History of Islamic Physics (Snell's Law)

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The discovery of the sine law of refraction is credited to Ibn Sahl who first proved the law in his works, published 984.
History:— "Snell's Law" (or "Sahl's Law" as it should be known) is arguably one of the most important laws in physical optics today, and traces it's origins back to 984, when it was first discovered by Abu Said al-Ala Ibn Sahl of Baghdad (940—1000),[1][2][3][4][5] in his manuscript "On the Burning of Instruments".[6] Naturally this important and crucial discovery has been challenged by some European authors,[n. 1] who would like to claim that it was discovered in Europe; however modern historians of science credit ibn Sahl with the discovery.[n. 2] However, it should be noted that this revelation took centuries to come to fruition, as Ibn Sahl was only credited with the discovery in 1990, when French scholar on the history of science, Rashed Roshdi, located his manuscripts in Tehran, Iran; which proved that it was actually the eponymous scientist who first came up with the concept and subsequently discovered the law.[7] Traditionally, the law was previously credited to the Dutchman, Willebrord Snellius (1580—1626), though he never claimed to have discovered it himself, as his manuscript was never formally published.[8] This overall historical confusion on who found the law of refraction first was down to the fact that knowledge of Sahl's work was simply lost as his pupil, Ibn Al Haytham (965–1040), rejected his teachers original work and so it was long assumed that Ibn Al Haytham did not know of the law, when he actually did; thereafter taking the Europeans 637 years to rediscover Sahl's correct law.[n. 3]
Applications:— One of the most important applications of the law are in the design of eye-glasses, which bend light in order to focus rays to the wearer's eyes.[13] Indeed, the law was being used by Ibn Sahl himself when he was designing lenses in the 10th century;[14] and could have possibly used them to correct eye sight; later the Europeans began designing eye lenses in the 1350s, using convex lenses, and in the 1450s concave lenses.[14] This law is also important with regards to telescopic and microscopic designs.[13] Indeed, without the law, the development of telescopes would not have moved forward.[15] It is also possible that the invention of the telescope may have been invented several times over, including during the Islamic Golden Age, well before the invention in 1608 became widely popular in Europe.[14] The law is so important and so vast that it is even used in military applications for the design of stealth fighter jets;[16] where the surfaces of such planes reflect incident radar pulses away from themselves based on the physics behind the law, but not in the direction of the pulse radar equipment so as to give away their position.[16] Using this law further, besides deflecting the classical sinusoidal waves, it also deflects the Dirac delta function.[16] Thermal noise is also able to be deflected if the law is followed correctly.[16] However it should be noted that further designs, or later developments in radar technology are now able to overcome the practical aspects of the law; thereby circumventing it.[16]
Ibn Sahl's law with Arabic annotation's translated.
The principal of total internal reflection.
Another important result of Sahl's work is that of optical fibres. These instruments are used to transmit converted electrical signals to light energy,[17] across large or small distances with minimal loss. Compared to conventional methods, in those of copper fibres used to transmit the same signals, efficiency is low, and there can be a significant amount of loss.[18][19] The most important industry where optical fibres are used currently is in internet technology, which contribute to the increase of download speeds.[20] Light, as a physical quantity, tends to travel in straight lines,[21] and it is extremely difficult to bend given the speed at which it travels, which is 300 million meters per second[21] (though it can be done, simply not without meta-materials,[22] unless black holes are accounted for).[23] In optical fibres, light is deliberately redirected in straight lines by hitting (or bouncing) it off at a particular angle.[24] This particular angle is the angle that is greater than the critical angle, which is otherwise known as "total internal reflection".[25] Importantly this angle can be calculated by the Sahl's law of refraction.[26] The photonics industry, of which fibre optics transmission is a part of, is as a result extremely lucrative, worth an estimated $721 billion dollars.[27] However, historical chronic mismanagement of fiber optics has remained problematic; despite firms having invested $90 billion dollars (1997—2001), only 2.6% of consumers used the technology.[28] Sahl's work therefore remains to be fully exploited.
The discovery of the sine law of refraction is credited to Ibn Sahl who first proved the law in his works, published 984.
History:— "Snell's Law" (or "Sahl's Law" as it should be known) is arguably one of the most important laws in physical optics today, and traces it's origins back to 984, when it was first discovered by Abu Said al-Ala Ibn Sahl of Baghdad (940—1000),[1][2][3][4][5] in his manuscript "On the Burning of Instruments".[6] Naturally this important and crucial discovery has been challenged by some European authors,[n. 4] who would like to claim that it was discovered in Europe; however modern historians of science credit ibn Sahl with the discovery.[n. 5] However, it should be noted that this revelation took centuries to come to fruition, as Ibn Sahl was only credited with the discovery in 1990, when French scholar on the history of science, Rashed Roshdi, located his manuscripts in Tehran, Iran; which proved that it was actually the eponymous scientist who first came up with the concept and subsequently discovered the law.[7] Traditionally, the law was previously credited to the Dutchman, Willebrord Snellius (1580—1626), though he never claimed to have discovered it himself, as his manuscript was never formally published.[8] This overall historical confusion on who found the law of refraction first was down to the fact that knowledge of Sahl's work was simply lost as his pupil, Ibn Al Haytham (965–1040), rejected his teachers original work and so it was long assumed that Ibn Al Haytham did not know of the law, when he actually did; thereafter taking the Europeans 637 years to rediscover Sahl's correct law.[n. 6]
Applications:— One of the most important applications of the law are in the design of eye-glasses, which bend light in order to focus rays to the wearer's eyes.[13] Indeed, the law was being used by Ibn Sahl himself when he was designing lenses in the 10th century;[14] and could have possibly used them to correct eye sight; later the Europeans began designing eye lenses in the 1350s, using convex lenses, and in the 1450s concave lenses.[14] This law is also important with regards to telescopic and microscopic designs.[13] Indeed, without the law, the development of telescopes would not have moved forward.[15] It is also possible that the invention of the telescope may have been invented several times over, including during the Islamic Golden Age, well before the invention in 1608 became widely popular in Europe.[14] The law is so important and so vast that it is even used in military applications for the design of stealth fighter jets;[16] where the surfaces of such planes reflect incident radar pulses away from themselves based on the physics behind the law, but not in the direction of the pulse radar equipment so as to give away their position.[16] Using this law further, besides deflecting the classical sinusoidal waves, it also deflects the Dirac delta function.[16] Thermal noise is also able to be deflected if the law is followed correctly.[16] However it should be noted that further designs, or later developments in radar technology are now able to overcome the practical aspects of the law; thereby circumventing it.[16]
Ibn Sahl's law with Arabic annotation's translated.
The principal of total internal reflection.
Another important result of Sahl's work is that of optical fibres. These instruments are used to transmit converted electrical signals to light energy,[17] across large or small distances with minimal loss. Compared to conventional methods, in those of copper fibres used to transmit the same signals, efficiency is low, and there can be a significant amount of loss.[18][19] The most important industry where optical fibres are used currently is in internet technology, which contribute to the increase of download speeds.[20] Light, as a physical quantity, tends to travel in straight lines,[21] and it is extremely difficult to bend given the speed at which it travels, which is 300 million meters per second[21] (though it can be done, simply not without meta-materials,[22] unless black holes are accounted for).[23] In optical fibres, light is deliberately redirected in straight lines by hitting (or bouncing) it off at a particular angle.[24] This particular angle is the angle that is greater than the critical angle, which is otherwise known as "total internal reflection".[25] Importantly this angle can be calculated by the Sahl's law of refraction.[26] The photonics industry, of which fibre optics transmission is a part of, is as a result extremely lucrative, worth an estimated $721 billion dollars.[27] However, historical chronic mismanagement of fiber optics has remained problematic; despite firms having invested $90 billion dollars (1997—2001), only 2.6% of consumers used the technology.[28] Sahl's work therefore remains to be fully exploited.

Sources

Footnotes

  1. ^ Some European books prefer to give Snell credit to this day, even though there is proof that the law was derived from the Muslims. For example; the following source claimed as much in 2016, citing old sources as evidence of a supposed "dispute" despite there being strong evidence that the Muslims discovered it from historians of science.
    1. Kamill Klem-Musatov; Henning C. Hoeber; Tijmen Jan Moser; Michael A. Pelissier (30 June 2016). Classical and Modern Diffraction Theory. SEG Books. p. 92. ISBN 978-1-56080-322-5.
    This source however debunks any sort of supposed "dispute" by showing that in 2002, historians of science gave a detailed account of who should actually be credited with the discovery.
    1. Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
    Quote: "Based on a recent analysis of Ibn Sahl’s work by the French scholar Roshdi Rashed, there is no doubt that Ibn Sahl correctly understood the sine law of refraction and that he should be acknowledged as its originator. From the viewpoint of modern physics, it is regrettable that his contributions were lost for so long, but this is certainly not the only historical triumph of falsity over perfectly correct theory. Perhaps the next question to ask is why science sometimes makes such regressive choices."
    A further note on the background of the authors of the above paper: Alistair Kwan is in the Department of History and Philosophy of Science, University of Melbourne, Australia. John Dudley and Eric Lantz are in the Laboratoire d’Optique P M Duffieux, Université de Franche-Comté, France, e-mail john.dudley@univ-fcomte.fr
  2. ^ For instance, Sabra (1994) and Simon (1996) dispute the claims that Ibn Sahl discovered it based on the fact that Alhazen (Sahl's pupil), did not reproduce the results in any of his work. However, this is in and of itself disputed by Kwan, Dudley and Lantz (2002) who confirm that Alhazen did not reproduce it, but that he did see the correct work of Sahl, only rejecting it and using the wrong formula that the Greeks had used.
    1. Kamill Klem-Musatov; Henning C. Hoeber; Tijmen Jan Moser; Michael A. Pelissier (30 June 2016). Classical and Modern Diffraction Theory. SEG Books. p. 92. ISBN 978-1-56080-322-5.
    2. Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
  3. ^ Polish author Witelo (1250–1275) translated Ibn Al Haytham's treaty "Opticae Thesaurus", which came into the hands of Johannes Kepler (1571–1630), where Keplar came close to discovering the law of refraction but only managed to produce an approximation. English mathematician, Thomas Harriot allegedly knew of the law as early as 1602, but he refused to share it with Keplar. Snell later wrote about the law of refraction in 1621 in his unpublished manuscript and thereafter René Descartes (1596–1650) popularised it in France. However, it Sahl beat all these scholars, by discovering it first in 984, 637 years before the Europeans would know of it.
    1. Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
    Descartes never credited Snell with discovering the law either; therefore Descartes was the first European to publish the law of refraction.
    1. J.J Stamnes (1 January 1986). Waves in Focal Regions: Propagation, Diffraction and Focusing of Light, Sound and Water Waves. CRC Press. p. 4. ISBN 978-0-85274-468-0.
  4. ^ Some European books prefer to give Snell credit to this day, even though there is proof that the law was derived from the Muslims. For example; the following source claimed as much in 2016, citing old sources as evidence of a supposed "dispute" despite there being strong evidence that the Muslims discovered it from historians of science.
    1. Kamill Klem-Musatov; Henning C. Hoeber; Tijmen Jan Moser; Michael A. Pelissier (30 June 2016). Classical and Modern Diffraction Theory. SEG Books. p. 92. ISBN 978-1-56080-322-5.
    This source however debunks any sort of supposed "dispute" by showing that in 2002, historians of science gave a detailed account of who should actually be credited with the discovery.
    1. Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
    Quote: "Based on a recent analysis of Ibn Sahl’s work by the French scholar Roshdi Rashed, there is no doubt that Ibn Sahl correctly understood the sine law of refraction and that he should be acknowledged as its originator. From the viewpoint of modern physics, it is regrettable that his contributions were lost for so long, but this is certainly not the only historical triumph of falsity over perfectly correct theory. Perhaps the next question to ask is why science sometimes makes such regressive choices."
    A further note on the background of the authors of the above paper: Alistair Kwan is in the Department of History and Philosophy of Science, University of Melbourne, Australia. John Dudley and Eric Lantz are in the Laboratoire d’Optique P M Duffieux, Université de Franche-Comté, France, e-mail john.dudley@univ-fcomte.fr
  5. ^ For instance, Sabra (1994) and Simon (1996) dispute the claims that Ibn Sahl discovered it based on the fact that Alhazen (Sahl's pupil), did not reproduce the results in any of his work. However, this is in and of itself disputed by Kwan, Dudley and Lantz (2002) who confirm that Alhazen did not reproduce it, but that he did see the correct work of Sahl, only rejecting it and using the wrong formula that the Greeks had used.
    1. Kamill Klem-Musatov; Henning C. Hoeber; Tijmen Jan Moser; Michael A. Pelissier (30 June 2016). Classical and Modern Diffraction Theory. SEG Books. p. 92. ISBN 978-1-56080-322-5.
    2. Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
  6. ^ Polish author Witelo (1250–1275) translated Ibn Al Haytham's treaty "Opticae Thesaurus", which came into the hands of Johannes Kepler (1571–1630), where Keplar came close to discovering the law of refraction but only managed to produce an approximation. English mathematician, Thomas Harriot allegedly knew of the law as early as 1602, but he refused to share it with Keplar. Snell later wrote about the law of refraction in 1621 in his unpublished manuscript and thereafter René Descartes (1596–1650) popularised it in France. However, it Sahl beat all these scholars, by discovering it first in 984, 637 years before the Europeans would know of it.
    1. Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
    Descartes never credited Snell with discovering the law either; therefore Descartes was the first European to publish the law of refraction.
    1. J.J Stamnes (1 January 1986). Waves in Focal Regions: Propagation, Diffraction and Focusing of Light, Sound and Water Waves. CRC Press. p. 4. ISBN 978-0-85274-468-0.

References

  1. ^ a b Charles H. Carman (23 March 2016). Renaissance Theories of Vision. Routledge. p. 15. ISBN 978-1-317-06640-8.
  2. ^ a b Frederick R. Chromey (27 May 2010). To Measure the Sky: An Introduction to Observational Astronomy. Cambridge University Press. p. 122. ISBN 978-0-521-76386-8.
  3. ^ a b John M. Henshaw (25 August 2014). An Equation for Every Occasion: Fifty-Two Formulas and Why They Matter. JHU Press. p. 81. ISBN 978-1-4214-1491-1.
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  5. ^ a b Ross Barrett; Pier Paolo Delsanto; Angelo Tartaglia (7 May 2016). Physics: The Ultimate Adventure. Springer International Publishing. p. 45. ISBN 978-3-319-31691-8.
  6. ^ a b c d Alistair Kwan, John Dudley and Eric Lantz (April 2002). Who really discovered Snell’s law?. Physics World. p. 64. Retrieved October 18th, 2016.
  7. ^ a b Roger L. Cooke (8 November 2012). The History of Mathematics: A Brief Course. John Wiley & Sons. p. 370. ISBN 978-1-118-46029-0.
  8. ^ a b Kuo-Nan Liou; Ping Yang (6 October 2016). Light Scattering by Ice Crystals: Fundamentals and Applications. Cambridge University Press. p. 118. ISBN 978-0-521-88916-2.
  9. ^ a b Ibn Sahl. February 23rd 2015. Iggy (University of Warwick). Retrieved October 20th, 2016.
  10. ^ a b Claude Phipps (5 October 2015). No Wonder You Wonder!: Great Inventions and Scientific Mysteries. Springer. p. 107-108. ISBN 978-3-319-21680-5.
  11. ^ a b Natural Sciences Quarterly Newsletter. October–December 2005. Vol. 3. No. 4. p. 5. UNESCO. Retrieved October 20th, 2016.
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  13. ^ a b c d Arun K. Varshneya (22 October 2013). Fundamentals of Inorganic Glasses. Elsevier. p. 456. ISBN 978-0-08-057150-8.
  14. ^ a b c d e f C.R. Kitchin (18 November 2013). Astrophysical Techniques, Sixth Edition. Taylor & Francis. p. 64. ISBN 978-1-4665-1115-6.
  15. ^ a b D. Graham Burnett (2005). Descartes and the Hyperbolic Quest: Lens Making Machines and Their Significance in the Seventeenth Century. American Philosophical Society. p. 10. ISBN 978-0-87169-953-4.
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