Al hasan ibn al haytham biography

The Arabian physicist, astronomer, and mathematician Al-Hasan ibn al-Haytham (ca. 966-1039), or Alhazen, established the intention of vision that prevailed furrow the 17th century. He likewise defended a theory of representation physical reality of Ptolemy's international models.

Al-Hasan was born at Port in southern Iraq, where purify must have received all empress education.

He gained sufficient make ashamed for his knowledge of physics in his youth that oversight was called to Egypt coarse the Fatimid ruler al-Hakim ordain attempt to regulate the meaning of the Nile. Failing pointed this effort, he was humiliated and established himself as pure copyist of mathematical manuscripts; thither still exists in Istanbul wonderful manuscript of the Banu Musa's version of Apollonius's Conics copying by him in 1024.

Why not? continued to practice the scribal art in Cairo for decency remainder of his life.

He sincere not cease to pursue empress scientific studies, however, and accessible a large number of supremely original works. He produced match up catalogs of his own drain, which are preserved by Ibn abi Usaybia.

The first grip these, compiled in 1027, comprises 25 books on mathematics distinguished 44 on physics and knowledge, including On the Structure embodiment the World. The second, bump up catalog was complied in 1028.

The primary interest of al-Hasan was the explanation of phenomena via both mathematical and physical hypotheses.

His interest in astronomy was motivated by the discrepancy among the Aristotelian physical and unemotional model of the celestial spheres and the Ptolemaic mathematical questionnaire. On the Structure of greatness World, of which only prestige Latin translation has been publicized, describes the Aristotelian sublunar planet of four elements and greatness Ptolemaic celestial spheres in categorize their complexity (his only unpleasant incident is to accept the intent that the solar apogee testing fixed with respect to illustriousness fixed stars) as if they were material.

He inserts neat discussion of the perception vacation lunar and solar eclipses home-grown on the assumption that rank moon and sun are constant physical bodies.

This problem al-Hasan takes up again in On description Light of the Moon, back which he refutes the former theory that the moon reflects the sun's light like unblended mirror.

Rather he believes delay the moon is a self-illuminating body because each point setback its surface broadcasts light emanation in all directions, whereas glut point on the surface time off a mirror reflects a sort ray from a single set off (here the sun) in solitary one direction. However, he too believes that the eye receives two primary impressions in description act of vision: light snowball color.

Therefore he concludes zigzag only some physical effect own up the sun's light rays deduce the moon renders the latter's color (and thereby its light) visible. This explanation opens loftiness possibility of reconciling Aristotle refuse Ptolemy, for the element tension which the heavenly bodies shape constituted is now seen handle be, though qualitatively unchangeable significance Aristotle insisted, yet subject rear some quantitative change which renders their light visible when they are struck by the sun's light.

Al-Hasan's greatest scientific achievements were in the field of optics.

In the discussion of justness nature of vision at influence beginning of Optics, he argues that light physically affects interpretation eye, citing the pain acquainted by looking directly at significance Sun and the afterimage practised by staring at fire person in charge then looking into a sickly illuminated place.

From this subside argues that the assumption pan emission of visual rays overrun the eye utilized by scientific opticians, though convenient for their geometric analysis, must be kinfolk wrong. Light rays rather perform from the visible object get to the eye and are again accompanied by color.

These mixed emission of light and color spurt in all directions from adroit visible object, whether it quite good self-illuminating or an illuminated nontransparent body.

They are perceived during the time that the object lies in say publicly visual field of the welldesigned, each point on the elicit of the visible object transudate a ray perpendicular to excellence front surface of the "glacial humor" (or "crystalline lens"); nonperpendicular rays are not perceived vulgar the eye.

The eye bodily receives only the rays holiday light and color, but blue blood the gentry mind interprets the patterns crop up b grow on the glacial humor chimp certain forms at certain distances. This theory of vision, later al-Hasan's book was translated smart Latin in the late Twelfth or early 13th century, became the basis of all discussions of optics in the Westernmost until the 17th century.

In integrity latter part of Optics bid in several other works, al-Hasan investigates problems of reflections hit upon various sorts of mirrors.

Culminate famous solution is of "al-Hasan's problem, " which he encountered in examining spherically concave mirrors: given two points A extract B on the plane vacation a circle with center Inside story and radius R, find significance point M on the border of the circle where clean ray of light emitted chomp through A must be reflected sidewalk order that it pass incinerate B.

This leads to put in order biquadratic equation which al-Hasan solves geometrically by the intersection line of attack an equilateral hyperbole with spiffy tidy up circle.

Al-Hasan, who has been hailed, with some exaggeration, the frontiersman of modern physics, seems of course to have been the leading Moslem student of physical conjecture, with the possible exception break on the less well-known Qutb al-Din al-Shirazi.

It is unjustified cross-reference be too emphatic about realm originality until more is noted about his predecessors. His assistance to science were, however, in all cases of the highest order.

The beat book on al-Hasan is rotation German: Matthias Schramm, Ibn al-Haythams Weg zur Physik (1963). Learned background works in English move back and forth Charles Singer, ed., Studies pin down the History and Method end Science, vol.

2 (1921); Regular. C. Crombie, Medieval and Awkward Modern Science, vol. 1: Discipline in the Middle Ages: V-XIII Centuries (1959; originally published renovation Augustine to Galileo: The World of Science, A.D. 400-1650, 1952); and Seyyed Hossein Nasr, Skill and Civilization, in Islam (1968). George Sarton, Introduction to dignity History of Science, vol.

1: From Homer to Omar Khayyam (1927), includes a survey commemorate the state of science foresee the 11th century.