**Abu Ali аль al-Hasan ibn al-Hasan ibn al-Khaysam al-Basri** ( Arabic: أبو علي الحسن بن الحسن بن الهيثم , 965 , Basra - 1039 , Cairo ) - Arabian universal scientist, mathematician , astronomer . In medieval Europe, it was mentioned under the Latinized name **Alhazen** ( **Alhazen** ) ^{[5]} .

Ibn al-Khaysam | |
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Arab. أبو علي الحسن بن الحسن بن الهيثم | |

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Place of Birth | Basra |

Date of death | or |

Place of death | |

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*There are articles on Wikipedia about other people with Kunya Abu Ali , the name of Hassan and Nisboy Basri*.

## Content

## Biography

Thanks to his outstanding abilities, Ibn al-Khaysam held the vizier position in his native Basra , but his love of science prompted him to leave this post and only engage in science. When a rumor reached the Egyptian caliph al-Hakim that Ibn al-Khaysam had drawn up a project to regulate the waters of the Nile by building a dam below Aswan , he invited the scientist to Egypt . However, on the spot, Ibn al-Khaysam was convinced of the impossibility of carrying out this project with the technical means of that time (almost a millennium before the construction of the existing Aswan Dam ). Upon learning of this, the Caliph was angry with the scientist, subjected him to house arrest and confiscated his property. To save the life of Ibn al-Khaysam was forced to pretend to be crazy until the death of al-Hakim. Under his successors, he received freedom and lived in high esteem in Cairo until his death.

In the list of doctors, given by the Syrian Ibn Abu Uusaybiyah , 92 works of Ibn al- Khaysam are mentioned, 89 of them are devoted to mathematics , astronomy , optics and mechanics . Ibn al-Khaysam combined rigorous experiments with rigorous mathematical evidence in his scientific studies. Often he is called the "father of optics."

In honor of the scientist named a crater on the moon .

## Math

In the Book of Commentaries on the Introduction to the Beginnings of Euclid , Ibn al-Haytham tried to prove the fifth postulate of Euclid. His proof was erroneous, but for the first time he examined the so-called “ Lambert Quadrangle ", in which the three internal angles are straight. He formulated three possible options for the fourth corner: sharp, straight, dull. A discussion of these three hypotheses has arisen many times in later studies of the fifth postulate .

In the treatise "On the measurement of a parabolic body," Ibn al-Khaysam gives formulas for the sum of consecutive squares, cubes and fourth degrees, and a number of other formulas for the sums of series. Using these formulas, he performs a calculation equivalent to computing a certain integral$\underset{0}{\overset{a}{\int}}\sqrt{x}dx$ .

In the treatise "On Isoperimetric Figures," Ibn al-Khaysam made an attempt to prove that the circle has the largest area of all figures of equal perimeter, and the ball is the largest volume of all bodies with equal surfaces.

Ibn al-Khaysam also owns the works “On the quadrature of a circle”, “On the measurement of a ball”, “On the construction of a heptagon”, “On the construction of a pentagon inscribed in a square”, “On the properties of the height of a triangle”, “On the compass for conical sections”, “On the extraction of the cubic root”, “On the parabola”, “On the hyperbole”, “On the magic square”. It is also known that he applied geometric methods to the solution of equations of the 4th degree.

## Optics

Ibn al-Khaysam belongs to the fundamental work on optics - “ ” (in 7 books).

In the field of physiological optics, he gives a description of the structure of the eye, following the ancient Greek scientist Galen , and on an experimental basis proves the groundlessness of the views of Plato and Euclid on light as rays that are emitted by the eye and "feel" objects. Ibn al-Khaysam put forward his own theory, according to which "natural light and colored rays affect the eye," and "the visual image is obtained using the rays that are emitted by visible bodies and enter the eye." Moreover, in the VI century. BC e. (that is, 17 centuries before al-Khaysam) Pythagoras expressed exactly the same (close to modern) idea that bodies become visible due to the particles emitted by them. Concepts very close to the modern understanding of various optical phenomena were developed by other predecessors of al-Khaysam - Aristotle (IV century B.C.), Plato (IV century B.C.), Euclid (III century B.C. .), Kleomed (I century A.D. ), Ptolemy (130 A.D.) and others. The main contribution of scientists who worked before al-Khaisam is not even their hypotheses about the nature of light, but that they found the laws of its direct distribution and reflection and knew how to use them.

Al-Khaysam believed that each point of the observed object can be associated with a certain perceiving point of the eye. He gave the correct representation of binocular vision . Finally, he suggested that the speed of light is finite.

Among the experiments conducted by the scientist, the experiments with a pinhole camera , experiments on the refraction of light, and experiments with various types of mirrors developing the doctrine of Diocles stand out .

In the XII century, the work under discussion was translated into Latin under the name “Treasure of Optics” (lat. *Opticae thesaurus* ) and had a great influence on the development of optics in Europe. The first major European essay on optics, Vitelo 's Perspective, is to a large extent a revision of the Ibn al-Hayesam treatise.

Ibn al-Khaysam also compiled a series of treatises on incendiary glasses and treatises "On the light of the moon", "On the halo and rainbow", "On the properties of shadows."

## Astronomy

Ibn al-Khaysam has a number of works on astronomy and geodesy: “On the light of the stars”, “On the forms of eclipses”, “On the motion of the moon”, “On the definition of the pole with the highest accuracy”, “On the parallax of the moon”, “On the clock lines” , “On the nature of traces visible on the surface of the Moon”, “On determining the meridian from one shadow”, “On horizontal sundials”, “On differences in the heights of the stars”, “On methods of observation”, “On determining the azimuth of the qibla” (qibla called the direction to Mecca), "On determining the distance between two cities using geometry", etc. .

In the “Book on the Form of the World,” Ibn al-Khaysam develops the idea stated by al-Fargani and al-Khazin about the massive etheric orbits of the planets.

## Notes

- ↑
^{1}^{2}National Library of Australia - 1960. - ↑ BNF ID : 2011 Open Data Platform .
- ↑
*German National Library , Berlin State Library , Bavarian State Library , etc.*Record # 118648160 // General regulatory control (GND) - 2012—2016. - ↑ Archive for the history of mathematics MacTyutor
- ↑ Temples, 1983 , p. 13.

## Literature

### Works of Ibn al-Khaysam

- Ibn al-Khaysam Hassan. A book of comments on the introduction of the book of Euclid's "Beginnings."
*Historical and mathematical research*, 11, 1958, p. 733-762. - Ibn al-Khaysam Hassan. A treatise on isoperimetric figures. Per. and approx. Jamal Ad-Dabbah. Historical and mathematical research, 17, 1966, p. 399-448.
- Ibn al-Khaysam Hassan. A book about measuring a ball.
*Physics and mathematics in the East*, 2 (5), 1968, p. 131-146.

### About him

*Kolchinsky I.G., Korsun A.A., Rodriguez M.G.*Astronomers: A Biographical Reference. - 2nd ed., Revised. and additional .. - Kiev: Naukova Dumka, 1986. - 512 p.*Kulieva G.Z.*The Theory of Compound Relations of Ibn al-Khaysam // Scientific notes of Azerbaijan. un-that. - 1963. - No. 4 .*Llozzi M.*History of Physics. - M .: Mir, 1970 .-- 464 p.*Rozhanskaya M.M.*Mechanics in the medieval East. - M .: Nauka, 1976 .-- 324 p.*Rosenfeld B.A., Yushkevich A.P.*Theory of parallel lines in the medieval East. - M .: Nauka, 1983 .-- 124 p.*Rosenfeld B.A.*Astronomy of the countries of Islam // Historical and astronomical research. - 1984.- T. 17 . - S. 67—122 .*Temples Yu. A.*Alkhazen (Latinized name of Abu Ali Haysam) // Physicists: Biographical Reference / Ed. A.I. Akhiezer . - Ed. 2nd, rev. and add. - M .: Nauka , 1983 .-- S. 13. - 400 p. - 200,000 copies. (in per.)*Roshdi Rashed.*A Polymath in the 10th century // Science. - 2002.*Nader El-Bizri*, A Philosophical Perspective on Alhazen's Optics, Arabic Sciences and Philosophy, Vol. 15, Issue 2 (2005), pp. 189-218 (Cambridge University Press)

## Links

*John J. O'Connor*and*Edmund F. Robertson*. Abu Ali al-Hasan ibn al-Haytham (English) - biography in the MacTutor archive.- Ibn al-Haitham on two Iraqi banknotes
- The Miracle of Light - a UNESCO article on Ibn Haitham
*AI Sabra*, “Ibn al-Haytham: Brief life of an Arab mathematician”