Alhazen

Abu Ali al -Hasan ibn al - Haitham (Persian ابن هيثم, Arabic أبو علي الحسن بن الهيثم, Abū ʿ Alī al DMG - Ḥasan ibn al - Haytham ), Latinized Alhazen (c. 965 in Basrah, † 1039 or 1040 in Cairo ) was a Muslim mathematician, optician and astronomer Arabic or Persian origin.

Life and work

Little is known about the life of Alhazen, but there were many legends about him in circulation, also found their way into later Western biographies. He was 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 was wrong, either to cover up his failure or to devote less administrative tasks as science, because he feared the wrath of al - Hakim, a mental illness before, after which he located at the al -Hakim founded the House of Wisdom throughout the Science turned. After the death of al - Hakim in the year 1021 it shall be recovered in a seemingly " miraculously " according to the legend.

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

However, of greatest importance are his optical experiments: Most scientists of antiquity, including Euclid and Ptolemy, took part in that so-called " lines of sight ", which should be based on the human eye, abtasteten the environment and thus created the visual impression in the brain, similar to a blind man who scans its environment with a staff. Aristotle, however, was of the view that light existed independently of the human eye and is paving its way from the objects into the eye through a medium. Alhazen, however, moved towards a new way the question by analyzing the structure of the eye. He recognized the importance of the lens in the eye and refuted in scientific experiments, the lines of sight theory.

Based on Ibn Sahl and refined, he expanded the theories of Ptolemy to the light refraction and reflection of light; in particular, it has recognized and described the suitability of curved glass surfaces for optical magnification. With this knowledge, he set forth reading stones from glass. He is considered the inventor of the magnifying glass and probably inspired with his writings Roger Bacon to the invention of glasses. He pointed out also attempts to mix colors and Camera Obscura.

Even today his name is associated with a problem of optics, the Alhazensche problem: He solved geometrically with conics the task to calculate a spherical mirror the point from which an object of a given distance is projected to a given image, suggesting a quartic equation leads or on the determination of the roots of a cubic equation ( so she would not be solved with ruler and compass ). The full algebraic solution was Peter Neumann 1997. The problem goes back to Ptolemy and employed, for example, Christian Huygens. Alhazen himself admitted in this connection with an early application of mathematical induction, the first formula for the sum of fourth powers ( the integer on sums of magnitude can be generalized ), and was thus the volume of the paraboloid. 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 takes place in the air surrounding the Earth. He noted that both the moon on the horizon and at the zenith of the same size. So he recognized the seemingly larger diameter of the moon near the horizon than a perception deception ( Moon illusion ). He also calculated the height of the atmosphere from the observation of sunsets.

He was also credited with the philosophy of science: He was the first systematically turned the inductive- experimental scientific method to, in the first experiments carried out and only then established on the basis of the experimental results theories; until then, it was common to gain knowledge only through logical conclusions and possibly conduct experiments to illustrate the theories found in this way.

He was concerned by the optics with astronomy and developed to new methods of spherical geometry. His Liber de mundo et coelo was widespread in the Christian West.

Alhazen possibly by Gerard of Cremona itself or in its vicinity into Latin translated Kitaab al - Manazir, which was distributed under the title Perspectiva or De aspectibus influenced optical and beyond philosophical theories since the late 13th century, especially the works of Roger Bacon, John Peckham and Vitelo of Alhazen's views influenced. The translation was published in 1572 by Friedrich Risner in Basel together with Witelos look at they Kepler Paralipomena ad Vitellionem relate.

Honors

The crater Alhazen on the Moon and the asteroid ( 59239 ) Alhazen named after al - Haitham.

To honor him, called the Aga Khan University ( Pakistan), its Department of Ophthalmology ( med: Ophthalmology ) "The Ibn -e- Haitham Associate Professor and Chief of Ophthalmology ".

A fictional portrait Alhazen is located on the in circulation since 2003 10.000 dinar banknote of the Iraqi dinar.

Works

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