founder of physics in the modern sense of the word; in fact he anticipated by six centuries the fertile ideas that were to mark the beginning of this new branch of science.
Another important medieval Muslim physicist who contributed towards experimental physics was Abū Rayhān al-Bīrūnī, who developed the earliest experimental method for mechanics. Ibn al-Haytham and Al-Biruni also introduced the earliest experimental methods for astronomy and astrophysics, while Al-Biruni and Al-Khazini unified statics with dynamics into the science of mechanics and combined hydrostatics with dynamics to create the field of hydrodynamics.
Islam and physicsEdit
- See also: Islam and science
The Qur'an contains an "insistence that the Universe is ruled by a single set of laws" which was "rooted in the Islamic concept of tawhîd, the unity of God", as well its "greater respect for empirical data than was common in the preceding Greek civilization" which inspired Muslims to place a greater emphasis on empirical observation, in contrast to ancient Greek philosophers such as the Platonists and Aristotelians who expressed a general distrust towards the senses and instead viewed reason alone as being sufficient to understanding nature. The Qur'an's insistence on observation, reason and contemplation ("see", "think" and "contemplate"), on the other hand, led Muslims to develop an early scientific method based on these principles, particularly empirical observation. Muhammad Iqbal says that it was:
... the general empirical attitude of the Qur'an which engendered in its followers a feeling of reverence for the actual, and ultimately made them the founders of modern science. It was a great point to awaken the empirical spirit in an age that renounced the visible as of no value in men's search after God.
Ibn al-Haytham (Alhazen) attributed his experimental method and scientific skepticism to his Islamic faith. He believed that human beings are inherently flawed and that only God is perfect. He reasoned that to discover the truth about nature, it is necessary to eliminate human opinion and error, and allow the universe to speak for itself. In The Winding Motion, Ibn al-Haytham further wrote that faith should only apply to prophets of Islam and not to any other authorities, in the following comparison between the Islamic prophetic tradition and the demonstrative sciences:
From the statements made by the noble Shaykh, it is clear that he believes in Ptolemy's words in everything he says, without relying on a demonstration or calling on a proof, but by pure imitation (taqlid); that is how experts in the prophetic tradition have faith in Prophets, may the blessing of God be upon them. But it is not the way that mathematicians have faith in specialists in the demonstrative sciences.
Ibn al-Haytham described his search for truth and knowledge as a way of leading him closer to God:
Al-Ghazali and Ali QushjiEdit
Ali Kuşçu's (Ali Qushji) (1403–1474) support for the Earth's rotation and his rejection of Aristotelian cosmology (which advocates a stationary Earth) was also motivated by religious opposition to Aristotelianism by orthodox Islamic theologians such as Al-Ghazali.
- See also: Islamic science and technology
Muslim scientists placed a greater emphasis on experimentation than previous ancient civilizations (for example, Greek philosophy placed a greater emphasis on rationality rather than empiricism), which was due to the emphasis on empirical observation found in the Qur'an and Sunnah, and the rigorous historical methods established in the science of hadith. Muslim scientists thus combined precise observation, controlled experiment and careful records with a new approach to scientific inquiry which led to the development of the scientific method. In particular, the empirical observations and experiments of Ibn al-Haytham (Alhazen) in his Book of Optics (1021) is seen as the beginning of the modern scientific method, which he first introduced to optics and astrophysics. 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.
Other early experimental methods were developed by Geber for alchemy and chemistry, by al-Kindi for the Earth sciences, and by Abū Rayhān al-Bīrūnī for astrophysics and mechanics. 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.
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.
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.
George Sarton wrote in the Introduction to the History of Science:
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.
Oliver Joseph Lodge wrote in the Pioneers of Science:
Thus the experimental method, reason and observation introduced by the Arabs were responsible for the rapid advancement of science during the medieval times.
Ibn al-Haytham, considered the "father of modern optics", used the scientific method to obtain the results in his famous Book of Optics (1021). 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. It is known that Roger Bacon 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. Ibn al-Haytham's scientific method was similar to the modern scientific method in that it consisted of the following procedures:
- Statement of problem
- Formulation of hypothesis
- Testing of hypothesis using experimentation
- Analysis of experimental results
- Interpretation of data and formulation of conclusion
- Publication of findings
An aspect associated with Ibn al-Haytham's optical research is related to systemic and methodological reliance on experimentation (i'tibar) and controlled testing in his scientific inquiries. Moreover, his experimental directives rested on combining classical physics ('ilm tabi'i) with mathematics (ta'alim; geometry in particular) in terms of devising the rudiments of what may be designated as a hypothetico-deductive procedure in scientific research. This mathematical-physical approach to experimental science supported most of his propositions in Kitab al-Manazir (The Optics; De aspectibus or Perspectivae) and gounded his theories of vision, light and colour, as well as his research in catoptrics and dioptrics. His legacy was further advanced through the 'reforming' of his Optics by Kamal al-Din al-Farisi (d. ca. 1320) in the latter's Kitab Tanqih al-Manazir (The Revision of [Ibn al-Haytham's] Optics).
The development of the scientific method is considered to be fundamental to modern science and some — especially philosophers of science and practicing scientists — consider earlier inquiries into nature to be pre-scientific. Some consider Ibn al-Haytham to be the "first scientist" for this reason.
Ibn al-Haytham also employed scientific skepticism and criticism, and emphasized the role of empiricism. He also explained the role of induction in syllogism, and criticized Aristotle for his lack of contribution to the method of induction, which Ibn al-Haytham regarded as superior to syllogism, and he considered induction to be the basic requirement for true scientific research.
The Book of Optics was the first book to emphasize the role of experimentation as a form of proof in scientific inquiry. He was also the first scientist to adopt a form of positivism in his approach, centuries before a term for positivism was coined. In his Book of Optics, he wrote that "we do not go beyond experience, and we cannot be content to use pure concepts in investigating natural phenomena", and that the understanding of these cannot be acquired without mathematics. After assuming that light is a material substance, he does not discuss its nature any further but confines his investigations to the diffusion and propagation of light. The only properties of light he takes into account are that which can be treated by geometry and verified by experiment, noting that energy is the only quality of light that can be sensed.
The concept of Occam's razor is also present in the Book of Optics. For example, after demonstrating that light is generated by luminous objects and emitted or reflected into the eyes, he states that therefore "the extramission of [visual] rays is superfluous and useless." In The Model of the Motions, Ibn al-Haytham also uses a form 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.
In his Aporias against Ptolemy, Ibn al-Haytham commented on the difficulty of attaining scientific knowledge:
Truth is sought for itself [but] the truths, [he warns] are immersed in uncertainties [and the scientific authorities (such as Ptolemy, whom he greatly respected) are] not immune from error...
He held that the criticism of existing theories—which dominated this book—holds a special place in the growth of scientific knowledge:
Therefore, the seeker after the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and deficiency. Thus the duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.
- See also: Abū Rayhān al-Bīrūnī
Abū Rayhān al-Bīrūnī (973-1048) also introduced an early scientific method in nearly every field of inquiry he studied. For example, in his treatise on mineralogy, Kitab al-Jamahir (Book of Precious Stones), Al-Biruni is "the most exact of experimental scientists", while in the introduction to his study of India, he declares that "to execute our project, it has not been possible to follow the geometric method" and develops comparative sociology as a scientific method in the field. He was also responsible for introducing the experimental method into mechanics, and was one of the first to conduct elaborate experiments related to astronomical phenomena.
Al-Biruni's scientific method was similar to the modern scientific method in many ways, particularly his emphasis on repeated experimentation. Biruni was concerned with how to conceptualize and prevent both systematic errors and random errors, such as "errors caused by the use of small instruments and errors made by human observers." He argued that if instruments produce random errors because of their imperfections or idiosyncratic qualities, then multiple observations must be taken, analyzed qualitatively, and on this basis, arrive at a "common-sense single value for the constant sought", whether an arithmetic mean or a "reliable estimate." He also introduced the method of checking tests during experiments.
- See also: Avicennism
In the Al-Burhan (On Demonstration) section of the The Book of Healing (1027), Avicenna discussed the philosophy of science and described an early scientific method of inquiry. He discusses Aristotle's Posterior Analytics and significantly diverged from it on several points. Avicenna discussed the issue of a proper methodology for scientific inquiry and the question of "How does one acquire the first principles of a science?" He asked how a scientist would arrive at "the initial axioms or hypotheses of a deductive science without inferring them from some more basic premises?" He explains that the ideal situation is when one grasps that a "relation holds between the terms, which would allow for absolute, universal certainty." Avicenna then adds two further methods for arriving at the first principles: the ancient Aristotelian method of induction (istiqra), and the method of examination and experimentation (tajriba). Avicenna criticized Aristotelian induction, arguing that "it does not lead to the absolute, universal, and certain premises that it purports to provide." In its place, he develops "a method of experimentation as a means for scientific inquiry."
Birunian method vs. Avicennian methodEdit
In comparison to Avicenna's scientific method where "general and universal questions came first and led to experimental work", al-Biruni developed scientific methods where "universals came out of practical, experimental work" and "theories are formulated after discoveries", like with inductivism. Due to differences between their scientific methods, al-Biruni referred to himself as a mathematical scientist and to Avicenna as a philosopher, during a debate between the two scholars.
In the history of optics, Al-Kindi (c. 801–873) was one of the earliest important writers on geometrical optics in the Islamic world. In a work known in the west as De radiis stellarum, al-Kindi developed a theory "that everything in the world ... emits rays in every direction, which fill the whole world."
Ibn Sahl and On Burning Mirrors and LensesEdit
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. He used this law to work out the shapes of lenses that focus light with no geometric aberrations, known as anaclastic lenses.
Beginning of physical opticsEdit
- See also: Book of Optics
Ibn al-Haytham (known in Western Europe as Alhacen or Alhazen) (965-1040), often regarded as the "father of optics" and a pioneer of the scientific method, formulated "the first comprehensive and systematic alternative to Greek optical theories." His key achievement was twofold: first, to insist that vision only occurred because of rays entering the eye and that rays postulated to proceed from the eye had nothing to do with it; the second was to define the physical nature of the rays discussed by earlier geometrical optical writers, considering them as the forms of light and color. This now forms the basis of modern physical optics. He developed a camera obscura to demonstrate that light and color from different candles can be passed through a single aperture in straight lines, without intermingling at the aperture. He then analyzed these physical rays according to the principles of geometrical optics. Ibn al-Haytham also employed the experimental scientific method as a form of demonstration in optics. He wrote many books on optics, most significantly the Book of Optics (Kitab al Manazir in Arabic), translated into Latin as the De aspectibus or Perspectiva, which disseminated his ideas to Western Europe and had great influence on the later developments of optics.
Ibn al-Haytham and Book of OpticsEdit
Ibn al-Haytham (Alhazen) (965-1039), in his broad theory of light and optics in his Book of Optics, explained vision, using geometry and anatomy, and 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 energy particles travelling in straight lines at a finite speed. He also speculated on the rectilinear propagation and electromagnetic aspects of light.
Alhazen 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 pioneer of modern physical 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. His Book of Optics has been ranked alongside Isaac Newton's Philosophiae Naturalis Principia Mathematica as one of the most influential books in the history of physics, for initiating a scientific revolution in optics and visual perception.
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.
The Book of Optics established experimentation as the norm of proof in optics, and gave optics a physico-mathematical conception at a much earlier date than the other mathematical disciplines of mechanics and astronomy. The book was influential in both the Islamic world and in Western Europe.
Beginning of physiological opticsEdit
Ibn al-Haytham discussed the topics of medicine and ophthalmology in the anatomical and physiological portions of the Book of Optics and in his commentaries on Galenic works. He accurately described the process of sight, the structure of the eye, image formation in the eye and the visual system. He also discovered the underlying principles of Hering's law of equal innervation, vertical horopters and binocular disparity, and improved on the theories of binocular vision, motion perception and horopters previously discussed by Aristotle, Euclid and Ptolemy.
He discussed ocular anatomy, and was the first author to deal with the "descriptive anatomy" and "functional anatomy" of the eye independently. Much of his decriptive anatomy was faithful to Galen's gross anatomy, but with significant differences in his approach. For example, the whole area of the eye behind the iris constitutes what Ibn al-Haytham uniquely called the uveal sphere, and his description of the eye was devoid of any teleological or humoral theories associated with Galenic anatomy. He also described the eye as being made up of two interesecting globes, which was essential to his functional anatomy of the eye.
After describing the construction of the eye, Ibn al-Haytham makes his most original anatomical contribution in describing the functional anatomy of the eye as an optical system, or optical instrument. His mulitple light-source experiment via a reduction slit with the camera obscura, also known as the lamp experiment, provided sufficient empirical grounds for him to develop his theory of corresponding point projection of light from the surface of an object to form an image on a screen. It was his comparison between the eye and the beam-chamber, or camera obscura, which brought about his synthesis of anatomy and optics, giving rise to a new field of optics now known as "physiological optics". As he conceptualized the essential principles of pinhole projection from his experiments with the pinhole camera, he considered image inversion to also occur in the eye, and viewed the pupil as being similar to an aperture. Regarding the process of image formation, however, he incorrectly agreed with Avicenna that the lens was the receptive organ of sight, but correctly hinted at the retina also being involved in the process.
Ibn al-Haytham (Alhazen; 965-1039), attempted to provide a scientific explanation for the rainbow phenomenon. In his Maqala fi al-Hala wa Qaws Quzah (On the Rainbow and Halo), he "explained the formation of rainbow as an image, which forms at a concave mirror. If the rays of light coming from a farther light source reflect to any point on axis of the concave mirror, they form concentric circles in that point. When it is supposed that the sun as a farther light source, the eye of viewer as a point on the axis of mirror and a cloud as a reflecting surface, then it can be observed the concentric circles are forming on the axis." He was not able to verify this because his theory that "light from the sun is reflected by a cloud before reaching the eye" did not allow for a possible experimental verification. This explanation was later repeated by Averroes, and, though incorrect, provided the groundwork for the correct explanations later given by Kamāl al-Dīn al-Fārisī and Theodoric of Freiberg.
Ibn al-Haytham's contemorary, Ibn Sīnā (Avicenna; 980-1037), provided an alternative explanation, writing "that the bow is not formed in the dark cloud but rather in the very thin mist lying between the cloud and the sun or observer. The cloud, he thought, serves simply as the background of this thin substance, much as a quicksilver lining is placed upon the rear surface of the glass in a mirror. Ibn Sīnā would change the place not only of the bow, but also of the color formation, holding the iridescence to be merely a subjective sensation in the eye." This explanation, however, was also incorrect.
Qutb al-Din al-Shirazi and Kamal al-Dīn al-FarisīEdit
In the late 13th and early 14th centuries, Qutb al-Din al-Shirazi (1236–1311) and his student Kamāl al-Dīn al-Fārisī (1260–1320) continued the work of Ibn al-Haytham, and they were the first to give the correct explanations for the rainbow phenomenon.
Qutb al-Din al-Shirazi (1236–1311) gave a fairly accurate explanation for the rainbow phenomenon. This was elaborated on by his student, Kamāl al-Dīn al-Fārisī (1260–1320), who gave a more mathematically satisfactory explanation of the rainbow. He "proposed a model where the ray of light from the sun was refracted twice by a water droplet, one or more reflections occurring between the two refractions." He verified this through extensive experimentation using a transparent sphere filled with water and a camera obscura.
As he noted in his Kitab Tanqih al-Manazir (The Revision of the Optics), al-Farisi used a large clear vessel of glass in the shape of a sphere, which was filled with water, in order to have an experimental large-scale model of a rain drop. He then placed this model within a camera obscura that has a controlled aperture for the introduction of light. He projected light unto the sphere and ultimately deducted through several trials and detailed observations of reflections and refractions of light that the colors of the rainbow are phenomena of the decomposition of light. His research had resonances with the studies of his contemporary Theodoric of Freiberg (without any contacts between them; even though they both relied on Ibn al-Haytham's legacy), and later with the experiments of Descartes and Newton in dioptrics (for instance, Newton conducted a similar experiment at Trinity College, though using a prism rather than a sphere).
Speed of lightEdit
Ibn al-Haytham speculated on the rectilinear propagation and electromagnetic aspects of light. He discovered that the speed of light is variable, with its speed decreasing in denser bodies. In order to establish that light travels in time and with finite speed, he undertook an experiment with a camera obscura and stated: “If the hole was covered with a curtain and the curtain was taken off, the light traveling from the hole to the opposite wall will consume time.” He also accurately described the refraction of light, and discovered the laws of refraction.
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." Abū Rayhān al-Bīrūnī (973-1048) also agreed that light has a finite speed, and he stated that the speed of light is immensely faster than the speed of sound.
Ibn Ma'udh and Liber de CrepisculisEdit
Abu 'Abd Allah Muhammad ibn Ma'udh, who lived in Al-Andalus during the second half of the 11th century, wrote a work on optics later translated into Latin as Liber de Crepisculis, which was mistakenly attributed to Alhazen. This was a "short work containing an estimation of the angle of depression of the sun at the beginning of the morning twilight and at the end of the evening twilight, and an attempt to calculate on the basis of this and other data the height of the atmospheric moisture responsible for the refraction of the sun's rays." Through his experiments, he obtained the accurate value of 18°, which comes close to the modern value.
Kitab Nūr Hadaqat al-Ibsār wa-Nūr Haqīqat al-AnzārEdit
In 1574, Taqi al-Din (1526–1585) wrote the last major Arabic work on optics, entitled Kitab Nūr Hadaqat al-Ibsār wa-Nūr Haqīqat al-Anzār (Book of the Light of the Pupil of Vision and the Light of the Truth of the Sights), which contains experimental investigations in three volumes on vision, the light's reflection, and the light's refraction.
The book deals with the structure of light, its diffusion and global refraction, and the relation between light and colour. In the first volume, he discusses "the nature of light, the source of light, the nature of the propagation of light, the formation of sight, and the effect of light on the eye and sight". In the second volume, he provides "experimental proof of the specular reflection of accidental as well as essential light, a complete formulation of the laws of reflection, and a description of the construction and use of a copper instrument for measuring reflections from plane, spherical, cylindrical, and conical mirrors, whether convex or concave." The third volume "analyses the important question of the variations light undergoes while travelling in mediums having different densities, i.e. the nature of refracted light, the formation of refraction, the nature of images formed by refracted light." In his writings he also seems to describe an early rudimentary telescope.
Abbas ibn Firnas: Parachute and glider flightEdit
In aeronautics, Abbas ibn Firnas (Armen Firman, 810-887) invented a primitive version of the parachute. John H. Lienhard described it in The Engines of Our Ingenuity as follows: "In 852, a new Caliph and a bizarre experiment: A daredevil named Armen Firman decided to fly off a tower in Cordova. He glided back to earth, using a huge winglike cloak to break his fall."
Abbas Ibn Firnas was also the first to make an attempt at controlled flight in a hang glider in 875, as opposed to earlier manned kite flights in ancient China which were not controllable. Ibn Firnas manuipulated the flight controls of his hang glider using two sets of artificial wings to adjust his altitude and to change his direction. He successfully returned to where he had lifted off from, but his landing was unsuccessful. Ibn Firnas' glider flight is considered the first attempt at heavier-than-air flight in aviation history. According to Philip Hitti in History of the Arabs: "Ibn Firnas was the first man in history to make a scientific attempt at flying." It may have inspired two later attempts at flight: one by Jauhari who died in either 1003 or 1008 while attempting to fly using two wooden wings with a rope from the roof of a mosque in Nishapur, Khorasan, Iran, and the other by Eilmer of Malmesbury between 1000 and 1010 in England.
Celebi brothers: Glider and rocket flightEdit
Also according to Evliya, Lagari Hasan Çelebi in 1633 took off with what was described as a cone-shaped rocket, glided with wings through the Bosporus from Topkapı Palace, and made a successful landing, winning him a position in the Ottoman army. The device was reported to have been a seven-pronged rocket powered by gunpowder.
Vacuum and suctionEdit
Al-Farabi (872-950) carried out an early experiment concerning the existence of vacuum, in which he investigated handheld plungers in water. He concluded that air's volume can expand to fill available space, and he suggested that the concept of perfect vacuum was incoherent.
Ibn al-Haytham (Alhazen, 965-1039) and the Mu'tazili theologians disagreed with Aristotle and Al-Farabi, and they supported the existence of a void. Using geometry, Ibn al-Haytham mathematically demonstrated that place (al-makan) is the imagined three-dimensional void between the inner surfaces of a containing body. Abū Rayhān al-Bīrūnī also states that there is no observable evidence that rules out the possibility of a vacuum.
Al-Jazari and Taqi al-Din: Pump inventionsEdit
Taqi al-Din's six-cylinder 'Monobloc' pump, invented in 1551, could also create a partial vacuum, which was formed "as the lead weight moves upwards, it pulls the piston with it, creating vacuum which sucks the water through a non return clack valve into the piston cylinder."
Motion and kinematicsEdit
Some of the earliest experiments in mechanics, particularly dynamics and kinematics, are described in Ibn al-Haytham's Book of Optics (1021). He used his results to explain certain optical phenomena using mechanical analogies. He conducted experiments with projectiles, and concluded that "it was only the impact of perpendicular projectiles on surfaces which was forceful enough to enable them to penetrate whereas the oblique ones were deflected. For example, to explain refraction from a rare to a dense medium, he used the mechanical analogy of an iron ball thrown at a thin slate covering a wide hole in a metal sheet. A perpendicular throw would break the slate and pass through, whereas an oblique one with equal force and from an equal distance would not." He used this result to explain explained how intense direct light hurts the eye: "Applying mechanical analogies to the effect of light rays on the eye, lbn al-Haytham associated 'strong' lights with perpendicular rays and 'weak' lights with oblique ones. The obvious answer to the problem of multiple rays and the eye was in the choice of the perpendicular ray since there could only be one such ray from each point on the surface of the object which could penetrate the eye."
Statics, dynamics, fluid mechanicsEdit
Abū Rayhān al-Bīrūnī (973-1048), and later Al-Khazini (fl. 1115-1130), were the first to apply experimental scientific methods to mechanics, especially 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 generalized the theory of the centre of gravity and applied 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.
In statics, al-Biruni measured the specific gravities of eighteen gemstones, and discovered that there is a correlation between the specific gravity of an object and the volume of water it displaces. He also introduced the method of checking tests during experiments, measured the weights of various liquids, and recorded the differences in weight between freshwater and saline water, and between hot water and cold water. During his experiments on mechanics, al-Biruni invented the conical measure, in order to find the ratio between the weight of a substance in air and the weight of water displaced, and to accurately measure the specific weights of the gemstones and their corresponding metals, which are very close to modern measurements. Al-Biruni also realized that acceleration is connected with non-uniform motion.
In 1121, Al-Khazini, in The Book of the Balance of Wisdom, invented a hydrostatic balance and proposed that the gravity or gravitational potential energy of a body varies depending on its distance from the centre of the Earth. In statics, al-Khazini 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.
The measurement of viscosity appears for the first time in an Arabic military treatise dating back to the early 14th century. The viscosity (qawam) of distillated oils is gauged by the number of "words", ranging from ten and thirty "words" for various oils. This is similar to the modern method, where viscosity is gauged by the number of seconds needed for a certain volume of oil to fall through a calibrated orifice.
First law of motion: InertiaEdit
Ibn al-Haytham (965-1039) enunciated the law of inertia, later 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.
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.
Avicenna (Ibn Sina) (980-1037), in The Book of Healing, developed an elaborate theory of motion, in which he made a distinction between the inclination and force of a projectile, and concluded that motion was a result of an inclination (mayl) transferred to the projectile by the thrower, and that projectile motion in a vacuum would not cease. This was the first alternative to the Aristotelian theory. In the Avicennan theory of motion, the violent inclination he conceived was non-self-consuming, a permanent force whose effect was dissipated only as a result of external agents such as air resistance. 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 makes him "the first to conceive such a permanent type of impressed virtue for non-natural motion." Such a self-motion (mayl) is "almost the opposite of the Aristotelian conception of violent motion of the projectile type, and it is rather reminiscent of the principle of inertia, i.e., Newton's first law of motion" states that an object in motion will stay in motion unless it is acted on by an external force. Avicenna's theory of motion was reminiscent of the later concept of inertia in classical mechanics, and later formed the basis of Jean Buridan's theory of impetus and exerted an influence on the work of Galileo Galilei.
Averroes (1126–1198) developed the notion that bodies have a (non-gravitational) inherent resistance to motion into physics, an idea that was adopted by Thomas Aquinas and subsequently by Johannes Kepler who referred to it as 'inertia'.
Second law of motion: Acceleration and momentumEdit
Avicenna's (980-1037) theory of mayl attempted to provide a quantitive relation between the weight and velocity of a moving body, resembling the concept of momentum. for which he is considered a pioneer of the concept of momentum.
Hibat Allah Abu'l-Barakat al-Baghdaadi (1080–1165) wrote a critique of Aristotelian physics entitled al-Mu'tabar, where he 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, considered "the fundamental law of classical mechanics" and an early foreshadowing of Newton's second law of motion. He also described acceleration as the rate of change of velocity. The 14th-century philosophers Jean Buridan and Albert of Saxony later refer to Abu'l-Barakat in explaining that the acceleration of a falling body is a result of its increasing impetus. Abu'l-Barakat also modified Avicenna's view on projectile motion, and stated that the mover imparts a violent inclination (mayl qasri) on the moved and that this diminishes as the moving object distances itself from the mover. Abu'l-Barakat also suggested that motion is relative, writing that "there is motion only if the relative positions of the bodies in question change."
Averroes (1126–1198) defined and measured force as "the rate at which work is done in changing the kinetic condition of a material body" and correctly argued "that the effect and measure of force is change in the kinetic condition of a materially resistant mass."
Third law of motion: ReactionEdit
Ibn Bajjah (Avempace) (d. 1138) argued that there is always a reaction force for every force exerted, which Shlomo Pines views as "a precursor to the Leibnizian idea of force" which "underlies Newton's third law of motion", though he did not necessarily refer to the reaction force as being equal to the exerted force. His theory of motion had an important influence on later physicists like Galileo.
Law of universal gravitation: Attraction forceEdit
Ja'far Muhammad ibn Mūsā ibn Shākir (800-873) of the Banū Mūsā hypothesized that 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. In his Astral Motion and The Force of Attraction, he also hypothesized that there was a force of attraction between heavenly bodies, which Robert Briffault views as a precursor to Newton's law of universal gravitation. 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".
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 stated that the heavenly bodies "were accountable to the laws of physics".
Al-Khazini, in 1121, proposed the concepts of gravitational potential energy and gravity at-a-distance. In The Book of the Balance of Wisdom (1121), he proposed that the gravity or gravitational potential energy of a body varies depending on its distance from the centre of the Earth.
Heat and energyEdit
In thermodynamics, Abu Rayhan Biruni (973-1048) appears to be the earliest to cite movement and friction as the cause of heat, which in turn produces the element of fire, and a lack of movement as the cause of cold near the geographical poles:
The earth and the water form one globe, surrounded on all sides by air. Then, since much of the air is in contact with the sphere of the moon, it becomes heated in consequence of the movement and friction of the parts in contact. Thus there is produced fire, which surrounds the air, less in amount in the proximity of the poles owing to the slackening of the movement there.
a) that [natural heat] would be the heat of a fiery atom that is broken, and b) that heat may occur through motion-change, the proof of this being through experiment.
Avicenna says in his book of heaven and earth, that heat is generated from motion in external things.
Law of conservation of massEdit
Pseudo-Majriti's Sage's Step/The Rank of the Wise (Rutbat al-hakim, c. 1009), later translated into Latin in 1252 (on the orders of King Alfonso X of Castile), includes alchemical formulae and instructions for purification of precious metals, and was the first to note the principle of conservation of mass, which he did in the course of his pathbreaking experiment on mercuric oxide:
I took natural quivering mercury, free from impurity, and placed it in a glass vessel shaped like an egg. This I put inside another vessel like a cooking pot, and set the whole apparatus over an extremely gentle fire. The outer pot was then in such a degree of heat that I could bear my hand upon it. I heated the apparatus day and night for forty day, after which I opened it. I found that the mercury (the original weight of which was a quarter of a pound) had been completely converted into red powder, soft to touch, the weight remaining as it was originally.
In the 13th century, Nasīr al-Dīn al-Tūsī also stated an early version of the law of conservation of mass, noting that a body of matter is able to change, but is not able to disappear. This is a fundamental concept underlying the laws of thermodynamics.
Biruni vs. AvicennaEdit
- See also: Early Islamic philosophy
Abū Rayhān al-Bīrūnī and Avicenna (Ibn Sina), who are regarded as two of the greatest polymaths in Persian history, were both colleagues and knew each other since the turn of the millennium. Biruni later engaged in a written debate with Avicenna, with Biruni criticizing the Peripatetic school for its adherence to Aristotelian physics and natural philosophy, while Avicenna and his student Ahmad ibn 'Ali al-Ma'sumi respond to Biruni's criticisms in writing.
This debate has been preserved in a book entitled al-As'ila wal-Ajwiba (Questions and Answers), in which al-Biruni attacks Aristotle's theories on physics and cosmology, and questions almost all of the fundamental Aristotelian physical axioms. For example, he rejects the notion that heavenly bodies have an inherent nature and asserts that their "motion could very well be compulsory"; maintains that "there is no observable evidence that rules out the possibility of vacuum"; and states that there is no inherent reason why planetary orbits must be circular and cannot be elliptical. He also argues that "the metaphysical axioms on which philosophers build their physical theories do not constitute valid evidence for the mathematical astronomer." This marks the first real distinction between the vocations of the philosopher-metaphysician (which he labelled Aristotle and Avicenna as) and that of the mathematician-scientist (which al-Biruni viewed himself as). In contrast to the philosophers, the only evidence that al-Biruni considered reliable were either mathematical or empirical evidence, and his systematic application of rigorous mathematical reasoning later led to the mathematization of Islamic astronomy and the mathematization of nature.
Biruni began the debate by asking Avicenna eighteen questions, ten of which were criticisms of Aristotle's On the Heavens, with his first question criticizing the Aristotelian theory of gravity for denying the existence of levity or gravity in the celestial spheres, and the Aristotelian notion of circular motion being an innate property of the heavenly bodies. Biruni's second question criticizes Aristotle's over-reliance on more ancient views concerning the heavens, while the third criticizes the Aristotelian view that space has only six directions. The fourth question deals with the continuity and discontinuity of physical bodies, while the fifth criticizes the Peripatetic denial of the possibility of there existing another world completely different from the world known to them. In his sixth question, Biruni rejects Aristotle's view on the celestial spheres having circular orbits rather than elliptic orbits. In his seventh question, he rejects Aristotle's notion that the motion of the heavens begins from the right side and from the east, while his eighth question concerns Aristotle's view on the fire element being spherical. The ninth question concerns the movement of heat, and the tenth question concerns the transformation of elements.
The eleventh question concerns the burning of bodies by radiation reflecting off a flask filled with water, and the twelfth concerns the natural tendency of the classical elements in their upward and downward movements. The thirteenth question deals with vision, while the fourteenth concerns habitation on different parts of Earth. His fifteenth question asks how two opposite squares in a square divided into four can be tangential, while the sixteenth question concerns vacuum. His seventeenth question asks "if things expand upon heating and contract upon cooling, why does a flask filled with water break when water freezes in it?" His eighteenth and final question concerns the observable phenomenon of ice floating on water.
After Avicenna responded to the questions, Biruni was unsatisfied with some of the answers and wrote back commenting on them, after which Avicenna's student Ahmad ibn 'Ali al-Ma'sumi wrote back on behalf of Avicenna.
Al-Ghazali and quantum mechanicsEdit
- See also: Al-Ghazali
It has been noted that Al-Ghazali's (1058-1111) theory of physical reality circa 1100 (related to atomism and occasionalism) anticipates some of the core principles of contemporary quantum physics (also known as quantum mechanics) by almost a millenium. In her 1993 paper, Causality Then and Now: Al Ghazali and Quantum Theory, the scholar Karen Harding stated:
"The extent of the commonalities is striking. For example, both deny that the regularities in the behavior of objects should be attributed to the existence of causal laws. Further, they agree that events in the world ate not strictly predictable. Both accept the idea that unexpected, unpredictable things can and do occur. According to al Ghazali's explanation, God is omnipotent and involved in the world at every moment and can, therefore, cause anything to happen. The Copenhagen Interpretation of quantum theory says that it is impossible to predict the exact behavior of an object based on physical laws. As a result, while one might expect a lead ball to fall when it is dropped, there is a definite possibility that the ball will rise instead."
In a 2003 paper, Ümit Yoksuloglu Devji and Eric L. Ormsby further elaborated on Harding's comparative analysis between Al-Ghazali's theory and contemporary quantum physics. They state:
"An of the above point to parallels between al-Ghazali's concept of the structure and machinations of the natural world, as outlined in the Seventeenth Discussion of Tahafut al-Falasifa, and the views of the quantum physicists regarding systems operating within the physical universe. For both, generally speaking, notions of an inherent causality gui ding events in the universe are rejected. As well, regarding the place of human consciousness, particularly in terms of the inability of human observation in discovering an objective reality, the views of both are in general agreement. The consequent reevaluation of what is possible and impossible is evident in both as weIl, although the two views differ in terms of the details. Finally, the work of both points to the need for a reconsideration of preexisting beliefs about the physical world and how it operates, from a human perspective."
Theory of relativityEdit
Hibat Allah Abu'l-Barakat al-Baghdaadi (Abu'l-Barakāt al-Baghdādī) (1080–1165) suggested that motion is relative, writing that "there is motion only if the relative positions of the bodies in question change." This anticipates some of the core principles of the theory of relativity.
Unlike preceding philosophers (as well as physicists living before the advent of relativity physics) who believed that time (like place) has an objective existence and is a fixed receptacle for objects and events, Mulla Sadra argued that time possesses an immaterial rather than objective existence and is abstracted from the trans-substantial motion of things and events.
This argument proves that the trans-substantial motion of objects exists in their essence and does not occur to them as an accident, and, thus, it is needless of a particular reason and cannot be questioned. In other words, we never ask ‘why does material substance have motion?’, for it is like asking ‘why is water wet?’, and ‘why is oil oily?’. Such a question is absurd, because it is similar to asking why water is water, or why oil is oil.
If the essence or inner nature of something – and, in philosophical terms, its quiddity – is fluid, nothing can stop its motion except for annihilation.
The general theory of relativity in modern physics confirmed Mulla Sadra’s philosophical theory, since in this theory ‘time’ is a part of everything, i.e., its fourth dimension, and everything has its own time, as well.
Ibn al-Haytham's Maqala fi daw al-qamar (On the Light of the Moon), which he wrote some time before his famous Book of Optics (1021), was the first successful attempt at combining mathematical astronomy with physics, and the earliest attempt at applying the experimental method to astronomy and astrophysics. Regarding moonlight, he disproved the universally held opinion that the moon reflects sunlight like a mirror and correctly concluded that it "emits light from those portions of its surface which the sun's light strikes." In order to prove that "light is emitted from every point of the moon's illuminated surface," he built an "ingenious experimental device." Ibn al-Haytham had "formulated a clear conception of the relationship between an ideal mathematical model and the complex of observable phenomena; in particular, he was the first to make a systematic use of the method of varying the experimental conditions in a constant and uniform manner, in an experiment showing that the intensity (physics) of the light-spot formed by the projection of the moonlight through two small apertures onto a screen diminishes constantly as one of the apertures is gradually blocked up."
In 1574, Taqi al-Din used astrophysics to explain the intromission model of vision. He stated since the stars are millions of kilometres away from the Earth and that the speed of light is constant, that if light had come from the eye, it would take too long for light "to travel to the star and come back to the eye. But this is not the case, since we see the star as soon as we open our eyes. Therefore the light must emerge from the object not from the eyes."
In astrophysics and celestial mechanics, the eldest Banū Mūsā brother, Ja'far Muhammad ibn Mūsā ibn Shākir (9th century), made significant contributions. He was the first to hypothesize that the heavenly bodies and celestial spheres are 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. In his Astral Motion and The Force of Attraction, Muhammad ibn Musa proposed that there is a force of attraction between heavenly bodies, foreshadowing Newton's law of universal gravitation.
Ibn al-Haytham (Alhazen), in his Book of Optics (1021), was the first to discover that the celestial spheres do not consist of solid matter, and he also discovered that the heavens are less dense than the air. These views were later repeated by Witelo and had a significant influence on the Copernican and Tychonic systems of astronomy. In his Epitome of Astronomy, he also insisted that the heavenly bodies "were accountable to the laws of physics."
Al-Biruni and Al-KazhiniEdit
Abū Rayhān al-Bīrūnī was also one of the first to conduct elaborate experiments related to astronomical phenomena. He supposed the Milky Way galaxy to be a collection of numerous nebulous stars, and in Khorasan, he observed and described the solar eclipse on April 8, 1019, and the lunar eclipse on September 17, 1019, in detail, and gave the exact latitudes of the stars during the lunar eclipse. Al-Biruni also theorized that gravity exists within the heavenly bodies and celestial spheres, and he criticized the Aristotelian views of them not having any levity or gravity and of circular motion being an innate property of the heavenly bodies. He also described the Earth's gravitation as:
In 1121, Al-Khazini, in his treatise The Book of the Balance of Wisdom, was the first to propose the theory that the "gravities" of bodies, or their gravitational potential energy, vary depending on their distances from the centre of the Earth. This phenomenon was not proven until the 18th century. He states:
For each heavy body of a known weight positioned at a certain distance from the centre of the universe, its gravity depends on the remoteness from the centre of the universe. For that reason, the gravities of bodies relate as their distances from the centre of the universe.
Fakhr al-Din al-RaziEdit
In the 12th century, Fakhr al-Din al-Razi criticized the idea of the Earth's centrality within the universe and "explores the notion of the existence of a multiverse in the context of his commentary" on the Qur'anic verse, "All praise belongs to God, Lord of the Worlds." He raises the question of whether the term "worlds" in this verse refers to "multiple worlds within this single universe or cosmos, or to many other universes or a multiverse beyond this known universe." He rejected the Aristotelian and Avicennian notions of a single universe revolving around a single world, and instead argued that there are more than "a thousand thousand worlds (alfa alfi 'awalim) beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has." He argued that there exists an infinite outer space beyond the known world, and that God has the power to fill the vacuum with an infinite number of universes.
Fakhr al-Din al-Razi also participated in the debate among Islamic scholars over whether the celestial spheres or orbits (falak) are "to be considered as real, concrete physical bodies" or "merely the abstract circles in the heavens traced out year in and year out by the various stars and planets." He points out that many astronomers prefer to see them as solid spheres "on which the stars turn," while others, such as the Islamic scholar Dahhak, view the celestial sphere as "not a body but merely the abstract orbit traced by the stars." Al-Razi himself remains "undecided as to which celestial models, concrete or abstract, most conform with external reality," and notes that "there is no way to ascertain the characteristics of the heavens," whether by "observable" evidence or by authority (al-khabar) of "divine revelation or prophetic traditions." He concludes that "astronomical models, whatever their utility or lack thereof for ordering the heavens, are not founded on sound rational proofs, and so no intellectual commitment can be made to them insofar as description and explanation of celestial realities are concerned."
In Islamic astronomy, some have described the achievements of the Maragha school in the 13th and 14th centuries as a "Maragha Revolution", "Maragha School Revolution", or "Scientific Revolution before the Renaissance". An important aspect of this revolution included the realization that astronomy should aim to describe the behaviour of physical bodies in mathematical language, and should not remain a mathematical hypothesis, which would only save the phenomena. The Maragha astronomers also realized that the Aristotelian view of motion in the universe being only circular or linear was not true, as the Tusi-couple developed by Nasīr al-Dīn al-Tūsī showed that linear motion could also be produced by applying circular motions only.
Unlike the ancient Greek and Hellenistic astronomers who were not concerned with the coherence between the mathematical and physical principles of a planetary theory, Islamic astronomers insisted on the need to match the mathematics with the real world surrounding them, which gradually evolved from a reality based on Aristotelian physics to one based on an empirical and mathematical physics after the work of Ibn al-Shatir. The Maragha Revolution was thus characterized by a shift away from the philosophical foundations of Aristotelian cosmology and Ptolemaic astronomy and towards a greater emphasis on the empirical observation and mathematization of astronomy and of nature in general, as exemplified in the works of Ibn al-Shatir, Ali al-Qushji, al-Birjandi and Shams al-Din al-Khafri.
Ibn al-Shatir (1304–1375) of Damascus, in A Final Inquiry Concerning the Rectification of Planetary Theory, incorporated the Urdi lemma, and eliminated the need for an equant by introducing an extra epicycle (the Tusi-couple), departing from the Ptolemaic system in a way that was mathematically identical to what Nicolaus Copernicus did in the 16th century. Unlike previous astronomers before him, Ibn al-Shatir was not concerned with adhering to the theoretical principles of natural philosophy or Aristotelian cosmology, but rather to produce a model that was more consistent with empirical observations. His model was thus in better agreement with empirical observations than any previous model, and was also the first that permitted empirical testing. His work thus marked a turning point in astronomy, which may be considered a "Scientific Revolution before the Renaissance". His rectified model was later adapted into a heliocentric model by Copernicus, which was mathematically achieved by reversing the direction of the last vector connecting the Earth to the Sun.
In the 9th century, Ja'far ibn Muhammad Abu Ma'shar al-Balkhi (Albumasar) developed a planetary model which some have interpreted as a heliocentric model. This is due to his orbital revolutions of the planets being given as heliocentric revolutions rather than geocentric revolutions, and the only known planetary theory in which this occurs is in the heliocentric theory. His work on planetary theory has not survived, but his astronomical data was later recorded by al-Hashimi and al-Biruni.
I have seen the astrolabe called Zuraqi invented by Abu Sa'id Sijzi. I liked it very much and praised him a great deal, as it is based on the idea entertained by some to the effect that the motion we see is due to the Earth's movement and not to that of the sky. By my life, it is a problem difficult of solution and refutation. [...] For it is the same whether you take it that the Earth is in motion or the sky. For, in both cases, it does not affect the Astronomical Science. It is just for the physicist to see if it is possible to refute it.
The work of Ali al-Qushji (d. 1474), who worked at Samarkand and then Istanbul, is seen as a late example of innovation in Islamic theoretical astronomy and it is believed he may have had an influence on Nicolaus Copernicus due to similar arguments concerning the Earth's rotation. Before al-Qushji, the only astronomer to present an empirical argument for the Earth's rotation was Nasīr al-Dīn al-Tūsī (d. 1274), who used the phenomena of comets to refute Ptolemy's claim that a stationery Earth can be determined through observation alone. Al-Tusi, however, accepted that the Earth was stationery on the basis of natural philosophy instead, particularly Aristotelian cosmology. In the 15th century, the influence of Aristotelian physics and natural philosophy was declining due to religious opposition. Al-Qushji, in his Concerning the Supposed Dependence of Astronomy upon Philosophy, thus rejected Aristotelian physics and completely separated natural philosophy from astronomy, allowing astrophysics to become a purely empirical and mathematical science. This allowed him to explore alternatives to the Aristotelian notion of a stationery Earth, as he explored the idea of a moving Earth. He elaborated on al-Tusi's argument and concluded, on the basis of empiricism rather than speculative philosophy, that the moving Earth theory is just as likely to be true as the stationary Earth theory and that it is not possible to empirically deduce which theory is true.
In the 16th century, the debate on the Earth's motion was continued by al-Birjandi (d. 1528), who in his analysis of what might occur if the Earth were rotating, develops a hypothesis similar to Galileo Galilei's notion of "circular inertia", which he described in the following observational test (as a response to one of Qutb al-Din al-Shirazi's arguments):
The small or large rock will fall to the Earth along the path of a line that is perpendicular to the plane (sath) of the horizon; this is witnessed by experience (tajriba). And this perpendicular is away from the tangent point of the Earth’s sphere and the plane of the perceived (hissi) horizon. This point moves with the motion of the Earth and thus there will be no difference in place of fall of the two rocks.
- See also: Early Islamic philosophy
In contrast to ancient Greek philosophers who believed that the universe had an infinite past with no beginning, medieval philosophers and theologians developed the concept of the universe having a finite past with a beginning (see Temporal finitism). This view was inspired by the creation myth shared by the three Abrahamic religions: Judaism, Christianity and Islam. The Egyptian Christian philosopher, John Philoponus, presented the first such argument against the ancient Greek notion of an infinite past. His arguments were adopted by many, most notably early Islamic philosopher, Al-Kindi (Alkindus); the Jewish philosopher, Saadia Gaon (Saadia ben Joseph); and the Islamic theologian, Al-Ghazali (Algazel). They, most notably Al-Ghazali, used two logical arguments against an infinite past, the first being the "argument from the impossibility of the existence of an actual infinite", which states:
- "An actual infinite cannot exist."
- "An infinite temporal regress of events is an actual infinite."
- ".•. An infinite temporal regress of events cannot exist."
The second argument, the "argument from the impossibility of completing an actual infinite by successive addition", states:
- "An actual infinite cannot be completed by successive addition."
- "The temporal series of past events has been completed by successive addition."
- ".•. The temporal series of past events cannot be an actual infinite."
Both arguments were adopted by later Christian philosophers and theologians, and the second argument in particular became more famous after it was adopted by Immanuel Kant in his thesis of the first antimony concerning time.
In the 12th century, Fakhr al-Din al-Razi presents an argument for the creation of a temporally finite universe, based upon the ideas of motion and rest. He describes the opposing arguments for an eternal universe with eternal bodies, and then argues that had a body (jism) "been eternal, in eternity it would have been either in motion or at rest." According to al-Razi, "both alternatives are absurd," therefore, a "body cannot be eternal."
Al-Ghazali and possible worldsEdit
Al-Ghazali, in The Incoherence of the Philosophers, defends the Ash'ari doctrine of a created universe that is temporally finite, against the Aristotelian doctrine of an eternal universe. In doing so, he proposed the modal theory of possible worlds, arguing that their actual world is the best of all possible worlds from among all the alternate timelines and world histories that God could have possibly created. His theory parallels that of Duns Scotus in the 14th century. While it is uncertain whether Al-Ghazali had any influence on Scotus, they both may have derived their theory from their readings of Avicenna's Metaphysics.
Fakhr al-Din al-Razi and multiverse theoryEdit
- See also: Islamic cosmology
Fakhr al-Din al-Razi (1149–1209), in dealing with his conception of physics and the physical world in his Matalib, discusses Islamic cosmology and astronomy. He criticizes the idea of the Earth's centrality within the universe and "explores the notion of the existence of a multiverse in the context of his commentary" on the Qur'anic verse, "All praise belongs to God, Lord of the Worlds." He raises the question of whether the term "worlds" in this verse refers to "multiple worlds within this single universe or cosmos, or to many other universes or a multiverse beyond this known universe." In volume 4 of the Matalib, Al-Razi states:
It is established by evidence that there exists beyond the world a void without a terminal limit (khala' la nihayata laha), and it is established as well by evidence that God Most High has power over all contingent beings (al-mumkinat). Therefore He the Most High has the power (qadir) to create a thousand thousand worlds (alfa alfi 'awalim) beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has of the throne (al-arsh), the chair (al-kursiyy), the heavens (al-samawat) and the earth (al-ard), and the sun (al-shams) and the moon (al-qamar). The arguments of the philosophers (dala'il al-falasifah) for establishing that the world is one are weak, flimsy arguments founded upon feeble premises.
Al-Razi rejected the Aristotelian and Avicennian view of the impossibility of multiple worlds or universes. He describes the main Aristotelian arguments against the existence of multiple worlds or universes, pointing out their weaknesses and refuting them. This rejection arose from his affirmation of atomism, as advocated by the Ash'ari school of Islamic theology, which entails the existence of vacant space in which the atoms move, combine and separate. He discussed more on the issue of the void in greater detail in volume 5 of the Matalib. He argued that God has the power to fill the vacuum with an infinite number of universes.
Al-Razi also argues that each of these universes may have its own possible "natural order" or physical laws. That other natural orders are possible, he argues, points to a willing maker who chooses one of many possibilities. 
Possibly the earliest and nearest approach to the discovery of the identity of lightning, and electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning (raad) applied to the electric ray. The electrostatic phenomena was also reported by Arabic naturalists and physicians.
Abbas Ibn Firnas: Artificial thunder and lightningEdit
Abbas Ibn Firnas' inventions in the 9th century included "some sort of metronome", and his attempt at creating an artificial weather simulation room, in which spectators saw stars and clouds, and were astonished by artificial thunder and lightning, which were produced by mechanisms hidden in his basement laboratory. How he achieved those artificial thunder and lightning effects is unknown, though it is possible that some electricity may have been involved.
Arabic writers were aware of magnetism since the 9th century, when Muhammad ibn Zakarīya Rāzi (Rhazes) wrote a treatise on the subject. In the 12th century, Ibn Bajjah (Avempace) described the properties of magnets and its attraction towards iron.
Like some of the ancient Hellenistic philosophers, the early Islamic philosophers were aware of the properties of natural plastic amber, and they observed that it can draw up small bits of paper.
After the arrival of an early compass from China around the 12th or 13th century, Islamic geography and navigational sciences became highly developed with the use of the magnetic compass. The first astronomical uses of the magnetic compass is also found in a treatise on astronomical instruments written by the Yemeni sultan al-Ashraf (d. 1296 AD) in 1282 AD (681 AH). This was the first reference to the compass in astronomical literature.
Al-Ashraf's compass used a steel needle magnetized by rubbing with a magnetic stone, due to steel needles keeping their magnetic property longer than iron needles. Al-Ashraf also provides detailed explanations on the magnetic properties of the needle. He was aware that when the end rubbed with the magnetic stone, that each head retains its attraction to turn north or south, referring to the fact that the head of the needle which is not rubbed has also changed its behavior. He also described two flaws of the early magnetic compass: "loss of magnetic properties and attrition of the cone", and wrote that these were the reasons why it was neglected by “the early scholars”. Al-Ashraf then develops an improved compass for use as a "Qibla indicator" instrument in order to find the direction to Mecca. Al-Ashraf's instrument was one of the earliest dry compasses, and appears to have been invented independently of Peter Peregrinus.
In the 14th century, Ibn al-Shatir invented the compass dial, a timekeeping device incorporating both a universal sundial and a magnetic compass. He invented it for the purpose of finding the direction of Qibla and the times of Salah prayers. The Arabs also invented the 32-point compass rose during the Middle Ages.
Muslim astronomers were aware of magnetic declination by the 15th century, when the Egyptian astronomer 'Izz al-Din al-Wafa'i (d. 1469/1471) measured it as 7 degrees from Cairo. A cartographic Qibla instrument, with a sundial and compass attached to it, was created by Muhammad Husayn in the 17th century.
Apparatus, instruments, devicesEdit
Ibn al-Haytham: Camera obscura and magnifying lensEdit
In the early 11th century, Ibn al-Haytham (Alhazen) gave the first clear description and correct analysis of the camera obscura and pinhole camera in his Book of Optics (1021). In his earlier Maqala fi daw al-qamar (On the Light of the Moon), in order to prove that "light is emitted from every point of the moon's illuminated surface," he built an "ingenious experimental device." The first optical research to describe a magnifying lens used in an instrument was also found in the Book of Optics written by Ibn al-Haytham. His work in light refraction, parabolic mirrors, as well as the creation of other instruments such as the camera obscura, also helped spark the Scientific Revolution.
Taqi al-Din and telescopeEdit
In the 16th century, Taqi al-Din Muhammad ibn Ma'ruf made an important discovery: the invention of an early rudimentary telescope, which he describes as an instrument that makes objects located far away appear closer to the observer. He states:
"I made a crystal (billawr) that has two lenses displaying in details the objects from long distances. When they look from one of its edges, people can see the sail of the ship in far. My instrument is similar to that of ancient Greeks which had made and placed on the Tower of Alexandria."
Al-Din further states that the instrument helps to see distant objects in detail by bringing them very close. He also states that he wrote another earlier treatise explaining the way this instrument is made and used, suggesting that he invented it some time before 1574. However, it is unknown whether or not he employed the instrument for his later astronomical observations at the Istanbul observatory of al-Din from 1577.
Al-Biruni and Al-KhaziniEdit
During his experiments on physics, Abū Rayhān al-Bīrūnī invented a conical measure, in order to find the ratio between the weight of a substance in air and the weight of water displaced, and to accurately measure the specific weights of the gemstones and their corresponding metals, which are very close to modern measurements.
Abū Rayhān al-Bīrūnī also invented the laboratory flask and pycnometer in the early 11th century, and the hydrostatic balance and steelyard were invented by Al-Khazini in the early 12th century. The earliest known descriptions for these instruments are found in al-Khazini's The Book of the Balance of Wisdom (1121). Al-Bīrūnī also invented the aerometer for measuring densities and for the appreciation of the temperature of liquids. It was described by Al-Khazini a century later.
Avicenna: Thermometer and refrigerated coilEdit
Also in the 11th century, Avicenna (Ibn Sina) invented the refrigerated coil, which condenses aromatic vapours, in order to produce essential oils through steam distillation. Ibn Sīnā was also the first to employ an air thermometer, to measure air temperature in his scientific experiments.
- See also: Muslim Agricultural Revolution, Inventions in medieval Islam, and Timeline of science and engineering in the Islamic world
Banu Musa brothers and Book of Ingenious DevicesEdit
- See also: Book of Ingenious Devices
In the 9th century, the Banū Mūsā brothers made advances in fluid mechanics and aerostatics, through their treatise on mechanical technology, the Book of Ingenious Devices. They described a number of early automatic controls in mechanics. Two-step level controls for fluids, an early form of discontinuous variable structure controls, was developed by the Banu Musa brothers. They also described an early feedback controller for fluids. According to Donald Routledge Hill, the Banu Musa brothers were "masters in the exploitation of small variations" in aerostatics and hydrostatic pressures and in using conical valves as "in-line" components in flow systems, "the first known use of conical valves as automatic controllers." They also described the use of other valves, including a plug valve, float valve and tap. The Banu Musa also developed an early fail-safe system where "one can withdraw small quantities of liquid repeatedly, but if one withdraws a large quantity, no further extractions are possible." The double-concentric siphon and the funnel with bent end for pouring in different liquids, neither of which appear in any earlier Greek works, were also original inventions by the Banu Musa brothers. Some of the other mechanisms they described include a float chamber and an early differential pressure.
Book of Knowledge of Ingenious Mechanical DevicesEdit
- See also: Al-Jazari
In 1206, Al-Jazari's Book of Knowledge of Ingenious Mechanical Devices described many hydraulic machines. Of particular importance were his water-raising pumps. The first known use of a crankshaft in a chain pump was in one of al-Jazari's saqiya machines. The concept of minimizing intermittent working is also first implied in one of al-Jazari's saqiya chain pumps, which was for the purpose of maximising the efficiency of the saqiya chain pump. Al-Jazari also invented a twin-cylinder reciprocating piston suction pump, which included the first suction pipes, suction pumping, double-action pumping, and made early uses of valves and a crankshaft-connecting rod mechanism. This pump is remarkable for three reasons: the first known use of a true suction pipe (which sucks fluids into a partial vacuum) in a pump, the first application of the double-acting principle, and the conversion of rotary to reciprocating motion, via the crankshaft-connecting rod mechanism. The suction pump invented by Al-Jazari later appeared in Europe from the 15th century.
Taqi al-Din: Steam turbine and vacuum pumpEdit
- See also: Taqi al-Din Muhammad ibn Ma'ruf
Taqi al-Din's six-cylinder 'Monobloc' pump, invented in 1551, could also create a partial vacuum, which was formed "as the lead weight moves upwards, it pulls the piston with it, creating vacuum which sucks the water through a non return clack valve into the piston cylinder." He also invented an early practical steam turbine as a prime mover for the first steam-powered and self-rotating spit, as described in his book, Al-Turuq al-samiyya fi al-alat al-ruhaniyya (The Sublime Methods of Spiritual Machines), completed in 1551 AD (959 AH).
In the 14th century, Ibn al-Shatir invented the compass dial, a timekeeping device incorporating both a universal sundial and a magnetic compass. He invented it for the purpose of finding the times of Salah prayers. The Arabs also invented the 32-point compass rose during the Middle Ages. A cartographic Qibla instrument with a sundial and compass attached to it was created by Muhammad Husayn in the 17th century.
- ↑ 1.0 1.1 Thiele, Rüdiger (August 2005), "In Memoriam: Matthias Schramm, 1928–2005", Historia Mathematica 32 (3): 271–274, Error: Bad DOI specified
- ↑ Thiele, Rüdiger (2005), "In Memoriam: Matthias Schramm", Arabic Sciences and Philosophy (Cambridge University Press) 15: 329–331, Error: Bad DOI specified
- ↑ 3.0 3.1 3.2 R. L. Verma, "Al-Hazen: father of modern optics", Al-Arabi, 8 (1969): 12-13
- ↑ 4.0 4.1 George Sarton, Introduction to the History of Science, "The Time of Al-Biruni"
- ↑ 5.0 5.1 5.2 5.3 Gorini, Rosanna (October 2003). "Al-Haytham the man of experience. First steps in the science of vision" (pdf). Journal of the International Society for the History of Islamic Medicine 2 (4): 53–55. Retrieved on 2008-09-25.</cite>
- ↑ 6.0 6.1 6.2 6.3 6.4 Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 642, in (Morelon & Rashed 1996, pp. 614–642):Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic approach so that two trends - statics and dynamics - turned out to be inter-related within a single science, mechanics.The combination of the dynamic approach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics.Archimedean statics formed the basis for creating the fundamentals of the science on specific weight. Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science.Arabic statics was an essential link in the progress of world science. It played an important part in the prehistory of classical mechanics in medieval Europe. Without it classical mechanics proper could probably not have been created.
- ↑ 7.0 7.1 7.2 7.3 Toomer, G. J. (December 1964), "Review: Ibn al-Haythams Weg zur Physik by Matthias Schramm", Isis 55 (4): 463–465 [463–4], Error: Bad DOI specified </li>
- ↑ 8.0 8.1 Dr. A. Zahoor (1997), Abu Raihan Muhammad al-Biruni, Hasanuddin University. </li>
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 O'Connor, John J.; Robertson, Edmund F., "Al-Biruni", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Al-Biruni.html. </li>
- ↑ Ahmad, I. A. (1995), "The impact of the Qur'anic conception of astronomical phenomena on Islamic civilization", Vistas in Astronomy 39 (4): 395–403, Error: Bad DOI specified </li>
- ↑ Ahmad, I. A. (June 3, 2002), "The Rise and Fall of Islamic Science: The Calendar as a Case Study" (PDF), Faith and Reason: Convergence and Complementarity, Al Akhawayn University, http://images.agustianwar.multiply.com/attachment/0/RxbYbQoKCr4AAD@kzFY1/IslamicCalendar-A-Case-Study.pdf, retrieved 2008-01-31 </li>
- ↑ 12.0 12.1 Bradley Steffens (2006). Ibn al-Haytham: First Scientist, Morgan Reynolds Publishing, ISBN 1599350246. (cf. Bradley Steffens, "Who Was the First Scientist?", Ezine Articles.) </li>
- ↑ Rashed (2007), p. 11. </li>
- ↑ 14.0 14.1 C. Plott (2000), Global History of Philosophy: The Period of Scholasticism, Pt. II, p. 465. ISBN 8120805518, Motilal Banarsidass Publ. </li>
- ↑ 15.0 15.1 15.2 (Ragep 2001a) </li>
- ↑ 16.0 16.1 (Ragep 2001b) </li>
- ↑ 17.0 17.1 17.2 Robert Briffault (1928). The Making of Humanity, p. 191. G. Allen & Unwin Ltd. </li>
- ↑ 18.0 18.1 Will Durant (1980). The Age of Faith (The Story of Civilization, Volume 4), p. 162-186. Simon & Schuster. ISBN 0671012002. </li>
- ↑ 19.0 19.1 Ahmad, I. A. (June 3, 2002), The Rise and Fall of Islamic Science: The Calendar as a Case Study, Faith and Reason: Convergence and Complementarity, Al Akhawayn University. Retrieved on 2008-01-31. </li>
(cf. C. A. Qadir (1990), Philosophy and Science in the lslumic World, Routledge, London)Observe nature and reflect over it.
(cf. Bettany, Laurence (1995), "Ibn al-Haytham: an answer to multicultural science teaching?", Physics Education 30: 247-252 )
- ↑ “You shall not accept any information, unless you verify it for yourself. I have given you the hearing, the eyesight, and the brain, and you are responsible for using them.”[Qur'an 17:36] </li>
- ↑ “Behold! In the creation of the heavens and the earth; in the alternation of the night and the day; in the sailing of the ships through the ocean for the benefit of mankind; in the rain which Allah Sends down from the skies, and the life which He gives therewith to an earth that is dead; in the beasts of all kinds that He scatters through the earth; in the change of the winds, and the clouds which they trail like their slaves between the sky and the earth - (Here) indeed are Signs for a people that are wise.”[Qur'an 2:164] </li>
- ↑ David Agar (2001). Arabic Studies in Physics and Astronomy During 800 - 1400 AD. University of Jyväskylä. </li>
- ↑ Koningsveld, Ronald; Stockmayer, Walter H.; Nies, Erik (2001), Polymer Phase Diagrams: A Textbook, Oxford University Press, pp. xii-xiii, ISBN 0198556349, OCLC 45736855 69291240 45375807 45736855 69291240 </li>
- ↑ Plinio Prioreschi, "Al-Kindi, A Precursor Of The Scientific Revolution", Journal of the International Society for the History of Islamic Medicine, 2002 (2): 17-19. </li>
- ↑ Robert Briffault (1928). The Making of Humanity, p. 202. G. Allen & Unwin Ltd. </li>
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- ↑ Oliver Joseph Lodge, Pioneers of Science, p. 9. </li>
- ↑ Muhammad Iqbal (1934, 1999), The Reconstruction of Religious Thought in Islam, Kazi Publications, ISBN 0686184823 </li>
- ↑ D. C. Lindberg, Theories of Vision from al-Kindi to Kepler, (Chicago, Univ. of Chicago Pr., 1976), pp. 60-7. </li>
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- ↑ Nader El-Bizri, "A Philosophical Perspective on Alhazen’s Optics," Arabic Sciences and Philosophy, Vol. 15, Issue 2 (2005), pp. 189-218 (Cambridge University Press) </li>
- ↑ Nader El-Bizri, "Ibn al-Haytham," in Medieval Science, Technology, and Medicine: An Encyclopedia, eds. Thomas F. Glick, Steven J. Livesey, and Faith Wallis (New York — London: Routledge, 2005), pp. 237-240. </li>
- ↑ Bradley Steffens (2006). Ibn al-Haytham: First Scientist, Morgan Reynolds Publishing, ISBN 1599350246. </li>
- ↑ Rashed, Roshdi; Armstrong, Angela (1994), The Development of Arabic Mathematics, Springer, pp. 345–6, ISBN 0792325656, OCLC 29181926 </li>
- ↑ Rashed, Roshdi (2007), "The Celestial Kinematics of Ibn al-Haytham", Arabic Sciences and Philosophy (Cambridge University Press) 17: 7–55 , Error: Bad DOI specified:In reforming optics he as it were adopted "positivism" (before the term was invented): we do not go beyond experience, and we cannot be content to use pure concepts in investigating natural phenomena. Understanding of these cannot be acquired without mathematics. Thus, once he has assumed light is a material substance, Ibn al-Haytham does not discuss its nature further, but confines himself to considering its propagation and diffusion. In his optics "the smallest parts of light", as he calls them, retain only properties that can be treated by geometry and verified by experiment; they lack all sensible qualities except energy.
- ↑ Alhazen; Smith, A. Mark (2001), Alhacen's Theory of Visual Perception: A Critical Edition, with English Translation and Commentary of the First Three Books of Alhacen's De Aspectibus, the Medieval Latin Version of Ibn al-Haytham's Kitab al-Manazir, DIANE Publishing, pp. 372 & 408, ISBN 0871699141, OCLC 163278565 185537919 47168716 163278528 163278565 185537919 47168716 </li>
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- ↑ (Glick, Livesey & Wallis 2005, p. 89-90) </li>
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- ↑ McGinnis, Jon (July 2003), "Scientific Methodologies in Medieval Islam", Journal of the History of Philosophy 41 (3): 307–327, Error: Bad DOI specified </li>
- ↑ 44.0 44.1 44.2 44.3 Dallal, Ahmad (2001-2002), The Interplay of Science and Theology in the Fourteenth-century Kalam, From Medieval to Modern in the Islamic World, Sawyer Seminar at the University of Chicago, http://humanities.uchicago.edu/orgs/institute/sawyer/archive/islam/dallal.html, retrieved 2008-02-02 </li>
- ↑ D. C. Lindberg (1976), Theories of Vision from al-Kindi to Kepler, Chicago: Univ. of Chicago Pr., p. 19 </li>
- ↑ K. B. Wolf, "Geometry and dynamics in refracting systems", European Journal of Physics 16, p. 14-20, 1995. </li>
- ↑ R. Rashed, "A pioneer in anaclastics: Ibn Sahl on burning mirrors and lenses", Isis 81, p. 464–491, 1990. </li>
- ↑ D. C. Lindberg, "Alhazen's Theory of Vision and its Reception in the West", Isis, 58 (1967), p. 322. </li>
- ↑ David C. Lindberg, "The Theory of Pinhole Images from Antiquity to the Thirteenth Century," Archive for History of the Exact Sciences, 5(1968):154-176. </li>
- ↑ D. C. Lindberg, Theories of Vision from al-Kindi to Kepler, (Chicago: Univ. of Chicago Pr., 1976), pp. 58-86. </li>
- ↑ Rashed, Roshdi (2007), "The Celestial Kinematics of Ibn al-Haytham", Arabic Sciences and Philosophy (Cambridge University Press) 17: 7–55 , Error: Bad DOI specified:In his optics "the smallest parts of light", as he calls them, retain only properties that can be treated by geometry and verified by experiment; they lack all sensible qualities except energy.
- ↑ J. J. O'Connor and E. F. Robertson (2002). Light through the ages: Ancient Greece to Maxwell, MacTutor History of Mathematics archive. </li>
- ↑ MacKay, R. J.; Oldford, R. W. (August 2000), "Scientific Method, Statistical Method and the Speed of Light", Statistical Science 15 (3): 254–78, Error: Bad DOI specified </li>
- ↑ 54.0 54.1 54.2 Sami Hamarneh (March 1972). Review of Hakim Mohammed Said, Ibn al-Haitham, Isis 63 (1), p. 119 </li>
- ↑ H. Salih, M. Al-Amri, M. El Gomati (2005). "The Miracle of Light", A World of Science 3 (3). UNESCO. </li>
- ↑ Sabra, A. I.; Hogendijk, J. P. (2003), The Enterprise of Science in Islam: New Perspectives, MIT Press, pp. 85–118, ISBN 0262194821, OCLC 50252039 237875424 50252039 </li>
- ↑ Hatfield, Gary (1996), "Was the Scientific Revolution Really a Revolution in Science?", in Ragep, F. J.; Ragep, Sally P.; Livesey, Steven John, Tradition, Transmission, Transformation: Proceedings of Two Conferences on Pre-modern Science held at the University of Oklahoma, Brill Publishers, p. 500, ISBN 9004091262, OCLC 234073624 234096934 19740432 234073624 234096934 </li>
- ↑ R. S. Elliott (1966). Electromagnetics, Chapter 1. McGraw-Hill. </li>
- ↑ Dijksterhuis, Fokko Jan (2004), Lenses and Waves: Christiaan Huygens and the Mathematical Science of Optics in the Seventeenth Century, Springer, pp. 113–5, ISBN 1402026978, OCLC 56533625 228400027 56533625:Through the influential work of Alhacen the onset of a physico-mathematical conception of optics was established at a much earlier time than would be the case in the other mathematical sciences.
- ↑ Steffens (cf.) </li>
- ↑ Bashar Saad, Hassan Azaizeh, Omar Said (October 2005). "Tradition and Perspectives of Arab Herbal Medicine: A Review", Evidence-based Complementary and Alternative Medicine 2 (4), p. 475-479 . Oxford University Press </li>
- ↑ <cite style="font-style:normal">Ian P. Howard (1996). "Alhazen's neglected discoveries of visual phenomena". Perception 25 (10): 1203–1217. doi:10.1068/p251203. PMID 9027923.</cite> </li>
- ↑ (Wade 1998) </li>
- ↑ (Howard & Wade 1996) </li>
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- ↑ Gul A. Russell, "Emergence of Physiological Optics", pp. 689-90, in (Morelon & Rashed 1996) </li>
- ↑ Gul A. Russell, "Emergence of Physiological Optics", p. 690, in (Morelon & Rashed 1996) </li>
- ↑ Gul A. Russell, "Emergence of Physiological Optics", p. 692, in (Morelon & Rashed 1996) </li>
- ↑ Gul A. Russell, "Emergence of Physiological Optics", p. 691, in (Morelon & Rashed 1996) </li>
- ↑ Gul A. Russell, "Emergence of Physiological Optics", p. 695-8, in (Morelon & Rashed 1996) </li>
- ↑ <cite class="book" style="font-style:normal" >N. J. Wade (1998). A Natural History of Vision. Cambridge, MA: MIT Press.</cite> </li>
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- ↑ 73.0 73.1 O'Connor, J. J.; Robertson, E. F. (November 1999). "Kamal al-Din Abu'l Hasan Muhammad Al-Farisi". MacTutor History of Mathematics archive, University of St Andrews. Retrieved on 2007-06-07. </li>
- ↑ Topdemir, Hüseyin Gazi (2007), "Kamal Al-Din Al-Farisi’s Explanation of the Rainbow" (PDF), Humanity & Social Sciences Journal 2 (1): 75–85 , http://www.idosi.org/hssj/hssj2(1)07/10.pdf, retrieved 2008-09-16 </li>
- ↑ Carl Benjamin Boyer (1954), "Robert Grosseteste on the Rainbow", Osiris 11: 247-258  </li>
- ↑ O'Connor, John J.; Robertson, Edmund F., "Al-Farisi", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Al-Farisi.html. </li>
- ↑ Nader El-Bizri, "Ibn al-Haytham", in Medieval Science, Technology, and Medicine: An Encyclopedia, eds. Thomas F. Glick, Steven J. Livesey, and Faith Wallis (New York — London: Routledge, 2005), pp. 237-240. </li>
- ↑ Nader El-Bizri, "Optics", in Medieval Islamic Civilization: An Encyclopedia, ed. Josef W. Meri (New York – London: Routledge, 2005), Vol. II, pp. 578-580 </li>
- ↑ Nader El-Bizri, "Al-Farisi, Kamal al-Din," in The Biographical Encyclopaedia of Islamic Philosophy, ed. Oliver Leaman (London — New York: Thoemmes Continuum, 2006), Vol. I, pp. 131-135 </li>
- ↑ Nader El-Bizri, "Ibn al-Haytham, al-Hasan", in The Biographical Encyclopaedia of Islamic Philosophy, ed. Oliver Leaman (London — New York: Thoemmes Continuum, 2006), Vol. I, pp. 248-255. </li>
- ↑ O'Connor, John J.; Robertson, Edmund F., "Abu Ali al-Hasan ibn al-Haytham", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Al-Haytham.html. </li>
- ↑ George Sarton, Introduction to the History of Science, Vol. 1, p. 710. </li>
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- ↑ 85.0 85.1 85.2 85.3 85.4 Topdemir, Hüseyin Gazi (1999), Takîyüddîn'in Optik Kitabi, Ministry of Culture Press, Ankara (cf. Dr. Hüseyin Gazi Topdemir (30 June 2008). "Taqi al-Din ibn Ma‘ruf and the Science of Optics: The Nature of Light and the Mechanism of Vision". FSTC Limited. Retrieved on 2008-07-04.) </li>
- ↑ Poore, Daniel. A History of Early Flight. New York: Alfred Knopf, 1952. </li>
- ↑ Smithsonian Institution. Manned Flight. Pamphlet 1990. </li>
- ↑ David W. Tschanz, Flights of Fancy on Manmade Wings, IslamOnline.net. </li>
- ↑ Parachutes, Principles of Aeronautics, Franklin Institute. </li>
- ↑ John H. Lienhard (2004). "'Abbas Ibn Firnas". The Engines of Our Ingenuity. episode 1910. NPR. KUHF-FM Houston. </li>
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- ↑ First Flights, Saudi Aramco World, January-February 1964, p. 8-9. </li>
- ↑ Harding, John (2006), Flying's strangest moments: extraordinary but true stories from over one thousand years of aviation history, Robson, pp. 1–2, ISBN 1861059345 </li>
- ↑ Philip Hitti, History of the Arabs </li>
- ↑ Lynn Townsend White, Jr. (Spring, 1961). "Eilmer of Malmesbury, an Eleventh Century Aviator: A Case Study of Technological Innovation, Its Context and Tradition", Technology and Culture 2 (2), p. 97-111 [100f.] </li>
- ↑ Çelebi, Evliya (2003). Seyahatname. Istanbul: Yapı Kredi Kültür Sanat Yayıncılık, p. 318. </li>
- ↑ Winter, Frank H. (1992). "Who First Flew in a Rocket?", Journal of the British Interplanetary Society 45 (July 1992), p. 275-80 </li>
- ↑ Harding, John (2006), Flying's strangest moments: extraordinary but true stories from over one thousand years of aviation history, Robson Publishing, p. 5, ISBN 1861059345 </li>
- ↑ Arabic and Islamic Natural Philosophy and Natural Science, Stanford Encyclopedia of Philosophy </li>
- ↑ El-Bizri, Nader (2007), "In Defence of the Sovereignty of Philosophy: Al-Baghdadi's Critique of Ibn al-Haytham's Geometrisation of Place", Arabic Sciences and Philosophy (Cambridge University Press) 17: 57–80, Error: Bad DOI specified </li>
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- ↑ Gul A. Russell, "Emergence of Physiological Optics", p. 695, in Morelon, Régis; Rashed, Roshdi (1996), Encyclopedia of the History of Arabic Science, 2, Routledge, ISBN 0415124107 </li>
- ↑ Will Durant (1950). The Age of Faith, p. 244. Simon and Shuster, New York. (cf. Khwarizm, Foundation for Science Technology and Civilisation.) </li>
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(cf. Abel B. Franco (October 2003). "Avempace, Projectile Motion, and Impetus Theory", Journal of the History of Ideas 64 (4), p. 521-546 .) </li>
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(cf. Abel B. Franco (October 2003), "Avempace, Projectile Motion, and Impetus Theory", Journal of the History of Ideas 64 (4): 521-546 ) </li>
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- Astronomy in medieval Islam
- Book of Optics
- Celestial spheres
- Early Islamic philosophy
- History of optics
- History of physics
- Islamic contributions to Medieval Europe
- Islamic Golden Age
- Islamic science and technology
- List of Muslim scientists
- Science in the Middle Ages
- Theory of impetus