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Alhazen in the eyes of early modern times: Portrait in an edition of the Selenography of Johannes Hevelius (1647)

Alhazen ( Arabic أبو علي الحسن بن الهيثم Abu Ali al-Hasan ibn al-Haitham , DMG Abū ʿAlī al-Ḥasan bin al-Haiṯam , also abbreviated Ibn al-Haiṯam and Ibn al-Heithem , Persian ابن هيثم, DMG Ibn Haiṯam , Latinized Alhacen , Avennathan or Avenetan , born around 965 in Basra ; died after 1040 in Cairo ), was a mathematician , optician and astronomer in the heyday of Islam . He made fundamental contributions to optics, astronomy, mathematics and meteorology .


Little is known about the life of Alhazen, but there were numerous legends about him that found their way into later western biographies. He worked in Cairo at the court of al-Hakim , where he proposed a project to regulate the Nile floods , which was rejected by the caliph. According to legend, he faked, either to cover up his failure or to devote himself less to administrative tasks than science, fearing the wrath of al-Hakim, a mental illness , after which he devoted himself entirely to the House of Wisdom founded by al-Hakim turned to science. After the death of al-Hakim in 1021, legend has it that he apparently recovered “miraculously”.



In his numerous mathematical works he dealt with problems of number theory and geometry .


Most important, however, are his optical experiments: most ancient scientists, including Euclid and Ptolemy , assumed that the visual impression in the brain was created by "rays of sight" that emanated from the human eye and scanned the environment, similar to a blind person who scans his surroundings with a stick. Aristotle, on the other hand, was of the opinion that light exists independently of the human eye and that it paves its way from objects to the eye via a medium. Alhazen, however, approached the question in a new way by analyzing the structure of the eye. He recognized the importance of the lens in the eye and refuted the visual ray theory in scientific experiments.

Building on Ibn Sahl , he also refined and expanded Ptolemy's theories on refraction and reflection ; in particular, he recognized and described the suitability of curved glass surfaces for optical magnification. With this knowledge he made reading stones out of glass. He is therefore considered the inventor of the magnifying glass and probably inspired Roger Bacon to invent glasses with his writings . He also carried out experiments on color mixing and camera obscura .

Engraving on the title page of the Thesaurus opticus . The illustration shows how Archimedes of Syracuse is said to have set Roman ships on fire with the help of parabolic mirrors.

Even today his name is connected to a problem of optics, the Alhazensche problem : He solved geometrically with conic sections the task of calculating in a spherical mirror the point from which an object is projected from a given distance to a given image, what onto a Equation of the fourth degree leads to the determination of the root of an equation of the third degree (so it could not be solved with a compass and ruler). The complete algebraic solution was found by Peter Neumann in 1997. The problem goes back to Ptolemy and occupied Christiaan Huygens , for example . In this context, Alhazen himself gave the first formula for the sum of fourth powers (which can also be generalized to sums of whole-number powers) with an early application of complete induction , and thus found the volume of the paraboloid . Thus he also plays a role in the early history of analysis.

Based on his findings in the field of optics, Alhazen discovered that refraction of light also takes place in the atmosphere of the earth. He found that the moon is the same size both on the horizon and at the zenith . So he recognized the apparently larger diameter of the moon near the horizon as a perception illusion ( moon illusion ). He also calculated the altitude of the atmosphere from observing sunsets.

After optics, he also dealt with astronomy and developed new methods of spherical geometry. His Liber de mundo et coelo and his concept of a geometric-perspective optics were widespread in the Christian Occident from around 1200 (fundamentally also for Dietrich von Freiberg ).

Philosophy of science

He also made an outstanding contribution to the theory of science : He was the first to systematically apply the inductive - experimental scientific method of working, in which experiments are first carried out and only then theories are set up on the basis of the experimental results; Until then, it was customary to gain knowledge only through logical conclusions and to carry out experiments at best to illustrate the theories found in this way.


Alhazen's Kitāb al-Manāzir, possibly translated into Latin by Gerhard von Cremona himself or in his vicinity, which was known under the title Perspectiva or De aspectibus , influenced optical and also philosophical theories since the late 13th century, in particular the works of Roger Bacon , Witelo and Johannes Peckham were shaped by Alhazen's views. The translation was published in 1572 by Friedrich Risner in Basel together with Witelos Optik; Kepler's Paralipomena ad Vitellionem refer to it.


The lunar crater Alhazen and the asteroid (59239) Alhazen are named after al-Haitham.

To honor him, the Aga Khan University (Pakistan) named its chair for ophthalmology (med .: Ophthalmologie) "The Ibn-e-Haitham Associate Professor and Chief of Ophthalmology".

A fictional image of Alhazen can be found on the 10,000 dinar banknote of the Iraqi dinar, which has been in circulation since 2003 .


  • Kitab-al-Manazir 1021. (Latin translation: Opticae Thesaurus or De aspectibus 1572). (German: Book of seeing or treasure of optics ).
  • Al-Shukūk ‛alā Batlamyūs . (Doubt about Ptolemy)
  • About the structure of the world ( Kitab fi hai at al alam , Latin translation: Liber de mundo et coelo, motibus planetarum etc. )
  • Model of the movements of each of the seven planets
  • Over the Milky Way


  • Jim Al-Khalili: Pathfinders: The Golden Age of Arabic Science. Allen Lane, London 2010, ISBN 978-1-84614-161-4 .
  • Hans Belting : Florence and Baghdad. A west-east history of the gaze. Beck, Munich 2008, ISBN 978-3-406-57092-6 .
  • Karl Kohl: About the light of the moon. An investigation by Ibn al Haitham. In: Meeting reports of the Physico-Medical Society in Erlangen. 56/57, 1926, ISSN  0371-2117 , pp. 305-398.
  • Fritz Krafft : Abu ʿAli al-Hasan Ibn al-Hasan Ibn al-Haitham. In: Fritz Krafft (Ed.): Advance into the unknown. Lexicon of great natural scientists. Weinheim / New York 1999, p. 187 f.
  • Tzvi Langermann: Ibn Al-Haytham. In: Thomas Hockey et al. (Ed.): The Biographical Encyclopedia of Astronomers. Springer, New York 2007, ISBN 978-0-387-31022-0 , pp. 556-557 ( online ).
  • David C. Lindberg : Eye and Light in the Middle Ages. The development of optics from Alkindi to Kepler. Suhrkamp, ​​Frankfurt am Main 1987, ISBN 3-518-57835-9 , pp. 47-160.
  • Roshdi Rashed Les mathématiques infinitésimales du IXe au XIe siècle , Volume 2 Ibn al-Haytham , London 1993, Volume 3 Ibn al-Haytham: Théorie des coniques, constructions géométriques et géométrie pratique , 2000, Volume 4: Ibn Al-Haytham: Méthodes g , transformations ponctuelles et philosophie des mathématiques , 2001, volume 5: Ibn al-Haytham: Astronomie, géométrie sphérique et trigonométrie , 2006 (volume 5 with the first edition in Arabic / French of five books by Rashed on astronomy and related geometry; a total of around 25 works on astronomy attributed to him)
  • Roshdi Rashed The celestial kinematics of Ibn al-haytham , Arabic Sciences and Philosophy, Volume 17, 2007, pp. 7-55.
  • Roshdi Rashed: Ibn Al-Haytham (Alhazen). In: Helaine Selin (Ed.): Encyclopaedia of the History of Science, Technology and Medicine in Non-Western Cultures. Volume 1: A-K. 2nd edition, Springer, Berlin - Heidelberg - New York 2008, ISBN 978-1-4020-4559-2 ( online ).
  • AI Sabra : Ibn Al-Haytham, Abū ʿ Alī Al-Ḥasan Ibn Al-Ḥasan . In: Charles Coulston Gillispie (Ed.): Dictionary of Scientific Biography . tape 6 : Jean Hachette - Joseph Hyrtl . Charles Scribner's Sons, New York 1972, p. 189-210 ( online ).
  • AI Sabra: The Optics of Ibn Al-Haytham. Books I-III: On Direct Vision . 2 volumes. Warburg Institute, London 1989, ISBN 0-85481-072-2 (= Studies of the Warburg Institute 40, 1-2).
  • Matthias Schramm : Ibn Al-Haytham's path to physics . Steiner, Wiesbaden 1963, ( Boethius 1, ISSN  0523-8226 ).
  • Gotthard Strohmaier: Alhazen - physics on the verge of madness. In: Spectrum of Science . 12/2004, ISSN  0170-2971 , pp. 90-97.
  • Graziella Federici Vescovini: Le teorie della luce e della visione ottica a dal IX al XV secolo. Studi sulla prospettiva medievale e altri saggi. Morlacchi, Perugia 2003, ISBN 88-88778-61-6 , ( Storia del pensiero filosofico e scientifico. ) Pp. 155-185.
  • Eilhard Wiedemann: Ibn al Haitam, an Arab scholar. In: Festschrift dedicated to J. Rosenthal at the end of his seventieth year . Thieme, Leipzig 1906, part 1, pp. 147–178.

Web links

Individual evidence

  1. ^ Richard Lorch: Ibn al-Haiṭam. In: Lexicon of the Middle Ages . Volume 5 (1991), Col. 315 f.
  2. a b J. Vernet: Ibn al-Hayt h on . ( [accessed June 16, 2017]).
  3. Roshdi Rashed: Ibn Al-Haytham (Alhazen). In: Helaine Selin (Ed.): Encyclopaedia of the History of Science, Technology and Medicine in Non-Western Cultures. Volume 1: A-K. 2nd edition, Springer, Berlin - Heidelberg - New York 2008, ISBN 978-1-4020-4559-2 states as certain dates of life: born in the second half of the 10th century, died after 1040.
    Gérard Simon: The Gaze in Ibn al-Haytham . In: The Medieval History Journal . tape 9 , no. 1 , August 11, 2016, p. 89-98 , doi : 10.1177 / 097194580500900105 ( [accessed June 16, 2017]).
  4. Roshdi Rashed: Ibn Al-Haytham (Alhazen). In: Helaine Selin (Ed.): Encyclopaedia of the History of Science, Technology and Medicine in Non-Western Cultures. Volume 1: A-K. 2nd edition, Springer, Berlin - Heidelberg - New York 2008, ISBN 978-1-4020-4559-2 , p. 1667: "The three most famous Islamic contributions to meteorology were: the Alexandrian mathematician / astronomer Ibn al-Haytham (Alhazen 965-1039), the Arabic-speaking Persian doctor Ibn Sina (Avicenna 980-1037) and the Spanish-Moorish doctor / lawyer Ibn Rushd (Averroes; 1126-1198). "
  5. Roshdi Rashed: Ibn Al-Haytham (Alhazen). In: Helaine Selin (Ed.): Encyclopaedia of the History of Science, Technology and Medicine in Non-Western Cultures. Volume 1: A-K. 2nd edition, Springer, Berlin - Heidelberg - New York 2008, ISBN 978-1-4020-4559-2 .
  6. Alhazen problem with Wolfram , sometimes also called Alhazen billiard problem because of the analogous problem with circular billiards
  7. ^ Victor J. Katz: Ideas of Calculus in Islam and India. In: Mathematics Magazine. Vol. 68, 1995, No. 3, pp. 163-174.
  8. Gundolf Keil : "blutken - bloedekijn". Notes on the etiology of the hyposphagma genesis in the 'Pommersfeld Silesian Eye Booklet' (1st third of the 15th century). With an overview of the ophthalmological texts of the German Middle Ages. In: Specialized prose research - Crossing borders. Volume 8/9, 2012/2013, pp. 7–175, here: pp. 8 f.