- Ibn al-Haytham
Infobox_Muslim scholars | notability = Muslim scientist| era =
Islamic Golden Age | color = #cef2e0 |
| image_caption = Ibn al-Haytham drawing taken from a 1982 Iraqi 10-dinar note. |
|name = Unicode|Abū ‘Alī al-Ḥasan ibn al-Ḥasan ibn al-Haytham
title= Ibn al-Haytham and Alhacen| birth = 965 | death = c. 1040 | Maddhab =Shi'a Muslim | school tradition= Ja'fari | Ethnicity =Arab and/or Persian
Region =Iraq (Mesopotamia ) andEgypt | main_interests =Anatomy , Astronomy, Engineering, Mathematics,Mechanics , Medicine,Optics , Ophthalmology, Philosophy, Physics, Psychology, Science
notable idea = Pioneer inoptics ,scientific method , experimental science,experimental physics ,experimental psychology ,visual perception , phenomenology,analytic geometry , non-Ptolemaic astronomy ,celestial mechanics
influences =Aristotle ,Euclid ,Ptolemy ,Galen ,Muhammad ,Banū Mūsā ,Thabit ibn Qurra ,al-Kindi ,Ibn Sahl , al-Qūhī
influenced =Khayyam ,al-Khazini ,Averroes ,Roger Bacon ,Witelo , Pecham,Farisi , Theodoric,Gersonides ,Alfonso , von Peuerbach,Taqi al-Din , Risner, Clavius,Kepler ,John Wallis ,Saccheri
works = "Book of Optics ", "Doubts Concerning Ptolemy", "On the Configuration of the World", "The Model of the Motions", "Treatise on Light", "Treatise on Place"
transl|ar|ALA|Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham (Arabic: ابو علی، حسن بن حسن بن هيثم, Latinized: Alhacen or (deprecated) Alhazen) (965 – c. 1039), was anArab [Harv|Smith|1992
Harv|Grant|2008
Harv|Vernet|2008
citation|url=http://www.encyclopedia.com/doc/1E1-IbnalHay.html|contribution=Ibn al-Haytham|title=Columbia Encyclopedia |edition=Sixth|year=2007|accessdate=2008-01-23|isbn=0787650757|author=Paul Lagasse|publisher=Columbia] and/or Persian [Harv|Child|Shuter|Taylor|1992|p=70
Harv|Dessel|Nehrich|Voran|1973|p=164
Harv|Samuelson|Crookes|p=497]polymath . [Harv|Hamarneh|1972: quote|A great man and a universal genius, long neglected even by his own people. Harv|Bettany|1995: quote|Ibn ai-Haytham provides us with the historical personage of a versatile universal genius.] He made significant contributions to the principles ofoptics , as well as toanatomy , astronomy, engineering, mathematics, medicine, ophthalmology, philosophy, physics, psychology,visual perception , and to science in general with his introduction of thescientific method . He is sometimes called al-Basri (Arabic: البصري), after his birthplace in the city ofBasra . He was also nicknamed "Ptolemaeus Secundus" ("Ptolemy the Second")Harv|Corbin|1993|p=149] or simply "The Physicist" [Harv|Lindberg|1967|p=331] in medieval Europe.Though born in what is now modern-day
Iraq around the year 965Harv|Lorch|2008] , he spent most of his life inCairo ,Egypt , dying there at the age of 76. In his over-confidence about the practical application of his mathematical knowledge, he assumed that he could regulate the floods caused by the overflow of theNile .Harv|Sabra|2003] After being ordered byAl-Hakim bi-Amr Allah , the sixth ruler of the Fatimid caliphate, to carry out this operation, he quickly perceived the inanity of what he was attempting to do, and retired from engineering. Fearing for his life, hefeigned madness Harv|Grant|2008] and was placed underhouse arrest , during and after which he devoted himself to his scientific work until his death.Ibn al-Haytham is regarded as the "father of modern optics" [Harv|Verma|1969] for his influential "
Book of Optics " (written while he was under house arrest), which correctly explained and proved the modern intromission theory of vision. He is also recognized so for hisexperiment s on optics, including experiments on lenses,mirror s,refraction , reflection, and the dispersion oflight into its constituent colours.He studiedbinocular vision and theMoon illusion , described the finite speed [Harv|MacKay|Oldford|2000] of light, and argued that it is made of particles [Harv|Rashed|2007|p=19: quote|"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."] travelling in straight lines.Harv|Hamarneh|1972|p=119] [Harv|O'Connor|Robertson|2002] Due to his formulation of a modernquantitative andempirical approach tophysics and science, he is considered the pioneer of the modern scientific methodHarv|Agar|2001] and the originator of the experimental nature of physics [Harv|Thiele|2005] and science. [Harv|Omar|1977] Author Bradley Steffens describes him as the "first scientist". [Harv|Steffens|2006] He is also considered byA. I. Sabra to be the founder ofexperimental psychology Harv|Khaleefa|1999] for his approach to visual perception andoptical illusion s,Harv|Steffens|2006, Chapter 5] and a pioneer of the philosophical field of phenomenology or the study ofconsciousness from afirst-person perspective .His "Book of Optics" has been ranked withIsaac Newton 's "Philosophiae Naturalis Principia Mathematica " as one of the most influential books in thehistory of physics ,Harv|Salih|Al-Amri|El Gomati|2005] for starting a revolution in optics and visual perception.Ibn al-Haytham's achievements include many advances in physics and mathematics. He gave the first clear description and correct analysis of the
camera obscura . He enunciatedFermat's principle of least time and the concept ofinertia (Newton's first law of motion ), and developed the concept ofmomentum . He described the attraction betweenmass es and was aware of the magnitude ofacceleration due to gravity at-a-distance.Harv|El-Bizri|2006] He stated that the heavenly bodies were accountable to the laws of physics and also presented a critique and reform of Ptolemaic astronomy. He was the first to stateWilson's theorem innumber theory , and he formulated theLambert quadrilateral and a concept similar toPlayfair's axiom Harv|Smith|1992] now used innon-Euclidean geometry . Moreover, he formulated and solved Alhazen's problem geometrically using early ideas related tocalculus andmathematical induction . In his optical research, he laid the foundations for the later development of telescopic astronomy,Harv|Marshall|1950] as well as for themicroscope and the use of optical aids inRenaissance art.Overview
Biography
Abū ‘Alī al-Hasan ibn al-Hasan ibn al-Haytham (and known in Europe as Alhacen or Alhazen) was born in
Basra , then under the rule of theBuyid dynasty of thePersian Empire and now part ofIraq , and he probably died inCairo ,Egypt . During theIslamic Golden Age , Basra was a "key centre of learning",Harv|Whitaker|2004] and he was educated there and inBaghdad , the capital of theAbbasid Caliphate , and the focus of the "high point of Islamic civilisation". During his time in Iraq, he worked as acivil servant and read many theological and scientific books.Harv|O'Connor|Robertson|1999]One account of his career has him summoned to Egypt by the
Al-Hakim bi-Amr Allah , ruler of theFatimid Caliphate , to regulate theflooding of the Nile , a task requiring an early attempt at building adam at the present site of theAswan Dam . [Harv|Rashed|2002b] After hisfield work made him aware of the impracticality of this scheme, and fearing the caliph's anger, hefeigned madness . He was kept underhouse arrest from 1011 until al-Hakim's death in 1021. [ [http://www.cgie.org.ir/shavad.asp?id=123&avaid=1917 the Great Islamic Encyclopedia] ] During this time, he wrote his influential "Book of Optics ".Although there are stories that Ibn al-Haytham fled to Syria, ventured into Baghdad later in his life, or was even in Basra when he pretended to be insane, it is certain that he was in Egypt by 1038 at the latest. During his time in Cairo, he became associated with
Al-Azhar University , as well the city's "House of Wisdom", [Harv|Van Sertima|1992|p=382] known as "Dar Al-Hekma" (House of Knowledge ), which was a library "second in importance" to Baghdad'sHouse of Wisdom . After his house arrest ended, he wrote scores of other treatises on physics, astronomy and mathematics. He later traveled to Islamic Spain. During this period, he had ample time for his scientific pursuits, which included optics, mathematics, physics, medicine, and the development of scientific methods; he left several outstanding books on these subjects.Legacy
Ibn al-Haythem made significant improvements in optics, physical science, and the scientific method which influenced the development of science for over five hundred years after his death. Ibn al-Haytham's work on optics is credited with contributing a new emphasis on experiment. His influence on
physical science s in general, and on optics in particular, has been held in high esteem and, in fact, ushered in a new era in optical research, both in theory and practice. The scientific method is considered to be so fundamental to modern science that some—especially philosophers of science and practising scientists—consider earlier inquiries into nature to be "pre-scientific". [Harv|Briffault|1928|p=190–202:quote|What we call science arose as a result of new methods of experiment, observation, and measurement, which were introduced into Europe 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. […] 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 Greeks were a foreign importation never thoroughly acclimatized in Greek culture. The Greeks systematized, generalized and theorized, but the patient ways of investigations, the accumulation of positive knowledge, the minute methods of science, detailed and prolonged observation and experimental inquiry were altogether alien to the Greek temperament. […] What we call science arose in Europe as a result of new spirit of enquiry, of new methods 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.]Richard Powers nominated Ibn al-Haytham's scientific method andscientific skepticism as the most influential idea of the second millennium.Harv|Powers|1999] Recipient of theNobel Prize in Physics Abdus Salam considered Ibn-al-Haytham "one of the greatest physicists of all time."Harv|Salam|1984:quote|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".]George Sarton , the father of thehistory of science , wrote that "Ibn Haytham's writings reveal his fine development of the experimental faculty" and considered him "not only the greatest Muslim physicist, but by all means the greatest of mediaeval times." [Harv|Sarton|1927, "The Time of Al-Biruni":quote|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. (cf. Harv|Dr. Zahoor|Dr. Haq|1997)] Robert S. Elliot considers Ibn al-Haytham to be "one of the ablest students of optics of all times." [Harv|Elliott|1966, Chapter 1:quote|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 author Bradley Steffens considers him to be the "first scientist". [Harv|Steffens|2006] The "Biographical Dictionary of Scientists" wrote that Ibn al-Haytham was "probably the greatest scientist of the Middle Ages" and that "his work remained unsurpassed for nearly 600 years until the time of Johannes Kepler." ["Alhazen", in Harv|Abbott|1983|p=75:quote|He was probably the greatest scientist of the Middle Ages and his work remained unsurpassed for nearly 600 years until the time of Johannes Kepler.] At a scientific conference in February 2007 as a part of theHockney-Falco thesis ,Charles M. Falco argued that Ibn al-Haytham's work on optics may have influenced the use of optical aids byRenaissance art ists. Falco said that his andDavid Hockney 's examples of Renaissance art "demonstrate a continuum in the use of optics by artists from "circa" 1430, arguably initiated as a result of Ibn al-Haytham's influence, until today." [Harv|Falco|2007]The Latin translation of his main work, "Kitab al-Manazir" ("Book of Optics"), exerted a great influence on Western science: for example, on the work of
Roger Bacon , who cites him by name, [Harv|Lindberg|1996|p=11, passim] and onJohannes Kepler . It brought about a great progress in experimental methods. His research incatoptrics (the study of optical systems using mirrors) centred on spherical and parabolic mirrors andspherical aberration . He made the observation that the ratio between theangle of incidence andrefraction 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, Ibn al-Haytham's work influenced
Averroes ' writings on optics,Harv|Topdemir|2007a|p=77] and his legacy was further advanced through the 'reforming' of his "Optics" by Persian scientistKamal al-Din al-Farisi (d. ca. 1320) in the latter's "Kitab Tanqih al-Manazir" ("The Revision of" [Ibn al-Haytham's] "Optics"). The correct explanations of the rainbow phenomenon given by al-Fārisī andTheodoric of Freiberg in the 14th Century depended on Ibn al-Haytham's "Book of Optics". [Harv|Topdemir|2007a|p=83] The work of Ibn al-Haytham and al-Fārisī was also further advanced in theOttoman Empire by polymathTaqi al-Din in his "Book of the Light of the Pupil of Vision and the Light of the Truth of the Sights" (1574). [Harv|Topdemir|1999 (cf. Harv|Topdemir|2008)]He wrote around 200 books, although very few have survived. Even 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 Alhazen crater on the Moon was named in his honour, as was the
asteroid "59239 Alhazen ". [cite web
last =
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title = 59239 Alhazen (1999 CR2)
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publisher =NASA
date =2006-03-22
url = http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=59239+Alhazen
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accessdate = 2008-09-20] Ibn al-Haytham is featured on the obverse of the Iraqi 10,000 dinars banknote issued in 2003,Harv|Murphy|2003] and on 10 dinar notes from 1982. A research facility thatUN weapons inspectors suspected of conducting chemical and biological weapons research in Saddam Hussein's Iraq was also named after him. [Harv|Burns|1999]"Book of Optics"
Ibn al-Haytham's most famous work is his seven volume Arabic treatise on
optics , "Kitab al-Manazir" ("Book of Optics"), written from 1011 to 1021.Harv|Steffens|2006 (cf. cite web|url=http://www.ibnalhaytham.net/custom.em?pid=571860|title=Critical Praise for "Ibn al-Haytham - First Scientist"|date=2006-12-01|accessdate=2008-01-23)] It has been ranked alongsideIsaac Newton 's "Philosophiae Naturalis Principia Mathematica " as one of the most influential books in physics for introducing an early scientific method, and for initiating a revolution in opticsHarv|Sabra|Hogendijk|2003|pp=85–118] andvisual perception .Harv|Hatfield|1996|p=500]"Optics" was translated into Latin by an unknown scholar at the end of the 12th century or the beginning of the 13th century. [Harv|Crombie|1971|p=147, n. 2] 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". [cite web|url=http://www.mala.bc.ca/~mcneil/cit/citlcalhazen1.htm|title=Alhazen (965-1040): Library of Congress Citations|publisher=Malaspina Great Books|accessdate=2008-01-23] 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. [Harv|Smith|2001|p=xxi] This work enjoyed a great reputation during theMiddle Ages . Works by Ibn al-Haytham on geometric subjects were discovered in theBibliothèque nationale inParis in 1834 by E. A. Sedillot. Other manuscripts are preserved in theBodleian Library atOxford and in the library ofLeiden . Ibn al-Haytham's optical studies were influential in several later developments, including thetelescope , which laid the foundations of telescopic astronomy, as well as of the moderncamera , themicroscope , and the use of optical aids inRenaissance art.Optics
Two major theories on vision prevailed in
classical antiquity . The first theory, the emission theory, was supported by such thinkers asEuclid andPtolemy , who believed that sight worked by the eye emitting rays oflight . The second theory, the intromission theory supported byAristotle and his followers, had physical forms entering the eye from an object. Ibn al-Haytham argued that the process of vision occurs neither by rays emitted from the eye, nor through physical forms entering it. He reasoned that a ray could not proceed from the eyes and reach the distant stars the instant after we open our eyes. He also appealed to common observations such as the eye being dazzled or even injured if we look at a very bright light. He instead developed a highly successful theory which explained the process of vision as rays of light proceeding to the eye from each point on an object, which he proved through the use ofexperiment ation. [Harv|Lindberg|1976|pp=60–7] His unification ofgeometrical optics with philosophical physics forms the basis of modernphysical optics . [Harv|Toomer|1964]Ibn al-Haytham proved that rays of light travel in straight lines, and carried out various experiments with lenses,
mirror s,refraction , and reflection. He was also the first to reduce reflected and refracted light rays into vertical and horizontal components, which was a fundamental development in geometric optics. [Harv|Heeffer|2003] He also discovered a result similar toSnell's law of sines, but did not quantify it and derive the law mathematically. [Harv|Sabra|1981 (cf. Harv|Mihas|2005|p=5)]Ibn al-Haytham also gave the first clear descriptionHarv|Kelley|Milone|Aveni|2005: quote|"The first clear description of the device appears in the "Book of Optics" of Alhazen."] and correct analysisHarv|Wade|Finger|2001: quote|"The principles of the camera obscura first began to be correctly analysed in the eleventh century, when they were outlined by Ibn al-Haytham."] of the
camera obscura andpinhole camera . WhileAristotle ,Theon of Alexandria ,Al-Kindi (Alkindus) andChinese philosopher Mozi had earlier described the effects of a single light passing through a pinhole, none of them suggested that what is being projected onto the screen is an image of everything on the other side of theaperture . Ibn al-Haytham was the first to demonstrate this with his lamp experiment where several different light sources are arranged across a large area. He was thus the first to successfully project an entire image from outdoors onto a screen indoors with the camera obscura. [Harv|Steffens|2006, [http://www.ibnalhaytham.net/custom.em?pid=673906 Chapter Five] ]In addition to physical optics, "The Book of Optics" also gave rise to the field of "physiological optics".Gul A. Russell, "Emergence of Physiological Optics", p. 689, in Harv|Morelon|Rashed|1996] Ibn al-Haytham discussed the topics of medicine, ophthalmology,
anatomy andphysiology , which included commentaries onGalen ic works. [Harv|Steffens|2006 (cf. cite web|url=http://ummahpulse.com/index.php?option=com_content&task=view&id=85&Itemid=54|title=Review by Sulaiman Awan|accessdate=2008-01-23)] He described the process of sight, [Harv|Saad|Azaizeh|Said|2005|p=476] the structure of the eye, image formation in the eye, and thevisual system . He also described what became known asHering's law of equal innervation , verticalhoropter s, andbinocular disparity ,Harv|Howard|1996] and improved on the theories ofbinocular vision ,motion perception and horopters previously discussed byAristotle ,Euclid andPtolemy .Harv|Wade|1998] Harv|Howard|Wade|1996]His most original anatomical contribution was his description of the functional anatomy of the eye as an optical system, [Gul A. Russell, "Emergence of Physiological Optics", p. 691, in Harv|Morelon|Rashed|1996] or optical instrument. His experiments with the camera obscura 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 camera obscura which brought about his synthesis of anatomy and optics, which forms the basis of 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 thepupil as being similar to an aperture. [Gul A. Russell, "Emergence of Physiological Optics", p. 695-8, in Harv|Morelon|Rashed|1996] Regarding the process of image formation, he incorrectly agreed withAvicenna that the lens was the receptive organ of sight, but correctly hinted at theretina being involved in the process.cientific method
Neuroscientist Rosanna Gorini notes that "according to the majority of the historians al-Haytham was the pioneer of the modern
scientific method ."Harv|Gorini|2003] [Harv|Rashed|2002a|p=773] Ibn al-Haytham developed rigorous experimental methods of controlled scientific testing to verify theoretical hypotheses and substantiate inductiveconjecture s. Ibn al-Haytham's scientific method was very similar to the modern scientific method and consisted of the following procedures:
#Observation
#Statement ofproblem
#Formulation ofhypothesis
#Testing of hypothesis usingexperiment ation
#Analysis of experimentalresult s
#Interpretation ofdata and formulation ofconclusion
#Publication of findingsAn 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 grounded his theories of vision, light and colour, as well as his research in catoptrics and
dioptrics (the study of the refraction of light). His legacy was further advanced through the 'reforming' of his "Optics" byKamal al-Din al-Farisi (d. ca. 1320) in the latter's "Kitab Tanqih al-Manazir" ("The Revision of" [Ibn al-Haytham's] "Optics").Harv|El-Bizri|2005a
Harv|El-Bizri|2005b]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 superflous and useless." [Harv|Smith|2001|pp=372 & 408]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 byPtolemy in 150 AD. It comprises drawing lines from two points in the plane of a circle meeting at a point on thecircumference and making equal angles with the normal at that point. This is equivalent to finding the point on the edge of a circularbilliard table at which a cue ball at a given point must be aimed in order to canon 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 weresic the light will be reflected to the eye of an observer." This leads to an equation of the fourth degree. [Harv|Weisstein] This eventually led Ibn al-Haytham to derive the earliest formula for the sum offourth power s; by using an early proof bymathematical induction , he developed a method that can be readily generalized to find the formula for the sum of any integral powers. He applied his result of sums on integral powers to find the volume of aparaboloid through integration. He was thus able to find theintegral s forpolynomial s up to the fourth degree, and came close to finding a general formula for the integrals of any polynomials. This was fundamental to the development ofinfinitesimal and integralcalculus .Harv|Katz|1995|pp=165-9 & 173-4] Ibn al-Haytham eventually solved the problem usingconic section s and a geometric proof, though many after him attempted to find an algebraic solution to the problem, which was finally found in 1997 by the Oxford mathematicianPeter M. Neumann . [Harv|Highfield|1997]Other contributions
Chapters 15–16 of the "Book of Optics" covered astronomy. Ibn al-Haytham was the first to discover that the
celestial spheres do not consist ofsolid matter. He also discovered that the heavens are less dense than the air. These views were later repeated byWitelo and had a significant influence on the Copernican andTychonic system s of astronomy. [Harv|Rosen|1985|pp=19–21]In philosophy, Ibn al-Haytham is considered a pioneer of phenomenology. He articulated a relationship between the physical and observable world and that of
intuition ,psychology andmental function s. His theories regardingknowledge andperception , linking the domains of science and religion, led to a philosophy ofexistence based on the direct observation ofreality from the observer's point of view. [Harv|Dr. Gonzalez|2002]In
Islamic psychology , Ibn al-Haytham is considered the founder ofexperimental psychology byA. I. Sabra , for his pioneering work on the psychology of visual perception andoptical illusion s. In the "Book of Optics ", Ibn al-Haytham was the first scientist to argue that vision occurs in the brain, rather than the eyes. He pointed out that personal experience has an effect on what people see and how they see, and that vision and perception are subjective.He came up with a theory to explain the
Moon illusion , which played an important role in the scientific tradition of medieval Europe. It was an attempt to the solve the problem of the Moon appearing larger near the horizon than it does while higher up in the sky. Arguing against Ptolemy's refraction theory, he redefined the problem in terms of perceived, rather than real, enlargement. He said that judging the distance of an object depends on there being an uninterrupted sequence of intervening bodies between the object and the observer. With the Moon however, there are no intervening objects. Therefore, since the size of an object depends on its observed distance, which is in this case inaccurate, the Moon appears larger on the horizon. Through works byRoger Bacon ,John Pecham andWitelo based on Ibn al-Haytham's explanation, the Moon illusion gradually came to be accepted as a psychological phenomenon, with Ptolemy's theory being rejected in the 17th century. [Harv|Hershenson|1989| pp=9–10]Omar Khaleefa has argued that Ibn al-Haytham should also be considered the founder of
psychophysics , a subdiscipline and precursor to modern psychology. Although Ibn al-Haytham made many subjective reports regarding vision, there is no evidence that he used quantitative psychophysical techniques and the claim has been rebuffed.Harv|Aaen-Stockdale|2008]Other works on physics
Optical treatises
Besides the "Book of Optics", Ibn al-Haytham wrote several other treatises on
optics . His "Risala fi l-Daw’" ("Treatise on Light") is a supplement to his "Kitab al-Manazir" ("Book of Optics"). The text contained further investigations on the properties ofluminance and its radiant dispersion through various transparent and translucent media. He also carried out further examinations into anatomy of theeye and illusions invisual perception . He analyzed thecamera obscura andpinhole camera , and investigated themeteorology of therainbow and thedensity of the atmosphere. Variouscelestial phenomena (including theeclipse , twilight, andmoonlight ) were also examined by him. He also made investigations intorefraction ,catoptrics ,dioptrics , spherical and parabolic mirrors, and magnifying lenses.In his treatise, "Mizan al-Hikmah" ("Balance of Wisdom"), Ibn al-Haytham discussed the
density of the atmosphere and related it toaltitude . He also studiedatmospheric refraction . He discovered that thetwilight only ceases or begins when the Sun is 19° below the horizon and attempted to measure the height of the atmosphere on that basis.Harv|Dr. Al Deek|2004]Astrophysics
In
astrophysics and thecelestial mechanics field of physics, Ibn al-Haytham, in his "Epitome of Astronomy", discovered that the heavenly bodies "were accountable to the laws of physics". [Harv|Duhem|1969|p=28] Ibn al-Haytham's "Mizan al-Hikmah" ("Balance of Wisdom") coveredstatics , astrophysics, and celestial mechanics. He discussed the theory of attraction betweenmass es, and it seems that he was also aware of the magnitude ofacceleration due to gravity at a distance. His "Maqala fi'l-qarastun" is a treatise on centres of gravity. Little is known about the work, except for what is known through the later works ofal-Khazini in the 12th century. In this treatise, Ibn al-Haytham formulated the theory that the heaviness of bodies varies with their distance from the centre of theEarth . [Harv|Professor Abattouy|2002]Another treatise, "Maqala fi daw al-qamar" ("On the Light of the Moon"), which he wrote some time before his famous "
Book of Optics ", was the first successful attempt at combining mathematical astronomy withphysics , and the earliest attempt at applying the experimental method to astronomy and astrophysics. He disproved the universally held opinion that theMoon reflectssunlight like amirror and correctly concluded that it "emits light from those portions of its surface which thesun 's light strikes." To prove that "light is emitted from every point of the Moon's illuminated surface," he built an "ingeniousexperiment al device." According to Matthias Schramm, Ibn al-Haytham hadformulated 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 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.Harv|Toomer|1964|pp=463–4]Mechanics
In the
dynamics andkinematics fields ofmechanics , Ibn al-Haytham's "Risala fi’l-makan" ("Treatise on Place") discussed theories on the motion of a body. He maintained that a body moves perpetually unless an external force stops it or changes its direction of motion. This was similar to the concept ofinertia , but was largely a hypotheses that was not verified by experimentation. The key breakthrough inclassical mechanics , the introduction offriction al force, was eventually made centuries later byGalileo Galilei , and then formulated asNewton's first law of motion .Also in his "Treatise on Place", Ibn al-Haytham disagreed with
Aristotle 's view that nature abhors a void, and he thus usedgeometry to demonstrate that place ("al-makan") is the imagined three-dimensional void between the inner surfaces of a containing body.Ibn al-Haytham also discovered the concept of
momentum (now part ofNewton's second law of motion ) around the same time as his contemporary,Avicenna (Ibn Sina).Harv|Nasr|2003]Astronomical works
"Doubts Concerning Ptolemy"
In his "Al-Shukūk ‛alā Batlamyūs", variously translated as "Doubts Concerning Ptolemy" or "Aporias against Ptolemy", published at some time between 1025 and 1028, Ibn al-Haytham criticized many of
Ptolemy 's works, including the "Almagest ", "Planetary Hypotheses", and "Optics", pointing out various contradictions he found in these works. He considered that some of the mathematical devices Ptolemy introduced into astronomy, especially theequant , failed to satisfy the physical requirement of uniform circular motion, and wrote a scathing critique of the physical reality of Ptolemy's astronomical system, noting the absurdity of relating actual physical motions to imaginary mathematical points, lines and circles: [Harv|Langerman|1990|pp=8–10]Ibn al-Haytham further criticized Ptolemy's model on other
empirical ,observation al andexperiment al grounds, [Harv|Sabra|1998|p=300] such as Ptolemy's use ofconjectural undemonstrated theories in order to "save appearances" of certainphenomena , which Ibn al-Haytham did not approve of due to his insistence onscientific demonstration . Unlike some later astronomers who criticized the Ptolemaic model on the grounds of being incompatible with Aristotelian natural philosophy, Ibn al-Haytham was mainly concerned with empirical observation and the internal contradictions in Ptolemy's works. [Harv|Pines|1986|pp=438–9]In his "Aporias against Ptolemy", Ibn al-Haytham commented on the difficulty of attaining scientific knowledge:
He held that the criticism of existing theories—which dominated this book—holds a special place in the growth of scientific knowledge:
"On the Configuration of the World"
In his "On the Configuration of the World", despite his criticisms directed towards Ptolemy, Ibn al-Haytham continued to accept the physical reality of the
geocentric model of the universe, [Some writers, however, argue that Alhazen's critique constituted a form of heliocentricity (see Harv|Qadir|1989|p=5–6 & 10).] presenting a detailed description of the physical structure of thecelestial spheres in his "On the Configuration of the World":While he attempted to discover the physical reality behind Ptolemy's mathematical model, he developed the concept of a single orb ("falak") for each component of Ptolemy's planetary motions. This work was eventually translated into
Hebrew andLatin in the 13th and 14th centuries and subsequently had an influence on astronomers such asGeorg von Peuerbach during the EuropeanMiddle Ages andRenaissance . [Harv|Langerman|1990|pp=34–41] [Harv|Gondhalekar|2001|p=21]"Model of the Motions of Each of the Seven Planets"
Ibn al-Haytham's "The Model of the Motions of Each of the Seven Planets", written in 1038, was a book on astronomy. The surviving manuscript of this work has only recently been discovered, with much of it still missing, hence the work has not yet been published in modern times. Following on from his "Doubts on Ptolemy" and "The Resolution of Doubts", Ibn al-Haytham described the first non-Ptolemaic model in "The Model of the Motions". His reform was not concerned with
cosmology , as he developed a systematic study of celestialkinematics that was completely geometric. This in turn led to innovative developments ininfinitesimal geometry . [Harv|Rashed|2007]His reformed
empirical model was the first to reject theequant [Harv|Rashed|2007|p=20 & 53] and eccentrics, [Harv|Rashed|2007|pp=33–4] separatenatural philosophy from astronomy, free celestial kinematics from cosmology, and reduce physical entities to geometric entities. The model also propounded theEarth's rotation about its axis, [Harv|Rashed|2007|pp=20 & 32–33] and the centres of motion were geometric points without any physical significance, likeJohannes Kepler 's model centuries later. [Harv|Rashed|2007|pp=51–2]In the text, Ibn al-Haytham also describes an early version of
Occam's razor , where he employs only minimal hypotheses regarding the properties that characterize astronomical motions, as he attempts to eliminate from his planetary model the cosmological hypotheses that cannot be observed from theEarth . [Harv|Rashed|2007|pp=35–6]Other astronomical works
Ibn al-Haytham distinguished astrology from astronomy, and he refuted the study of
astrology , due to the methods used by astrologers beingconjectural rather thanempirical , and also due to the views of astrologers conflicting with that of orthodoxIslam . [Harv|Saliba|1994|pp=60 & 67–69]Ibn al-Haytham also wrote a treatise entitled "On the Milky Way", in which he solved problems regarding the
Milky Way galaxy andparallax . [Harv|Rashed|2007] In antiquity,Aristotle believed the Milky Way to be caused by "the ignition of the fiery exhalation of some stars which were large, numerous and close together" and that the "ignition takes place in the upper part of theatmosphere , in the region of the world which is continuous with the heavenly motions." [Harv|Montada|2007] Ibn al-Haytham refuted this and "determined that because the Milky Way had no parallax, it was very remote from theearth and did not belong to the atmosphere." [Harv|Bouali|Zghal|Lakhdar|2005] He wrote that if the Milky Way was located around theEarth's atmosphere , "one must find a difference in position relative to the fixed stars." He described two methods to determine the Milky Way's parallax: "either when one observes the Milky Way on two different occasions from the same spot of the earth; or when one looks at it simultaneously from two distant places from the surface of the earth." He made the first attempt at observing and measuring the Milky Way's parallax, and determined that since the Milky Way had no parallax, then it does not belong to the atmosphere. [Harv|Mohamed|2000|pp=49-50]In 1858, Muhammad Wali ibn Muhammad Ja'far, in his "Shigarf-nama", claimed that Ibn al-Haytham wrote a treatise "Maratib al-sama" in which he conceived of a planetary model similar to the
Tychonic system where the planets orbit the Sun which in turn orbits the Earth. However, the "verification of this claim seems to be impossible," since the treatise is not listed among the knownbibliography of Ibn al-Haytham. [Harv|Arjomand|1997|pp=5–24]Mathematical works
In mathematics, Ibn al-Haytham built on the mathematical works of
Euclid andThabit ibn Qurra . He systemizedconic section s andnumber theory , carried out some early work onanalytic geometry , and worked on "the beginnings of the link betweenalgebra andgeometry ." This in turn had an influence on the development ofRené Descartes 'sgeometric analysis andIsaac Newton 'scalculus .Geometry
In
geometry , Ibn al-Haytham developedanalytical geometry and established a link betweenalgebra and geometry. Ibn al-Haytham also discovered a formula for adding the first 100 natural numbers (which may later have been intuited byCarl Friedrich Gauss as a youth). Ibn al-Haytham used a geometric proof to prove the formula. [Harv|Rottman|2000, Chapter 1]Ibn al-Haytham made the first attempt at proving the Euclidean
parallel postulate , the fifth postulate in Euclid's "Elements", using a proof by contradiction, [Harv|Eder|2000] where he introduced the concept of motion and transformation into geometry. [Harv|Katz|1998|p=269: quote|In effect, this method characterized parallel lines as lines always equidisant from one another and also introduced the concept of motion into geometry.] He formulated theLambert quadrilateral , which Boris Abramovich Rozenfeld names the "Ibn al-Haytham–Lambert quadrilateral",Harv|Rozenfeld|1988|p=65] and his attempted proof also shows similarities toPlayfair's axiom . His theorems onquadrilateral s, including the Lambert quadrilateral, were the first theorems onelliptical geometry andhyperbolic geometry . These theorems, along with his alternative postulates, such as Playfair's axiom, can be seen as marking the beginning ofnon-Euclidean geometry . His work had a considerable influence on its development among the later Persian geometersOmar Khayyám andNasīr al-Dīn al-Tūsī , and the European geometersWitelo ,Gersonides ,Alfonso ,John Wallis ,Giovanni Girolamo Saccheri Harv|Rozenfeld|Youschkevitch|1996|p=470: quote|Three scientists, Ibn al-Haytham, Khayyam and al-Tusi, had made the most considerable contribution to this branch of geometry whose importance came to be completely recognized only in the nineteenth century. In essence their propositions concerning the properties of quadrangles which they considered assuming that some of the angles of these figures were acute of obtuse, embodied the first few theorems of the hyperbolic and the elliptic geometries. Their other proposals showed that various geometric statements were equivalent to the Euclidean postulate V. It is extremely important that these scholars established the mutual connection between tthis postulate and the sum of the angles of a triangle and a quadrangle. By their works on the theory of parallel lines Arab mathematicians directly influenced the relevant investigations of their European counterparts. The first European attempt to prove the postulate on parallel lines - made by Witelo, the Polish scientists of the thirteenth century, while revising Ibn al-Haytham's "Book of Optics" ("Kitab al-Manazir") - was undoubtedly prompted by Arabic sources. The proofs put forward in the fourteenth century by the Jewish scholar Gersonides, who lived in southern France, and by the above-mentioned Alfonso from Spain directly border on Ibn al-Haytham's demonstration. Above, we have demonstrated that "Pseudo-Tusi's Exposition of Euclid" had stimulated borth J. Wallis's and G. Saccheri's studies of the theory of parallel lines.] andChristopher Clavius . [Harv|Rozenfeld|Youschkevitch|1996|p=93]In elementary geometry, Ibn al-Haytham attempted to solve the problem of
squaring the circle using the area of lunes (crescent shapes), but later gave up on the impossible task. Ibn al-Haytham also tackled other problems in elementary (Euclidean) and advanced (Apollonian and Archimedean) geometry, some of which he was the first to solve.Number theory
His contributions to
number theory includes his work onperfect number s. In his "Analysis and Synthesis", Ibn al-Haytham was the first to realize that every even perfect number is of the form 2"n"−1(2"n" − 1) where 2"n" − 1 is prime, but he was not able to prove this result successfully (Euler later proved it in the 18th century).Ibn al-Haytham solved problems involving congruences using what is now called
Wilson's theorem . In his "Opuscula", Ibn al-Haytham considers the solution of a system of congruences, and gives two general methods of solution. His first method, the canonical method, involved Wilson's theorem, while his second method involved a version of theChinese remainder theorem .Other works
"Influence of Melodies on the Souls of Animals"
In psychology and
musicology , Ibn al-Haytham's "Treatise on the Influence of Melodies on the Souls of Animals" was the earliest treatise dealing with the effects of music on animals. In the treatise, he demonstrates how a camel's pace could be hastened or retarded with the use of music, and shows other examples of how music can affectanimal behaviour andanimal psychology , experimenting with horses, birds and reptiles. Through to the 19th century, a majority of scholars in the Western world continued to believe that music was a distinctly human phenomenon, but experiments since then have vindicated Ibn al-Haytham's view that music does indeed have an effect on animals.Harv|Plott|2000|p=461]Engineering
In engineering, one account of his career as a
civil engineer has him summoned to Egypt by the FatimidCaliph ,Al-Hakim bi-Amr Allah , to regulate theflooding of theNile River. He carried out a detailed scientific study of the annualinundation of the Nile River, and he drew plans for building adam , at the site of the modern-dayAswan Dam . His field work, however, later made him aware of the impracticality of this scheme, and he soonfeigned madness so he could avoid punishment from the Caliph. [Harv|Plott|2000, Pt. II, p. 459]According to
Al-Khazini , Ibn al-Haytham also wrote a treatise providing a description on theconstruction of awater clock . [Harv|Hassan|2007]Philosophy
In
early Islamic philosophy , Ibn al-Haytham's "Risala fi’l-makan" ("Treatise on Place") presents a critique ofAristotle 's concept ofplace (topos ). Aristotle's "Physics" stated that the place of something is the two-dimensional boundary of the containing body that is at rest and is in contact with what it contains. Ibn al-Haytham disagreed and demonstrated that place (al-makan) is the imagined three-dimensional void between the inner surfaces of the containing body. He showed that place was akin tospace , foreshadowingRené Descartes 's concept of place in the "Extensio" in the 17th century. Following on from his "Treatise on Place", Ibn al-Haytham's "Qawl fi al-Makan" ("Discourse on Place") was a treatise which presents geometric demonstrations for his geometrization ofplace , in opposition toAristotle 's philosophical concept of place, which Ibn al-Haytham rejected on mathematical grounds.Abd-el-latif , a supporter of Aristotle's philosophical view of place, later criticized the work in "Fi al-Radd ‘ala Ibn al-Haytham fi al-makan" ("A refutation of Ibn al-Haytham’s place") for its geometrization of place.Harv|El-Bizri|2007]Ibn al-Haytham also discussed space perception and its epistemological implications in his "
Book of Optics ". Hisexperiment al proof of the intromission model of vision led to changes in the way thevisual perception of space was understood, contrary to the previous emission theory of vision supported byEuclid andPtolemy . In "tying the visual perception of space to prior bodily experience, Alhacen unequivocally rejected theintuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size forcorrelation, sight can tell us next to nothing about such things." [Harv|Smith|2005|pp=219–40]Theology
Ibn al-Haytham was a devout
Muslim , who was a follower of Shi'ite Islamic theology [Harv|Sabra|1978a|p=54] .Ibn al-Haytham wrote a work on Islamic theology, in which he discussed
prophet hood and developed a system of philosophical criteria to discern its false claimants in his time. [Harv|Plott|2000, Pt. II, p. 464] He also wrote a treatise entitled "Finding the Direction of Qibla by Calculation", in which he discussed finding theQibla , whereSalah prayers are directed towards, mathematically.Ibn al-Haytham attributed his
experiment alscientific method andscientific skepticism to hisIslam ic faith. The Islamic holy book theQur'an , for example, placed a strong emphasis onempiricism . [Harv|Qadir|1990|pp=24-5: quote|"Muslims are inspired in the first instance by the numerous verses of the Quran which invite believers to observe nature and reflect over it." (cf. Harv|Bettany|1995|p=247)] [cite quran|17|36|quote=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.] [cite quran|2|164|quote=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.] He also believed thathuman beings are inherently flawed and that onlyGod is perfect. Hereason ed that to discover thetruth aboutnature , it is necessary to eliminate humanopinion anderror , and allow theuniverse to speak for itself. He wrote in his "Doubts Concerning Ptolemy":In "The Winding Motion", Ibn al-Haytham further wrote that
faith (or "taqlid " "imitation") should only apply toprophets of Islam and not to any other authorities, in the following comparison between the Islamic prophetic tradition and the demonstrative sciences:Ibn al-Haytham described his search for truth and
knowledge as a way of leading him closer to God:Works
Ibn al-Haytham was a pioneer in many areas of science, making significant contributions in varying disciplines. His optical writings influenced many Western intellectuals such as
Roger Bacon ,John Pecham ,Witelo ,Johannes Kepler . [Harv|Lindberg|1967] His pioneering work onnumber theory ,analytic geometry , and the link betweenalgebra andgeometry , also had an influence onRené Descartes 'sgeometric analysis andIsaac Newton 'scalculus .Harv|Faruqi|2006|pp=395–6:quote|In seventeenth century Europe the problems formulated by Ibn al-Haytham (965–1041) became known as 'Alhazen's problem'. […] Al-Haytham’s contributions to geometry and number theory went well beyond the Archimedean tradition. Al-Haytham also worked on analytical geometry and the beginnings of the link between algebra and geometry. Subsequently, this work led in pure mathematics to the harmonious fusion of algebra and geometry that was epitomised by Descartes in geometric analysis and by Newton in the calculus. Al-Haytham was a scientist who made major contributions to the fields of mathematics, physics and astronomy during the latter half of the tenth century.]According to medieval biographers, Ibn al-Haytham wrote more than 200 works on a wide range of subjects,Harv|Steffens|2006 (
cf. Citation|first=Bradley|last=Steffens|title=Who Was the First Scientist?|publisher=Ezine Articles)] of which at least 96 of his scientific works are known. Most of his works are now lost, but more than 50 of them have survived to some extent. Nearly half of his surviving works are on mathematics, 23 of them are on astronomy, and 14 of them are on optics, with a few on other subjects.Harv|Rashed|2002a|p=773] Not all his surviving works have yet been studied, but some of the ones that have are given below.Harv|Topdemir|2007b] [Harv|Rashed|2007|pp=8-9]*"
Book of Optics "
*"Analysis and Synthesis"
*"Balance of Wisdom"
*"Corrections to the Almagest"
*"Discourse on Place"
*"Exact Determination of the Pole"
*"Exact Determination of the Meridian"
*"Finding the Direction of Qibla by Calculation"
*"Horizontal Sundials"
*"Hour Lines"
*"Doubts Concerning Ptolemy"
*"Maqala fi'l-Qarastun"
*"On Completion of the Conics"
*"On Seeing the Stars"
*"On Squaring the Circle"
*"On the Burning Sphere"
*"On the Configuration of the World"
*"On the Form of Eclipse"
*"On the Light of Stars"
*"On the Light of the Moon"
*"On the Milky Way"
*"On the Nature of Shadows"
*"On the Rainbow and Halo"
*"Opuscula"
*"Resolution of Doubts Concerning the Almagest"
*"Resolution of Doubts Concerning the Winding Motion"
*"The Correction of the Operations in Astronomy"
*"The Different Heights of the Planets"
*"The Direction of Mecca"
*"The Model of the Motions of Each of the Seven Planets"
*"The Model of the Universe"
*"The Motion of the Moon"
*"The Ratios of Hourly Arcs to their Heights"
*"The Winding Motion"
*"Treatise on Light"
*"Treatise on Place"
*"Treatise on the Influence of Melodies on the Souls of Animals"Notes
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date=June 1975External links
* [http://www-personal.umich.edu/~jbourj/money4.htm Ibn al-Haytham on two Iraqi banknotes]
* [http://unesdoc.unesco.org/images/0014/001412/141236E.pdf The Miracle of Light – a UNESCO article on Ibn al-Haytham]
* [http://www.malaspina.org/alhazen.htm Biography from Malaspina Global Portal]
* [http://www.amaana.org/ISWEB/contents.htm#pos9 Short biographies on several "Muslim Heroes and Personalities" including Ibn al-Haytham]
* [http://www.telegraph.co.uk/htmlContent.jhtml?html=/archive/1997/04/01/ngre01.html Report by the Telegraph of a modern day solution of Alhazen's problem]
* [http://www.unhas.ac.id/~rhiza/arsip/saintis/haitham.html Biography by Dr. A. Zahoor]
* [http://web.archive.org/web/19991013041615/http://www.ionet.net/~usarch/WTB-Services/MiddleEast/WTB-ME-Thinkers-IbnAlHaitham.shtml Biography from ioNET via the Wayback Machine]
* [http://web.archive.org/web/20060211032459/http://www.bbc.co.uk/history/historic_figures/alhazen.shtml Biography from the BBC via the Wayback Machine]
* [http://www.trincoll.edu/depts/phil/philo/phils/muslim/alhazen.html Biography from Trinity College (Connecticut)]
* [http://micro.magnet.fsu.edu/optics/timeline/people/alhazen.html Biography from Molecular Expressions]Persondata
NAME = al-Haytham, Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn
ALTERNATIVE NAMES = Alhacen; Alhazen; al-Basri
SHORT DESCRIPTION = Scientist
DATE OF BIRTH = 965
PLACE OF BIRTH =Basra ,Persian Empire
DATE OF DEATH = c. 1040
PLACE OF DEATH =Cairo ,Egypt
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