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 موضوع: بحث في الانجليزية للسنة الثانية ثانوي ibn alHaytham الإثنين يناير 19, 2015 7:40 pm  
 ibn alHaytham Abu Ali alHasan ibn alHasan ibn alHaytham was a prominent scientist and polymath from the ‘Golden Age’ of Muslim civilization. He is commonly referred to as Ibn alHaytham, and sometimes as alBasri, after his birthplace in the city of Basra.Ibn alHaytham made significant contributions to the principles of optics, as well as to physics, astronomy, mathematics, ophthalmology, philosophy, visual perception, and to the scientific method. He was also nicknamed Ptolemaeus Secundus ("Ptolemy the Second") or simply "The Physicist" in medieval Europe. Ibn alHaytham wrote insightful commentaries on works by Aristotle, Ptolemy, and the Greek mathematician Euclid.Born circa 965, in Basra, Iraq, he lived mainly in Cairo, Egypt, dying there at age 76. Overconfident about practical application of his mathematical knowledge, he assumed that he could regulate the floods of the Nile.After being ordered by alHakim biAmr Allah, the sixth ruler of the Fatimid caliphate, to carry out this operation, he quickly perceived the impossibility of what he was attempting to do, and retired from engineering. Fearing for his life, he feigned madness and was placed under house arrest, during and after which he devoted himself to his scientific work until his death. Biography Born c. 965 in Basra, which was then part of the Buyid emirate, to an Arab family.He arrived in Cairo under the reign of Fatimid Caliph alHakim, a patron of the sciences who was particularly interested in astronomy.Ibn alHaytham has proposed to the Caliph a hydraulic project to improve regulation of the flooding of the Nile, a task requiring an early attempt at building a dam at the present site of the Aswan Dam. His field work convinced him of the technical impracticality of this scheme.[18] AlHaytham continued to live in Cairo, in the neighborhood of the famous University of alAzhar, until his death after 1040.[10] Legend has it that after deciding the scheme was impractical and fearing the caliph's anger, Alhazen feigned madness and was kept under house arrest from 1011 until alHakim's death in 1021.[19] During this time, he wrote his influential Book of Optics and continued to write further treatises on astronomy, geometry, number theory, optics and natural philosophy. Legacy: Alhazen made significant contributions to optics, number theory, geometry, astronomy and natural philosophy. Alhazen's work on optics is credited with contributing a new emphasis on experiment.His main work, Kitab alManazir (Book of Optics) was known in Islamicate societies mainly, but not exclusively, through the thirteenthcentury commentary by Kamāl alDīn alFārisī, the Tanqīḥ alManāẓir lidhawī labṣār wa lbaṣā'ir. In alAndalus, it was used by the eleventhcentury prince of the Banu Hud dynasty of Zaragossa and author of an important mathematical text, alMu'taman ibn Hūd. A Latin translation of the Kitab alManazir was made probably in the late twelfth or early thirteenth century. This translation was read by and greatly influenced a number of scholars in Catholic Europe including: Roger Bacon, Robert Grosseteste, Witelo, Giambattista della Porta,Leonardo Da Vinci, Galileo Galilei, Christian Huygens, René Descartes, and Johannes Kepler. His research in catoptrics (the study of optical systems using mirrors) centred on spherical and parabolic mirrors and spherical aberration. He made the observation that the ratio between the angle of incidence and refraction does not remain constant, and investigated the magnifying power of a lens. His work on catoptrics also contains the problem known as "Alhazen's problem". Meanwhile in the Islamic world, Alhazen's work influenced Averroes' writings on optics, and his legacy was further advanced through the 'reforming' of his Optics by Persian scientist Kamal alDin alFarisi (died ca. 1320) in the latter's Kitab Tanqih alManazir (The Revision of [Ibn alHaytham's] Optics). Alhazen wrote as many as 200 books, although only 55 have survived, and many of those have not yet been translated from Arabic.[citation needed] Some of his treatises on optics survived only through Latin translation. During the Middle Ages his books on cosmology were translated into Latin, Hebrew and other languages. The crater Alhazen on the Moon is named in his honour, as was the asteroid 59239 Alhazen. In honour of Alhazen, the Aga Khan University (Pakistan) named its Ophthalmology endowed chair as "The IbneHaitham Associate Professor and Chief of Ophthalmology". Alhazen, by the name Ibn alHaytham, is featured on the obverse of the Iraqi 10,000dinar banknote issued in 2003, and on 10dinar notes from 1982. A research facility that UN weapons inspectors suspected of conducting chemical and biological weapons research in Saddam Hussein's Iraq was also named after him. Book of Optics: Alhazen's most famous work is his sevenvolume treatise on optics Kitab alManazir (Book of Optics), written from 1011 to 1021.Optics was translated into Latin by an unknown scholar at the end of the 12th century or the beginning of the 13th century.[39] It was printed by Friedrich Risner in 1572, with the title Opticae thesaurus: Alhazeni Arabis libri septem, nuncprimum editi; Eiusdem liber De Crepusculis et nubium ascensionibus .Risner is also the author of the name variant "Alhazen"; before Risner he was known in the west as Alhacen, which is the correct transcription of the Arabic name.[41] This work enjoyed a great reputation during the Middle Ages. Works by Alhazen on geometric subjects were discovered in the Bibliothèque nationale in Paris in 1834 by E. A. Sedillot. Other manuscripts are preserved in the Bodleian Library at Oxford and in the library of Leiden. Alhazen's problem :His work on catoptrics in Book V of the Book of Optics contains a discussion of what is now known as Alhazen's problem, first formulated by Ptolemy in 150 AD. It comprises drawing lines from two points in the plane of a circle meeting at a point on the circumference and making equal angles with the normal at that point. This is equivalent to finding the point on the edge of a circular billiard table at which a cue ball at a given point must be aimed in order to carom off the edge of the table and hit another ball at a second given point. Thus, its main application in optics is to solve the problem, "Given a light source and a spherical mirror, find the point on the mirror where the light will be reflected to the eye of an observer." This leads to an equation of the fourth degree. This eventually led Alhazen to derive a formula for the sum of fourth powers, where previously only the formulas for the sums of squares and cubes had been stated. His method can be readily generalized to find the formula for the sum of any integral powers, although he did not himself do this (perhaps because he only needed the fourth power to calculate the volume of the paraboloid he was interested in). He used his result on sums of integral powers to perform what would now be called an integration, where the formulas for the sums of integral squares and fourth powers allowed him to calculate the volume of a paraboloid. Alhazen eventually solved the problem using conic sections and a geometric proof. His solution was extremely long and complicated and may not have been understood by mathematicians reading him in Latin translation. Later mathematicians used Descartes' analytical methods to analyse the problem, with a new solution being found in 1997 by the Oxford mathematician Peter M. Neumann. Recently, Mitsubishi Electric Research Laboratories (MERL) researchers Amit Agrawal, Yuichi Taguchi and Srikumar Ramalingam solved the extension of Alhazen's problem to general rotationally symmetric quadric mirrors including hyperbolic, parabolic and elliptical mirrors. They showed that the mirror reflection point can be computed by solving an eighth degree equation in the most general case. If the camera (eye) is placed on the axis of the mirror, the degree of the equation reduces to six. Alhazen's problem can also be extended to multiple refractions from a spherical ball. Given a light source and a spherical ball of certain refractive index, the closest point on the spherical ball where the light is refracted to the eye of the observer can be obtained by solving a tenth degree equation. Optical treatises : Besides the Book of Optics, Alhazen wrote several other treatises on the same subject, including his Risala fi lDaw’ (Treatise on Light). He investigated the properties of luminance, the rainbow, eclipses, twilight, and moonlight. Experiments with mirrors and magnifying lenses provided the foundation for his theories on catoptrics.In his treatise Mizan alHikmah (Balance of Wisdom), Alhazen discussed the density of the atmosphere and related it to altitude. He also studied atmospheric refraction. Mechanics :In his work, Alhazen discussed theories on the motion of a body. In his Treatise on Place, Alhazen disagreed with Aristotle's view that nature abhors a void, and he used geometry in an attempt to demonstrate that place (almakan) is the imagined threedimensional void between the inner surfaces of a containing body. Geometry: In geometry, Alhazen developed analytical geometry and the link between algebra and geometry. He developed a formula for adding the first 100 natural numbers, using a geometric proof to prove the formula.Alhazen explored what is now known as the Euclidean parallel postulate, the fifth postulate in Euclid's Elements, using a proof by contradiction, and in effect introducing the concept of motion into geometry. He formulated the Lambert quadrilateral, which Boris Abramovich Rozenfeld names the "Ibn alHaytham–Lambert quadrilateral". His theorems on quadrilaterals, including the Lambert quadrilateral, were the first theorems on elliptical geometry and hyperbolic geometry. These theorems, along with his alternative postulates, such as Playfair's axiom, can be seen as marking the beginning of nonEuclidean geometry. His work had a considerable influence on its development among the later Persian geometers Omar Khayyám and Nasīr alDīn alTūsī, and the European geometers Witelo, Gersonides, and Alfonso.In elementary geometry, Alhazen attempted to solve the problem of squaring the circle using the area of lunes (crescent shapes), but later gave up on the impossible task. The two lunes formed from a right triangle by erecting a semicircle on each of the triangle's sides, inward for the hypotenuse and outward for the other two sides, are known as the lunes of Alhazen; they have the same total area as the triangle itself. Philosophy:In his Treatise on Place, Alhazen disagreed with Aristotle's view that nature abhors a void, and he used geometry in an attempt to demonstrate that place (almakan) is the imagined threedimensional void between the inner surfaces of a containing body. Abdellatif, a supporter of Aristotle's philosophical view of place, later criticized the work in Fi alRadd ‘ala Ibn alHaytham fi almakan (A refutation of Ibn alHaytham’s place) for its geometrization of place.Alhazen also discussed space perception and its epistemological implications in his Book of Optics. In "tying the visual perception of space to prior bodily experience, Alhacen unequivocally rejected the intuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size for correlation, sight can tell us next to nothing about such things
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