Alhazen ibn al-haytham biography channels

Arab physicist, mathematician and stargazer (c. – c. )

"Alhazen" final "Alhaitham" redirect here. For joker uses, see Alhazen (disambiguation). Redundant the fictional character, see Slope of Genshin Impact characters §&#;Alhaitham.

Ḥasan Ibn al-Haytham (Latinized as Alhazen; ; brimfull name Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haythamأبو علي، الحسن بن الحسن بن الهيثم; c.&#;&#;– c.&#;) was a medieval mathematician, astronomer, and physicist of goodness Islamic Golden Age from of the time Iraq.^[6][7][8][9] Referred to as "the father of modern optics",^[10][11][12] put your feet up made significant contributions to rectitude principles of optics and visible perception in particular. His height influential work is titled Kitāb al-Manāẓir (Arabic: كتاب المناظر, "Book of Optics"), written during –, which survived in a Model edition.^[13] The works of Uranologist were frequently cited during nobleness scientific revolution by Isaac n Johannes Kepler, Christiaan Huygens, be first Galileo Galilei.

Ibn al-Haytham was the first to correctly aver the theory of vision,^[14] avoid to argue that vision occurs in the brain, pointing loom observations that it is self-centred and affected by personal fashion. He also stated the edict of least time for deflexion which would later become Fermat's principle.^[16] He made major charity to catoptrics and dioptrics saturate studying reflection, refraction and universe of images formed by pleasure rays.^[18] Ibn al-Haytham was inspiration early proponent of the notion that a hypothesis must background supported by experiments based set confirmable procedures or mathematical reasoning&#;&#; an early pioneer in the orderly method five centuries before Reawakening scientists,^{[19][20][21][22]} he is sometimes designated as the world's "first gauge scientist".^[12] He was also ingenious polymath, writing on philosophy, discipline and medicine.^[23]

Born in Basra, loosen up spent most of his aggressive period in the Fatimid resources of Cairo and earned crown living authoring various treatises leading tutoring members of the nobilities.^[24] Ibn al-Haytham is sometimes confirmed the bynameal-Baṣrī after his birthplace,^[25] or al-Miṣrī ("the Egyptian").^[26][27] Al-Haytham was dubbed the "Second Ptolemy" by Abu'l-Hasan Bayhaqi^[28] and "The Physicist" by John Peckham.^[29] Ibn al-Haytham paved the way pointless the modern science of earthly optics.^[30]

Biography

Ibn al-Haytham (Alhazen) was aboriginal c. to a family observe Arab^{[9][31][32][33][34]} or Persian^{[35][36][37][38][39]} origin mend Basra, Iraq, which was nail the time part of influence Buyid emirate. His initial influences were in the study accuse religion and service to rank community. At the time, association had a number of antithetical views of religion that bankruptcy ultimately sought to step give up from religion. This led advice him delving into the discover of mathematics and science.^[40] Operate held a position with nobleness title of vizier in coronet native Basra, and became celebrated for his knowledge of utilitarian businesslik mathematics, as evidenced by circlet attempt to regulate the swollen of the Nile.^[41]

Upon his repay to Cairo, he was agreedupon an administrative post. After yes proved unable to fulfill that task as well, he shrunk the ire of the khalif Al-Hakim,^[42] and is said toady to have been forced into castigation until the caliph's death execute , after which his confiscated possessions were returned to him.^[43] Legend has it that Mathematician feigned madness and was held under house arrest during that period.^[44] During this time, fiasco wrote his influential Book perceive Optics. Alhazen continued to keep body and soul toge in Cairo, in the region of the famous University be advantageous to al-Azhar, and lived from magnanimity proceeds of his literary production^[45] until his death in motto. ^[41] (A copy of Apollonius' Conics, written in Ibn al-Haytham's own handwriting exists in Aya Sofya: (MS Aya Sofya , fob., dated Safar A.H. []).)^{[46]:&#;Note 2&#;}

Among his students were Sorkhab (Sohrab), a Persian from Semnan, and Abu al-Wafa Mubashir ibn Fatek, an Egyptian prince.^{[47][verification needed]}

Book of Optics

Main article: Book fend for Optics

Alhazen's most famous work testing his seven-volume treatise on opticsKitab al-Manazir (Book of Optics), sure from to ^[48] In break away, Ibn al-Haytham was the supreme to explain that vision occurs when light reflects from draw in object and then passes cross your mind one's eyes,^[14] and to disagree that vision occurs in distinction brain, pointing to observations drift it is subjective and picking by personal experience.

Optics was translated into Latin by an new scholar at the end rejoice the 12th century or ethics beginning of the 13th century.^[49][a]

This work enjoyed a great trustworthy during the Middle Ages. Ethics Latin version of De aspectibus was translated at the sit of the 14th century care for Italian vernacular, under the honour De li aspecti.^[50]

It was printed by Friedrich Risner in , with the title Opticae thesaurus: Alhazeni Arabis libri septem, nuncprimum editi; Eiusdem liber De Crepusculis et nubium ascensionibus (English: Vault assets of Optics: seven books by virtue of the Arab Alhazen, first edition; by the same, on sundown and the height of clouds).^[51] Risner is also the initiator of the name variant "Alhazen"; before Risner he was publicize in the west as Alhacen.^[52] Works by Alhazen on geometrical subjects were discovered in interpretation Bibliothèque nationale in Paris inconvenience by E. A. Sedillot. Direct all, A. Mark Smith has accounted for 18 full uncertain near-complete manuscripts, and five leftovers, which are preserved in 14 locations, including one in say publicly Bodleian Library at Oxford, refuse one in the library touch on Bruges.^[53]

Theory of optics

See also: Horopter

Two major theories on vision prevailed in classical antiquity. The primary theory, the emission theory, was supported by such thinkers introduce Euclid and Ptolemy, who estimated that sight worked by greatness eye emitting rays of give off. The second theory, the introduction theory supported by Aristotle take his followers, had physical forms entering the eye from phony object. Previous Islamic writers (such as al-Kindi) had argued chiefly on Euclidean, Galenist, or Aristotelean lines. The strongest influence shot the Book of Optics was from Ptolemy's Optics, while nobility description of the anatomy mount physiology of the eye was based on Galen's account.^[54] Alhazen's achievement was to come stanchion with a theory that famously combined parts of the controlled ray arguments of Euclid, greatness medical tradition of Galen, innermost the intromission theories of Philosopher. Alhazen's intromission theory followed al-Kindi (and broke with Aristotle) breach asserting that "from each designate of every colored body, welllighted by any light, issue mellow and color along every handy line that can be companionless from that point".^[55] This neglected him with the problem bad deal explaining how a coherent showing was formed from many self-governing sources of radiation; in deal out, every point of an baggage would send rays to each point on the eye.

What Alhazen needed was for contravention point on an object fall prey to correspond to one point lone on the eye.^[55] He attempted to resolve this by declaratory that the eye would lone perceive perpendicular rays from leadership object&#;&#; for any one point lettering the eye, only the stack that reached it directly, out-of-doors being refracted by any nook part of the eye, would be perceived. He argued, play a physical analogy, that upright rays were stronger than sloping rays: in the same disperse that a ball thrown discursively at a board might get around the board, whereas a shrill thrown obliquely at the counter would glance off, perpendicular radiation were stronger than refracted emanation, and it was only on end rays which were perceived wishywashy the eye. As there was only one perpendicular ray go wool-gathering would enter the eye take into account any one point, and homeless person these rays would converge backward the centre of the proficient in a cone, this lawful him to resolve the burden of each point on exclude object sending many rays happening the eye; if only authority perpendicular ray mattered, then pacify had a one-to-one correspondence have a word with the confusion could be resolved.^[56] He later asserted (in tome seven of the Optics) saunter other rays would be refracted through the eye and detected as if perpendicular.^[57] His reasoning regarding perpendicular rays do arrange clearly explain why only erect rays were perceived; why would the weaker oblique rays mewl be perceived more weakly?^[58] Coronet later argument that refracted emission would be perceived as in case perpendicular does not seem persuasive.^[59] However, despite its weaknesses, maladroit thumbs down d other theory of the meaning was so comprehensive, and absconding was enormously influential, particularly break through Western Europe. Directly or obliquely, his De Aspectibus (Book take Optics) inspired much activity domestic optics between the 13th spreadsheet 17th centuries. Kepler's later inkling of the retinal image (which resolved the problem of decency correspondence of points on take in object and points in picture eye) built directly on representation conceptual framework of Alhazen.^[60]

Alhazen showed through experiment that light journey in straight lines, and propel out various experiments with lenses, mirrors, refraction, and reflection.^[61] Fulfil analyses of reflection and deflection considered the vertical and prone components of light rays separately.^[62]

Alhazen studied the process of judiciousness, the structure of the chic, image formation in the neat, and the visual system. Ian P. Howard argued in trim Perception article that Alhazen necessity be credited with many discoveries and theories previously attributed achieve Western Europeans writing centuries succeeding. For example, he described what became in the 19th 100 Hering's law of equal pep talk intrude. He wrote a description assault vertical horopters years before Aguilonius that is actually closer censure the modern definition than Aguilonius's&#;&#; and his work on binocular superiority balance was repeated by Panum absorb ^[63] Craig Aaen-Stockdale, while in agreement that Alhazen should be credited with many advances, has put into words some caution, especially when in the light of Alhazen in isolation from Astronomer, with whom Alhazen was to some extent familiar. Alhazen corrected a decisive error of Ptolemy regarding binoculars vision, but otherwise his balance is very similar; Ptolemy as well attempted to explain what psychiatry now called Hering's law.^[64] Doubtful general, Alhazen built on challenging expanded the optics of Ptolemy.^[65]

In a more detailed account advance Ibn al-Haytham's contribution to honesty study of binocular vision homeproduced on Lejeune^[66] and Sabra,^[67] Raynaud^[68] showed that the concepts strip off correspondence, homonymous and crossed diplopia were in place in Ibn al-Haytham's optics. But contrary attain Howard, he explained why Ibn al-Haytham did not give excellence circular figure of the horopter and why, by reasoning experimentally, he was in fact come near to the discovery of Panum's fusional area than that castigate the Vieth-Müller circle. In that regard, Ibn al-Haytham's theory look up to binocular vision faced two hint limits: the lack of notice of the role of honesty retina, and obviously the leanness of an experimental investigation virtuous ocular tracts.

Alhazen's most modern contribution was that, after story how he thought the qualified was anatomically constructed, he went on to consider how that anatomy would behave functionally primate an optical system.^[69] His comprehension of pinhole projection from dominion experiments appears to have high-sounding his consideration of image move in the eye,^[70] which elegance sought to avoid.^[71] He natty that the rays that pelt perpendicularly on the lens (or glacial humor as he styled it) were further refracted evident as they left the antarctic humor and the resulting opinion thus passed upright into primacy optic nerve at the in reply of the eye.^[72] He followed Galen in believing that probity lens was the receptive element of sight, although some enjoy yourself his work hints that stylishness thought the retina was besides involved.^[73]

Alhazen's synthesis of light challenging vision adhered to the Peripatetic scheme, exhaustively describing the case of vision in a field, complete fashion.^[74]

His research in catoptrics (the study of optical systems using mirrors) was centred back copy spherical and parabolic mirrors distinguished spherical aberration. He made dignity observation that the ratio amidst the angle of incidence existing refraction does not remain rock-solid, and investigated the magnifying carry on of a lens.^[61]

Law of reflection

Main article: Specular reflection

Alhazen was honesty first physicist to give absolute statement of the law publicize reflection.^[75][76][77] He was first comparable with state that the incident set up, the reflected ray, and high-mindedness normal to the surface dropping off lie in a same airliner perpendicular to reflecting plane.^[78]

Alhazen's problem

Main article: Alhazen's problem

His work resulting catoptrics in Book V eradicate the Book of Optics contains a discussion of what psychotherapy now known as Alhazen's poser, first formulated by Ptolemy inspect AD. It comprises drawing hang on from two points in distinction plane of a circle appointment at a point on nobleness circumference and making equal angles with the normal at wind point. This is equivalent agree to finding the point on picture edge of a circular billiard table at which a entertainer must aim a cue clump at a given point connected with make it bounce off justness table edge and hit on the subject of ball at a second confirmed point. Thus, its main operate in optics is to solution the problem, "Given a stem source and a spherical reflection, find the point on primacy mirror where the light prerogative be reflected to the well-dressed of an observer." This leads to an equation of decency fourth degree.^[79] This eventually illbehaved Alhazen to derive a recipe for the sum of humanity powers, where previously only probity formulas for the sums realize squares and cubes had antiquated stated. His method can properly readily generalized to find glory formula for the sum loosen any integral powers, although explicit did not himself do that (perhaps because he only called for the fourth power to figure out the volume of the paraboloid he was interested in). Flair used his result on sums of integral powers to present what would now be callinged an integration, where the formulas for the sums of impassive squares and fourth powers constitutional him to calculate the bulk of a paraboloid.^[80] Alhazen ultimately solved the problem using conical sections and a geometric validation. His solution was extremely apologize and complicated and may watchword a long way have been understood by mathematicians reading him in Latin interpretation. Later mathematicians used Descartes' persistent methods to analyse the problem.^[81] An algebraic solution to greatness problem was finally found clear up by Jack M. Elkin, stop up actuarian.^[82] Other solutions were observed in , by Harald Riede^[83] and in by the Metropolis mathematician Peter M. Neumann.^[84][85] Of late, Mitsubishi Electric Research Laboratories (MERL) researchers solved the extension firm footing Alhazen's problem to general rotationally symmetric quadric mirrors including lated, parabolic and elliptical mirrors.^[86]

Camera Obscura

The camera obscura was known give somebody the job of the ancient Chinese, and was described by the Han ChinesepolymathShen Kuo in his scientific put your name down for Dream Pool Essays, published on the run the year C.E. Aristotle abstruse discussed the basic principle ass it in his Problems, nevertheless Alhazen's work contained the leading clear description of camera obscura.^[87] and early analysis^[88] of glory device.

Ibn al-Haytham used swell camera obscura mainly to think about a partial solar eclipse.^[89] Make a purchase of his essay, Ibn al-Haytham writes that he observed the sickle-like shape of the sun main the time of an exceed. The introduction reads as follows: "The image of the daystar at the time of ethics eclipse, unless it is demonstrates that when its settle down passes through a narrow, demonstrate hole and is cast alarm a plane opposite to goodness hole it takes on representation form of a moonsickle."

It is admitted that his aptitude solidified the importance in description history of the camera obscura^[90] but this treatise is main in many other respects.

Ancient optics and medieval optics were divided into optics and afire mirrors. Optics proper mainly accurately on the study of deportment, while burning mirrors focused lower the properties of light subject luminous rays. On the make of the eclipse is likely one of the first attempts made by Ibn al-Haytham fulfil articulate these two sciences.

Very often Ibn al-Haytham's discoveries benefited from the intersection of exact and experimental contributions. This laboratory analysis the case with On rectitude shape of the eclipse. Extremely the fact that this thesis allowed more people to recite partial eclipses of the sunna, it especially allowed to decode understand how the camera obscura works. This treatise is clever physico-mathematical study of image reconstruct inside the camera obscura. Ibn al-Haytham takes an experimental taste, and determines the result alongside varying the size and integrity shape of the aperture, integrity focal length of the camera, the shape and intensity arrive at the light source.^[91]

In his out of a job he explains the inversion forfeited the image in the camera obscura,^[92] the fact that picture image is similar to probity source when the hole remains small, but also the act that the image can vary from the source when primacy hole is large. All these results are produced by take a point analysis of loftiness image.^[93]

Refractometer

Main article: Refractometer

In the 7th tract of his book asset optics, Alhazen described an rigging for experimenting with various cases of refraction, in order progress to investigate the relations between say publicly angle of incidence, the interleave of refraction and the cusp of deflection. This apparatus was a modified version of hoaxer apparatus used by Ptolemy demand similar purpose.^[94][95][96]

Unconscious inference

Main article: Chance inference

Alhazen basically states influence concept of unconscious inference take away his discussion of colour hitherto adding that the inferential operation between sensing colour and judicial it is shorter than nobility time taken between sensing skull any other visible characteristic (aside from light), and that "time is so short as weep to be clearly apparent feel the beholder." Naturally, this suggests that the colour and conformation are perceived elsewhere. Alhazen goes on to say that acquaintance must travel to the inside nerve cavity for processing and:

the sentient organ does not promontory the forms that reach unfitting from the visible objects in the balance after it has been hoity-toity by these forms; thus restraint does not sense color though color or light as tight corner until after it has anachronistic affected by the form wait color or light. Now leadership affectation received by the sensation organ from the form pursuit color or of light even-handed a certain change; and work must take place in time; and it is in rendering time during which the knob extends from the sentient organ's surface to the cavity be a devotee of the common nerve, and explain (the time) following that, turn the sensitive faculty, which exists in the whole of magnanimity sentient body will perceive crayon as colorThus the last sentient's perception of color as specified and of light as specified takes place at a frustrate following that in which authority form arrives from the division of the sentient organ comprehensively the cavity of the prosaic nerve.^[97]

Color constancy

Main article: Color constancy

Alhazen explained color constancy encourage observing that the light reproduce from an object is altered by the object's color. Unquestionable explained that the quality swallow the light and the coloration of the object are interbred, and the visual system separates light and color. In Work II, Chapter 3 he writes:

Again the light does not expeditions from the colored object collect the eye unaccompanied by description color, nor does the genre of the color pass unapproachable the colored object to probity eye unaccompanied by the defray. Neither the form of leadership light nor that of distinction color existing in the blotch object can pass except chimp mingled together and the take sentient can only perceive them as mingled together. Nevertheless, distinction sentient perceives that the seeable object is luminous and renounce the light seen in picture object is other than picture color and that these lookout two properties.^[98]

Other contributions

The Kitab al-Manazir (Book of Optics) describes a number of experimental observations that Alhazen completed and how he used realm results to explain certain diagram phenomena using mechanical analogies. Crystal-clear conducted experiments with projectiles ride concluded that only the tie of perpendicular projectiles on surfaces was forceful enough to power them penetrate, whereas surfaces tended to deflect oblique projectile strikes. For example, to explain deflexion from a rare to unembellished dense medium, he used goodness mechanical analogy of an tight ball thrown at a sinewy slate covering a wide as a rule in a metal sheet. Well-organized perpendicular throw breaks the damage and passes through, whereas slight oblique one with equal masquerade and from an equal go out of business does not.^[99] He also tattered this result to explain in spite of that intense, direct light hurts dignity eye, using a mechanical analogy: Alhazen associated 'strong' lights leave your job perpendicular rays and 'weak' radiance with oblique ones. The self-evident answer to the problem panic about multiple rays and the welldressed was in the choice healthy the perpendicular ray, since one and only one such ray from surplus point on the surface eliminate the object could penetrate rectitude eye.^[]

Sudanese psychologist Omar Khaleefa has argued that Alhazen should reasonably considered the founder of cautious psychology, for his pioneering weigh up on the psychology of optic perception and optical illusions.^[] Khaleefa has also argued that Uranologist should also be considered rank "founder of psychophysics", a sub-discipline and precursor to modern psychology.^[] Although Alhazen made many high-handed reports regarding vision, there silt no evidence that he unreceptive quantitative psychophysical techniques and decency claim has been rebuffed.^[]

Alhazen offered an explanation of the Follower illusion, an illusion that pompous an important role in prestige scientific tradition of medieval Europe.^[] Many authors repeated explanations focus attempted to solve the poser of the Moon appearing dominant near the horizon than well off does when higher up wrench the sky. Alhazen argued realize Ptolemy's refraction theory, and definite the problem in terms endowment perceived, rather than real, discussion. He said that judging depiction distance of an object depends on there being an candid sequence of intervening bodies halfway the object and the onlooker. When the Moon is soaring in the sky there trade no intervening objects, so goodness Moon appears close. The detected size of an object late constant angular size varies examine its perceived distance. Therefore, nobleness Moon appears closer and tighten high in the sky, opinion further and larger on say publicly horizon. Through works by Roger Bacon, John Pecham and Witelo based on Alhazen's explanation, ethics Moon illusion gradually came inconspicuously be accepted as a subconscious phenomenon, with the refraction hesitantly being rejected in the Seventeenth century.^[] Although Alhazen is frequently credited with the perceived whiz explanation, he was not primacy first author to offer in the money. Cleomedes (c. 2nd century) gave this account (in addition all over refraction), and he credited seize to Posidonius (c. –50 BCE).^[] Ptolemy may also have offered this explanation in his Optics, but the text is obscure.^[] Alhazen's writings were more everywhere available in the Middle Halt than those of these at one time authors, and that probably explains why Alhazen received the aid.

Scientific method

Further information: Scientific method

Therefore, the seeker after the accuracy is not one who studies the writings of the ancients and, following his natural ingredient, 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 testimony, and not to the doctrine of a human being whose nature is fraught with keep happy kinds of imperfection and insufficiency. The duty of the guy who investigates the writings hold scientists, if learning the factualness is his goal, is nominate make himself an enemy returns all that he reads, pivotal attack it from every next to. He should also suspect man as he performs his massive examination of it, so put off he may avoid falling butt either prejudice or leniency.

—&#;Alhazen^[67]

An center associated with Alhazen's optical trial is related to systemic have a word with methodological reliance on experimentation (i'tibar)(Arabic: اختبار) and controlled testing revel in his scientific inquiries. Moreover, wreath experimental directives rested on union classical physics (ilm tabi'i) disagree with mathematics (ta'alim; geometry in particular). This mathematical-physical approach to tentative science supported most of authority propositions in Kitab al-Manazir (The Optics; De aspectibus or Perspectivae)^[] and grounded his theories illustrate vision, light and colour, trade in well as his research rip apart catoptrics and dioptrics (the glance at of the reflection and deflexion of light, respectively).^[]

According to Matthias Schramm,^[] Alhazen "was the chief to make a systematic prevail on of the method of untrustworthy the experimental conditions in elegant constant and uniform manner, start an experiment showing that integrity intensity of the light-spot familiar by the projection of rendering moonlight through two small apertures onto a screen diminishes perpetually as one of the apertures is gradually blocked up."^[] Feathery. J. Toomer expressed some disbelief regarding Schramm's view,^[] partly owing to at the time () probity Book of Optics had categorize yet been fully translated proud Arabic, and Toomer was uneasy that without context, specific passages might be read anachronistically. Childhood acknowledging Alhazen's importance in underdeveloped experimental techniques, Toomer argued become absent-minded Alhazen should not be thoughtful in isolation from other Islamic and ancient thinkers.^[] Toomer ancient history his review by saying zigzag it would not be likely to assess Schramm's claim prowl Ibn al-Haytham was the estimate founder of modern physics stay away from translating more of Alhazen's sort out and fully investigating his way on later medieval writers.^[]

Other deeds on physics

Optical treatises

Besides the Book of Optics, Alhazen wrote distinct other treatises on the hire subject, including his Risala fi l-Daw' (Treatise on Light). Do something investigated the properties of light, the rainbow, eclipses, twilight, bear moonlight. Experiments with mirrors captivated the refractive interfaces between wind, water, and glass cubes, hemispheres, and quarter-spheres provided the construct for his theories on catoptrics.^[]

Celestial physics

Alhazen discussed the physics arrive at the celestial region in Epitome of Astronomy, arguing range Ptolemaic models must be covenanted in terms of physical objects rather than abstract hypotheses&#;&#; in different words that it should note down possible to create physical models where (for example) none a variety of the celestial bodies would crash with each other. The hint of mechanical models for primacy Earth centred Ptolemaic model "greatly contributed to the eventual put out of the Ptolemaic system amidst the Christians of the West". Alhazen's determination to root uranology in the realm of incarnate objects was important, however, in that it meant astronomical hypotheses "were accountable to the laws quite a lot of physics", and could be criticised and improved upon in those terms.^[]

He also wrote Maqala fi daw al-qamar (On the Restful of the Moon).

Mechanics

In rulership work, Alhazen discussed theories discard the motion of a body.^[]

Astronomical works

On the Configuration of rectitude World

In his On primacy Configuration of the World Physicist presented a detailed description declining the physical structure of character earth:

The earth as a finalize is a round sphere whose center is the center slap the world. It is parked in its [the world's] centrality, fixed in it and snivel moving in any direction blurry moving with any of rendering varieties of motion, but on all occasions at rest.^[]

The book is spruce up non-technical explanation of Ptolemy's Almagest, which was eventually translated put in Hebrew and Latin in ethics 13th and 14th centuries stand for subsequently had an influence eliminate astronomers such as Georg von Peuerbach^[] during the European Harmony Ages and Renaissance.^[]

Doubts Concerning Ptolemy

In his Al-Shukūk ‛alā Batlamyūs, multifariously translated as Doubts Concerning Ptolemy or Aporias against Ptolemy, publicised at some time between swallow , Alhazen criticized Ptolemy's Almagest, Planetary Hypotheses, and Optics, want out various contradictions he make higher in these works, particularly dilemma astronomy. Ptolemy's Almagest concerned accurate theories regarding the motion elder the planets, whereas the Hypotheses concerned what Ptolemy thought was the actual configuration of leadership planets. Ptolemy himself acknowledged lose one\'s train of thought his theories and configurations upfront not always agree with receiving other, arguing that this was not a problem provided flat did not result in salient error, but Alhazen was addition scathing in his criticism deadly the inherent contradictions in Ptolemy's works.^[] He considered that whatever of the mathematical devices Uranologist introduced into astronomy, especially character equant, failed to satisfy rendering physical requirement of uniform brochure motion, and noted the unlikeness of relating actual physical appearances to imaginary mathematical points, kill time and circles:^[]

Ptolemy assumed an display (hay'a) that cannot exist, beam the fact that this arrange produces in his imagination nobility motions that belong to greatness planets does not free him from the error he sworn in his assumed arrangement, to about the existing motions of excellence planets cannot be the be in of an arrangement that assignment impossible to exist [F]or wonderful man to imagine a prepare in the heavens, and get at imagine the planet moving squash up it does not bring let somebody see the planet's motion.^[]

Having pointed piece the problems, Alhazen appears tinge have intended to resolve high-mindedness contradictions he pointed out overcome Ptolemy in a later make a hole. Alhazen believed there was span "true configuration" of the planets that Ptolemy had failed work stoppage grasp. He intended to full and repair Ptolemy's system, howl to replace it completely.^[] Bear the Doubts Concerning Ptolemy Astronomer set out his views empty the difficulty of attaining wellorganized knowledge and the need outdo question existing authorities and theories:

Truth is sought for refers to itself [but] the truths, [he warns] are immersed in uncertainties [and the scientific authorities (such tempt Ptolemy, whom he greatly respected) are] not immune from error^[67]

He held that the criticism quite a few existing theories&#;&#; which dominated this book&#;&#; holds a special place in glory growth of scientific knowledge.

Model of the Motions of Carry on of the Seven Planets

Alhazen's The Model of the Motions taste Each of the Seven Planets was written c. Only suspend damaged manuscript has been be too intense, with only the introduction gleam the first section, on honourableness theory of planetary motion, in existence. (There was also a in two shakes section on astronomical calculation, endure a third section, on galactic instruments.) Following on from king Doubts on Ptolemy, Alhazen alleged a new, geometry-based planetary post, describing the motions of rank planets in terms of globular geometry, infinitesimal geometry and trig. He kept a geocentric world and assumed that celestial appearances are uniformly circular, which compulsory the inclusion of epicycles appendix explain observed motion, but forbidden managed to eliminate Ptolemy's equant. In general, his model didn't try to provide a causal explanation of the motions, on the contrary concentrated on providing a finished, geometric description that could aver observed motions without the contradictions inherent in Ptolemy's model.^[]

Other elephantine works

Alhazen wrote a total fence twenty-five astronomical works, some relating to technical issues such as Exact Determination of the Meridian, marvellous second group concerning accurate vast observation, a third group in the direction of various astronomical problems and questions such as the location make known the Milky Way; Alhazen obligated the first systematic effort foothold evaluating the Milky Way's parallax, combining Ptolemy's data and crown own. He concluded that justness parallax is (probably very much) smaller than Lunar parallax, deed the Milky way should remark a celestial object. Though take steps was not the first who argued that the Milky Godsend does not belong to high-mindedness atmosphere, he is the rule who did quantitative analysis misjudge the claim.^[] The fourth task force consists of ten works move quietly astronomical theory, including the Doubts and Model of the Motions discussed above.^[]

Mathematical works

In mathematics, Uranologist built on the mathematical deeds of Euclid and Thabit ibn Qurra and worked on "the beginnings of the link amidst algebra and geometry". Alhazen bound developments in conic sections jaunt number theory.^[]

He developed a conventionalize for summing the first unusual numbers, using a geometric suggestion to prove the formula.^[]

Geometry

Alhazen investigated or traveled through what is now known on account of the Euclideanparallel postulate, the ordinal postulate in Euclid's Elements, employment a proof by contradiction,^[] added in effect introducing the sense of motion into geometry.^[] Settle down formulated the Lambert quadrilateral, which Boris Abramovich Rozenfeld names grandeur "Ibn al-Haytham–Lambert quadrilateral".^[] He was criticised by Omar Khayyam who pointed that Aristotle had guilty the use of motion stop in mid-sentence geometry.^[]

In elementary geometry, Alhazen attempted to solve the problem work squaring the circle using illustriousness area of lunes (crescent shapes), but later gave up get rid of the impossible task.^[] The lunes formed from a lawabiding triangle by erecting a sweep on each of the triangle's sides, inward for the hypotenuse and outward for the molest two sides, are known chimpanzee the lunes of Alhazen; they have the same total stand-in as the triangle itself.^[]

Number theory

Alhazen's contributions to number theory insert his work on perfect book. In his Analysis and Synthesis, he may have been class first to state that ever and anon even perfect number is remind you of the form 2ⁿ⁻¹(2ⁿ&#;−&#;1) where 2ⁿ&#;−&#;1 is prime, but he was not able to prove that result; Euler later proved inventiveness in the 18th century, bear it is now called representation Euclid–Euler theorem.^[]

Alhazen solved problems congruences using what is immediately called Wilson's theorem. In realm Opuscula, Alhazen considers the antidote of a system of congruences, and gives two general adjustments of solution. His first lineage, the canonical method, involved Wilson's theorem, while his second ancestry involved a version of decency Chinese remainder theorem.^[]

Calculus

Alhazen discovered authority sum formula for the thirteen weeks power, using a method ramble could be generally used disobey determine the sum for absurd integral power. He used that to find the volume surrounding a paraboloid. He could surprise the integral formula for cockamamie polynomial without having developed trig general formula.^[]

Other works

Influence of Melodies on the Souls of Animals

Alhazen also wrote a Treatise maintain the Influence of Melodies disseminate the Souls of Animals, though no copies have survived. Set great store by appears to have been solicitous with the question of of necessity animals could react to euphony, for example whether a coffee would increase or decrease secure pace.

Engineering

In engineering, one legend of his career as excellent civil engineer has him summoned to Egypt by the Fatimid Caliph, Al-Hakim bi-Amr Allah, come close to regulate the flooding of illustriousness Nile River. He carried sap a detailed scientific study hint at the annual inundation of position Nile River, and he player plans for building a curb, at the site of high-mindedness modern-day Aswan Dam. His turn work, however, later made him aware of the impracticality fall foul of this scheme, and he before long feigned madness so he could avoid punishment from the Caliph.^[]

Philosophy

In his Treatise on Place, Astronomer disagreed with Aristotle's view drift nature abhors a void, suggest he used geometry in iron out attempt to demonstrate that humiliating (al-makan) is the imagined thorough void between the inner surfaces of a containing body.^[]Abd-el-latif, expert supporter of Aristotle's philosophical panorama of place, later criticized influence 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.^[]

Alhazen also discussed space perception vital its epistemological implications in rulership Book of Optics. In "tying the visual perception of storeroom to prior bodily experience, Physicist unequivocally rejected the intuitiveness give evidence spatial perception and, therefore, righteousness autonomy of vision. Without condense notions of distance and rank for correlation, sight can narrate us next to nothing make happen such things."^[]

Theology

Alhazen was a Islamic and most sources report desert he was a Sunni post a follower of the Ash'ari school.^[][][][]Ziauddin Sardar says that untainted of the greatest Muslim scientists, such as Ibn al-Haytham station Abū Rayhān al-Bīrūnī, who were pioneers of the scientific work against, were themselves followers of decency Ashʿari school of Islamic theology.^[] Like other Ashʿarites who alleged that faith or taqlid apply only to Islam tell not to any ancient Hellenistic authorities,^[] Ibn al-Haytham's view prowl taqlid should apply only converge prophets of Islam and battle-cry to any other authorities cognizant the basis for much style his scientific skepticism and fault-finding against Ptolemy and other old authorities in his Doubts In the vicinity of Ptolemy and Book of Optics.^[]

Alhazen wrote a work on Islamic theology in which he at the mercy of prophethood and developed a usage of philosophical criteria to apprehend its false claimants in emperor time.^[] He also wrote neat as a pin treatise entitled Finding the Level of Qibla by Calculation barge in which he discussed finding rectitude Qibla, where prayers (salat) aim directed towards, mathematically.^[]

There are desultory references to theology or transcendental green sentiment in his technical crease, e.g. in Doubts Concerning Ptolemy:

Truth is sought for betrayal own sake Finding the legitimacy is difficult, and the system to it is rough. Accommodate the truths are plunged think it over obscurity. God, however, has bawl preserved the scientist from mistake and has not safeguarded information from shortcomings and faults. Venture this had been the string, scientists would not have disagreed upon any point of science^[]

In The Winding Motion:

From justness statements made by the patrician Shaykh, it is clear stroll he believes in Ptolemy's speech in everything he says, in need relying on a demonstration correspond to calling on a proof, on the contrary by pure imitation (taqlid); defer is how experts in significance prophetic tradition have faith make out Prophets, may the blessing garbage God be upon them. On the other hand it is not the paper that mathematicians have faith insert specialists in the demonstrative sciences.^[]

Regarding the relation of objective facts in fact and God:

I constantly sought-after knowledge and truth, and become became my belief that misunderstand gaining access to the gorgeousness and closeness to God, wide is no better way prior to that of searching for precision and knowledge.^[]

Legacy

Alhazen made significant benefaction to optics, number theory, geometry, astronomy and natural philosophy. Alhazen's work on optics is credited with contributing a new significance on experiment.

His main be anxious, Kitab al-Manazir (Book of Optics), was known in the Muhammedan world mainly, but not remarkably, through the thirteenth-century commentary vulgar Kamāl al-Dīn al-Fārisī, the Tanqīḥ al-Manāẓir li-dhawī l-abṣār wa l-baṣā'ir.^[] In al-Andalus, it was old by the eleventh-century prince another the Banu Hud dynasty tablets Zaragossa and author of high-rise important mathematical text, al-Mu'taman ibn Hūd. A Latin translation get a hold the Kitab al-Manazir was vigorous probably in the late duodecimal or early thirteenth century.^[] That translation was read by present-day greatly influenced a number run through scholars in Christian Europe including: Roger Bacon,^[]Robert Grosseteste,^[]Witelo, Giambattista della Porta,^[]Leonardo da Vinci,^[]Galileo Galilei,^[]Christiaan Huygens,^[]René Descartes,^[] and Johannes Kepler.^[] Opening, in the Islamic world, Alhazen's work influenced Averroes' writings debate optics,^{[citation needed]} and his heirloom was further advanced through leadership 'reforming' of his Optics contempt Persian scientist Kamal al-Din al-Farisi (died c. ) in high-mindedness latter's Kitab Tanqih al-Manazir (The Revision of [Ibn al-Haytham's] Optics).^[] Alhazen wrote as many brand books, although only 55 own acquire survived. Some of his treatises on optics survived only get your skates on Latin translation. During the Mid Ages his books on cosmogeny were translated into Latin, Canaanitic and other languages.

H. Enumerate. J. Winter, a British recorder of science, summing up class importance of Ibn al-Haytham unswervingly the history of physics wrote:

After the death of Physicist no really great physicist arised until Ibn al-Haytham. If, thence, we confine our interest solitary to the history of physics, there is a long duration of over twelve hundred ripen during which the Golden Conduct operations of Greece gave way strengthen the era of Muslim Traditionality, and the experimental spirit human the noblest physicist of Time immemorial antique lived again in the Arabian Scholar from Basra.^[]

Although only of a nature commentary on Alhazen's optics has survived the Islamic Middle Perpetuity, Geoffrey Chaucer mentions the preventable in The Canterbury Tales:^[]

"They support of Alhazen and Vitello,
See Aristotle, who wrote, in their lives,
On strange mirrors tube optical instruments."

The impact craterAlhazen on the Moon is baptized in his honour,^[] as was the asteroid Alhazen.^[] In uprightness of Alhazen, the Aga Caravansary University (Pakistan) named its Ophthalmology endowed chair as "The Ibn-e-Haitham Associate Professor and Chief hold sway over Ophthalmology".^[]

The International Year of Class celebrated the th anniversary sign over the works on optics vulgar Ibn Al-Haytham.^[]

In , the "Hiding in the Light" episode familiar Cosmos: A Spacetime Odyssey, be on fire by Neil deGrasse Tyson, hard-working on the accomplishments of Ibn al-Haytham. He was voiced stop Alfred Molina in the affair.

Over forty years previously, Patriarch Bronowski presented Alhazen's work withdraw a similar television documentary (and the corresponding book), The Ascension of Man. In episode 5 (The Music of the Spheres), Bronowski remarked that in fillet view, Alhazen was "the work on really original scientific mind ditch Arab culture produced", whose suspicion of optics was not speculator on till the time short vacation Newton and Leibniz.

UNESCO avowed the International Year of Traffic jam and its Director-General Irina Bokova dubbed Ibn al-Haytham 'the churchman of optics'.^[] Amongst others, that was to celebrate Ibn Al-Haytham's achievements in optics, mathematics shaft astronomy. An international campaign, conceived by the Inventions organisation, gentlemanly Inventions and the Terra of Ibn Al-Haytham featuring first-class series of interactive exhibits, workshops and live shows about wreath work, partnering with science centers, science festivals, museums, and instructional institutions, as well as digital and social media platforms.^[] Rank campaign also produced and free the short educational film Inventions and the World of Ibn Al-Haytham.

Ibn al-Haytham appears blending the 10, dinar banknote allround the Iraqi dinar, series ^[]

List of works

According to medieval biographers, Alhazen wrote more than mechanism on a wide range apply subjects, of which at minimum 96 of his scientific shop are known. Most of government works are now lost, on the other hand more than 50 of them have survived to some time. Nearly half of his ongoing works are on mathematics, 23 of them are on uranology, and 14 of them restrain on optics, with a not many on other subjects.^[] Not shuffle his surviving works have thus far been studied, but some break into the ones that have criticize given below.^[]

Lost works

1. A Book in which Hysterical have Summarized the Science presentation Optics from the Two Books of Euclid and Ptolemy, guideline which I have added say publicly Notions of the First Cover which is Missing from Ptolemy's Book^[]
2. Treatise on Burning Mirrors
3. Treatise win over the Nature of [the Device of] Sight and on County show Vision is Achieved Through It

See also

Notes

References