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| Fields of physics studied included ] and ], ] (including ], ], ] and ]), and ]. | Fields of physics studied included ] and ], ] (including ], ], ] and ]), and ]. | ||
| ==Overview== | |||
| In medieval Islam, ] began in ] and ],<ref name=Thiele>{{citation|first=Rüdiger|last=Thiele|title=In Memoriam: Matthias Schramm, 1928–2005|journal=Historia Mathematica|volume=32|issue=3|date=August 2005|pages=271–274|doi=10.1016/j.hm.2005.05.002}}</ref> with the work of the ], ] (known as ''Alhazen'' in the ]),<ref>{{citation|first=Rüdiger|last=Thiele|year=2005|title=In Memoriam: Matthias Schramm|journal=Arabic Sciences and Philosophy|publisher=]|volume=15|pages=329–331|doi=10.1017/S0957423905000214}}</ref> who is considered the "father of modern ]"<ref name=Verma/> and the most important ] of the ],<ref name=Sarton>], ''Introduction to the History of Science'', "The Time of Al-Biruni"</ref> for having developed the earliest ]al ] in his '']''.<ref name=Gorini>{{Citation |last=Gorini |first=Rosanna |title=Al-Haytham the man of experience. First steps in the science of vision |journal=Journal of the International Society for the History of Islamic Medicine |volume=2 |issue=4 |pages=53–55 |month=October | year=2003 |url=http://www.ishim.net/ishimj/4/10.pdf |format=pdf |accessdate=2008-09-25 |postscript=.}}</ref> | |||
| ], the "father of the ]", wrote in his ''Introduction to the History of Science'':<ref name=Sarton/> | |||
| {{quote| was not only the greatest Muslim physicist, but by all means the greatest of ].}} | |||
| {{quote|Ibn Haytham's writings reveal his fine development of the experimental faculty. His tables of corresponding ] and ] of light passing from one medium to another show how closely he had approached discovering the ], later attributed to ]. He accounted correctly for twilight as due to ], 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.}} | |||
| Matthias Schramm wrote in his ''Ibn al-Haythams Weg zur Physik'': | |||
| {{quote|Through a closer examination of Ibn al-Haytham's conceptions of ]s and of the role they play in his theory of ] ], it becomes evident that he was the true founder of physics in the modern sense of the word; in fact he anticipated by six centuries the fertile ideas that were to mark the beginning of this new branch of science.<ref name=Thiele/>}} | |||
| Another important medieval ] physicist who contributed towards experimental physics was ], who developed the earliest experimental method for ].<ref name=Rozhanskaya-642/> Ibn al-Haytham<ref name=Toomer/> and Al-Biruni<ref name=Zahoor/><ref name=Biruni/> also introduced the earliest experimental methods for ] and ], while Al-Biruni and ] unified ] with ] into the ] of mechanics and combined ] with dynamics to create the field of ].<ref name=Rozhanskaya-642/> | |||
| ==Islam and physics== | |||
| The ] contains an "insistence that the ] is ruled by a single ]"{{Cite quote|date=May 2010}} which was "rooted in the ]ic concept of '']'', the unity of God", as well its "greater respect for ] ] than was common in the preceding ]"{{Cite quote|date=May 2010}} which inspired Muslims to place a greater emphasis on empirical ],<ref>{{citation|first= I. A.|last= Ahmad |title= The impact of the Qur'anic conception of astronomical phenomena on Islamic civilization |journal= Vistas in Astronomy |volume= 39 |issue= 4 |year= 1995 |pages= 395–403 |doi= 10.1016/0083-6656(95)00033-X }}</ref> in contrast to ancient ] such as the ] and ] who expressed a general distrust towards the ]s and instead viewed ] alone as being sufficient to understanding nature. The Qur'an's insistence on observation, reason and ] ("see", "think" and "contemplate"), on the other hand, led Muslims to develop an early ] based on these principles, particularly empirical observation. ] says that it was:<ref>{{citation|first= I. A.|last= Ahmad |contribution= The Rise and Fall of Islamic Science: The Calendar as a Case Study |title= Faith and Reason: Convergence and Complementarity |publisher= ] |date= June 3, 2002 |url= http://images.agustianwar.multiply.com/attachment/0/RxbYbQoKCr4AAD@kzFY1/IslamicCalendar-A-Case-Study.pdf |format= PDF |accessdate= 2008-01-31 }}</ref> | |||
| {{quote|… the general empirical attitude of the Qur'an which engendered in its followers a feeling of reverence for the actual, and ultimately made them the founders of modern ]. It was a great point to awaken the empirical spirit in an age that renounced the visible as of no value in men's search after God.}} | |||
| ] (Alhazen) attributed his ]al method and ] to his Islamic faith. He believed that human beings are inherently flawed and that only ] 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.<ref name=Ezine>(] Bradley Steffens, "Who Was the First Scientist?", '']''.)</ref> In ''The Winding Motion'', Ibn al-Haytham further wrote that faith should only apply to ] and not to any other authorities, in the following comparison between the Islamic prophetic tradition and the demonstrative sciences: | |||
| {{quote|From the statements made by the noble ], it is clear that he believes in ]'s words in everything he says, without relying on a demonstration or calling on a proof, but by pure imitation (]); that is how ] have faith in Prophets, may the blessing of God be upon them. But it is not the way that mathematicians have faith in specialists in the demonstrative sciences {{Harv|Rashed|2007|p=11}}.}} | |||
| Ibn al-Haytham described his search for truth and knowledge as a way of leading him closer to God: | |||
| {{quote|I constantly sought knowledge and truth, and it became my belief that for gaining access to the ] and closeness to God, there is no better way than that of searching for truth and knowledge {{Harv|Plott|Gray|Dolin|2000|p=465}}.}} | |||
| ]'s (1403–1474) support for the ] and his rejection of ] (which advocates a stationary Earth) was also motivated by religious opposition to ] by orthodox ] such as ] {{harvard citations|last=Ragep|year1=2001a|year2=2001b}}{{Page number|date=May 2010}}. | |||
| ==Scientific method== | |||
| Muslim scientists placed a greater emphasis on ]ation than previous ]s (for example, ] placed a greater emphasis on ] rather than ]) <ref name=Briffault>{{Harvnb|Briffault|1919|p=191}}</ref><ref name=Durant>] (1980). ''The Age of Faith (], Volume 4)'', p. 162-186. Simon & Schuster. ISBN 0671012002.</ref> which was due to the emphasis on ] ] found in the ],<ref name=Ahmad/><ref>{{cite quran|2|164|quote=Behold! In the creation of the heavens and the earth; in the alternation of the night and the day; in the sailing of the ships through the ocean for the benefit of mankind; in the rain which Allah Sends down from the skies, and the life which He gives therewith to an earth that is dead; in the beasts of all kinds that He scatters through the earth; in the change of the winds, and the clouds which they trail like their slaves between the sky and the earth - (Here) indeed are Signs for a people that are wise.}}</ref> and the rigorous ]s established in the ].<ref name=Ahmad>Ahmad, I. A. (June 3, 2002), , ''Faith and Reason: Convergence and Complementarity'', ]. Retrieved on 2008-01-31.</ref> Muslim scientists thus combined precise observation, ] and careful records<ref name=Durant/> with a new<ref name=Briffault/> approach to scientific ] which led to the development of the ].<ref name=Gorini/> In particular, the empirical observations and experiments of ] (Alhazen) in his '']'' (1021) is seen as the beginning of the modern scientific method, which he first introduced to ] and ].<ref name=Toomer/> Rosanna Gorini writes: | |||
| {{quote|According to the majority of the ]s 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.<ref name=Gorini/>}} | |||
| Other early experimental methods were developed by ] for ],<ref name=Koningsveld>{{citation|title=Polymer Phase Diagrams: A Textbook|first1=Ronald|last1=Koningsveld|first2=Walter H.|last2=Stockmayer|first3=Erik|last3=Nies|year=2001|publisher=]|isbn=0198556349|pages=xii-xiii|oclc=45375807 45736855 69291240}}</ref> by ] for the ]s,<ref name=Plinio>Plinio Prioreschi, "Al-Kindi, A Precursor Of The Scientific Revolution", ''Journal of the International Society for the History of Islamic Medicine'', 2002 (2): 17-19.</ref> and by ] for astrophysics<ref name=Biruni>{{MacTutor|id=Al-Biruni|title=Al-Biruni}}</ref> and ].<ref name=Rozhanskaya-642/> The most important development of the scientific method, the use of experimentation and quantification to distinguish between competing scientific theories set within a generally empirical orientation, was introduced by Muslim scientists. | |||
| ] wrote in ''The Making of Humanity'': | |||
| {{quote|The debt of our science to that of the ]s does not consist in startling discoveries or revolutionary theories; science owes a great deal more to Arab culture, it owes its existence. The ancient world was, as we saw, pre-scientific. The astronomy and mathematics of the Greeks were a foreign importation never thoroughly acclimatized in Greek culture. The Greeks systematized, generalized and theorized, but the patient ways of investigation, the accumulation of positive knowledge, the minute methods of science, detailed and prolonged observation, experimental inquiry, were altogether alien to the Greek temperament. What we call science arose in Europe as a result of a new spirit of inquiry, of new methods of investigation, of the method of experiment, observation, measurement, of the development of mathematics in a form unknown to the Greeks. That spirit and those methods were introduced into the European world by the Arabs.<ref name=Briffault/>}} | |||
| {{quote|Science is the most momentous contribution of ] to the ], but its fruits were slow in ripening. Not until long after ] culture had sunk back into darkness did the giant to which it had given birth, rise in his might. It was not science only which brought Europe back to life. Other and manifold influences from the civilization of Islam communicated its first glow to European life {{Harv|Briffault|1919|p=202}}.}} | |||
| ] wrote in the ''Introduction to the History of Science'': | |||
| {{quote|The main, as well as the least obvious, achievement of the Middle Ages was the creation of the experimental spirit and this was primarily due to the Muslims down to the 12th century.<ref name=Salam/>}} | |||
| ] wrote in the ''Pioneers of Science'': | |||
| {{quote|The only effective link between the old and the new science is afforded by the Arabs. The ] come as an utter gap in the scientific history of Europe, and for more than a thousand years there was not a scientific man of note except in ].<ref>{{Citation|title= Pioneers of Science |last= Lodge |first= Oliver Joseph |authorlink= Oliver Joseph Lodge |year= 1893 |publisher= ] |page= 9 }}</ref>}} | |||
| ] wrote in '']'': | |||
| {{quote|Thus the experimental method, reason and observation introduced by the Arabs were responsible for the rapid advancement of science during the medieval times.<ref name=Iqbal>] (1934, 1999), '']'', Kazi Publications, ISBN 0686184823</ref>}} | |||
| ===Alhazenian method=== | |||
| {{See also|Ibn al-Haytham|Book of Optics}} | |||
| ], considered the "father of modern ]",<ref name=Verma/> used the scientific method to obtain the results in his famous '']'' (1021). In particular, he combined observations, experiments and rational arguments to show that his modern intromission theory of ], where ] of ] are emitted from objects rather than from the eyes, is scientifically correct, and that the ancient ] supported by ] and ] (where the eyes emit rays of light), and the ancient intromission theory supported by ] (where objects emit physical particles to the eyes), were both wrong.<ref>D. C. Lindberg, ''Theories of Vision from al-Kindi to Kepler'', (Chicago, Univ. of Chicago Pr., 1976), pp. 60-7.</ref> It is known that ] was familiar with Ibn al-Haytham's work. | |||
| Ibn al-Haytham developed rigorous experimental methods of controlled ] in order to verify theoretical ] and substantiate ] ]s.<ref name=Bizri/> Ibn al-Haytham's scientific method was similar to the modern scientific method in that it consisted of the following procedures:<ref name="Ezine"/> | |||
| #] | |||
| #Statement of ] | |||
| #Formulation of ] | |||
| #Testing of hypothesis using ]ation | |||
| #Analysis of experimental ]s | |||
| #Interpretation of ] and formulation of conclusion | |||
| #] of findings | |||
| An aspect associated with ]'s optical research is related to systemic and methodological reliance on experimentation (''i'tibar'') and controlled testing in his scientific inquiries. Moreover, his experimental directives rested on combining classical physics ('''ilm tabi'i'') with mathematics (''ta'alim''; geometry in particular) in terms of devising the rudiments of what may be designated as a ] in scientific research. This mathematical-physical approach to experimental science supported most of his propositions in ''Kitab al-Manazir'' (''The Optics''; ''De aspectibus'' or ''Perspectivae'') and gounded his theories of vision, light and colour, as well as his research in catoptrics and dioptrics. His legacy was further advanced through the 'reforming' of his ''Optics'' by ] (d. ca. 1320) in the latter's ''Kitab Tanqih al-Manazir'' (''The Revision of'' ''Optics'').<ref>Nader El-Bizri, "A Philosophical Perspective on Alhazen’s Optics," ''Arabic Sciences and Philosophy'', Vol. 15, Issue 2 (2005), pp. 189-218 (Cambridge University Press)</ref><ref name="Bizri2005-237">Nader El-Bizri, "Ibn al-Haytham," in ''Medieval Science, Technology, and Medicine: An Encyclopedia'', eds. Thomas F. Glick, Steven J. Livesey, and Faith Wallis (New York — London: Routledge, 2005), pp. 237-240.</ref> | |||
| The development of the scientific method is considered to be fundamental to ] and some — especially ] and practicing scientists — consider earlier inquiries into nature to be ''pre-scientific''. Some consider Ibn al-Haytham to be the "first ]" for this reason.<ref>{{Citation|first= Bradley |last= Steffens |year= 2006 |title= Ibn al-Haytham: First Scientist |publisher= Morgan Reynolds Publishing, |isbn= 1599350246 }}</ref> | |||
| Ibn al-Haytham also employed ] and ], and emphasized the role of ]. He also explained the role of ] in ], and criticized ] for his lack of contribution to the method of induction, which Ibn al-Haytham regarded as superior to syllogism, and he considered induction to be the basic requirement for true scientific research {{Harv|Plott|Gray|Dolin|2000|p=462}}. | |||
| The ''Book of Optics'' emphasized the role of experimentation as a form of proof in scientific inquiry.<ref>{{Citation | last1=Rashed | first1=Roshdi | last2=Armstrong | first2=Angela | year=1994 | title=The Development of Arabic Mathematics | publisher=] | isbn=0792325656 | pages=345–6 | oclc=29181926}}</ref> Al-Haytham adopted a form of ] in his approach, centuries before a term for positivism was coined. In his ''Book of Optics'', he wrote that "we do not go beyond experience, and we cannot be content to use pure concepts in investigating natural phenomena", and that the understanding of these cannot be acquired without mathematics. After assuming that light is a material substance, he does not discuss its nature any further but confines his investigations to the diffusion and propagation of light. The only properties of light he takes into account are that which can be treated by geometry and verified by experiment, noting that ] is the only quality of light that can be sensed.<ref name="Rashed2007">{{Harvnb|Rashed|2007|pp=7–55}}: {{quote|In reforming optics he as it were adopted "positivism" (before the term was invented): we do not go beyond ], and we cannot be content to use pure concepts in investigating natural phenomena. Understanding of these cannot be acquired without mathematics. Thus, once he has assumed light is a material substance, Ibn al-Haytham does not discuss its nature further, but confines himself to considering its propagation and diffusion. In his optics "the smallest parts of light", as he calls them, retain only properties that can be treated by geometry and verified by experiment; they lack all sensible qualities except energy.}}</ref> | |||
| The concept of ] is also present in the ''Book of Optics''. For example, after demonstrating that light is generated by luminous objects and emitted or reflected into the eyes, he states that therefore "the ] of rays is superfluous and useless."<ref>{{citation|title=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|last1=]|first2=A. Mark|last2=Smith|year=2001|publisher=DIANE Publishing|isbn=0871699141|pages=372 & 408|oclc=163278528 163278565 185537919 47168716}}</ref> In ''The Model of the Motions'', Ibn al-Haytham also uses a form of Occam's razor, where he employs only minimal hypotheses regarding the properties that characterize astronomical motions, as he attempts to eliminate from his planetary model the ] hypotheses that cannot be observed from ].<ref name="Rashed2007" /> | |||
| In his ''Aporias against Ptolemy'', Ibn al-Haytham commented on the difficulty of attaining scientific knowledge: | |||
| {{quote|Truth is sought for itself the truths, are immersed in uncertainties not immune from error...<ref name=Sabra>] (2003). , '']'', October-December 2003.</ref>}} | |||
| He held that the criticism of existing theories—which dominated this book—holds a special place in the growth of scientific knowledge: | |||
| {{quote|Therefore, the seeker after the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and deficiency. Thus the duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.<ref name=Sabra/>}} | |||
| ===Birunian and Avicennian methods=== | |||
| {{See also|Abū Rayhān al-Bīrūnī|Avicennism}} | |||
| ] (973-1048) also introduced an early scientific method in nearly every field of ] he studied. For example, in his treatise on ], ''Kitab al-Jamahir'' (''Book of Precious Stones''), Al-Biruni is "the most ] of ]al scientists", while in the introduction to his ], he declares that "to execute our project, it has not been possible to follow the geometric method" and develops ] as a scientific method in the field.<ref name=Sardar>{{citation|first=Ziauddin|last=Sardar|author-link=Ziauddin Sardar|year=1998|contribution=Science in Islamic philosophy|title=Islamic Philosophy|publisher=]|url=http://www.muslimphilosophy.com/ip/rep/H016.htm|accessdate=2008-02-03}}</ref> He was also responsible for introducing the experimental method into ],<ref name=Rozhanskaya-642/> and was one of the first to conduct elaborate experiments related to ] phenomena.<ref name=Zahoor>Dr. A. Zahoor (1997), , ].{{Self-published inline|date=December 2009}}</ref> | |||
| Al-Biruni's scientific method was similar to the modern scientific method in many ways, particularly his emphasis on repeated experimentation. Biruni was concerned with how to conceptualize and prevent both ]s and ], such as "errors caused by the use of small instruments and errors made by human observers." He argued that if instruments produce random errors because of their imperfections or idiosyncratic qualities, then multiple observations must be taken, ], and on this basis, arrive at a "common-sense single value for the constant sought", whether an ] or a "reliable ]."<ref>{{Harv|Glick|Livesey|Wallis|2005|pp=89–90}}</ref> He also introduced the method of ] during ]s.<ref name=Rozhanskaya/> | |||
| In the ''Al-Burhan'' (''On Demonstration'') section of the '']'' (1027), ] discussed the ] and described an early scientific method of ]. He discusses ]'s '']'' and significantly diverged from it on several points. Avicenna discussed the issue of a proper methodology for scientific inquiry and the question of "How does one acquire the first principles of a science?" He asked how a scientist would arrive at "the initial ]s or ] of a ] science without inferring them from some more basic premises?" He explains that the ideal situation is when one grasps that a "relation holds between the terms, which would allow for absolute, universal certainty." Avicenna then adds two further methods for arriving at the ]s: the ancient ] method of ] (''istiqra''), and the method of ] and ]ation (''tajriba''). Avicenna criticized Aristotelian induction, arguing that "it does not lead to the absolute, universal, and certain premises that it purports to provide." In its place, he develops "a method of experimentation as a means for scientific inquiry."<ref>{{citation|last=McGinnis|first=Jon|title=Scientific Methodologies in Medieval Islam|journal=Journal of the History of Philosophy|volume=41|issue=3|date=July 2003|pages=307–327|doi=10.1353/hph.2003.0033}}</ref> | |||
| In comparison to Avicenna's scientific method where "general and universal questions came first and led to ]al work", al-Biruni developed scientific methods where "universals came out of practical, experimental work" and "theories are formulated after discoveries", like with ].<ref name=Sardar/> Due to differences between their scientific methods, al-Biruni referred to himself as a mathematical ] and to Avicenna as a ], during a debate between the two scholars.<ref name=Dallal>{{citation|first=Ahmad|last=Dallal|year=2001-2002|title=The Interplay of Science and Theology in the Fourteenth-century Kalam|publisher=From Medieval to Modern in the Islamic World, Sawyer Seminar at the ] |url=http://humanities.uchicago.edu/orgs/institute/sawyer/archive/islam/dallal.html |accessdate=2008-02-02}}</ref> | |||
| ==Optics== | |||
| ===Geometrical optics=== | |||
| In the ], ] (c. 801–873) was one of the earliest important writers on ] in the Islamic world. In a work known in the west as ''De radiis stellarum'', al-Kindi developed a theory "that everything in the world ... emits rays in every direction, which fill the whole world."<ref>D. C. Lindberg (1976), ''Theories of Vision from al-Kindi to Kepler'', Chicago: Univ. of Chicago Pr., p. 19</ref> | |||
| ]'s manuscript showing his discovery of the law of ] (]).]] | |||
| ] (c. 940-1000), a mathematician and physicist connected with the court of ], wrote a treatise ''On Burning Mirrors and Lenses'' in 984 in which he set out his understanding of how ]s and ]es bend and focus ]. Ibn Sahl is credited with discovering the law of ], now usually called ].<ref>K. B. Wolf, "Geometry and dynamics in refracting systems", ''European Journal of Physics'' '''16''', p. 14-20, 1995.</ref><ref name=rashed90>R. Rashed, "A pioneer in anaclastics: Ibn Sahl on burning mirrors and lenses", '']'' '''81''', p. 464–491, 1990.</ref> He used this law to work out the shapes of lenses that focus light with no geometric aberrations, known as ]es. | |||
| ===Beginning of physical optics=== | |||
| {{Main|Book of Optics}} | |||
| ] (known in ] as ''Alhacen'' or ''Alhazen'') (]-]), often regarded as the "father of optics"<ref name=Verma>R. L. Verma, "Al-Hazen: father of modern optics", ''Al-Arabi'', 8 (1969): 12-13</ref> and a pioneer of the ], formulated "the first comprehensive and systematic alternative to Greek optical theories."<ref>D. C. Lindberg, "Alhazen's Theory of Vision and its Reception in the West", ''Isis'', 58 (1967), p. 322.</ref> His key achievement was twofold: first, to insist that vision only occurred because of rays entering the eye and that rays postulated to proceed from the eye had nothing to do with it; the second was to define the physical nature of the rays discussed by earlier geometrical optical writers, considering them as the forms of light and color. This now forms the basis of modern ]. He developed a ] to demonstrate that light and color from different candles can be passed through a single aperture in straight lines, without intermingling at the aperture.<ref>David C. Lindberg, "The Theory of Pinhole Images from Antiquity to the Thirteenth Century," ''Archive for History of the Exact Sciences'', 5(1968):154-176.</ref> He then analyzed these physical rays according to the principles of ]. Ibn al-Haytham also employed the ]al ] as a form of demonstration in ]. He wrote many books on optics, most significantly the '']'' (''Kitab al Manazir'' in ]), translated into ] as the ''De aspectibus'' or ''Perspectiva'', which disseminated his ideas to Western Europe and had great influence on the later developments of optics.<ref>D. C. Lindberg, ''Theories of Vision from al-Kindi to Kepler'', (Chicago: Univ. of Chicago Pr., 1976), pp. 58-86.</ref> | |||
| ] (Alhazen) developed the ] and ] for his experiments on ] and ].]] | |||
| ] (Alhazen) (965-1039), in his broad theory of ] and ] in his '']'', explained ], using ] and ], and stated that each point on an illuminated area or object radiates ] rays in every direction, but that only one ray from each point, which strikes the eye perpendicularly, can be seen. The other rays strike at different angles and are not seen. He used the example of the ] and ], which produces an inverted image, to support his argument. This contradicted Ptolemy's theory of vision that objects are seen by rays of light emanating from the eyes. Alhacen held light rays to be streams of minute ]<ref>{{Harvnb|Rashed|2007}}: {{quote|In his optics "the smallest parts of light", as he calls them, retain only properties that can be treated by geometry and verified by experiment; they lack all sensible qualities except energy.}}</ref> travelling in straight lines<ref>J. J. O'Connor and E. F. Robertson (2002). , '']''.</ref> at a ].<ref>{{citation|title=Scientific Method, Statistical Method and the Speed of Light|first1=R. J.|last1=MacKay|first2=R. W.|last2=Oldford|journal=Statistical Science|volume=15|issue=3|date=August 2000|pages=254–78|doi=10.1214/ss/1009212817}}</ref><ref name=Hamarneh>Sami Hamarneh (March 1972). Review of Hakim Mohammed Said, ''Ibn al-Haitham'', '']'' '''63''' (1), p. 119</ref> He also speculated on the ] and ] aspects of light,<ref name=Hamarneh/> and discovered that the speed of light is variable, with its speed decreasing in denser bodies.<ref>{{MacTutor|id=Al-Haytham|title=Abu Ali al-Hasan ibn al-Haytham}}</ref> In order to establish that light travels in time and with finite speed, he undertook an ] with a ] and stated: “If the hole was covered with a curtain and the curtain was taken off, the light traveling from the hole to the opposite wall will consume time.” He also accurately described the ], and discovered the laws of ]. | |||
| Alhazen also carried out experiments on the dispersion of light into its constituent colours. His major work ''Kitab al-Manazir'' was translated into ] in the ], as well as his book dealing with the colors of sunset. He dealt at length with the theory of various physical phenomena like ]s, ]s, and the ]. He also attempted to explain ] and the ]. Through these extensive researches on optics, he is considered the pioneer of modern ]. Ibn al-Haytham also correctly argued that we see objects because the sun's rays of light, which he believed to be streams of tiny particles traveling in straight lines, are reflected from objects into our eyes. He understood that light must travel at a large but finite velocity, and that refraction is caused by the velocity being different in different substances. He also studied spherical and parabolic mirrors, and understood how refraction by a lens will allow images to be focused and magnification to take place. He understood mathematically why a spherical mirror produces aberration. His '']'' has been ranked alongside ]'s '']'' as one of the most influential books in the ],<ref>H. Salih, M. Al-Amri, M. El Gomati (2005). "The Miracle of Light", ''A World of Science'' '''3''' (3). ].</ref> for initiating a ] in ]<ref>{{citation|last1=Sabra|first1=A. I.|author1-link=A. I. Sabra|last2=Hogendijk|first2=J. P.|title=The Enterprise of Science in Islam: New Perspectives|pages=85–118|publisher=]|isbn=0262194821|year=2003|oclc=237875424 50252039}}</ref> and ].<ref>{{Citation |last=Hatfield |first=Gary |contribution=Was the Scientific Revolution Really a Revolution in Science? |editor1-last=Ragep |editor1-first=F. J. |editor2-last=Ragep |editor2-first=Sally P. |editor3-last=Livesey |editor3-first=Steven John |year=1996 |title=Tradition, Transmission, Transformation: Proceedings of Two Conferences on Pre-modern Science held at the University of Oklahoma |page=500 |publisher=] |isbn=9004091262 |oclc=19740432 234073624 234096934}}</ref> | |||
| Robert S. Elliot wrote the following on ] (Alhacen): | |||
| {{quote|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 ], notably that of Roger Bacon and Kepler. This treatise discussed concave and convex mirrors in both ] and ] geometries, anticipated ], 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.<ref>R. S. Elliott (1966). ''Electromagnetics'', Chapter 1. ].</ref>}} | |||
| The ''Book of Optics'' established experimentation as the norm of proof in optics,<ref name=Gorini/> and gave optics a physico-mathematical conception at a much earlier date than the other mathematical disciplines of ] and ].<ref>{{Citation | last=Dijksterhuis | first=Fokko Jan | year=2004 | title=Lenses and Waves: Christiaan Huygens and the Mathematical Science of Optics in the Seventeenth Century | publisher=] | isbn=1402026978 | pages=113–5 | oclc=228400027 56533625}}: {{quote|Through the influential work of Alhacen the onset of a physico-mathematical conception of optics was established at a much earlier time than would be the case in the other mathematical sciences.}}</ref> The book was influential in both the Islamic world and in Western Europe. | |||
| ===Beginning of physiological optics=== | |||
| {{Main|Book of Optics}} | |||
| ] discussed the topics of ] and ] in the ] and ] portions of the ''Book of Optics'' and in his commentaries on ]ic works.<ref>Steffens (])</ref> He accurately described the process of sight,<ref>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 . ]</ref> the structure of the ], ] formation in the eye and the ]. He also discovered the underlying principles of ], vertical ]s and ],<ref name=Howard>{{Citation | author=Ian P. Howard | year=1996 | title=Alhazen's neglected discoveries of visual phenomena | journal=Perception | volume=25 | issue=10 | pages=1203–1217 | doi=10.1068/p251203 | pmid=9027923 | postscript=.}}</ref> and improved on the theories of ], ] and horopters previously discussed by ], ] and ] ({{Harvnb|Wade|1998}}{{Page number|date=May 2010}}, {{Harvnb|Howard|Wade|1996}}{{Page number|date=May 2010}}). | |||
| He discussed ocular anatomy, dealing with the "descriptive anatomy" and "functional anatomy" of the eye independently.<ref name="Russell1996-689">{{Harvnb|Russell|1996|p=689}}</ref> Much of his decriptive anatomy was faithful to Galen's ], but with significant differences in his approach {{Harv|Russell|1996|pp=689–90}}. For example, the whole area of the eye behind the ] constitutes what Ibn al-Haytham uniquely called the '']l sphere'', and his description of the eye was devoid of any ] or ] theories associated with Galenic anatomy {{Harv|Russell|1996|p=690}}. He also described the eye as being made up of two interesecting globes, which was essential to his functional anatomy of the eye {{Harv|Russell|1996|p=692}}. | |||
| After describing the construction of the eye, Ibn al-Haytham makes his most original anatomical contribution in describing the functional anatomy of the eye as an optical system {{Harv|Russell|1996|p=691}}, or optical instrument. His mulitple light-source experiment via a reduction slit with the ], also known as the lamp experiment, provided sufficient ] grounds for him to develop his theory of corresponding point projection of light from the surface of an object to form an image on a screen. It was his comparison between the eye and the beam-chamber, or ''camera obscura'', which brought about his synthesis of anatomy and optics, giving rise to a new field of optics now known as "physiological optics". As he conceptualized the essential principles of pinhole projection from his experiments with the ], he considered image inversion to also occur in the eye,<ref name="Russell1996-689" /> and viewed the ] as being similar to an ] {{Harv|Russell|1996|pp=695–8}}. Regarding the process of image formation, however, he incorrectly agreed with ] that the ] was the receptive organ of sight, but correctly hinted at the ] also being involved in the process {{Harv|Wade|1998}}{{Page number|date=May 2010}}. | |||
| ===Rainbow phenomenon=== | |||
| ] (Alhazen; 965-1039), attempted to provide a scientific explanation for the ] phenomenon. In his ''Maqala fi al-Hala wa Qaws Quzah'' (''On the Rainbow and Halo''), he "explained the formation of rainbow as an image, which forms at a concave mirror. If the rays of light coming from a farther light source reflect to any point on axis of the concave mirror, they form concentric circles in that point. When it is supposed that the sun as a farther light source, the eye of viewer as a point on the axis of mirror and a cloud as a reflecting surface, then it can be observed the concentric circles are forming on the axis."<ref name=Topdemir-77>{{citation|first=Hüseyin Gazi|last=Topdemir|title=Kamal Al-Din Al-Farisi’s Explanation of the Rainbow|journal=Humanity & Social Sciences Journal|volume=2|issue=1|pages=75–85 |year=2007|url=http://www.idosi.org/hssj/hssj2(1)07/10.pdf|format=PDF|accessdate=2008-09-16}}</ref> He was not able to verify this because his theory that "light from the sun is reflected by a cloud before reaching the eye" did not allow for a possible ]al verification.<ref name=MacTutor/> This explanation was later repeated by ],<ref name=Topdemir-77/> and, though incorrect, provided the groundwork for the correct explanations later given by ] and ].<ref name=Topdemir-77/> | |||
| Ibn al-Haytham's contemporary, ] (Avicenna; 980-1037), provided an alternative explanation, writing "that the bow is not formed in the dark cloud but rather in the very thin mist lying between the cloud and the sun or observer. The cloud, he thought, serves simply as the background of this thin substance, much as a quicksilver lining is placed upon the rear surface of the glass in a mirror. Ibn Sīnā would change the place not only of the bow, but also of the color formation, holding the iridescence to be merely a subjective sensation in the eye."<ref>] (1954), "Robert Grosseteste on the Rainbow", ''Osiris'' '''11''': 247-258 </ref> This explanation, however, was also incorrect.<ref name=Topdemir-77/> | |||
| ] (1236–1311) gave a fairly accurate explanation for the rainbow phenomenon. This was elaborated on by his student, ] (1260–1320), who gave a more mathematically satisfactory explanation of the rainbow. He "proposed a model where the ray of light from the sun was refracted twice by a water droplet, one or more reflections occurring between the two refractions." He verified this through extensive experimentation using a transparent sphere filled with water and a ].<ref name=MacTutor>{{cite web | |||
| | author=O'Connor, J. J.; Robertson, E. F. | month=November | year=1999 | |||
| | url=http://www-gap.dcs.st-and.ac.uk/~history/Biographies/Al-Farisi.html | |||
| | title=Kamal al-Din Abu'l Hasan Muhammad Al-Farisi | |||
| | publisher=], University of St Andrews | accessdate=2007-06-07 }}</ref> As he noted in his ''Kitab Tanqih al-Manazir'' (''The Revision of The Optics''), al-Farisi used a large clear vessel of glass in the shape of a sphere, which was filled with water, in order to have an experimental large-scale model of a rain drop. He then placed this model within a camera obscura that has a controlled ] for the introduction of light. He projected light unto the sphere and ultimately deducted through several trials and detailed observations of reflections and refractions of light that the colors of the rainbow are phenomena of the decomposition of light. His research had resonances with the studies of his contemporary ] (without any contacts between them; even though they both relied on Ibn al-Haytham's legacy), and later with the experiments of ] and ] in dioptrics (for instance, Newton conducted a similar experiment at Trinity College, though using a prism rather than a sphere).<ref name="Bizri2005-237"/><ref>Nader El-Bizri, "Optics", in ''Medieval Islamic Civilization: An Encyclopedia'', ed. Josef W. Meri (New York – London: Routledge, 2005), Vol. II, pp. 578-580</ref><ref>Nader El-Bizri, "Al-Farisi, Kamal al-Din," in ''The Biographical Encyclopaedia of Islamic Philosophy'', ed. Oliver Leaman (London — New York: Thoemmes Continuum, 2006), Vol. I, pp. 131-135</ref><ref>Nader El-Bizri, "Ibn al-Haytham, al-Hasan", in ''The Biographical Encyclopaedia of Islamic Philosophy'', ed. Oliver Leaman (London — New York: Thoemmes Continuum, 2006), Vol. I, pp. 248-255.</ref> | |||
| ===Later Islamic optics=== | |||
| ] (980-1037) agreed that the ] is finite, as he "observed that if the perception of light is due to the emission of some sort of particles by a luminous source, the speed of light must be finite."<ref>], ''Introduction to the History of Science'', Vol. 1, p. 710.</ref> ] (973-1048) also agreed that light has a finite speed, and he stated that the speed of light is immensely faster than the ].<ref name=Biruni/> | |||
| Abu 'Abd Allah Muhammad ibn Ma'udh, who lived in ] during the second half of the 11th century, wrote a work on optics later translated into Latin as ''Liber de crepisculis'', which was mistakenly attributed to Alhazen. This was a "short work containing an estimation of the angle of depression of the sun at the beginning of the morning ] and at the end of the evening twilight, and an attempt to calculate on the basis of this and other data the height of the atmospheric moisture responsible for the refraction of the sun's rays." Through his experiments, he obtained the accurate value of 18°, which comes close to the modern value.<ref>{{citation|title=The Authorship of the Liber de crepusculis, an Eleventh-Century Work on Atmospheric Refraction|first==A. I.|last=Sabra|author-link=A. I. Sabra|journal=]|volume=58|issue=1|date=Spring 1967|pages=77–85 |doi=10.1086/350185}}</ref> | |||
| {{Unreferenced section|date=June 2010}} | |||
| In 1574, ] (1526–1585) wrote the last major Arabic work on optics, entitled ''Kitab Nūr hadaqat al-ibsār wa-nūr haqīqat al-anzār'' (''Book of the Light of the Pupil of Vision and the Light of the Truth of the Sights''), which contains ]al investigations in three volumes on ], the ]'s ], and the light's ].{{Citation needed|date=May 2010}} The book deals with the structure of light, its ] and global refraction, and the relation between light and ]. In the first volume, He discusses "the nature of light, the source of light, the nature of the propagation of light, the formation of sight, and the effect of light on the eye and sight". He also provides the first satisfactory explanation for the formation of ] in the Islamic world, clearly stating that colour is formed as a result of reflection and refraction of light, two centuries before ] discussed the formation of colour. Like his predecessors Ibn al-Haytham and al-Farisi, Taqi al-Din also supported the intromission model of vision, where light is reflected from objects into the eyes. Whereas his predecessors constructed instruments such as the ] and ] to demonstrate this, Taqi al-Din instead used a simpler example from ] to demonstrate it. He stated that if the ray of light had come from the eye, it would take too long to see the ]s, which are millions of kilometres away from the ]. He then states that since the ] is constant, "it would take too long for it to travel to the star and come back to the eye. But this is not the case, since we see the star as soon as we open our eyes. Therefore the light must emerge from the object not from the eyes. In the second volume,Taqi al-Din provides "experimental proof of the ] of accidental as well as essential light, a complete formulation of the laws of reflection, and a description of the construction and use of a copper instrument for measuring reflections from ], ], and conical ]s, whether convex or concave." The third volume analyzes "the important question of the variations light undergoes while travelling in ] having different ], i.e. the nature of refracted light, the formation of refraction, the nature of images formed by refracted light." He also came very close to formulating ] of sines, though he did not find the exact constant ratio between the sine of incidences and refraction angles. | |||
| There is also a description of what sounds like an early rudimentary ], which he describes: | |||
| {{quote|"I made a crystal (''billawr'') that has two ]es displaying in details the objects from long distances. When they look from one of its edges, people can see the sail of the ship in far."}} | |||
| Taqi al-Din states that he wrote another treatise explaining the way this instrument is made and used but the treatise has not survived to the present day. | |||
| ==Experimental mechanics== | |||
| ] was a ] who introduced the ]al ] to ], unified ] and ] into the science of mechanics, and combined the fields of ] with dynamics to create ].{{Citation needed|date=May 2010}}]] | |||
| ===Statics and dynamics=== | |||
| ] (872-950) {{Reference necessary|carried out an early ] concerning the existence of ],|date=April 2010}} in which he investigated handheld plungers in water. He concluded that air's volume can expand to fill available space, and he suggested that the concept of perfect vacuum was incoherent.<ref>, '']''</ref>{{Failed verification|date=April 2010}} However, ] (Alhazen, 965-1039) and the ] ] disagreed with ] and Al-Farabi, and they supported the existence of a void. Using ], Ibn al-Haytham ] demonstrated that place (''al-makan'') is the imagined three-dimensional void between the inner surfaces of a containing body.<ref>{{Citation |last=El-Bizri |first=Nader |year=2007 |title=In Defence of the Sovereignty of Philosophy: Al-Baghdadi's Critique of Ibn al-Haytham's Geometrisation of Place |journal=Arabic Sciences and Philosophy |volume=17 |pages=57–80 |publisher=] |doi=10.1017/S0957423907000367 }}</ref> ] also states that there is no observable evidence that rules out the possibility of a vacuum.<ref name=Dallal/> | |||
| Some of the earliest experiments in ] are described in ]'s '']'' (1021). He used his results to explain certain optical phenomena using mechanical analogies. He conducted experiments with ]s, and concluded that "it was only the impact of ] projectiles on surfaces which was forceful enough to enable them to penetrate whereas the ] ones were deflected. For example, to explain refraction from a rare to a dense medium, he used the mechanical analogy of an iron ball thrown at a thin slate covering a wide hole in a metal sheet. A perpendicular throw would break the slate and pass through, whereas an oblique one with equal force and from an equal distance would not." He used this result to explain explained how intense direct light hurts the eye: "Applying mechanical analogies to the effect of light rays on the eye, lbn al-Haytham associated 'strong' lights with perpendicular rays and 'weak' lights with oblique ones. The obvious answer to the problem of multiple rays and the eye was in the choice of the perpendicular ray since there could only be one such ray from each point on the surface of the object which could penetrate the eye."{{Harv|Russell|1996|p=695}} | |||
| ] (973-1048), and later ] (] 1115-1130), applied experimental ]s to ], especially the fields of ] and ], particularly for determining ]s, such as those based on the theory of ] and ]. Muslim physicists unified statics and dynamics into the science of mechanics, and they combined the fields of ] with dynamics to give birth to ]. They applied the mathematical theories of ]s and ] techniques, and introduced ]ic and fine ] techniques into the field of statics. They were also generalized the theory of the ] and applied it to ] bodies. They also founded the theory of the ] ] and created the "science of ]" which was later further developed in medieval Europe.<ref name=Rozhanskaya-642>{{Harvnb|Rozhanskaya|1996|p=642}}: | |||
| {{quote|Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic approach so that two trends - statics and dynamics - turned out to be inter-related within a single science, mechanics.}} | |||
| {{quote|The combination of the dynamic approach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics.}} | |||
| {{quote|Archimedean statics formed the basis for creating the fundamentals of the science on specific weight. Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science.}} | |||
| {{quote|Arabic statics was an essential link in the progress of world science. It played an important part in the prehistory of classical mechanics in medieval Europe. Without it classical mechanics proper could probably not have been created.}}</ref> | |||
| In ], al-Biruni measured the ] of eighteen ]s, and discovered that there is a correlation between the specific gravity of an object and the ] of water it displaces.{{Citation needed|date=May 2010}} He also introduced the method of ] during ]s, measured the ]s of various liquids, and recorded the differences in weight between ] and ], and between hot and cold water.<ref name=Rozhanskaya>{{Harvnb|Rozhanskaya|1996|pp=638–9}}</ref> During his ]s on mechanics, al-Biruni invented the ],<ref name="Marshall Clagett 1961 p. 64">Marshall Clagett (1961). ''The Science of Mechanics in the Middle Ages'', p. 64. ].</ref> in order to find the ratio between the ] of a substance in air and the weight of water displaced, and to accurately measure the specific weights of the gemstones and their corresponding ]s, which are very close to modern measurements.<ref name=Rozhanskaya/> Al-Biruni also realized that ] is connected with non-uniform motion, which is part of ].<ref name=Biruni/> | |||
| In 1121, ], in ''The Book of the Balance of Wisdom'', invented a ]<ref>Robert E. Hall (1973), "Al-Biruni", '']'', Vol. VII, p. 336</ref> and proposed that the ] or ] of a body varies depending on its distance from the “centre of the Universe” {{Harv|Rozhanskaya|1996|p=621}}. In ], al-Khazini showed awareness of the weight of the air and of its decrease in ] with ], and discovered that there was greater density of water when nearer to the Earth's centre.{{Citation needed|date=May 2010}} | |||
| The ] was invented in 1206 by the ] and ], ]. The suction pump later appeared in Europe from the 15th century.<ref name=Hill2/><ref name=Hassan-Pump/> ]'s six-cylinder 'Monobloc' pump, invented in 1551, could also create a partial ], which was formed "as the lead weight moves upwards, it pulls the piston with it, creating vacuum which sucks the water through a non return clack valve into the piston ]."<ref name=Machines>{{cite web|author=]|title=The Machines of Al-Jazari and Taqi Al-Din|url=http://www.muslimheritage.com/topics/default.cfm?ArticleID=466|publisher=22nd Annual Conference on the History of Arabic Sciences|date=23–25 October 2001|accessdate=2008-07-16}}</ref> | |||
| The measurement of ] appears in an Arabic military treatise dating back to the early 14th century. The viscosity (''qawam'') of ] oils is gauged by the number of "words", ranging from ten and thirty "words" for various oils. This is similar to the modern method, where viscosity is gauged by the number of seconds needed for a certain volume of oil to fall through a ].<ref>{{citation|last=]|title=Chemical Technology in Arabic Military Treatises|journal=Annals of the New York Academy of Sciences|publisher=]|year=1987|pages=153–166 }}</ref> | |||
| ===Aerodynamics=== | |||
| In ], ] (Armen Firman, 810-887) invented a primitive version of the ].<ref name=Poore>Poore, Daniel. A History of Early Flight. New York: Alfred Knopf, 1952.</ref><ref name=Smithsonian>Smithsonian Institution. Manned Flight. Pamphlet 1990.</ref><ref>David W. Tschanz, , '']''. | |||
| </ref><ref>, ''Principles of Aeronautics'', ].</ref> John H. Lienhard described it in ''The Engines of Our Ingenuity'' as follows: "In 852, a new Caliph and a bizarre experiment: A daredevil named Armen Firman decided to fly off a tower in Cordova. He glided back to earth, using a huge winglike cloak to break his fall."<ref>{{cite episode |title='Abbas Ibn Firnas |credits=John H. Lienhard |series=The Engines of Our Ingenuity |serieslink=The Engines of Our Ingenuity |network=NPR |station=KUHF-FM Houston |airdate=2004 |number=1910 |transcripturl=http://www.uh.edu/engines/epi1910.htm}}</ref> | |||
| Abbas Ibn Firnas made an attempt at ] in a ] in 875, as opposed to earlier manned ] flights in ancient China which were not controllable. Ibn Firnas manuipulated the ] of his hang glider using two sets of artificial ]s to adjust his ] and to change his direction. He successfully returned to where he had lifted off from, but his ] was unsuccessful.<ref name=White>] (Spring, 1961). "Eilmer of Malmesbury, an Eleventh Century Aviator: A Case Study of Technological Innovation, Its Context and Tradition", ''Technology and Culture'' '''2''' (2): 97-111 </ref><ref>, '']'', January-February 1964, p. 8-9.</ref> Ibn Firnas' ] flight is considered the first attempt at ] flight in ].<ref>{{citation|title=Flying's strangest moments: extraordinary but true stories from over one thousand years of aviation history|first=John|last=Harding|publisher=Robson|year=2006|isbn=1861059345|pages=1–2}}</ref> According to ] in '']'': "Ibn Firnas was the first man in history to make a scientific attempt at flying."<ref>], '']''</ref> It may have inspired two later attempts at flight: one by ] who died in either 1003 or 1008 while attempting to fly using two wooden wings with a rope from the roof of a mosque in ], ], ], and the other by ] between 1000 and 1010 in ].<ref name="White"/> | |||
| According to ] in the 17th century, the ] aviator ] made a successful glider flight with artificial wings between 1630-1632.<ref name="Evliyâ Çelebi">Çelebi, Evliya (2003). ''Seyahatname''. Istanbul: Yapı Kredi Kültür Sanat Yayıncılık, p. 318.</ref> Also according to Evliya, ] in 1633 took off with what was described as a cone-shaped ], ] with wings through the ] from ], and made a successful landing, winning him a position in the ].<ref>Winter, Frank H. (1992). "Who First Flew in a Rocket?", Journal of the British Interplanetary Society 45 (July 1992), p. 275-80</ref> The device was reported to have been a seven-pronged rocket powered by ].<ref>{{citation|title=Flying's strangest moments: extraordinary but true stories from over one thousand years of aviation history|first=John|last=Harding|publisher=]|year=2006|isbn=1861059345|page=5}}</ref> | |||
| ==Theoretical physics== | |||
| ===Theory of impetus=== | |||
| {{See also|Theory of impetus|Avicennism#Avicennian physics|l2=Avicennian physics}} | |||
| ] (980-1037), in '']'', developed an elaborate theory of motion, in which he made a distinction between the ] and ] of a ], and concluded that motion was a result of an inclination (''mayl'') transferred to the projectile by the thrower, and that ] in a vacuum would not cease.<ref name=Espinoza>Fernando Espinoza (2005). "An analysis of the historical development of ideas about motion and its implications for teaching", ''Physics Education'' '''40''' (2), p. 141</ref> This was the first alternative to the Aristotelian theory.<ref name=Sayili/> In the ] theory of motion, the violent inclination he conceived was non-self-consuming, a permanent force whose effect was dissipated only as a result of external agents such as air resistance,<ref name=Espinoza/><ref name=Sayili/> making him "the first to conceive such a permanent type of impressed virtue for non-natural motion." Such a self-motion (''mayl'') is "almost the opposite of the Aristotelian conception of violent motion of the projectile type, and it is rather reminiscent of the principle of ], i.e., ]."<ref>{{Harvnb|Sayılı|1987|p=477}}: {{quote|Ibn Sina adopted this idea in its rough outline, but the violent inclination as he conceived it was a non-self-consuming one. It was a permanent force whose effect got dissipated only as a result of external agents such as air resistance. He is apparently the first to conceive such a permanent type of impressed virtue for non-natural motion. Indeed, self-motion of the type conceived by Ibn Sina is almost the opposite of the Aristotelian conception of violent motion of the projectile type, and it is rather reminiscent of the principle of inertia, i.e., Newton's first law of motion.}}</ref> His theory of ''mayl'' also attempted to provide a quantitive relation between the ] and ] of a moving body, resembling the concept of ].<ref name=Razavi>{{citation|title=The Islamic intellectual tradition in Persia|author= Seyyed ] & Mehdi Amin Razavi|publisher=]|year=1996|isbn=0700703144|page=72}}</ref> for which he is considered a pioneer of the concept of momentum.<ref>{{cite encyclopedia |last= Nasr |first= Seyyed Hossein |authorlink= Hossein Nasr |editor= Philip P. Wiener |encyclopedia= Dictionary of the History of Ideas |title= Islamic Conception Of Intellectual Life |url= |accessdate= |edition= |year= 1973 |publisher= ] |volume= 2 |location= New York |id= |isbn= 9780684132938 |oclc= |doi= |pages= 65 |ref= }}</ref><ref name="Razavi"/> His theory of motion was reminiscent of the concept of ] in ], and later formed the basis of ]'s ] and exerted an influence on the work of ].<ref name=Sayili>{{Harvnb|Sayılı|1987}}{{Page number|date=May 2010}}</ref> | |||
| ] (1080–1165) wrote a critique of ] entitled ''al-Mu'tabar'', where he negated ]'s idea that a constant ] produces uniform motion, as he realized that a force applied continuously produces ], considered "the fundamental law of ]" and an early foreshadowing of ].<ref>{{cite encyclopedia | |||
| | last = ] | |||
| | title = Abu'l-Barakāt al-Baghdādī , Hibat Allah | |||
| | encyclopedia = ] | |||
| | volume = 1 | |||
| | pages = 26–28 | |||
| | publisher = Charles Scribner's Sons | |||
| | location = New York | |||
| | year = 1970 | |||
| | isbn = 0684101149 | |||
| }} | |||
| <br>(] Abel B. Franco (October 2003). "Avempace, Projectile Motion, and Impetus Theory", ''Journal of the History of Ideas'' '''64''' (4), p. 521-546 .)</ref> He also described acceleration as the rate of change of ].<ref>A. C. Crombie, ''Augustine to Galileo 2'', p. 67.</ref> The 14th-century philosophers ] and ] later refer to Abu'l-Barakat in explaining that the acceleration of a falling body is a result of its increasing ]. Abu'l-Barakat also modified ]'s view on ], and stated that the mover imparts a violent inclination (''mayl qasri'') on the moved and that this diminishes as the moving object distances itself from the mover.<ref>{{citation|title=Pseudo-Avicenna, Liber Celi Et Mundi: A Critical Edition|first=Oliver|last=Gutman|publisher=]|year=2003|isbn=9004132287|page=193}}</ref> Abu'l-Barakat also suggested that motion is ], writing that "there is motion only if the relative positions of the bodies in question change."<ref name=Langermann>{{citation|first=Y. Tzvi|last=Langermann|year=1998|contribution=al-Baghdadi, Abu 'l-Barakat (fl. c.1200-50)|title=Islamic Philosophy|publisher=]|url=http://www.muslimphilosophy.com/ip/rep/J008.htm|accessdate=2008-02-03}}</ref> | |||
| ===Biruni versus Avicenna debate=== | |||
| {{See also|Early Islamic philosophy}} | |||
| ] and ] (Ibn Sina), who are regarded as two of the greatest ]s in ], were both colleagues and knew each other since the turn of the millennium. Biruni later engaged in a written ] with Avicenna, with Biruni criticizing the ] for its adherence to ] and ], while Avicenna and his student Ahmad ibn 'Ali al-Ma'sumi respond to Biruni's criticisms in writing.<ref name=Berjak/> | |||
| This debate has been preserved in a book entitled ''al-As'ila wal-Ajwiba'' (''Questions and Answers''), in which al-Biruni attacks Aristotle's theories on ] and ], and questions almost all of the fundamental ] physical ]s. For example, he rejects the notion that ] have an ] and asserts that their "motion could very well be compulsory"; maintains that "there is no observable ] that rules out the possibility of ]"; and states that there is no inherent reason why planetary ]s must be ] and cannot be ]. He also argues that "the ] axioms on which ] build their physical theories do not constitute valid evidence for the mathematical astronomer." This marks the first real distinction between the ]s of the ]-metaphysician (which he labelled Aristotle and Avicenna as) and that of the ]-] (which al-Biruni viewed himself as). In contrast to the philosophers, the only evidence that al-Biruni considered reliable were either mathematical or ], and his systematic application of rigorous mathematical reasoning later led to the mathematization of ] and the mathematization of ].<ref name=Dallal/> | |||
| Biruni began the debate by asking Avicenna eighteen questions, ten of which were criticisms of ]'s '']'', with his first question criticizing the ] for denying the existence of ] or ] in the ]s, and the Aristotelian notion of ] being an ] of the heavenly bodies.<ref name=Berjak>{{Citation|last= Nasr |first= Seyyed Hossein |authorlink= Hossein Nasr |last2= Mohaghegh |first2= Mehdi |authorlink2= Mehdi Mohaghegh |coauthors= Rafik Berjak and ], translators |year= 1995 |title= Al-As'ilah wa'l-Ajwibah |trans_title= Questions and Answers |journal= Islam & Science |series= Ibn Sina--Al-Biruni correspondence |issue= June 2003 |at= part 1/8 |publisher= International Institute of Islamic Thought |location= Kuala Lumpur |issn= |doi= |bibcode= |oclc= |id= |url= http://www.thefreelibrary.com/IBN+Sina--Al-Biruni+correspondence.-a0119627460 |accessdate= 2010-05-08|postscript= . }}</ref> Biruni's second question criticizes Aristotle's over-reliance on more ancient views concerning the ]s, while the third criticizes the Aristotelian view that ] has only six directions. The fourth question deals with the continuity and discontinuity of ], while the fifth criticizes the Peripatetic denial of the possibility of there existing another ] completely different from the world known to them.<ref>{{Citation|last= Nasr |first= Seyyed Hossein |authorlink= Hossein Nasr |last2= Mohaghegh |first2= Mehdi |authorlink2= Mehdi Mohaghegh |coauthors= Rafik Berjak and ], translators |year= 1995 |title= Al-As'ilah wa'l-Ajwibah |trans_title= Questions and Answers |journal= Islam & Science |series= Ibn Sina--Al-Biruni correspondence |issue= December 2003 |at= part 2/8 |publisher= International Institute of Islamic Thought |location= Kuala Lumpur |issn= |doi= |bibcode= |oclc= |id= |url= http://www.thefreelibrary.com/IBN+Sina--Al-Biruni+correspondence.-a0119627460 |language= |accessdate= 2010-05-08|postscript= . }}</ref> | |||
| In his sixth question, Biruni rejects Aristotle's view on the ]s having ]s rather than ]s. In his seventh question, he rejects Aristotle's notion that the motion of the heavens begins from the right side and from the ], while his eighth question concerns Aristotle's view on the ] being ]. The ninth question concerns the movement of ], and the tenth question concerns the transformation of ]s.<ref>{{Citation|last= Nasr |first= Seyyed Hossein |authorlink= Hossein Nasr |last2= Mohaghegh |first2= Mehdi |authorlink2= Mehdi Mohaghegh |coauthors= Rafik Berjak and ], translators |year= 1995 |title= Al-As'ilah wa'l-Ajwibah |trans_title= Questions and Answers |journal= Islam & Science |series= Ibn Sina--Al-Biruni correspondence |issue= June 2004 |at= part 3/8 |publisher= International Institute of Islamic Thought |location= Kuala Lumpur |issn= |doi= |bibcode= |oclc= |id= |url= http://www.thefreelibrary.com/IBN+Sina--Al-Biruni+correspondence.-a0119627460 |language= |accessdate= 2010-05-08|postscript= . }}</ref> | |||
| The eleventh question concerns the burning of bodies by ] reflecting off a flask filled with ], and the twelfth concerns the natural tendency of the ]s in their upward and downward movements. The thirteenth question deals with ], while the fourteenth concerns ] on different parts of ]. His fifteenth question asks how two opposite ] in a square divided into four can be ]ial, while the sixteenth question concerns ]. His seventeenth question asks "if things expand upon heating and contract upon cooling, why does a flask filled with water break when water freezes in it?" His eighteenth and final question concerns the observable phenomenon of ] floating on water.<ref>{{Citation|last= Nasr |first= Seyyed Hossein |authorlink= Hossein Nasr |last2= Mohaghegh |first2= Mehdi |authorlink2= Mehdi Mohaghegh |coauthors= Rafik Berjak and ], translators |year= 1995 |title= Al-As'ilah wa'l-Ajwibah |trans_title= Questions and Answers |journal= Islam & Science |series= Ibn Sina--Al-Biruni correspondence |issue= December 2004 |at= part 4/8 |publisher= International Institute of Islamic Thought |location= Kuala Lumpur |issn= |doi= |bibcode= |oclc= |id= |url= http://www.thefreelibrary.com/IBN+Sina--Al-Biruni+correspondence.-a0119627460 |language= |accessdate= 2010-05-08|postscript= . }}</ref> | |||
| After Avicenna responded to the questions, Biruni was unsatisfied with some of the answers and wrote back commenting on them, after which Avicenna's student Ahmad ibn 'Ali al-Ma'sumi wrote back on behalf of Avicenna.<ref name=Berjak/> | |||
| ===Other theories on mechanics=== | |||
| ] (800-873) of the ] hypothesized that ] and ] were subject to the same ] as ], unlike the ancients who believed that the celestial spheres followed their own set of physical laws different from that of Earth.<ref name=Saliba/> In his ''Astral Motion'' and ''The Force of Attraction'', he also hypothesized that there was a ] of ] between ],<ref>K. A. Waheed (1978). ''Islam and The Origins of Modern Science'', p. 27. Islamic Publication Ltd., Lahore.</ref> which ] views as a precursor to ].<ref name=Briffault/> ] (836-901) rejected the ] and ] notions of a "natural place" for each ]. He instead proposed a theory of ] in which both the upward and downward motions are caused by ], and that the order of the universe is a result of two competing ] (''jadhb''): one of these being "between the ] and ] elements", and the other being "between all parts of each element separately".<ref>Mohammed Abattouy (2001). "Greek Mechanics in Arabic Context: Thabit ibn Qurra, al-Isfizarı and the Arabic Traditions of Aristotelian and Euclidean Mechanics", ''Science in Context'' '''14''', p. 205-206. ].</ref> | |||
| ] (965-1039) discussed the theory of ] between ]es, and it seems that he was aware of the ] of ] due to ] and he stated that the heavenly bodies "were accountable to the ]".<ref name=Duhem>{{Harvnb|Duhem|1969|p=28}}</ref> Ibn al-Haytham also enunciated the law of ], later known as ], when he stated that a body moves ] unless an external force stops it or changes its direction of motion.<ref name=Bizri>Dr. ], "Ibn al-Haytham or Alhazen", in Josef W. Meri (2006), ''Medieval Islamic Civilization: An Encyclopaedia'', Vol. II, p. 343-345, ], New York, London.</ref> He also developed the concept of ],<ref>{{Citation|last= Nasr |first= Seyyed Hossein |authorlink= Hossein Nasr |year= 2003 |title= The achievements of Ibn Sina in the field of science and his contributions to its philosophy |journal= Islam & Science |publisher= |location= |issn= |doi= |bibcode= |oclc= |id= |url= http://www.thefreelibrary.com/The+achievements+of+IBN+SINA+in+the+field+of+science+and+his...-a0119627473 |accessdate= 2010-05-08|postscript= . }}</ref> though he did not quantify this concept mathematically. | |||
| ] winning physicist ] wrote the following on ]: | |||
| {{quote|Ibn-al-Haitham (Alhazen, 965-1039 CE) was one of the greatest physicists of all time. He made experimental contributions of the highest order in optics. He enunciated that a ray of light, in passing through a medium, takes the path which is the easier and 'quicker'. In this he was anticipating ] by many centuries. He enunciated the law of inertia, later to become Newton's first law of motion. Part V of ]'s "''Opus Majus''" is practically an annotation to Ibn al Haitham's ''Optics''.<ref name=Salam>] (1984), "Islam and Science". In C. H. Lai (1987), ''Ideals and Realities: Selected Essays of Abdus Salam'', 2nd ed., World Scientific, Singapore, p. 179-213.</ref>}} | |||
| ] (973-1048) appears to be the earliest to cite ] and ] as the cause of ], which in turn produces the ], and a lack of movement as the cause of cold near the ]s: | |||
| {{quote|The earth and the water form one globe, surrounded on all sides by air. Then, since much of the air is in contact with the sphere of the moon, it becomes heated in consequence of the movement and friction of the parts in contact. Thus there is produced fire, which surrounds the air, less in amount in the proximity of the poles owing to the slackening of the movement there.<ref>{{Citation|title= Part 1 - the Historical, Social and Economic Setting |last= Asimov |first= Muchamed Sajfitdinovič |publisher= ] |year= 1999 |series= History of civilizations of Central Asia / ; The age of achievement: A.D. 750 to the end of the fifteenth century |volume= 4 |isbn= 8120815955 |oclc= 247617131 |pages= 211–2 }}</ref>}} | |||
| ] (Avempace) (d. 1138) argued that there is always a ] force for every force exerted, which ] views as "a precursor to the ]ian idea of force" which "underlies ]",<ref>] (1964), "La dynamique d’Ibn Bajja", in ''Mélanges Alexandre Koyré'', I, 442-468 , Paris | |||
| <br>(] Abel B. Franco (October 2003), "Avempace, Projectile Motion, and Impetus Theory", ''Journal of the History of Ideas'' '''64''' (4): 521-546 )</ref> though he did not refer to the reaction force as being equal to the exerted force.<ref>Abel B. Franco (October 2003), "Avempace, Projectile Motion, and Impetus Theory", ''Journal of the History of Ideas'' '''64''' (4):521-546 )</ref> His theory of motion had an important influence on later physicists like Galileo.<ref>Ernest A. Moody (1951), "Galileo and Avempace: The Dynamics of the Leaning Tower Experiment (I)", ''Journal of the History of Ideas'' '''12''' (2): 163-193</ref> | |||
| ] (1126–1198) defined and measured ] as "the rate at which ] is done in changing the ] condition of a material ]"<ref>Ernest A. Moody (June 1951). "Galileo and Avempace: The Dynamics of the Leaning Tower Experiment (II)", ''Journal of the History of Ideas'' '''12''' (3), p. 375-422 .</ref> and correctly argued "that the effect and measure of force is change in the kinetic condition of a materially ] ]."<ref>Ernest A. Moody (June 1951). "Galileo and Avempace: The Dynamics of the Leaning Tower Experiment (II)", ''Journal of the History of Ideas'' '''12''' (3), p. 375-422 .</ref> He also developed the notion that bodies have a (non-gravitational) inherent resistance to motion into physics, an idea that was adopted by ] and subsequently by ] who referred to it as ']'.<ref>See e.g. Sorabji 1988 ''Matter,Space and Motion'' p284</ref> In the 13th century, ʻAbd Allah Baydawi hypothesized that ] is due to either one of two possibilities:<ref name=Elliott>{{citation|title=Nature, man and God in medieval Islam: ʻAbd Allah Baydawi's text, Tawaliʻ al-anwar min matali' al-anzar|first1=ʻAbd Allāh ibn ʻUmar|last1=Bayḍāwī|first2=Maḥmūd ibn ʻAbd al-Raḥmān|last2=Iṣfahānī|first3=Edwin Elliott|last3=Calverley|first4=James Wilson|last4=Pollock|year=2002|publisher=]|isbn=9004121021|pages=409 & 492|location=Leiden|oclc=47023538}}</ref> | |||
| {{quote|a) that would be the heat of a fiery atom that is broken, and b) that heat may occur through motion-change, the proof of this being through experiment.}} | |||
| In 1253, a ] text entitled ''Speculum Tripartitum'' stated the following regarding ]'s theory on ]: | |||
| {{quote|Avicenna says in his book of heaven and earth, that heat is generated from motion in external things.<ref>{{citation|title=On the Fringes of the Corpus Aristotelicum: the Pseudo-Avicenna Liber Celi Et Mundi|last=Gutman|first=Oliver|journal=Early Science and Medicine|volume=2|issue=2|year=1997|publisher=]|pages=109–28|doi=10.1163/157338297X00087}}</ref>}} | |||
| In the 13th century, ] stated a version of the law of ], noting that a body of ] is able to change, but is not able to disappear.<ref>Farid Alakbarov (Summer 2001). , ''Azerbaijan International'' '''9''' (2).</ref> In the early 16th century, ] developed a hypothesis similar to Galileo's notion of "circular inertia"{{Harv|Ragep|2001a}} {{Page number|date=May 2010}}. The Muslim developments in mechanics laid the foundations for the later development of ] in ].<ref>{{Harvnb|Rozhanskaya|1996|p=642}}: {{quote|Arabic statics was an essential link in the progress of world science. It played an important part in the prehistory of classical mechanics in medieval Europe. Without it classical mechanics proper could probably not have been created.}}</ref> | |||
| ==Astrophysics== | |||
| {{Main|Islamic astronomy}} | |||
| ]'s ''Maqala fi daw al-qamar'' (''On the Light of the Moon''), which he wrote some time before his famous '']'' (1021), was a successful attempt at combining mathematical ] with ], and an early attempt at applying the ] to astronomy and ]. Regarding ], he disproved the universally held opinion that the ] reflects ] like a ] and correctly concluded that it "emits light from those portions of its surface which the ]'s light strikes." In order to prove that "light is emitted from every point of the moon's illuminated surface," he built an "ingenious ]al device." Ibn al-Haytham had "formulated a clear conception of the relationship between an ideal mathematical model and the complex of observable phenomena; in particular, he was the first to make a systematic use of the method of varying the experimental conditions in a constant and uniform manner, in an experiment showing that the ] of the light-spot formed by the projection of the ] through two small ]s onto a screen diminishes constantly as one of the apertures is gradually blocked up."<ref name=Toomer>{{citation|first=G. J.|last=Toomer|title=Review: ''Ibn al-Haythams Weg zur Physik'' by Matthias Schramm|journal=]|volume=55|issue=4|date=December 1964|pages=463–465 |doi=10.1086/349914}}</ref> | |||
| In 1574, Taqi al-Din used astrophysics to explain the intromission model of vision. He stated since the ]s are millions of kilometres away from the ] and that the ] is constant, that if light had come from the eye, it would take too long for light "to travel to the star and come back to the eye. But this is not the case, since we see the star as soon as we open our eyes. Therefore the light must emerge from the object not from the eyes."{{Citation needed|date=May 2010}} | |||
| ===Celestial mechanics=== | |||
| {{See also|Islamic cosmology|Celestial spheres}} | |||
| In ] and ], the eldest ] brother, ] (9th century), made significant contributions. He was the first to hypothesize that the ] and ] are subject to the same ] as ], unlike the ancients who believed that the celestial spheres followed their own set of physical laws different from that of Earth {{Harv|Saliba|1994a|p=116}}. In his ''Astral Motion'' and ''The Force of Attraction'', Muhammad ibn Musa proposed that there is a ] of ] between ],<ref>{{citation|first=K. A.|last=Waheed|year=1978|title=Islam and The Origins of Modern Science|page=27|publisher=Islamic Publication Ltd., ]}}</ref> foreshadowing ].<ref name=Briffault/> | |||
| ] (Alhazen), in his '']'' (1021), was the first to discover that the ] do not consist of ] matter, and he also discovered that the heavens are less dense than the air. These views were later repeated by ] and had a significant influence on the ] and ]s of ] {{Harv|Rosen|1985|pp=19–20 & 21}}. In his ''Epitome of Astronomy'', he also insisted that the heavenly bodies "were accountable to the ]".<ref name=Duhem/> | |||
| ] was also one of the first to conduct elaborate experiments related to ] phenomena. He supposed the ] to be a collection of numerous ], and in ], he observed and described the ] on April 8, 1019, and the ] on September 17, 1019, in detail, and gave the exact ]s of the stars during the lunar eclipse.<ref name=Biruni/> Al-Biruni also theorized that gravity exists within the ] and ], and he criticized the ] views of them not having any ] or gravity and of ] being an ] of the heavenly bodies.<ref name=Berjak/> He also described the Earth's ] as: | |||
| {{quote|The attraction of all things towards the centre of the earth {{Harv|Saliba|1980|p=249}}.}} | |||
| In 1121, ], in his treatise ''The Book of the Balance of Wisdom'', proposed the theory that the "]" of bodies, or their ], vary depending on their distances from the centre of the Earth. This phenomenon was not proven until the 18th century. He states:{{quote|For each heavy body of a known weight positioned at a certain distance from the centre of the universe, its gravity depends on the remoteness from the centre of the universe. For that reason, the gravities of bodies relate as their distances from the centre of the universe {{Harv|Rozhanskaya|1996|p=621}}.}} | |||
| In the 12th century, ] criticized the idea of the ] within the universe and "explores the notion of the existence of a ] in the context of his commentary" on the ]ic verse, "All praise belongs to God, Lord of the Worlds." He raises the question of whether the term "]s" in this verse refers to "multiple worlds within this single ] or ], or to many other universes or a multiverse beyond this known universe." He rejected the ] and ] notions of a single universe revolving around a single world, and instead argued that there are more than "a thousand thousand worlds (''alfa alfi 'awalim'') beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has."<ref name=Setia>{{citation|title=Fakhr Al-Din Al-Razi on Physics and the Nature of the Physical World: A Preliminary Survey|author=Adi Setia|journal=Islam & Science|volume=2|year=2004|url=http://findarticles.com/p/articles/mi_m0QYQ/is_2_2/ai_n9532826/|accessdate=2010-03-02}}</ref> He argued that there exists an infinite ] beyond the known world,<ref name=Iskenderoglu>{{citation|title=Fakhr al-Dīn al-Rāzī and Thomas Aquinas on the question of the eternity of the world|author=Muammer İskenderoğlu|publisher=]|year=2002|isbn=9004124802|page=79}}</ref> and that God has the power to fill the ] with an infinite number of universes.<ref name=Cooper>{{citation|title=al-Razi, Fakhr al-Din (1149-1209)|work=]|author=John Cooper|year=1998|publisher=]|url=http://www.muslimphilosophy.com/ip/rep/H044.htm|accessdate=2010-03-07}}</ref> | |||
| ===Maragha Revolution=== | |||
| ] was a ] who provided ] for the ] but remained a supporter of ].]] | |||
| {{Main|Maragheh observatory}} | |||
| In ], some have described the achievements of the ] in the 13th and 14th centuries as a "Maragha Revolution", "Maragha School Revolution", or "] before the ]". An important aspect of this revolution included the realization that astronomy should aim to describe the behaviour of ] in ] language, and should not remain a mathematical ], which would only save the ]. The Maragha astronomers also realized that the ] view of ] in the universe being only circular or ] was not true, as the ] developed by ] showed that linear motion could also be produced by applying ]s only {{Harv|Saliba|1994b|pp=245, 250, 256–257}}. | |||
| Unlike the ancient ] who were not concerned with the coherence between the mathematical and physical principles of a planetary theory, Islamic astronomers insisted on the need to match the ] with the real world surrounding them,<ref>{{citation|first=George|last=Saliba|author-link=George Saliba|date=Autumn 1999|title=Seeking the Origins of Modern Science?|journal=BRIIFS|volume=1|issue=2|url=http://www.riifs.org/review_articles/review_v1no2_sliba.htm |accessdate=2008-01-25}}</ref> which gradually evolved from a reality based on ] to one based on an ] and mathematical ] after the work of Ibn al-Shatir. The Maragha Revolution was thus characterized by a shift away from the philosophical foundations of ] and ] and towards a greater emphasis on the empirical observation and ] of astronomy and of ] in general, as exemplified in the works of ], ], ] and Shams al-Din al-Khafri<ref name="Dallal"/>{{Harv|Saliba|1994b|pp=42, 80}} {{Harv|Huff|2003|pp=217–8}}. | |||
| ] (]–]) of ], in ''A Final Inquiry Concerning the Rectification of Planetary Theory'', incorporated the Urdi lemma, and eliminated the need for an equant by introducing an extra epicycle (the ]), departing from the Ptolemaic system in a way that was mathematically identical to what ] did in the 16th century. Unlike previous astronomers before him, Ibn al-Shatir was not concerned with adhering to the theoretical principles of ] or Aristotelian ], but rather to produce a model that was more consistent with ] observations. His model was thus in better agreement with empirical ]s than any previous model,<ref name=Saliba-1994>{{Harvnb|Saliba|1994b|pp=233–234 & 240}}</ref> and was also the first that permitted empirical ].<ref>Y. M. Faruqi (2006). "Contributions of Islamic scholars to the scientific enterprise", ''International Education Journal'' '''7''' (4): 395-396.</ref> His work thus marked a turning point in astronomy, which may be considered a "Scientific Revolution before the Renaissance".<ref name=Saliba-1994/> His rectified model was later adapted into a ] by Copernicus {{Harv|Gill|2005}}, which was mathematically achieved by reversing the direction of the last vector connecting the Earth to the Sun.<ref name=Saliba>{{Harvnb|Saliba|1999}}</ref> | |||
| ===Earth's motion=== | |||
| ] elaborated on Tusi's ] evidence for the Earth's motion but rejected Aristotelian physics and ], allowing ] to become a purely empirical and mathematical science.]] | |||
| In the 9th century, ] (Albumasar) developed a planetary model which some have interpreted as a ]. This is due to his ] of the planets being given as heliocentric revolutions rather than ] revolutions, and the only known planetary theory in which this occurs is in the heliocentric theory. His work on planetary theory has not survived, but his astronomical data was later recorded by al-Hashimi and ].<ref>] (1987). "The Heliocentric System in Greek, Persian and Hindu Astronomy", ''Annals of the New York Academy of Sciences'' '''500''' (1), 525–545 .</ref> | |||
| In the 11th century, ], in response to ] and ] who believed in ] and/or the ], wrote in his ''Indica'' {{Harvnb|Nasr|1993|pp=135–136}} : | |||
| {{quote|I have seen the astrolabe called Zuraqi invented by Abu Sa'id Sijzi. I liked it very much and praised him a great deal, as it is based on the idea entertained by some to the effect that the motion we see is due to the Earth's movement and not to that of the sky. By my life, it is a problem difficult of solution and refutation. For it is the same whether you take it that the Earth is in motion or the sky. For, in both cases, it does not affect the Astronomical Science. It is just for the ] to see if it is possible to refute it.}} | |||
| The work of ] (d. 1474), who worked at ] and then ], is seen as a late example of innovation in Islamic theoretical astronomy and it is believed he may have had an influence on ] due to similar arguments concerning the ]. Before al-Qushji, the only astronomer to present an ] argument for the Earth's rotation was ] (d. 1274), who used the phenomena of ]s to refute ]'s claim that a stationery Earth can be determined through observation alone. Al-Tusi, however, accepted that the Earth was stationery on the basis of ] instead, particularly ]. In the 15th century, the influence of ] and natural philosophy was declining due to religious opposition. Al-Qushji, in his ''Concerning the Supposed Dependence of Astronomy upon Philosophy'', thus rejected Aristotelian physics and completely separated natural philosophy from astronomy, allowing astrophysics to become a purely empirical and mathematical science. This allowed him to explore alternatives to the Aristotelian notion of a stationery Earth, as he explored the idea of a moving Earth. He elaborated on al-Tusi's argument and concluded, on the basis of ] rather than speculative philosophy, that the moving Earth theory is just as likely to be true as the stationary Earth theory and that it is not possible to ]ly deduce which theory is true {{harvard citations|last=Ragep|year1=2001a|year2=2001b}}{{Page number|date=May 2010}} <ref>Edith Dudley Sylla, "Creation and nature", in Arthur Stephen McGrade (2003), pp. 178-179, ], ISBN 0521000637.</ref> | |||
| In the 16th century, the debate on the Earth's motion was continued by ] (d. 1528), who in his analysis of what might occur if the Earth were rotating, develops a hypothesis similar to ]'s notion of "circular ]" {{Harv|Ragep|2001b|pp=63–4}}, which he described in the following observational test (as a response to one of ]'s arguments): | |||
| {{quote|The small or large rock will fall to the Earth along the path of a line that is perpendicular to the plane (''sath'') of the horizon; this is witnessed by experience (''tajriba''). And this perpendicular is away from the tangent point of the Earth’s sphere and the plane of the perceived (''hissi'') horizon. This point moves with the motion of the Earth and thus there will be no difference in place of fall of the two rocks {{Harv|Ragep|2001a|pp=152–3}}.}} | |||
| ==Apparatus, instruments and devices== | |||
| {{See also|Alchemy and chemistry in Islam|Islamic astronomy|Islamic geography}} | |||
| ===Optical instruments=== | |||
| ] (Alhazen) gave the first clear description<ref name=Kelley>David H. Kelley, : | |||
| {{quote|The first clear description of the device appears in the ''Book of Optics'' of Alhazen.}}</ref> and correct analysis<ref>{{Citation |last=Wade |first=Nicholas J. |last2=Finger |first2=Stanley |year=2001 |title=The eye as an optical instrument: from camera obscura to Helmholtz's perspective |journal=Perception |volume=30 |issue=10 |pages=1157–1177 |doi=10.1068/p3210 |pmid=11721819 }}: | |||
| {{quote|The principles of the camera obscura first began to be correctly analysed in the eleventh century, when they were outlined by Ibn al-Haytham.}}</ref> of the ] and ] in his '']'' (1021). In his earlier ''Maqala fi daw al-qamar'' (''On the Light of the Moon''), in order to prove that "light is emitted from every point of the moon's illuminated surface," he built an "ingenious ]al device."<ref name=Toomer/> The first optical research to describe a ] used in an instrument was also found in the '']'' written by ].<ref name= Sabra2>Sabra, A. I. & Hogendijk, J. P. (2003), The Enterprise of Science in Islam: New Perspectives, MIT Press, pp. 85-118, ISBN 0262194821</ref> His work in light ], ]s, as well as the creation of other instruments such as the ], also helped spark the ].<ref name= Sabra2/><ref>] (University of Illinois), Best Idea; Eyes Wide Open, '']'', April 18, 1999.{{Verify credibility|date=November 2008}}</ref> | |||
| ===Laboratory apparatus=== | |||
| During his ]s on physics, ] invented a ],<ref name="Marshall Clagett 1961 p. 64"/> in order to find the ratio between the weight of a substance in air and the weight of water displaced, and to accurately measure the specific weights of the gemstones and their corresponding metals, which are very close to modern measurements {{Harv|Rozhanskaya|1996|p=639}}. | |||
| ] also invented the ] and ] in the early 11th century, and the ] and ] were invented by ] in the early 12th century. The earliest known descriptions for these instruments are found in al-Khazini's ''The Book of the Balance of Wisdom'' (1121).<ref name=Hall>Robert E. Hall (1973). "Al-Khazini", ''Dictionary of Scientific Biography'', Vol. VII, p. 346.</ref>{{Failed verification|date=April 2010}} Al-Bīrūnī also invented the ] for measuring densities and for the appreciation of the temperature of liquids. It was described by Al-Khazini a century later.{{Harv|Rozhanskaya|1996|p=639}} {{Failed verification|date=April 2010}} | |||
| Also in the 11th century, ] (Ibn Sina) invented the ], which condenses ] vapours, in order to produce ]s through ].<ref>{{citation|title=Aromatherapy: A Practical Approach|first=Vicki|last=Pitman|publisher=]|year=2004|isbn=0748773460|page=xi}}</ref><ref>{{citation|title=The Basics of Chemistry|first=Richard|last=Myers|publisher=]|year=2003|isbn=0313316643|page=14}}</ref>{{Failed verification|date=April 2010}}<ref name=Ericksen>Marlene Ericksen (2000), ''Healing with Aromatherapy'', p. 9, ], ISBN 0658003828</ref>{{Failed verification|date=April 2010}} | |||
| ===Mechanical devices=== | |||
| {{See also|Muslim Agricultural Revolution|Inventions in medieval Islam|Timeline of science and engineering in the Islamic world}} | |||
| In the 9th century, the ] brothers made advances in ] and ], through their treatise on mechanical technology, the '']''. They described a number of early ]s in mechanics.<ref name=Hassan>], </ref> Two-step level controls for fluids, an early form of discontinuous ]s, was developed by the Banu Musa brothers.<ref>{{citation|title=Soft variable-structure controls: a survey|author=J. Adamy & A. Flemming|journal=Automatica|volume=40|issue=11|date=November 2004|publisher=]|pages=1821–1844|doi=10.1016/j.automatica.2004.05.017}}</ref> They also described an early ] for fluids.<ref name=Mayr>Otto Mayr (1970). ''The Origins of Feedback Control'', ].</ref> According to ], the Banu Musa brothers were "masters in the exploitation of small variations" in aerostatics and ] pressures and in using conical ]s as "in-line" components in flow systems, "the first known use of conical valves as automatic controllers."<ref name=Hill/> They also described the use of other valves, including a ],<ref name="Mayr"/><ref name=Hill>], "Mechanical Engineering in the Medieval Near East", ''Scientific American'', May 1991, p. 64-69. (] ], )</ref> ]<ref name=Mayr/> and ].<ref name=Hill-1979>{{citation|title=The book of ingenious devices (Kitāb al-ḥiyal)|author=] (authors), ] (translator)|publisher=]|year=1979|isbn=9027708339|pages=74–7}}</ref> The Banu Musa also developed an early ] system where "one can withdraw small quantities of liquid repeatedly, but if one withdraws a large quantity, no further extractions are possible."<ref name=Hill/> The double-concentric ] and the ] with bent end for pouring in different liquids, neither of which appear in any earlier Greek works, were also original inventions by the Banu Musa brothers.<ref name=Hill-21>{{citation|title=The book of ingenious devices (Kitāb al-ḥiyal)|author=] (authors), ] (translator)|publisher=]|year=1979|isbn=9027708339|page=21}}</ref> Some of the other mechanisms they described include a ]<ref name=Hassan/> and an early ].<ref>{{citation|title=], Episode 12: Machines of the East|publisher=]|url=http://www.youtube.com/watch?v=n6gdknoXww8|accessdate=2008-09-06}}</ref> | |||
| In 1206, ]'s ''Book of Knowledge of Ingenious Mechanical Devices'' described many hydraulic machines. Of particular importance were his water-raising ]s. The first known use of a ] in a ] was in one of al-Jazari's ] machines. The concept of minimizing ] is also first implied in one of al-Jazari's saqiya chain pumps, which was for the purpose of maximising the efficiency of the saqiya chain pump.<ref name=Hill-776>{{cite encyclopedia|last= Hill |first= Donald Routledge |authorlink= Donald Routledge Hill |editor= Roshdi Rashed |encyclopedia= ] |title= Engineering |url= |accessdate= |edition= |year= 1996 |publisher= ] |volume= 3/3 |location= London |id= |isbn= 0-415-02063-8 |oclc= |doi= |pages= 751–795 }}</ref> Al-Jazari also invented a ] ] ] suction pump, which included the first ] pipes, suction pumping, ] pumping, and made early uses of valves and a ]-] mechanism. This pump is remarkable for three reasons: the first known use of a true suction pipe (which sucks fluids into a partial ]) in a pump, the first application of the ] principle, and the conversion of ] to ], via the crankshaft-connecting rod mechanism.<ref name=Hill2>], "Mechanical Engineering in the Medieval Near East", '']'', May 1991, pp. 64-9 (] ], )</ref><ref name="Hassan-Pump"/><ref name=Hill-1996>] (1996), ''A History of Engineering in Classical and Medieval Times'', ], pp. 143 & 150-2</ref> The suction pump invented by Al-Jazari later appeared in Europe from the 15th century.<ref name=Hill2>], "Mechanical Engineering in the Medieval Near East", ''Scientific American'', May 1991, pp. 64-69 (] ], )</ref><ref name=Hassan-Pump>{{cite web|author=]|title=The Origin of the Suction Pump: Al-Jazari 1206 A.D.|url=http://www.history-science-technology.com/Notes/Notes%202.htm|accessdate=2008-07-16}}</ref> | |||
| ]'s six-cylinder pump, invented in 1551, could also create a partial ].{{Citation needed|date=May 2010}} It incorporated lead weights and pistons and was used for drawing water.{{Citation needed|date=May 2010}} He also invented an early practical ] as a prime mover for the first ]ed and self-rotating ], as described in his book, ''Al-Turuq al-samiyya fi al-alat al-ruhaniyya'' (''The Sublime Methods of Spiritual Machines''), completed in 1551 AD (959 AH).<ref name=Hassan>{{cite web |url=http://www.history-science-technology.com/Notes/Notes%201.htm |title=Taqi al-Din and the First Steam Turbine |accessdate=2008-03-29 |last=Hassan |first=Ahmad Y |authorlink=Ahmad Y Hassan |work=History of Science and Technology in Islam}}</ref> | |||
| ===Magnetic instruments=== | |||
| In the 14th century, ] invented the ], a ]keeping device incorporating both a universal ] and a magnetic ]. He invented it for the purpose of finding the times of ] prayers.<ref name=King-1983>{{Harvnb|King|1983|pp=547–8}}</ref> The ]s also invented the 32-point ] during the Middle Ages.<ref name=Tibbetts>G. R. Tibbetts (1973), "Comparisons between Arab and Chinese Navigational Techniques", ''Bulletin of the School of Oriental and African Studies'' '''36''' (1), p. 97-108 .</ref> A ] ] instrument with a sundial and compass attached to it<ref name=King-1997>David A. King (1997), "Two Iranian World Maps for Finding the Direction and Distance to Mecca", ''Imago Mundi'' '''49''': 62-82 </ref> was created by Muhammad Husayn in the 17th century.<ref name=Iqbal-King>{{Citation|last1= King |first1= David A. |title= World-Maps for Finding the Direction and Distance to Mecca: Innovation and Tradition in Islamic Science |type= |edition= |series= |volume= |year= 1999 |origyear= 1999 |publisher= ] |location= Leiden |isbn= 90-04-11367-3 |oclc= |doi= |id= {{ISSN|0169-8719}} |page= |pages= |at= |chapter= |chapterurl= |quote= |ref= harv |bibcode= |laysummary= http://www.thefreelibrary.com/David+A.+King+%281999%29%2c+World-Maps+for+Finding+the+Direction+and...-a0119627458 |laydate= Jun 1, 2003 }}</ref> | |||
| ==Other experiments== | |||
| Other ]s related to physics include ]' invention of "some sort of ]",<ref name=White/> and his attempt at creating an ] ] room, in which spectators saw stars and clouds, and were astonished by artificial thunder and lightning, which were produced by mechanisms hidden in his basement laboratory.<ref name=White/><ref>{{citation|title=Muslim Spain 711-1492 A.D|first=S. M.|last=Imamuddin|publisher=]|year=1981|isbn=9004061312|page=166|oclc=8319676}}</ref> Possibly the earliest and nearest approach to the discovery of the identity of lightning, and ] from any other source, is to be attributed to the Arabs, who before the 15th century had the ] word for lightning (''raad'') applied to the ].<ref name="EncyclopediaAmericana">''The ]; a library of universal knowledge'' (1918), ]: Encyclopedia Americana Corp</ref> The ] phenomena was also reported by ] and ].<ref>{{citation|title=Review: Electric Fish|first=Peter|last=Moller|journal=BioScience|volume=41|issue=11|date=December 1991|pages=794–6 |doi=10.2307/1311732|url=http://jstor.org/stable/1311732|publisher=American Institute of Biological Sciences|last2=Kramer|first2=Bernd}}</ref> | |||
| ===Magnetism=== | |||
| {{See also|Islamic geography|Islamic astronomy}} | |||
| Arabic writers were aware of ] since the 9th century, when ] (Rhazes) wrote a treatise on the subject. In the 12th century, ] (Avempace) described the properties of ]s and its attraction towards ].<ref>{{citation|title=History of Islamic Philosophy|last= Seyyed ]|first=Oliver Leaman|year=1996|publisher=Routledge|isbn=0415131596|pages=206 & 305|oclc=174920627 32050152 61982465}}</ref> Like some of the ancient ], the ] were also aware of the properties of natural plastic ], and they observed that it can draw up small bits of ].<ref>{{citation|title=Beyond Atoms and the Void|first=Philip|last=Morrison|journal=New Literary History|volume=23|issue=4|year=1992|pages=797–814 |doi=10.2307/469170|url=http://jstor.org/stable/469170|publisher=The Johns Hopkins University Press}}</ref> | |||
| After the arrival of an early ] from ] around the 12th or 13th century, ] and navigational sciences became highly developed with the use of the magnetic compass. The first astronomical uses of the magnetic ] is also found in a treatise on astronomical instruments written by the ]i ] al-] (d. 1296 AD) in 1282 AD (]). This was the first reference to the compass in astronomical literature.<ref>Emilie Savage-Smith (1988), "Gleanings from an Arabist's Workshop: Current Trends in the Study of Medieval Islamic Science and Medicine", '']'' '''79''' (2): 246-266 </ref> | |||
| Al-Ashraf's compass used a steel needle magnetized by rubbing with a ]ic stone, due to steel needles keeping their magnetic property longer than iron needles. Al-Ashraf also provides detailed explanations on the magnetic properties of the needle. He was aware that when the end rubbed with the magnetic stone, that each head retains its attraction to turn north or south, referring to the fact that the head of the needle which is not rubbed has also changed its behavior. He also described two flaws of the early magnetic compass: "loss of magnetic properties and ] of the cone", and wrote that these were the reasons why it was neglected by “the early scholars”. Al-Ashraf then develops an improved compass for use as a "] indicator" instrument in order to find the direction to ]. Al-Ashraf's instrument was one of the earliest dry compasses, and appears to have been invented independently of ].<ref>{{citation|title=Two Early Arabic Sources On The Magnetic Compass|first=Petra G.|last=Schmidl|journal=Journal of Arabic and Islamic Studies|year=1996-1997|volume=1|pages=81–132}}</ref> | |||
| In the 14th century, ] invented the ], a ]keeping device incorporating both a universal ] and a magnetic ]. He invented it for the purpose of finding the direction of Qibla and the times of ] prayers.<ref name=King-1983/> The ]s also invented the 32-point ] during the Middle Ages.<ref name=Tibbetts/> | |||
| Muslim astronomers were aware of ] by the 15th century, when the Egyptian ] 'Izz al-Din al-Wafa'i (d. 1469/1471) measured it as 7 degrees from ].<ref>{{citation|title=Turkish Mosque Orientation and the Secular Variation of the Magnetic Declination|first=Frank E.|last=Barmore|journal=Journal of Near Eastern Studies|volume=44|issue=2|date=April 1985|publisher=]|pages=81–98 |doi=10.1086/373112}}</ref> A ] Qibla instrument with a sundial and compass attached to it<ref name=King-1997/> was created by Muhammad Husayn in the 17th century.<ref name=Iqbal-King/> | |||
| ==Notes== | ==Notes== | ||
Revision as of 21:37, 18 July 2010
Main article: Science in medieval IslamPhysics in medieval Islam In the course of the expansion of the Islamic world, Muslim scholars encountered the science, mathematics, and medicine of antiquity through the works of Aristotle, Archimedes, Galen, Ptolemy, Euclid, and others. These works and the important commentaries on them were the wellspring of science during the Medieval period. They were translated into Arabic, the lingua franca of this period Islamic scholarship had inherited Aristotelian physics from the Greeks and during the Islamic Golden Age developed it further, especially placing emphasis on observation and a priori reasoning, formulating crude forms of the scientific method.
Fields of physics studied included optics and magnetism, mechanics (including statics, dynamics, kinematics and motion), and astronomy.
Notes
References
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See also
- Astronomy in medieval Islam
- Book of Optics
- Celestial spheres
- Early Islamic philosophy
- History of optics
- History of physics
- Islamic contributions to Medieval Europe
- Islamic Golden Age
- List of Muslim scientists
- Science in medieval Islam
- Science in the Middle Ages
- Theory of impetus
External links
- Zaimeche, Salah; Al-Hassani, Salim; Alp, Talip; Salem, Ahmed (2001). "Astronomical Observatories in the Classical Islamic Culture". MuslimHeritage.com. Foundation for Science Technology and Civilisation. Retrieved 2010-05-08.
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