The Book of Optics (Arabic: Kitab al-Manazir, Latin: De Aspectibus) was a seven volume treatise on optics, physics, anatomy, mathematics and psychology written by the Iraqi Arab Muslim scientist Ibn al-Haytham (Latinized as Alhacen or Alhazen in Europe) from 1011 to 1021, when he was under house arrest in Cairo, Egypt. Arabic (ar الْعَرَبيّة (informally ar عَرَبيْ) in terms of the number of speakers is the largest living member of the Semitic language Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and For a topic outline on this subject see List of basic Iraq topics. The araB gene Promoter is a bacterial promoter activated by e L-arabinose binding TemplateInfobox Muslim scholars --> ( Arabic: ابو علی، حسن بن حسن بن هيثم Latinized In Justice and Law, house arrest (also called home confinement, home detention, or electronic monitoring) is a measure by which Cairo () which means "the Vanquisher" or "the Triumphant" is the capital and largest city of Egypt. This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics. The book had an important influence on the development of optics, and science in general, as it drastically transformed the understanding of light and vision, and introduced the experimental scientific method. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or Scientific method refers to bodies of Techniques for investigating phenomena As a result, Ibn al-Haytham has been described as the "father of optics", the "pioneer of the modern scientific method", and the "first scientist". A scientist, in the broadest sense refers to any person that engages in a systematic activity to acquire Knowledge or an individual that engages in such practices ^[1] The Book of Optics has been ranked alongside Isaac Newton's Philosophiae Naturalis Principia Mathematica as one of the most influential books in the history of physics,^[2] for initiating a scientific revolution in optics^[3] and visual perception. Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements The Philosophiæ Naturalis Principia Mathematica ( Latin: "mathematical principles of natural philosophy" often Principia The modern discipline of Physics emerged in the 17th century following in traditions of inquiry established by Galileo Galilei, René Descartes, Isaac The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also ^[4]

The Book of Optics also contains the earliest discussions and descriptions of the psychology of visual perception and optical illusions,^[5] as well as experimental psychology,^[6] and the earliest descriptions of the camera obscura, a precursor to the modern camera. Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also This article is about visual perception See Optical Illusion (Album for information about the Time Requiem album Experimental psychology approaches Psychology as one of the natural sciences investigates it using the experimental method. The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment A camera is a device used to capture images either as still Photographs or as sequences of moving images ( Movies or Videos. In medicine and ophthalmology, the book also made important advances in eye surgery, as it correctly explained the process of sight for the first time. Ophthalmology was one of the foremost branches in medieval Islamic medicine. Eye surgery, also known as orogolomistician surgery or ocular surgery, is Surgery performed on the Eye or its Adnexa, typically by ^[7] The work also had an influence on the use of optical aids in Renaissance art and the development of the telescope and microscope. The Renaissance (from French Renaissance, meaning "rebirth" Italian: Rinascimento, from re- "again" and nascere Art refers to a diverse range of Human activities creations and expressions that are appealing to the Senses or Emotions of a human individual A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are ^[8]

Contents 1 Overview 1.1 Optics and vision 1.2 Scientific method 1.3 Legacy 1.4 Latin translations 2 Volumes 2.1 Book I 2.2 Books II–III 2.3 Books IV–VII 3 Treatise on Light 4 Other contributions 4.1 Alhazen's problem 4.2 Astronomy 4.3 Biomedical sciences 4.4 Hockney-Falco thesis 4.5 Phenomenology 4.6 Psychology 4.7 Theology 5 See also 6 References

Overview

Optics and vision

In classical antiquity, there were two major theories on vision. Classical antiquity (also the classical era or classical period) is a broad term for a long period of cultural History centered on the Mediterranean In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also The first theory, the emission theory, was supported by such thinkers as Euclid and Ptolemy, who believed that sight worked by the eye emitting rays of light. Emission theory or extramission theory is the proposal that Visual perception is accomplished by rays of Light emitted by the Eyes This Euclid ( Greek:.) fl 300 BC also known as Euclid of Alexandria, is often referred to as the Father of Geometry Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca In Optics, a ray is an idealized narrow Beam of light. Rays are used to model the propagation of Light through an optical system by dividing the real light Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 The second theory, the intromission theory, supported by Aristotle and his followers, had physical forms entering the eye from an object. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. Alhacen argued on the basis of common observations (such as the eye being dazzled or even injured if we look at a very bright light) and logical arguments (such as how a ray could proceeding from the eyes reach the distant stars the instant after we open our eye) to maintain that we cannot see by rays being emitted from the eye nor through physical forms entering the eye. Alhacen instead developed a highly successful theory which explained the process of vision by rays of light proceeding to the eye from each point on an object, which he proved through the use of experimentation. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or ^[9]

Ibn al-Haytham proved that rays of light travel in straight lines, and carried out a number of experiments with lenses, mirrors, refraction, and reflection. A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. Refraction is the change in direction of a Wave due to a change in its Speed. Reflection is the change in direction of a Wave front at an interface between two different media so that the wave front returns into the medium from which ^[10] He was also the first to reduce reflected and refracted light rays into vertical and horizontal components, which was a fundamental development in geometric optics. ^[11] He also discovered a result similar to Snell's law of sines, but did not quantify it and derive the law mathematically. In Optics and Physics, Snell's law (also known as Descartes' law or the law of refraction) is a formula used to describe the relationship ^[12] Ibn al-Haytham is also credited with the invention of the camera obscura and pinhole camera. The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment A' pinhole camera' is a very simple Camera with no lens and a single very small Aperture. ^[13] Alhacen also wrote on the refraction of light, especially on atmospheric refraction, for example, the cause of morning and evening twilight. Refraction is the change in direction of a Wave due to a change in its Speed. He solved the problem of finding the point on a convex mirror at which a ray coming from one point is reflected to another point. A curved mirror is a Mirror with a curved reflective surface which may be either convex (bulging outward or concave (bulging inward He also experimented on the dispersion of light into its constituent colours,^[10] speculated on the finite speed, rectilinear propagation and electromagnetic aspects of light,^[14] and argued that rays of light are streams of tiny particles travelling in straight lines. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Rectilinear propagation is a Wave property which states that waves propagate (move or spread out in straight Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of In Optics, a ray is an idealized narrow Beam of light. Rays are used to model the propagation of Light through an optical system by dividing the real light A subatomic particle is an elementary or composite Particle smaller than an Atom. ^[15]

Ibn al-Haytham made a thorough examination of the passage of light through various media and discovered the laws of refraction. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Refraction is the change in direction of a Wave due to a change in its Speed. He also carried out the first experiments on the dispersion of light into its constituent colours. ^[10] His book Kitab al-Manazir (Book of Optics) was translated into Latin in the Middle Ages, as also was his book dealing with the colours of sunset. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. He dealt at length with the theory of various physical phenomena such as shadows, eclipses, and the rainbow, and speculated on the physical nature of light. A shadow is an area where direct light from a light source cannot reach due to obstruction by an object An eclipse is an astronomical event that occurs when one Celestial object moves into the shadow of another A rainbow is an optical and meteorological phenomenon that causes a spectrum of Light to appear in the Sky when the Sun He is the first to describe accurately the various parts of the eye and give a scientific explanation of the process of vision. Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also He also attempted to explain binocular vision and the apparent increase in size of the Sun and the Moon when near the horizon. Binocular vision is vision in which both Eyes are used together The Moon illusion is an Optical illusion in which the Moon appears larger near the Horizon than it does while higher up in the Sky. The Sun (Sol is the Star at the center of the Solar System. The horizon ( Ancient Greek ὁ ὁρίζων, /ho horídzôn/ from ὁρίζειν, "to limit" is the apparent line that separates He is known for the earliest use of the camera obscura. The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment He contradicted Ptolemy's and Euclid's theory of vision that objects are seen by rays of light emanating from the eyes; according to him the rays originate in the object of vision and not in the eye. Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca Euclid ( Greek:.) fl 300 BC also known as Euclid of Alexandria, is often referred to as the Father of Geometry Through these extensive researches on optics, he has been considered as the father of modern optics.

In his work on optics, Alhacen described sight as the inference of distinct properties of two similar and dissimilar objects. The eye perceives the size, shape, transparency (color and light), position, and motion from cognitive distinction which is entirely different from perceiving by mere sensation the characteristics of the object. The faculty of the mind, for Alhacen, includes perceiving through judgement and inference of distinct properties of similar objects outline and structure. Alhacen continues this body of work by concluding that the discrimination performed by the faculty of judgment and inference is in addition to sensing the objects visible form and not by pure sensation alone. We recognize visible objects that we frequently see. Recognition of an object is not pure sensation because we do not recognize everything we see. Ultimately, recognition does not take place without remembering. Recognition is due to the inference because of our mental capacity to conclude what objects are. Alhacen uses our ability to recognize species and likening their characteristics to that of similar individuals to support recognition associated and processed by inference. Alhacen further concludes that we are processing visual stimuli in very short intervals which allows us to recognize and associate objects through inference but we do not need syllogism to recognize it. These premises are stored infinitely in our souls.

Sami Hamarneh writes several examples of Ibn al-Haytham's descriptions which are correct according to modern optics:^[14]

1. "He explained that sight results from the light penetrating the eye from the object, thus initiating a revolt against the ancient belief that visionary rays emanate from the eye. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain In Optics, a ray is an idealized narrow Beam of light. Rays are used to model the propagation of Light through an optical system by dividing the real light Emission theory or extramission theory is the proposal that Visual perception is accomplished by rays of Light emitted by the Eyes This "
2. "He showed that the corneal region of the eye is curved and is close to the conjunctiva; but the cornea do not coalesce with the conjunctiva. The cornea is the transparent front part of the Eye that covers the iris, Pupil, and Anterior chamber. The conjunctiva is a clear membrane that covers the Sclera (white part of the Eye) and lines the inside of the Eyelids It is made of lymphoid tissue "
3. "He suggested that the inner surface of the cornea at the point where it joins the foramen of the eye becomes concave in accordance with the curvature of its outer surface. In Mathematics, curvature refers to any of a number of loosely related concepts in different areas of geometry The edges of the surfaces of the foramen and the middle part of the corneal regions become even but not one. "
4. "He endeavored by use of hyperbola and geometric optics to chart and formulate basic laws on reflection, and on atmospheric and light-ray refraction. In Geometry, a hyperbola ( Greek, "over-thrown" has several equivalent definitions Atmospheric Refraction is the deviation of Light or other Electromagnetic wave from a straight line as it passes through the atmosphere due to the Refraction is the change in direction of a Wave due to a change in its Speed. He speculated on electromagnetic aspects of light, its velocity, and its rectilinear propagation. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of Rectilinear propagation is a Wave property which states that waves propagate (move or spread out in straight He recorded formation of an image in a camera obscura during an eclipse of the sun (the principle of the pinhole camera). An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured A' pinhole camera' is a very simple Camera with no lens and a single very small Aperture. "
5. "He stated that the lens is that part of the eye where vision is felt first. The lens is a transparent biconvex structure in the Eye that along with the Cornea, helps to Refract Light to be focused In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also "
6. "He theorized on how the image is transmitted through the optic nerve to the brain and made a distinction between luminous and nonluminous bodies. The optic nerve, also called cranial nerve II, is the Nerve that transmits visual information from the Retina to the Brain. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain Luminance is a photometric measure of the density of Luminous intensity in a given direction "

The Book of Optics is considered by some to mark the beginning of experimental psychology. Experimental psychology approaches Psychology as one of the natural sciences investigates it using the experimental method. Ibn al-Haytham made use of his experimental method in his pioneering work on the psychology of visual perception and optical illusions. Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also This article is about visual perception See Optical Illusion (Album for information about the Time Requiem album While his investigations and experiments on psychology and visual perception included sensation, variations in sensitivity, sensation of touch, perception of colours, perception of darkness, the psychological explanation of the moon illusion, and binocular vision. In Psychology, sensation is the first stage in the biochemical and neurologic events that begins with the impinging of a stimulus upon the receptor cells of a In Psychology and the Cognitive sciences perception is the process of attaining awareness or understanding of sensory Information. The Moon illusion is an Optical illusion in which the Moon appears larger near the Horizon than it does while higher up in the Sky. Binocular vision is vision in which both Eyes are used together ^[6]

Other apparatus Ibn al-Haytham described in the Book of Optics, besides the camera obscura, include "specially arranged dark chambers, specially designed apertures for the controlled admission of light," and "viewing tubes". Laboratory equipment refers to the various Tools and Equipment used by Scientists working in a Laboratory. The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment ^[16]

Scientific method

Roshdi Rashed notes that "by promoting the use of experiments in scientific research, al-Haytham played an important part in setting the scene for modern science. "^[17] Rosanna Gorini wrote the following on the Book of Optic's introduction of the scientific method:

"According to the majority of the historians al-Haytham was the pioneer of the modern scientific method. Scientific method refers to bodies of Techniques for investigating phenomena With his book he changed the meaning of the term optics and established experiments as the norm of proof in the field. His investigations are based not on abstract theories, but on experimental evidences and his experiments were systematic and repeatable. "^[18]

Ibn al-Haytham's scientific method was very similar to the modern scientific method and consisted of the following procedures:^[19]

1. Observation
2. Statement of problem
3. Formulation of hypothesis
4. Testing of hypothesis using experimentation
5. Analysis of experimental results
6. Interpretation of data and formulation of conclusion
7. Publication of findings

From Ibn al-Haytham to the present day, the emphasis of the scientific method has always been on seeking truth:

"Truth is sought for its own sake. TemplateInfobox Muslim scholars --> ( Arabic: ابو علی، حسن بن حسن بن هيثم Latinized The meaning of the word truth extends from Honesty, Good faith, and Sincerity in general to agreement with Fact or Reality And those who are engaged upon the quest for anything for its own sake are not interested in other things. Finding the truth is difficult, and the road to it is rough. . . . "^[20]

"How does light travel through transparent bodies? Light travels through transparent bodies in straight lines only. . . . We have explained this exhaustively in our Book of Optics. But let us now mention something to prove this convincingly: the fact that light travels in straight lines is clearly observed in the lights which enter into dark rooms through holes. . . . the entering light will be clearly observable in the dust which fills the air. "^[21]

The conjecture that "Light travels through transparent bodies in straight lines only", was corroborated by Alhacen only after years of effort. His demonstration of the conjecture was to place a straight stick or a taut thread next to the light beam, to prove that light travels in a straight line. ^[22]

The term "experiment" itself may have origins in the Book of Optics. Ibn al-Haytham used the Arabic terms i'tabara, 'itibar and mu'tabir to refer to his experiments. During the Latin translation of the book, these terms were rendered into Latin as experimentare (or experiri), experimentum and experimentatar respecively. ^[23]

Legacy

Robert S. Elliot wrote the following on the Book of Optics:

"Alhazen was one of the ablest students of optics of all times and published a seven-volume treatise on this subject which had great celebrity throughout the medieval period and strongly influenced Western thought, notably that of Roger Bacon and Kepler. For the Nova Scotia premier see Roger Bacon (politician. Roger Bacon, O Johannes Kepler (ˈkɛplɚ ( December 27 1571 &ndash November 15 1630) was a German Mathematician, Astronomer This treatise discussed concave and convex mirrors in both cylindrical and spherical geometries, anticipated Fermat's law of least time, and considered refraction and the magnifying power of lenses. A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. A cylinder is one of the most basic curvilinear geometric shapes the Surface formed by the points at a fixed distance from a given Straight line, the axis "Globose" redirects here See also Globose nucleus. A sphere (from Greek σφαίρα - sphaira, "globe In Optics, Fermat's principle or the principle of least time is the idea that the path taken between two points by a ray of light is the path that can be A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging It contained a remarkably lucid description of the optical system of the eye, which study led Alhazen to the belief that light consists of rays which originate in the object seen, and not in the eye, a view contrary to that of Euclid and Ptolemy. In Optics, a ray is an idealized narrow Beam of light. Rays are used to model the propagation of Light through an optical system by dividing the real light Euclid ( Greek:.) fl 300 BC also known as Euclid of Alexandria, is often referred to as the Father of Geometry Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca "^[24]

George Sarton, the father of the history of science, wrote in the Introduction to the History of Science:

"Ibn Haytham's writings reveal his fine development of the experimental faculty. George Alfred Leon Sarton (1884-1956 was a Belgian -American Polymath, historian of science, and father of the writer May Sarton. Science is a body of empirical, theoretical, and practical knowledge about the natural world, produced by a global community of researchers His tables of corresponding angles of incidence and refraction of light passing from one medium to another show how closely he had approached discovering the law of constancy of ratio of sines, later attributed to Snell. Angle of incidence is a measure of deviation of something from "straight on" for example in the approach of a ray to a surface or the angle In Optics and Physics, Snell's law (also known as Descartes' law or the law of refraction) is a formula used to describe the relationship “Snellius” redirects here For the lunar crater named Snellius see Snellius (crater. He accounted correctly for twilight as due to atmospheric refraction, estimating the sun's depression to be 19 degrees below the horizon, at the commencement of the phenomenon in the mornings or at its termination in the evenings. Atmospheric Refraction is the deviation of Light or other Electromagnetic wave from a straight line as it passes through the atmosphere due to the "^[25]

Latin translations

Optics was translated into Latin by an unknown scholar at the end of the 12th century or the beginning of the 13th century. The Renaissance of the 12th century saw a major search by European scholars for new learning which led them to the Arabic fringes of Europe especially to Islamic ^[26] It was printed by Friedrich Risner in 1572, with the title Opticae thesaurus: Alhazeni Arabis libri septem, nuncprimum editi; Eiusdem liber De Crepusculis et nubium ascensionibus [2]. Friedrich Risner (died 1580 was a German mathematician from Hersfeld, Hesse. Risner is also the author of the name variant "Alhazen", before him he was known in the west as Alhacen, which is correct transcription of the Arabic name. ^[27] This work enjoyed a great reputation during the Middle Ages. Works by Alhacen on geometrical subjects were discovered in the Bibliothèque nationale in Paris in 1834 by E. Paris (ˈpærɨs in English; in French) is the Capital of France and the country's largest city A. Sedillot. Other manuscripts are preserved in the Bodleian Library at Oxford and in the library of Leiden. The Bodleian Library ( the main Research library of the University of Oxford, is one of the oldest libraries in Europe, and in England Oxford is currently bidding for the 2010 Wikimania Conference Oxford () is a city, and the County town of Oxfordshire, "Leyden" redirects here For other uses see Leyden (disambiguation. Ibn al-Haytham's optical studies were influential in a number of later developments, such as the telescope, which laid the foundations of telescopic astronomy. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. ^[28]

Volumes

Book I

In Book I of the treatise, Ibn al-Haytham begins by writing an introduction to the systematic approach he will use for his investigations on optics, and correctly explains how vision is perceived by rays of light travelling in straight lines from an object to the eye:^[5]

"We should distinguish the properties of particulars, and gather by induction what pertains to the eye when vision takes place and what is found in the manner of sensation to be uniform, unchanging, manifest, and not subject to doubt. Induction or inductive reasoning, sometimes called inductive logic, is the process of Reasoning in which the premises of an argument are believed After which we should ascend in our inquiry and reasonings, gradually and orderly, criticizing premises and exercising caution in regard to conclusions—our aim in all that we make subject to inspection and review being to employ justice, not to follow prejudice, and to take care in all that we judge and criticize that we seek the truth and not be swayed by opinion. "

"Straight lines [exist between] the surface of the eye [and] each point on the seen surface of the object. An accurate experimental examination of this fact may be easily made with the help of rulers and tubes. A ruler, or rule, is an instrument used in Geometry, Technical drawing and engineering/building to measure distances and/or to rule straight Tubing is a Pipe or hollow cylinder for the conveyance of fluids (liquids or gases [. . . ] If…he covers any part of the opening, then there will be screened off only that portion…that lies on a straight line with the eye and the screening body—this straightness being secured by the ruler and the straightness of the tube, [. . . ] It follows from this experiment, with a necessity that dispels doubt, that sight does not perceive any visible object existing with it in the same atmosphere, this perception being not by reflection, except through straight lines alone that can be imagined to extend between the surface of the object and the surface of the eye. Sight does not perceive any visible object unless there exists in the object some light, which the object possesses of itself or which radiates upon it from another object. "

He also states that his investigation of light will be based on experimental evidence rather than on abstract theory, and notes that light is always the same from every source, using sunlight, fire, and a mirror as examples. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or --> Abstraction is the process or result of generalization by reducing the information Sunlight, in the broad sense is the total spectrum of the Electromagnetic radiation given off by the Sun. Fire is the heat and light energy released during a Chemical reaction, in particular a combustion reaction. A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. He then examines the anatomical structure of the eye, and proposes the first use of a camera obscura. ^[10]

Books II–III

Book II of the treatise contains a discussion on visual perception. In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also ^[10] In Book III, he pioneered the psychology of visual perception and optical illusions, being the first scientist to argue that vision occurs in the brain, rather than the eyes. Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and This article is about visual perception See Optical Illusion (Album for information about the Time Requiem album A scientist, in the broadest sense refers to any person that engages in a systematic activity to acquire Knowledge or an individual that engages in such practices He pointed out that personal experience has an effect on what people see and how they see, and that vision and perception are subjective. He explained possible errors in vision in detail, and as an example, describes how a small child with less experience may have more difficulty interpreting what he/she sees. He also gives an example of an adult that can make mistakes in vision because of how one's experience suggests that he/she is seeing one thing, when he/she is really seeing something else. ^[5]

Books IV–VII

Book IV deals with the theory of reflection mathematically, while Book V deals with the influential Alhazen's problem. Book VI examines errors in vision due to reflection, while the final volume, Book VII, examines refraction. Refraction is the change in direction of a Wave due to a change in its Speed. ^[10]

Treatise on Light

Ibn al-Haytham's Risala fi l-Daw’ (Treatise on Light) is a supplement to his Kitab al-Manazir (Book of Optics). The text contained further investigations on the properties of luminance and its radiant dispersion through various transparent and translucent media. Luminance is a photometric measure of the density of Luminous intensity in a given direction Radiance and spectral radiance are radiometric measures that describe the amount of light that passes through or is emitted from a particular area and falls In Optics, transparency (also called pellucidity) is the Material property of allowing He also carried out further observations, investigations and examinations on the anatomy of the eye, the camera obscura and pinhole camera, the illusions in visual perception, the meteorology of the rainbow and the density of the atmosphere, various celestial phenomena (including the eclipse, twilight, and moonlight), refraction, catoptrics, dioptrics, spherical and parabolic mirrors, and magnifying lenses. Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain The camera obscura (Latin dark chamber) is an optical device used for example in drawing or for entertainment A' pinhole camera' is a very simple Camera with no lens and a single very small Aperture. This article is about visual perception See Optical Illusion (Album for information about the Time Requiem album In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary A rainbow is an optical and meteorological phenomenon that causes a spectrum of Light to appear in the Sky when the Sun The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " An eclipse is an astronomical event that occurs when one Celestial object moves into the shadow of another Twilight is the time before Sunrise, called Dawn, and the time after Sunset, called Dusk. Moonlight is the light that comes to Earth from the Moon. This light does not originate from the Moon but is actually reflected Sunlight. Refraction is the change in direction of a Wave due to a change in its Speed. Catoptrics deals with the phenomena of reflected light and image-forming optical systems using Mirrors From the Greek κατοπτρικός (specular Dioptrics is the study of the Refraction of light especially by lenses. "Globose" redirects here See also Globose nucleus. A sphere (from Greek σφαίρα - sphaira, "globe In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular magnifying glass (called a hand lens in laboratory contexts is a convex lens which is used to produce a magnified Image of an object ^[29]

According to Giambattista della Porta, Ibn al-Haytham was the first to give a correct explanation of the apparent increase in the size of the Moon and Sun when near Earth's horizon, known as the Sun and Moon illusion respectively. Giambattista della Porta (1535?1 - 1615 also known as Giovanni Battista Della Porta was an Italian scholar Polymath and Playwright who The Sun (Sol is the Star at the center of the Solar System. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The horizon ( Ancient Greek ὁ ὁρίζων, /ho horídzôn/ from ὁρίζειν, "to limit" is the apparent line that separates The Moon illusion is an Optical illusion in which the Moon appears larger near the Horizon than it does while higher up in the Sky. ^[30] (Ptolemy made earlier attempts at explaining it, according to Roger Bacon. Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca For the Nova Scotia premier see Roger Bacon (politician. Roger Bacon, O )

Other contributions

While the Book of Optics was mainly concerned with the field of optics, the book also had a significant influence on several other fields of science, mathematics and philosophy. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and Philosophy is the study of general problems concerning matters such as existence knowledge truth beauty justice validity mind and language

Alhazen's problem

Ibn al-Haytham's work on catoptrics in Book V of the Book of Optics contains the important mathematical problem known as Alhazen's problem. Catoptrics deals with the phenomena of reflected light and image-forming optical systems using Mirrors From the Greek κατοπτρικός (specular It comprises drawing lines from two points in the plane of a circle meeting at a point on the circumference and making equal angles with the normal at that point. The circumference is the distance around a closed Curve. Circumference is a kind of Perimeter. This leads to an equation of the fourth degree. In Mathematics, a quartic equation is one which can be expressed as a Quartic function equalling zero This eventually led Ibn al-Haytham to derive the earliest formula for the sum of the fourth powers, and using an early proof by mathematical induction, he developed a method for determining the general formula for the sum of any integral powers, which was fundamental to the development of infinitesimal and integral calculus. In Arithmetic and Algebra, the fourth power of a number n is the result of multiplying n by itself four times Mathematical induction is a method of Mathematical proof typically used to establish that a given statement is true of all Natural numbers It is done by proving that The European Space Agency 's INTErnational Gamma-Ray Astrophysics Laboratory ( INTEGRAL) is detecting some of the most energetic radiation that comes from space Infinitesimals (from a 17th century Modern Latin coinage infinitesimus, originally referring to the " Infinite[[ th]]" member of a series have The European Space Agency 's INTErnational Gamma-Ray Astrophysics Laboratory ( INTEGRAL) is detecting some of the most energetic radiation that comes from space Calculus ( Latin, calculus, a small stone used for counting is a branch of Mathematics that includes the study of limits, Derivatives ^[31]

Ibn al-Haytham solved the problem using conic sections and a geometric proof, but Alhazen's problem remained influential in Europe, when later mathematicians such as Christiaan Huygens, James Gregory, Guillaume de l'Hôpital, Isaac Barrow, and many others, attempted to find an algebraic solution to the problem, using various methods, including analytic methods of geometry and derivation by complex numbers. In Mathematics, a conic section (or just conic) is a Curve obtained by intersecting a cone (more precisely a circular Conical surface Christiaan Huygens (ˈhaɪgənz in English ˈhœyɣəns in Dutch) ( April 14, 1629 &ndash July 8, 1695) was a Dutch James Gregory may refer to James Gregory (writer (?-2003 South African prison guard author of Goodbye Bafana James Gregory (astronomer Guillaume François Antoine Marquis de l'Hôpital (1661 &ndash February 2, 1704) was a French Mathematician. Isaac Barrow (October 1630 &ndash May 4, 1677) was an English scholar and Mathematician who is generally given credit for his early role Analytic geometry, also called coordinate geometry and earlier referred to as Cartesian geometry or analytical geometry, is the study of Geometry Complex plane In Mathematics, the complex numbers are an extension of the Real numbers obtained by adjoining an Imaginary unit, denoted ^[32] Mathematicians were not able to find an algebraic solution to the problem until the end of the 20th century. ^[5]

Astronomy

Chapters 15-16 of the Book of Optics dealt with astronomy. Ibn al-Haytham was the first to discover that the celestial spheres do not consist of solid matter, and he also discovered that the heavens are less dense than the air:^[33]

"The body of heaven differs . The celestial spheres or celestial orbs were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, and developed by Aristotle A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. . . from the air. [. . . ] In fineness, the body of air being denser than the body of heaven, [which is] finer than the body of air. The entire heaven differs from the transparency of air. The body in which the fixed stars are, differs in transparency from the air. The body of heaven is finer than the body of air, that is, it is more transparent. In the heavens there is no clear body that is dense. "

These views were later repeated by Witelo and had a significant influence on the Copernican and Tychonic systems of astronomy. Witelo - also known as Erazmus Ciolek Witelo, Witelon, Vitellio, Vitello, Vitello Thuringopolonis, Vitulon, Erazm See also Nicolaus Copernicus, Heliocentrism Earlier theories See also Heliocentrism Early traces of a Heliocentric model The Tychonic system (or Tychonian system) was a model of the Solar system published by Tycho Brahe in the late 16th century which combined what he saw as ^[33]

Biomedical sciences

Ibn al-Haytham discussed the topics of medicine, ophthalmology and eye surgery in the anatomical and physiological portions of the Book of Optics and in his commentaries on Galenic works. Ophthalmology was one of the foremost branches in medieval Islamic medicine. Eye surgery, also known as orogolomistician surgery or ocular surgery, is Surgery performed on the Eye or its Adnexa, typically by Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration Physiology (from Greek grc φύσις physis, "nature origin" and grc -λογία -logia) is the study of the mechanical physical Galen ( Greek: Γαληνός Galēnos; Latin: Claudius Galenus, Aelius Galenus, Claudius Aelius Galenus, or ^[34] He made several improvements to eye surgery and accurately described the process of sight,^[35] the structure of the eye, image formation in the eye and the visual system. Eye surgery, also known as orogolomistician surgery or ocular surgery, is Surgery performed on the Eye or its Adnexa, typically by Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain The visual system is the part of the Nervous system which allows organisms to see. He also discovered the underlying principles of Hering's law of equal innervation, binocular vision, motion perception, vertical horopters, and binocular disparity. Hering's law of equal innervation is used to explain the conjugacy of Eye movements ( Saccades in Stereoptic animals Binocular vision is vision in which both Eyes are used together Motion perception is the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs In studies of Binocular vision the horopter is a volume centred on the fixation point that contains all points in space that yield single vision Binocular disparity refers to the difference in image location of an object seen by the left and right Eyes resulting from the eyes' horizontal separation ^[36]

Regarding the process of image formation, he incorrectly agreed with Avicenna that the lens was the receptive organ of sight, but hinted at the retina also being involved in the process. An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually TemplateInfobox Muslim scholars --> ( Persian /ابو علی الحسین ابن عبدالله ابن سینا (born The lens is a transparent biconvex structure in the Eye that along with the Cornea, helps to Refract Light to be focused The vertebrate retina is a light sensitive part inside the inner layer of the Eye. ^[37]

Hockney-Falco thesis

Main article: Hockney-Falco thesis

At a scientific conference in February 2007, Charles M. Falco argued that Ibn al-Haytham's work on optics may have influenced the use of optical aids by Renaissance artists. The Hockney-Falco thesis is a controversial theory of Art history, advanced by artist David Hockney and physicist Charles M Charles M Falco (born August 17 1948 is an American experimental Physicist and an expert on the magnetic and optical properties of thin film materials The Renaissance (from French Renaissance, meaning "rebirth" Italian: Rinascimento, from re- "again" and nascere Art refers to a diverse range of Human activities creations and expressions that are appealing to the Senses or Emotions of a human individual Falco said that his and David Hockney's examples of Renaissance art "demonstrate a continuum in the use of optics by artists from circa 1430, arguably initiated as a result of Ibn al-Haytham's influence, until today. David Hockney, CH, RA, (born 9 July 1937 is an English Artist, based in Los Angeles California, United States "^[38]

His principle of linear perspective was also employed in the art of Leonardo da Vinci and other Renaissance artists. Perspective (from Latin perspicere to see through in the graphic arts such as drawing is an approximate representation on a flat surface (such as paper of an image as it is perceived Leonardo di ser Piero da Vinci ( April 15 1452 – May 2 1519 was an Italian Polymath, having been a scientist Mathematician, Engineer ^[39]

Phenomenology

In philosophy, Ibn al-Haytham is considered a pioneer of phenomenology. Early Islamic philosophy or classical Islamic philosophy is a period of intense philosophical development beginning in the 2nd century AH of the Islamic calendar He articulated a relationship between the physical and observable world and that of intuition, psychology and mental functions. In philosophy the World is everything that makes up Reality. While clarifying the Concept of world has arguably always been among the basic tasks of Western Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and Mental functions and cognitive Processes are terms often used interchangeably (although not always correctly so the term cognitive tends to have specific His theories regarding knowledge and perception, linking the domains of science and religion, led to a philosophy of existence based on the direct observation of reality from the observer's point of view. Knowledge is defined ( Oxford English Dictionary) variously as (i expertise and skills acquired by a person through experience or education the theoretical or practical understanding In Psychology and the Cognitive sciences perception is the process of attaining awareness or understanding of sensory Information. In common usage existence is the world of which we are aware through our senses but in Philosophy the word has a more specialized meaning and is often contrasted with Reality, in everyday usage means "the state of things as they actually exist" Much of his thought on phenomenology was not further developed until the 20th century. ^[40]

Psychology

Ibn al-Haytham is considered by some to be the founder of experimental psychology,^[6] for his pioneering work on the psychology of visual perception and optical illusions. Experimental psychology approaches Psychology as one of the natural sciences investigates it using the experimental method. Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and In Psychology, visual perception is the ability to interpret information from Visible light reaching the Eyes The resulting Perception is also This article is about visual perception See Optical Illusion (Album for information about the Time Requiem album ^[5] Ibn al-Haytham made many subjective reports regarding vision and can therefore be argued to be the first "psychologist".

In the Book of Optics, Ibn al-Haytham was the first scientist to argue that vision occurs in the brain, rather than the eyes. He pointed out that personal experience has an effect on what people see and how they see, and that vision and perception are subjective. He explained possible errors in vision in detail, and as an example described how a small child with less experience may have more difficulty interpreting what he or she sees. He also gave an example of how an adult can make mistakes in vision due to experience that suggests that one is seeing one thing, when one is really seeing something else. ^[5]

In the Book of Optics, Ibn al-Haytham also developed the "concept of a sensory core that interprets visual stimuli" and which was "highly sophisticated, incorporating mathematical, anatomical and physiopsychological components. In a Sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of an Organism. Physiological psychology is a subdivision of Biological psychology that studies the neural mechanisms of perception and behavior through direct manipulation of the brains of "^[41]

Ibn al-Haytham also described what became known as Hering's law of equal innervation, vertical horopters, and binocular disparity,^[36] and improved on the theories of binocular vision, motion perception and horopters previously discussed by earlier scholars such as Aristotle, Euclid and Ptolemy. Hering's law of equal innervation is used to explain the conjugacy of Eye movements ( Saccades in Stereoptic animals In studies of Binocular vision the horopter is a volume centred on the fixation point that contains all points in space that yield single vision Binocular disparity refers to the difference in image location of an object seen by the left and right Eyes resulting from the eyes' horizontal separation Binocular vision is vision in which both Eyes are used together Motion perception is the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. Euclid ( Greek:.) fl 300 BC also known as Euclid of Alexandria, is often referred to as the Father of Geometry Claudius Ptolemaeus ( Greek: Klaúdios Ptolemaîos; after 83 &ndash ca ^[37][42]

Omar Khaleefa has argued that Ibn al-Haytham should be considered the founder of psychophysics,^[6] contrary to the orthodox opinion that Gustav Fechner founded this field in 1860 with the publication of his Elements of Psychophysics. Psychophysics is a subdiscipline of Psychology dealing with the relationship between physical stimuli and their subjective correlates or Percepts Gustav Theodor Fechner ( April 19, 1801 &ndash November 28, 1887) was a German experimental Psychologist. Year 1860 ( MDCCLX) was a Leap year starting on Sunday (link will display the full calendar of the Gregorian Calendar (or a Leap year starting There is, however, no evidence that Ibn al-Haytham employed any quantitative psychophysical techniques, so this remains a minority opinion.

Theology

Ibn al-Haytham attributed his experimental scientific method and scientific skepticism to his Islamic faith. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or Scientific method refers to bodies of Techniques for investigating phenomena Scientific skepticism or rational skepticism ( also spelled scepticism) sometimes referred to as skeptical inquiry, is a scientific or practical For other meanings including people named 'Islam' see Islam (disambiguation. He believed that human beings are inherently flawed and that only God is perfect. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus God is the principal or sole Deity in Religions and other belief systems that worship one deity. He reasoned that to discover the truth about nature, it is necessary to eliminate human opinion and error, and allow the universe to speak for itself. Reason involves the ability to think understand and draw Conclusions in an Abstract way as in Human thinking The meaning of the word truth extends from Honesty, Good faith, and Sincerity in general to agreement with Fact or Reality Nature, in the broadest sense is equivalent to the natural world, physical universe, material world or material universe. An opinion is a Person 's Ideas and thoughts towards something which it is either impossible to verify the truth of or the truth of which is thought unimportant to The word error has different meanings and usages relative to how it is conceptually applied The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy ^[19]

Ibn al-Haytham described his search for truth and knowledge as a way of leading him closer to God:

"I constantly sought knowledge and truth, and it became my belief that for gaining access to the effulgence and closeness to God, there is no better way than that of searching for truth and knowledge. Knowledge is defined ( Oxford English Dictionary) variously as (i expertise and skills acquired by a person through experience or education the theoretical or practical understanding "^[43]

See also

• Ibn al-Haytham
• Optics
• Scientific method
• Islamic science
• History of science

References

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