Book of Optics

From Wikipedia, the free encyclopedia

Jump to: navigation, search

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. 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. 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".[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]

The Book of Optics also contains the earliest discussions and descriptions of psychophysics and experimental psychology,[3] the psychology of visual perception,[4] and the camera obscura, a precursor to the modern camera. 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.[5] The work also had an influence on the use of optical aids in Renaissance art and the development of the telescope and microscope.[6]

Contents

[edit] Overview

In classical antiquity, there were two major theories on vision. 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. The second theory, the intromission theory, supported by Aristotle and his followers, had physical forms entering the eye from an object. 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.[7]

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.[8] 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.[9] He also discovered a result similar to Snell's law of sines, but did not quantify it and derive the law mathematically.[10] Ibn al-Haytham is also credited with the invention of the camera obscura and pinhole camera.[11] Alhacen also wrote on the refraction of light, especially on atmospheric refraction, for example, the cause of morning and evening twilight. 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. He also experimented on the dispersion of light into its constituent colours,[8] speculated on the finite speed, rectilinear propagation and electromagnetic aspects of light,[12] and argued that rays of light are streams of tiny particles travelling in straight lines.[13]

Ibn al-Haytham made a thorough examination of the passage of light through various media and discovered the laws of refraction. He also carried out the first experiments on the dispersion of light into its constituent colours.[8] 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. 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. He is the first to describe accurately the various parts of the eye and give a scientific explanation of the process of vision. He also attempted to explain binocular vision and the apparent increase in size of the Sun and the Moon when near the horizon. He is known for the earliest use of the camera obscura. 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. 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:[12]

  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."
  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."
  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. 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. He speculated on electromagnetic aspects of light, its velocity, and its rectilinear propagation. He recorded formation of an image in a camera obscura during an eclipse of the sun (the principle of the pinhole camera)."
  5. "He stated that the lens is that part of the eye where vision is felt first."
  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 Book of Optics also marked the beginning of psychophysics and experimental psychology. Ibn al-Haytham made use of his experimental method in his pioneering work on the psychology of visual perception. He was the first to combine physics and psychology to form psychophysics, 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.[3]

[edit] Scientific method

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. 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."[14]

Ibn al-Haytham's scientific method was very similar to the modern scientific method and consisted of the following procedures:[15]

  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
Image:Classical spectacular laser effects.jpg
Ibn al-Haytham proved that light travels in straight lines using the scientific method.

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. 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. ..."[16]

"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."[17]

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.[18]

[edit] 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. 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. 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."[19]

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. 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. 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."[20]

[edit] 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.[21] 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]. 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.[22] 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. A. Sedillot. Other manuscripts are preserved in the Bodleian Library at Oxford and in the library of Leiden. 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.[23]

[edit] Volumes

[edit] 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:[4]

"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. 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. [...] 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. He then examines the anatomical structure of the eye, and proposes the first use of a camera obscura.[8]

[edit] Books II-III

Book II of the treatise contains a discussion on visual perception.[8] In Book III, he pioneered the psychology of visual perception, being 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, 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.[4]

[edit] 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.[8]

[edit] 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. 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.[24]

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.[25] (Ptolemy made earlier attempts at explaining it, according to Roger Bacon.)

[edit] 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.

[edit] 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. 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. This leads to an equation of the fourth degree. 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.[26]

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.[27] Mathematicians were not able to find an algebraic solution to the problem until the end of the 20th century.[4]

[edit] 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:[28]

"The body of heaven differs ... 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.[28]

[edit] 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.[29] He made several improvements to eye surgery and accurately described the process of sight,[30] the structure of the eye, image formation in the eye and the visual system. He also discovered the underlying principles of Hering's law of equal innervation, binocular vision, motion perception, vertical horopters, and binocular disparity.[31]

[edit] 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. 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."[32]

[edit] Phenomenology

In philosophy, Ibn al-Haytham is considered a pioneer of phenomenology. He articulated a relationship between the physical and observable world and that of intuition, psychology and mental functions. 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. Much of his thought on phenomenology was not further developed until the 20th century.[33]

[edit] Psychology

Ibn al-Haytham is considered by some to be the founder of psychophysics and experimental psychology,[3] for his pioneering work on the psychology of visual perception.[4]

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.[4]

[edit] Theology

Ibn al-Haytham attributed his experimental scientific method and scientific skepticism to his Islamic faith. He believed that human beings are inherently flawed and that only God is perfect. 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.[15]

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."[34]

[edit] See also

[edit] References

  1. ^ Bradley Steffens (2006), Ibn al-Haytham: First Scientist, Morgan Reynolds Publishing, ISBN 1599350246. (cf. Reviews of Ibn al-Haytham: First Scientist, The Critics, Barnes & Noble.)
  2. ^ H. Salih, M. Al-Amri, M. El Gomati (2005). "The Miracle of Light", A World of Science 3 (3). UNESCO.
  3. ^ a b c Omar Khaleefa (Summer 1999). "Who Is the Founder of Psychophysics and Experimental Psychology?", American Journal of Islamic Social Sciences 16 (2).
  4. ^ a b c d e f Bradley Steffens (2006). Ibn al-Haytham: First Scientist, Chapter 5. Morgan Reynolds Publishing. ISBN 1599350246.
  5. ^ Bashar Saad, Hassan Azaizeh, Omar Said (October 2005). "Tradition and Perspectives of Arab Herbal Medicine: A Review", Evidence-based Complementary and Alternative Medicine 2 (4), p. 475-479 [476]. Oxford University Press.
  6. ^ Richard Powers (University of Illinois), Best Idea; Eyes Wide Open, New York Times, April 18, 1999.
  7. ^ D. C. Lindberg, Theories of Vision from al-Kindi to Kepler, (Chicago, Univ. of Chicago Pr., 1976), pp. 60-7.
  8. ^ a b c d e f Dr. Mahmoud Al Deek. "Ibn Al-Haitham: Master of Optics, Mathematics, Physics and Medicine, Al Shindagah, November-December 2004.
  9. ^ Albrecht Heeffer. Kepler’s near discovery of the sine law: A qualitative computational model, Ghent University, Belgium.
  10. ^ A. I. Sabra (1981), Theories of Light from Descartes to Newton, Cambridge University Press. (cf. Pavlos Mihas, Use of History in Developing ideas of refraction, lenses and rainbow, p. 5, Demokritus University, Thrace, Greece.)
  11. ^ Nicholas J. Wade, Stanley Finger (2001), "The eye as an optical instrument: from camera obscura to Helmholtz's perspective", Perception 30 (10), p. 1157-1177.
  12. ^ a b Sami Hamarneh (March 1972). Review of Hakim Mohammed Said, Ibn al-Haitham, Isis 63 (1), p. 119.
  13. ^ J. J. O'Connor and E. F. Robertson (2002). Light through the ages: Ancient Greece to Maxwell, MacTutor History of Mathematics archive.
  14. ^ Rosanna Gorini (2003). "Al-Haytham the Man of Experience. First Steps in the Science of Vision", International Society for the History of Islamic Medicine. Institute of Neurosciences, Laboratory of Psychobiology and Psychopharmacology, Rome, Italy.
  15. ^ a b Bradley Steffens (2006). Ibn al-Haytham: First Scientist, Morgan Reynolds Publishing, ISBN 1599350246. (cf. Bradley Steffens, "Who Was the First Scientist?", Ezine Articles.)
  16. ^ Alhazen (Ibn Al-Haytham) Critique of Ptolemy, translated by S. Pines, Actes X Congrès internationale d'histoire des sciences, Vol I Ithaca 1962, as referenced on p.139 of Shmuel Sambursky (ed. 1974) Physical Thought from the Presocratics to the Quantum Physicists ISBN 0-87663-712-8
  17. ^ Alhazen, translated into English from German by M. Schwarz, from "Abhandlung über das Licht", J. Baarmann (ed. 1882) Zeitschrift der Deutschen Morgenländischen Gesellschaft Vol 36 as referenced on p.136 by Shmuel Sambursky (1974) Physical thought from the Presocratics to the Quantum Physicists ISBN 0-87663-712-8
  18. ^ p.136, as quoted by Shmuel Sambursky (1974) Physical thought from the Presocratics to the Quantum Physicists ISBN 0-87663-712-8
  19. ^ R. S. Elliott (1966). Electromagnetics, Chapter 1. McGraw-Hill.
  20. ^ Dr. A. Zahoor and Dr. Z. Haq (1997). Quotations from Famous Historians of Science, Cyberistan.
  21. ^ A. C. Crombie, Robert Grosseteste and the Origins of Experimental Science, 1100 - 1700, (Oxford: Clarendon Press, 1971), p. 147, n. 2.
  22. ^ Smith, A Mark (2001). Alhacen's theory of visual perception: a critical edition, with English translation and commentary, of the first three books of Alhacen's De aspectibus, the medieval Latin version of Ibn al-Haytham's Kitab al-Manazir. Vol 1. Philadelphia: American Philosophical Society, xxi. ISBN 9780871699145. .
  23. ^ O. S. Marshall (1950). "Alhazen and the Telescope", Astronomical Society of the Pacific Leaflets 6, p. 4.
  24. ^ Dr. Nader El-Bizri, "Ibn al-Haytham or Alhazen", in Josef W. Meri (2006), Medieval Islamic Civilization: An Encyclopaedia, Vol. II, p. 343-345, Routledge, New York, London.
  25. ^ Vernon O. Georgia (2003). A History of the Muslim World to 1405: The Making of a Civilization, p. 200. Prentice Hall. ISBN 0-13-098389-6.
  26. ^ Victor J. Katz (1995). "Ideas of Calculus in Islam and India", Mathematics Magazine 68 (3), p. 163-174.
  27. ^ John D. Smith (1992). "The Remarkable Ibn al-Haytham", The Mathematical Gazette 76 (475), p. 189-198.
  28. ^ a b Edward Rosen (1985), "The Dissolution of the Solid Celestial Spheres", Journal of the History of Ideas 46 (1), p. 13-31 [19-20, 21].
  29. ^ Steffens (cf. Review by Sulaiman Awan)
  30. ^ Bashar Saad, Hassan Azaizeh, Omar Said (October 2005). "Tradition and Perspectives of Arab Herbal Medicine: A Review", Evidence-based Complementary and Alternative Medicine 2 (4), p. 475-479 [476]. Oxford University Press
  31. ^ Ian P. Howard (1996). "Alhazen's neglected discoveries of visual phenomena". Perception 25 (10): 1203 – 1217.
  32. ^ Falco, Charles M. "Ibn al-Haytham and the Origins of Modern Image Analysis", presented at a plenary session at the International Conference on Information Sciences, Signal Processing and its Applications, 12–15 February 2007. Sharjah, United Arab Emirates (U.A.E.). [1]
  33. ^ Dr Valérie Gonzalez, "Universality and Modernity", The Ismaili United Kingdom, December 2002, p. 50-53.
  34. ^ C. Plott (2000), Global History of Philosophy: The Period of Scholasticism, Pt. II, p. 465. ISBN 8120805518, Motilal Banarsidass Publ.
Retrieved from "http://india.smashits.com/wikipedia/Book_of_Optics"
Views
Personal tools

Toolbox