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Problems of physics in the Middle Ages in the East
Nazila Bagir Soltanova, Associate Professor, Leading Researcher, PhD, Institute of Physics of NASA E-mail: muzeyfizika@yahoo.com
Problems of physics in the Middle Ages in the East
Abstract: The article deals with the East of the Middle Ages. The principal directions of development of physics of that period are mentioned here: mechanics, optics, warmth, magnetism, acoustics, astronomy.
Keywords: science, the Middle ages, physics, the East.
There is foggy period in the history of development of the world science. It is difficult to see anything there for a modern investigator, not because that there is anything in the mist, but because that they don’t want to see anything there. This mist is artificial. We are speaking about the Middle Ages period of the history of science. Our task is cleaning out this mist and showing the Renaissance of the East — the scientific basis of the West. We are standing on the shoulders of the past. If there wasn’t the past, there wouldn’t be “today" either. We have no right to deny the past.
An independent, so called Arabic science appeared in the East of the Middle Ages — it was the science of the Islamic Middle Ages. The Arabic conquerors didn’t destroy the ancient civilization. The became the custodians, the savers of the ancient science and in their turn the succeeding cell and history of development of science. The antic science reached to us in great degree in the rewritten manuscripts and translations of the antic literature. The “House of wisdom” (832 Baghdad) — written by Al-Mamun is the proof of the foregoing. Besides the madrasah where besides religion, mathematics and astronomy were taught too, the universities, libraries, academies — the scientific centers were established in the Islamic countries. The people of the countries of the Middle and Near East consolidated politically and economically and related with each other by one religion and language (the Arabic language became the language of science and culture) obtained the possibility of free exchange of the spiritual valuables.
The Muslim scientists investigated the scientific knowledge engendered at Ancient India, China and Greece, then transferred, worked out, systematized and complemented them at the different scientific centers of the Islamic world. The Eastern Europe got them from here. The Muslim scientists were the ancestors of all new scientific disciplines and directions. The labor of early Muslim scientists remained the source of the scientific knowledge for long term which drew the information of the Eastern world and partially, European epoch of
Renaissance. Most of the labor established the basis of the syllabus of the European universities. Marquis Daf-ferin wrote: “Europe is indebted to the Muslim science, Muslim art and Muslim literature for revival from the darkness” [2].
The Physics of the Middle ages began to be developed with the comments on the work of the Ancient Greek scientists. But, these comments became more original gradually and in the result the independent physics grew up from them. The directions of development of physics of the Middle ages are mechanics, optics, warmth, magnetism, acoustics. The mathematic plays an independent role in the progress of physics in the Middle Ages.
The encyclopedic treatises were divided into the statement of theoretical and practical science. The theoretical science is logics, physics (natural science), mathematical sciences and metaphysics (philosophy and theology). The practical science also includes ethics, economics and politics [8].
Besides physics, physics included chemistry, geology, mineralogy, meteorology, botany, zoology, medicine and psychology in our meaning too. The mathematic sciences included arithmetic, algebra, geometry, astronomy, theory of music, optics, hydraulics, statics (science of weights), theory of mechanisms.
Learning of the process of formation of the eastern mechanics allows tracing the tendency to axiomatization and geometrization in a spirit of Euclide and Archimed (statics), to working out of the qualitative theory within the framework of philosophic learning of movement and to declining of body in the different environments and the source of this movement, to separation of learning of simple machines and mechanisms. The system of Ptolo-maeuslays on the basis of the astronomic models of the movement of the celestial bodies.
The influence of the eastern tradition was principally reflected on the static and kinematic methods of astronomy. This is the development of numerical arithmetic — algebraic methods in the static, the specific adoption of decisions of practical tasks related to the lever rule and
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calculation of the specific weight of metals and minerals. Commenting on labor of Archimed upon the hydrostatics served as the moment of development of the theory of weights and weighting and development of the methods of determination of the specific weight.
In the result of the translating and commenting activities, distinctive scientific tendency was established already in the IX century where the Greek methods were applied to the wide scope of theoretical and practical problems. Furthermore, its scientists, methods, applications were born which gave the results of the maximum meaning for that period. There were such cases when the results of that period could determine the science for a century (works of Biruni, Tusi...).
The style of the composition of the East of the Middle ages was very interesting, the influence of antic, selfbased, generated form of labor is felt in the certain degree. All of them concern the composition on mechanics, astronomy, static. Great importance was given to the systematic description of the material, its fullness, exactness and strictness of formation and proofs. This tendency was strengthened in the X-XI centuries.
The XII century may be ascribed to the second stage of development of the mechanics in the Middle Ages. The authors widely used the successes of the mathematics modern for them in their mechanical and astronomic compositions: calculation — algorithmic, arithmetic and algebraic methods, flat and spherical trigonometry.
The requirements of the epoch are changed in the XIII-XV centuries — the new, more exact methods are developed for the astronomic calculations based on the adoption of kinematic — geometric modeling of the movement of the celestial bodies. It required further development of the approximating methods of settlement of the equalization of the second and higher degrees. The XIII-XV centuries are ascribed to the activities of two big scientific schools of the East of the middle ages: of Maragin headed by Al-Tusi and of Samarkand headed by Ulugbey [5].
The geometric statics is ascribed to the section of geometry in the classification of science of the scientists of the East of the Middle Ages, but it is considered separately as the “science on gravity”: IbnSina (X century) separates out the “science on gravity” and the “science on devices” in his classification. The “science on upwell-ing” is separated out specially in some encyclopedias [7].
Definite historical condition contributed to the special development of the static in the East of the Middle Ages. Increase of the monetary circulation and internal and external commerce required permanent
improvement the weighting methods and the system of measures and weights. It stipulated principal development of science on weighting — establishment of numerous constructions of different types of weights and development of the theoretical basis of it — the science on equilibrium in its geometric and kinematic forms. Development of the science on simple machines and their combinations stipulated the necessity of improvement of the technique of transportation of loads.
The notion on the center of gravity was appeared on the work of Archimed and was developed about the labors of the scientists of the Middle Ages. The classic results of Archimed obtained in the geometric statics are generalized and spread on the space ofbodies and the systems of bodies. Using and stating all axioms ofArchimed related to the notion of the center of gravity of the system of bodies already applied to the real bodies the scientists complete this system of the axioms of Archimed by their own statements. In the science of that period the notion on the center of gravity in the significant degree was relied on the dynamic traditions. The scientists of the East of the Middle Ages connected the center of gravity with the understanding of the center of the world which according to Archimed is the “natural place”, tendency was put in every body and completed by “natural” movement. The treatment of the notion of the center of gravity of these scientists is implied from the notion of weight as power having the character of the gravitation.
The author of the book on the “Weight of wisdom” (1121 year) Al-Hazini, a famous physicist and astronomer of the XII century was the student of Omer Khayyam and worked at court of the sultan ofSeljukSanjar. The book on the “Weight of wisdom” represents the description of the questions of the theoretical and practical statics of that time and is written as a modern scientific monograph. The purpose of the treatise is the theoretical basis of the construction of the “weight of wisdom”, the method of working with them known by the author about all modifications of the beam balance applied in the different spheres of the scientific and practical activities of that epoch. Al-Hazini writes: “We certify that the understanding of all notions in the problems about the center of gravity, about the gravity and lightness and features (bodies) in the liquid and air. from those that are known by us (from the ancient times) are very useful in the science on air”. The problem on the specific weight is historically related with the theory ofweighting. The data obtained from Al-Hazini coincide with modern data. It is interesting to state than the specific weight of mercury was weighted specially by Robert Broil in 1627 in the East, though that his result was
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13.357 instead of modern 13.546 (at 20 °C), meanwhile, Al-Hazini gives 13.57. The measuring methods and schedules of the specific weight of 50 substances are given in the book. Such kinds of schedules were published at the end of the XVIII century in Europe (“Course on chemistry", A. L. Lavuaze). The first measuring of the specific weight was implemented by A. Kirkher in the XVIII century in Europe.
The problem on equilibrium of weights and weighting are set and settled in whole circle of treatises on “karastun”. The Arabic world “karastun” is obviously drawn from the word “haristiyon” by which the Roman asymmetrical beam balance was called. There is a point of view that “haristiyon” is identified by its own name as Haristiyon or Ariston about which FilonaByzantine devoted his composition to it has data about it. The treatise of the brothers Banu Musa, SabitibnKorra, KostaibnLuk, Elisa bar Shinay are known about karastun. The description of karastun leads Al-Biruni to his “Science on stars”.
The book of “Weight of wisdom” by Al-Khazini and the “Book on karastun” by SabitibnKorra played important role in formation of the mechanics of the Islamic countries and exerted influence on its development in Europe.
Up to the middle of the XVII century the word “mechanics” meant the practice of establishment and utilization of machines and mechanisms, i.e, some “art” referred to the elementary theory of five simple machines (lever, block, gate, wedge, screw), the “art” which the theoretical basis was the statics. The scientists of the Islamic countries called the mechanics as “ilm al-khiyal”, i. e., learning of ingenuities — word-for-word translation of the Greek term. The initial meaning of the Greek word (mechane)
means the machine as variety of every possible “contrivances” and the first meaning of the word “mechanic” means expert. Polymathic engineers were called mechanics in the Roman empire in the last centuries.
The mechanics of the East of the middle ages didn’t only showed interest to the fundamental questions of theory but they also got the results having serious theoretical meaning and some of them exerted great influence on the European science of the XIII-XVII centuries.
Learning of the process of formation of the eastern mechanics allows tracing the tendency of the axiomatiza-tionand geometrizationin a spirit of Euclidand Archimed (statics) to the working out of qualitative theories within the framework of general philosophic learning of movement and fall of bodies in the different environments and sources of this movement, to separation out of learning of simple machines and mechanisms [3].
The dynamic direction was first of all relied on the basis of the translation and commenting and development of the compositions of Aristotle. It engendered a whole series of treatises devoted to the problem of reasons, the source and the essence of movement, as well as to the special sections in the treatises of the philosophic compositions. However, these questions were touched in the mechanical compositions, most of all in the treatises on statics too. Therefore, it is not always possible to separate out the problems of statics and dynamics and to learn them isolated from each other. At the same time it is possible to determine clearly the circle of problems of the dynamics of that time. These are the problems of existence in the emptiness and the possibility of movement in the emptiness, the problem of movement in the resisting environment, the mechanism of transfer of movement, free dropping of bodies and movement of bodies thrown angularly in the horizon. Just these questions were the principal subject of learning and commenting.
The compositions of IbnSinawere widely known in the East of the Middle Ages: “the Book of notions”, “the Book on healing”, “the Book on rescue”. The physical sections of these encyclopedic content of the compositions were devoted to the questions on the essence of the movements.
The Greek optics had its tendency. The scientists of the East of the middle Ages analyze and criticize this optics, make repetitive or additional experiences, got their own certain conclusions and developed their own theories and studies. The Egyptian Ibn-al-Khaysam (965-1039) known as Alkhazena in Europe was a big physicist. His principal studies were devoted to the optics. He worked out the theory of vision, described the anatomic structure of eyes and offered a suggestion that the receiver of the description was the crystalline lens. His point ofview overruled till the XVII century when it was found out that the description appeared on the retina.
Alkhazen used the devices applied today in the demonstrative practices for learning the rules on reflection of lights from different mirrors. Alkhazen improved the formation of the law on reflection and determined for the first time that the normal of the surface of the mirror incident and the reflected beam were on aplane. Alkhazen distinguished seven types of mirrors: flat, salient and incurved, cylindrical and conic, salient and incurved spherical mirrors. He tested the rule on reflection of light on them. Learning the reflection of beams on the incurved mirrors Alkhazen determined for the first time the focusing was better when the diameter of
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the mirror was bigger. This service was ascribed by mistake to Rodger Bacon. Alkhazendescribes preparation of the apparatus for learning of light refractionin his book “Treasure of optics" [2].
The problems of optics and the features of the vision took an important place among the problems of physics learned by IbnSina and his student Bahmanyar. They discuss it in details at the “Book on healing” by IbnSina and “at-Ttahsil” Bahmanyar. The questions on essence of light and transparency, light are investigated and different optical theories are discussed.
The optics was investigated by School of Maragin too. The labors of at-Tusi give information about it: “The treatise about reflection and light refraction”, “Optics of Euclid”, “Treatise about learning of rainbow”, “Abstraction of the world”. At-Tusi writes in the “Treatise about learning of rainbow” that: “the angle of dropping is equal to the angle of reflection and they shall be on one plane”, “Reflection and retraction is concrete and their existence is undoubted”. The treatise on “the Abstraction ofword” by at-Tusi deals with the corpuscular theory of light.
Explanation of the rainbow coinciding with the theory of the German scientist Teodoric was suggested before in the Muslim East. The anonymous labor considered belonging to al-Faris where this theory was described represented the comment to the “treasure of optics” of Alkhazen and reached to us in one manuscript kept at Leiden. The author of the comments refers to the composition of Kutb-ad-Dina ash-Shirazi whom he calls the author of the rainbow theory.
The establishment of the kinematic methods -geometric modulating of movements of the celestial bodies may be considered the basis for the kinematic tasks. The source of the development of the kinetic presentations was the Greek astronomy. The “celestial kinematics” of that period was developed. The mathematical apparatus of the methods of kinematics — the geometric modeling were the spherical geometry and spherical astronomy. Kinematics was factually inseparable from the astronomy in the antique world. This tendency was kept in the science of the East of the Middle Ages too [1].
The founder ofthe School ofMaragin, the scientist — EncyclopaedistNasir-ad-Din-at-Tusi was engaged in the theoretical problems of movement of the planet besides the questions of the observatory astronomy too. It is obviously noted in the “Memorial of astronomy”. There is a range of other labors of at-Tusi in this direction. The principal mass of the sources of astronomy of the East of the middle Ages is ziji, i.e, collection of trigonometric and astronomic schedules and rules of solution
of the problems of practical astronomy which is usually preceded by more or less short theoretical introduction containing the description of the pictures of the World and necessary information from the mathematics and essentially, the trigonometry and the spherical astronomy. The rules are accompanied by geometric proofs. The calculation schedules in the sexagesimal system. The spherical astronomic basis of the kinematic astronomic modeling is introduced as the necessary element to the composition of all zijis of the Middle Ages without any exclusion. At-Tusi separates out the trigonometry as an independent science.
The scientists of the Islamic countries (al-Khorezmi, al-Khasib, Abu-l-Vafa, at-Tusi, Ulugbey) contributed to the improvement of the mathematical fundament of astronomy. They exerted great influence on development of trigonometry: modern trigonometric functions as sine, cosine, tangents, cotangents were introduced ad a range of theorems were proved and the schedules were developed by them.
“ZijIlhani” is the astronomic catalogue drawn up by the staff of the observatory of Maragin under the leadership of at-Tusi. At-Tusi followed the theory of geocentric systems of planets in all theoretical problems. These labors didn’t lose their importance in the new period either. The famous specialist on the celestial mechanics M. F. Subbotin writes about at-Tusi: “Nasreddin composes famous «Ilkhan schedules». These schedule will be the best memory of his fame. Composing of these schedules on the basis of special observations and critical processing of the mathematical theories of Ptolomaeus, Nasreddin implemented that program which Tikho-Brage made the purpose in lifethirty years later. It shows how deeply Nasreddin recognized the needs of science and how correctly he put next problems” [2].
Famous “Revolution of Maragin” is the theory of movement of planets established by the school of at-Tusi and denying equant and other elements of the theory of Ptolomaeusas the fundament of the mathematical astronomy (at-Tusi, ash-Shirazi, al-Ordi, as-Shatir, al-Kashi, al-Kushchi, al-Khafri). Also the question on possibility of turning of the Earth around the axis was discussed.
Obviously, Copernic was familiar with the works of the scientists of the observatory of Maragan establishing the Revolution of Maraginwhile establishing his heliocentric system of the world. Copernic applies the same mathematical construction as the scientists of Maragin (at-Tusi, ash-Shirazi, al-Ordi) for solution of the problem of equant frequently using the same designation of
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points in the geometric drawings as at-Tusi. He used the same terms while speaking about rotation of the Earth around its axis as at-Tusiused.
Following the movement of the celestial bodies, the problem of the forms of the celestial bodies was touched. Al-Biruni expresses that the Earth is not ball-shaped, it has the form of an egg or lentil (oblong or oblate ellipsoid rotation). Does it mean anything? It is clear, the scientists of the X century stated the ball-shaped form of the Earth. But such kind of idea was appeared in Europe in the XVI century. Just the scientists of the Islamic countries forwarded the fundamental requirements: the astro-
nomic theory is a part of physics. The European astronomy was in the level of the Muslim astronomy only in the XV century thanks to the activities of the Viennese astronomers Purbakh and Regimont. The reason of this beginning was related with the fact that the works of the astronomers of Maragin and Samarkand Schools were available for the European scientists.
The science of the Islamic countries exerted fruitful influence on development of the European science and enriched it both by their own discoveries and the discoveries which were passed to the Muslim art from Greeks, Indians, Syrians and etc.
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