Ibn al-Haytham

Ḥasan Ibn al-Haytham (<a href="/facts/Latinization_of_names/69CA5FuQ">Latinized</a> as Alhazen; /ælˈhæzən/; full name Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham أبو علي، الحسن بن الحسن بن الهيثم; c. 965 – c. 1040) was a medieval <a href="/facts/Mathematics_in_medieval_Islam/TACUEnlp">mathematician</a>, <a href="/facts/Astronomy_in_the_medieval_Islamic_world/hw8HxDHz">astronomer</a>, and <a href="/facts/Physics_in_the_medieval_Islamic_world/VbUCtwNK">physicist</a> of the <a href="/facts/Islamic_Golden_Age/yAeG2rBA">Islamic Golden Age</a> from present-day Iraq. Referred to as "the father of modern optics", he made significant contributions to the principles of <a href="/facts/Optics/p0vq4S1T">optics</a> and <a href="/facts/Visual_perception/g7Tfaq2l">visual perception</a> in particular. His most influential work is titled <a href="/facts/Book_of_Optics/SmYrlPcg">Kitāb al-Manāẓir</a> (<a href="/facts/Arabic/A1e66hVV">Arabic</a>: كتاب المناظر, "Book of Optics"), written during 1011–1021, which survived in a Latin edition. The works of Alhazen were frequently cited during the scientific revolution by <a href="/facts/Isaac_Newton/4L7gTncN">Isaac Newton</a>, <a href="/facts/Johannes_Kepler/wk6GTN3C">Johannes Kepler</a>, <a href="/facts/Christiaan_Huygens/GtBqoBVm">Christiaan Huygens</a>, and <a href="/facts/Galileo_Galilei/98VT2z3v">Galileo Galilei</a>.
Ibn al-Haytham was the first to correctly explain the theory of vision, and to argue that vision occurs in the brain, pointing to observations that it is subjective and affected by personal experience. He also stated the principle of least time for refraction which would later become <a href="/facts/Fermat%2527s_principle/UL9XumdW">Fermat's principle</a>. He made major contributions to catoptrics and dioptrics by studying reflection, refraction and nature of images formed by light rays. Ibn al-Haytham was an early proponent of the concept that a hypothesis must be supported by experiments based on confirmable procedures or mathematical reasoning – an early pioneer in the <a href="/facts/Scientific_method/182j8RWE">scientific method</a> five centuries before <a href="/facts/History_of_science_in_the_Renaissance/pR2jEdy3">Renaissance scientists</a>, he is sometimes described as the world's "first true scientist". He was also a <a href="/facts/Polymath/eqIfjQRu">polymath</a>, writing on <a href="/facts/Philosophy/zAH5PVD6">philosophy</a>, <a href="/facts/Theology/N71Fyw2M">theology</a> and <a href="/facts/Medicine/2fnp90Je">medicine</a>.
Born in <a href="/facts/Basra/eA5CacwL">Basra</a>, he spent most of his productive period in the <a href="/facts/Fatimid_Caliphate/jgmF2I5C">Fatimid</a> capital of <a href="/facts/Cairo/dXjj60ar">Cairo</a> and earned his living authoring various treatises and tutoring members of the nobilities. Ibn al-Haytham is sometimes given the <a href="/facts/Nisba_(onomastics)/056hj9rC">byname</a> al-Baṣrī after his birthplace, or al-Miṣrī ("the Egyptian"). Al-Haytham was dubbed the "Second <a href="/facts/Ptolemy/htudGQTQ">Ptolemy</a>" by <a href="/facts/Abu%2527l-Hasan_Bayhaqi/2pS0MfcH">Abu'l-Hasan Bayhaqi</a> and "The Physicist" by <a href="/facts/John_Peckham/GMktLKuo">John Peckham</a>. Ibn al-Haytham paved the way for the modern science of physical optics.

Ibn al-Haytham open-in-new

Ibn al-Haytham