Who is ibn al-haytham?

Answer 1

Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham (Arabic: ابو علی، حسن بن حسن بن هيثم, Latinized: Alhacen or (deprecated) Alhazen) (965 - c. 1039), was an Arab[2] and/or Persian[3] polymath.[4] He made significant contributions to the principles of optics, as well as to anatomy, astronomy, engineering, mathematics, medicine, ophthalmology, philosophy, physics, psychology, visual perception, and to science in general with his introduction of the scientific method. He is sometimes called al-Basri (Arabic: البصري), after his birthplace in the city of Basra.[5] He was also nicknamed Ptolemaeus Secundus ("Ptolemy the Second")[6] or simply "The Physicist"[7] in medieval Europe. Though born in what is now modern-day Iraq around the year 965[1], he spent most of his life in Cairo, Egypt, dying there at the age of 76.[6] In his over-confidence about the practical application of his mathematical knowledge, he assumed that he could regulate the floods caused by the overflow of the Nile.[8] After being ordered by Al-Hakim bi-Amr Allah, the sixth ruler of the Fatimid caliphate, to carry out this operation, he quickly perceived the inanity of what he was attempting to do, and retired from engineering. Fearing for his life, he feigned madness[1][9] and was placed under house arrest, during and after which he devoted himself to his scientific work until his death.[6] Ibn al-Haytham is regarded as the "father of modern optics"[10] for his influential Book of Optics (written while he was under house arrest), which correctly explained and proved the modern intromission theory of vision. He is also recognized so for his experiments on optics, including experiments on lenses, mirrors, refraction, reflection, and the dispersion of light into its constituent colours.[11] He studied binocular vision and the Moon illusion, described the finite speed[12][13] of light, and argued that it is made of particles[14] travelling in straight lines.[13][15] Due to his formulation of a modern quantitative and empirical approach to physics and science, he is considered the pioneer of the modern scientific method[16][17] and the originator of the experimental nature of physics[18] and science.[19] Author Bradley Steffens describes him as the "first scientist".[20] He is also considered by A. I. Sabra to be the founder of experimental psychology[21] for his approach to visual perception and optical illusions,[22] and a pioneer of the philosophical field of phenomenology or the study of consciousness from a first-person perspective. His Book of Optics has been ranked with Isaac newton's Philosophiae Naturalis Principia Mathematica as one of the most influential books in the history of physics,[23] for starting a revolution in optics[24] and visual perception.[25] Ibn al-Haytham's achievements include many advances in physics and mathematics. He gave the first clear description[26] and correct analysis[27] of the camera obscura. He enunciated Fermat's principle of least time and the concept of inertia (Newton's first law of motion),[28] and developed the concept of momentum.[29] He described the attraction between masses and was aware of the magnitude of acceleration due to gravity at-a-distance.[30] He stated that the heavenly bodies were accountable to the laws of physics and also presented a critique and reform of Ptolemaic astronomy. He was the first to state Wilson's theorem in number theory, and he formulated the Lambert quadrilateral[31] and a concept similar to Playfair's axiom[32] now used in non-Euclidean geometry. Moreover, he formulated and solved Alhazen's problem geometrically using early ideas related to calculus and mathematical induction.[33] In his optical research, he laid the foundations for the later development of telescopic astronomy,[34] as well as for the microscope and the use of optical aids in Renaissance art.[35]