synonymPtolemy (Ptolemy, Egyptian astronomer) Generally refers to Claudius Ptolemy
Claudius Ptolemy（ancient GreekWords: \ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ ῖ 8150;LatinClaudius Ptolemaeus, about 90-168)Greecemathematician,astronomer，geographerAnd astrologers.He livesAlexanderHe has a Latin name, how manyhistorianThink this implies that he is also a Roman citizen.He quoted the words of Greek philosophers, and used the observations of Babylon and the Babylonian theory of the moon.The 14th century astronomer Theodore Melittnitz said that his birthplace wasGreeceHermiou, Tolemes（GreekIn Thebaid (Greek: \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\.
Ptolemy wrote several scientific papers, three of whichByzantium, Islam andWestern EuropeScience is very important.The first is now calledAlmagestAstronomical papers (i.e《Astronomy》）, although it was originally called "Mathematical Thesis" (M α θη μ α τ τ κ ὴ ∑∑ ντα ξ τ),MathēmatikēSyntaxis）, and then called the Great Paper (Ἡ ε γ ≤ λ η∑ Ἡ t ττα ξη),HMegálē）Again.The second one is geography，This is a comprehensive discussion of the geographical knowledge of the Greeks and Romans.The third is the astrology thesis, which he tried to makeCosmic modelAdapt to the currentAristotlenatural philosophy。This is sometimes calledApotelesmatika(Ἀ πτε λ ε σ μ α τ κ ≤), but more commonly known asAstrology Four BooksIn Greek (ττρ≤ ββλ ο), it means "four books" or LatinQuadripartitum。[1]
Claudius Ptolemaeus“Geocentric theory”OfA master, was born in Tolmadayi, Egypt in about 90 ADAlexanderHe lived and worked in the city and died in 168.Both parentsGreek。In 127 AD, the young Ptolemy was sent to Alexandria to study.There, he read many books and learnedAstrometryandGeodesy。He lived for a long timeAlexanderCity, until 151, died in 168.[2]
Claudius Ptolemy
Little is known about Ptolemy's life so far.The most important information comes from the relevant records in his works handed down from generation to generation, followed byRoman EmpireAnd some of the stories circulated by Byzantine writers - usually quite suspicious.Almagest, the most important book in Ptolemy（《Astronomy》), which records some of his own worksAstronomical observationThis is to determine his ageWork locationThe most reliable information.The Ptolemaic astronomical observation records in the book "The Supreme Theory", the earliest date is March 26, 127 AD, and the latest date is February 2, 141 AD.It can be seen that Ptolemy was once active inImperium RomanumemperorHadrian (Hadrian, 117-138) andAnthony(Antoninus, 138-161 AD) The Age of Two Emperors.The Great Theory is Ptolemy's early work, and he has written many works since then. It is inferred from these works that Ptolemy was very active in the era of Emperor Hadrian, and he lived untilMarcus Aurelius (Marcus Aurlius, 161-180 AD) Emperor era.
According to the observation records left by Ptolemy, all his astronomical observations were made in Alexandria, Egypt (under the Roman Empire at that time)Alexandria, EgyptThe provincial capital of).There is a saying that he was born inUpper EgyptPtolemais (today's Ptolemais in Egypt), which may be correct, but this theory comes from later ages (late to about 1360), and there is noCircumstantial evidence。
Ptolemy's name contains some information for speculation.Ptolemaeus indicated that he was an Egyptian resident, but his ancestors were Greeks or some Hellenized people;Claudius showed that he hadRoman citizenship, which is probablyRoman emperorClaudius(Claudius, 41-54 AD) or Nero (54-68 AD).[2]
Academic viewpoints
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astronomy
In the ancientCosmologyIn Chinese, people regard the sky as a lid, and the ground as a flat plate supported by pillars.
Ptolemy Map
In the fourth and third centuries BC, the Greeks had two different views on the movement of celestial bodies:OdoxAs a representative, he explained the movement of celestial bodies from the perspective of geometry, and decomposed the complex periodic phenomena in the sky into several simpleperiodic motion ；He also assigned a circular orbit, or a spherical shell, to each simple periodic motion. He believed that the celestial bodies all do it on the circumference centered on the earthUniform circular motionAnd 27 spheres are used to explain the movement of celestial bodiesAristotleThe number of spherical layers is increased to 56.The other is based onAlistarkAs a representative, he believes that the earth rotates on its own axis every day and circles the sun in a circular orbit every year,sunlightAnd stars are stationary, while planets are centered around the sunCircular motion。However, no one expressed understanding or acceptance of Alistark's opinion at that time, because it was different from what people saw with the naked eye.
Claudius Ptolemy
Ptolemy put forward his ownCosmic structureTheory, namely "geocentric theory".In fact, the geocentric theory was initiated by Aristotle, who believed that the movement of the universe was driven by God.He said that the universe is a finite sphere, divided into heaven and earth. The earth is at the center of the universe, so the sun and the moon move around the earth, and objects always fall to the ground.There are 9 equidistant celestial layers outside the earth, and the order from inside to outside is:MoonDaysMercuryHeaven, Venus, Sun, MarsJupiterDaysSaturnThe sky, the star sky and the prime force sky are all empty.Each layer will not move by itself. God has pushed the star layer, and the star layer drives all the layers to move.The earth, where people live, stands quietly in the center of the universe.Ptolemy fully inherited Aristotle's geocentric theory, and used the data accumulated by his predecessors and his own long-term observations to write an eight volume version of On the Great.In the book, he expanded Aristotle's 9 layers of sky to 11 layers, changed the original power sky to crystal sky, and added the highest sky andClean fireDays.Ptolemy imagined that the planets moved around a smaller circle, and the center of each circle moved around the circle centered on the Earth.He called the circle around the earth "even wheel" and each small circle "current wheel".At the same time, suppose that the earth is not exactly at the center of the mean wheel, but deviates a certain distance, and the mean wheel is some eccentric circles;In addition to the above orbits, the Sun Moon planets, together with many stars, orbit the Earth once a day.Ptolemy, a mathematical picture that does not reflect the actual structure of the universe, perfectly explained the planetary motion observed at that time, and achieved practical value in navigation, which is widely believed by people.[2]
Ptolemy's celestial model was popular for thousands of years because of its advantages and historical reasons.Its main features are:
1. The uniform angular velocity movement around a center is in line with the prevailing thought at that timePlatoThe hypothesis of "is also suitable for Aristotle's physics and is easily accepted.".
2. Predicted the movement position of the planet with different combinations of several circular orbits, which is little different from the actual situation. Compared with the previous system, it is improved, and can also explain the brightness change of the planet.
3. The statement that the earth does not move is a comforting assumption for people's life at that time, and also conforms toChristian faith。
Under the historical conditions at that time, Ptolemy's theory of planetary system was of progressive significance.First, it affirms that the earth is a suspended sphere without pillars.Secondly, it can be distinguished from the stellar objects that the planets and the sun and the moon are a group of objects closer to the Earthsolar systemA critical step identified from the stars.
Ptolemy himself claimed that his system did not have physical authenticity, but was just a mathematical scheme for calculating the positions of celestial bodies.As for the church's use and maintenance of geocentrism, it was more than a thousand years after Ptolemy's death.The reason why the church maintains the geocentric doctrine is just to distort it to prove the image of heaven and hell on earth depicted in the doctrine. If other doctrines are popular when compiling the doctrine, perhaps the church will also use them.So, Ptolemy'sCosmologyThere was no necessary connection with religion.
After Ptolemy's astronomical works were known to Europe by Arab scholars, they remained influential in Europe for a long time, at least until the 16th century.Before that, there was no westernephemerisIt was not calculated according to Ptolemy's theory.Although the accuracy of ephemeris has been improvedancient GreekThe current round – even wheel system has a function similar to series expansion, that is, to increase the calculatedaccuracy, you can add a small wheel to the current wheel, let the heart of the small wheel go around the current wheel, and let the celestial body go around the small wheel.As long as the radius, bypass direction and speed of the wheels are properly adjusted, the requirements can be met.Theoretically, small wheels can be continuously increased to obtain higher accuracy, which is exactly what some astronomers have done.But its disadvantage is also obvious, that is, it is too cumbersome.Later Copernicus《Celestial motion theory》This expression was abandoned in, and the more conciseHeliocentric theory。
geography
Ptolemy also made outstanding achievements in geography.He believed that the research object of geography should be the whole earth, mainly studying its shape, sizeLongitude and latitudeDetermination of andMap projectionMethods, etc.He made a similar model for measuring longitude and latitudeArmillary sphereInstruments for（Astrolabe）And later famous in EuropeAngular distanceMeasuring instrument。Ptolemy has eight volumes of geography works, six of which are location tables marked with longitude and latitude.Most of his locations seem to be based on hisPrime meridianAnd the distance between horizontal latitudes expressed in radians, because none of its longitude is measured from astronomy, and only a few latitudes are measured in this way.Ptolemy used the smaller value of the earth's circumference measured by Bochthonis, which made all his land distance expressed in radians exaggerated, because he set the distance of each radian as 500 Greek miles instead of 600 Greek miles.In this way, from Europe to AsiaAtlanticIt seems that the ocean surface distance is much smaller than that calculated by Eratosthene, and this calculation finally leads toColumbusAn attempt to sail from the west to Asia.Ptolemy was much more familiar with the world than his predecessors,EratostheniThe east side of the map only goes to IndiaGangesBut Ptolemy knewMalay PeninsulaAnd "the country of silk", namely China.
In Ptolemy's Annals of Geography, it was recorded by Marinus in his Introduction to Geography that a Macedonian businessman named Maes Titianus first went from the Euphrates River to the Lithinos Prygos in Central Asia, and then from the stone tower to Sera (Luoyang, the capital of the Eastern Han Dynasty) in Seres,It describes the overland Silk Road from Stone Tower to Sierra City - "Sierra Road"This is consistent with the time and historical facts of the envoys of Munchdoule who arrived in Luoyang in November, 100 AD, and were received and given the 'golden purple ribbon' by the Eastern Han Dynasty government in the Book of the Later Han Dynasty.[3]
Other information
In mathematics, he used the combination of circular motion to explain the movement of celestial bodies, which was considered to be absolutely accurate at that time.He also demonstratedquadrilateralThe famousPtolemy Theorem 。He also studied optics and thought that when light is refractedAngle of incidenceAndRefraction angleIs proportional.
work
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Ptolemy wrote four important books:《Astronomy》（Almagest）、《Guide to Geography》Geography, Tetrabiblos and Optics.In addition, chronology andAstrologyAnd other works.
Astronomy
Ptolemy lunar motion model
Ptolemy summed up the achievements of Greek ancient astronomy and wrote 13 volumes of The Complete Astronomy.The duration of one year is determined andCatalogue, DescriptionPrecessionCorrection caused by refraction, givingeclipseCalculation method, etc.He used Greek astronomers, especially HipparchusHipparchus ）A large number of observations and research resultsEccentric circleOr small wheelSystem interpretationCelestial motionThe geocentric theory ofGeocentric systemNamed after himPtolemy geocentric system[2]。This great work was made in astronomy at that timeencyclopedia, untilKeplerIt is a must read book for astronomers.
Ptolemy's geocentric system
《Astronomy》- 500 years of Greek astronomy andcosmologyThe peak of thought has ruled the astronomical world for 13 centuries.Such a complex book with staggered knowledge cannot be completed by a single person.Ptolemy's reliance on his pioneers, especially Hippachas, need not be concealed.The basic problem he faced was to try to explain the motion of celestial bodies on the premise that the universe was centered on the Earth and all celestial bodies were rotating in a completely circular orbit at a uniform speed.Because the actual celestial bodies pressElliptical orbitIn order to maintain the original basic assumptions, it is necessary to consider some very complexgeometry。Ptolemy used three complex original ideas: this wheel, eccentric circle andEven wheel。He can tell Mars, Venus andMercuryThe orbits of and so on are given reasonable descriptions respectively, but if they are put in a model, their scales and periods will conflict.However, no matter what shortcomings the system has, it has been popular for 1300 years and was not used until the 15th centuryCopernicusOverthrow.
Guide to Geography
Ptolemy《Guide to Geography》Eight volumes, which he drewWorld mapIt also discusses the principles of astronomy.
stayGuide to GeographyIn his book, Ptolemy fully explained how to determine latitude and longitude lines mathematically.However, none of themMeridianYesAstronomical methodCertainly, only a few latitude lines are calculated in this way.He reduced the distance measured on land to degrees and determined the location of the area on this uncertain grid.The distance on the sea is almost a guess.He putCanary IslandsThey were placed 7 ° east of their real position, so the whole grid positioning can only be wrong.The influence of Geography Guide on Western world outlook is almost the same《Astronomy》As huge and lasting.
《Guide to Geography》In the early 9th century, there was an Arabic translation of the book, which describedinaccurateThe originalarabicThe translation has been lost, but the direct relationship between the book and Islamic geographyIndirect impactIt is noteworthy.The Guide to Geography appeared around 1406, which was translated from Greek by J. AngelusLatinTranslation.Because even at that time (1200 years after its publication), this book was still relevant to the general geographical situation of the known worldBest Guide, so it quickly became popular.Until the 16th century, manyCartographyProgress in the 16th century provided a powerful stimulus.PtolemaicprojectionIt was criticized, which led to the emergence of various new projection methods.The first projection method in GeographyMercator Mercator was criticized in the map of Europe in 1554, and the second projection method has received more criticism since 1511.However, Ptolemy's Guide to Geography provided the earliest map projection method with mathematical basis for future generations.
The detailed research of modern scholars shows that C. Columbus (1451-1506) began to change at his placeHuman historyI have carefully read at least five books before my voyage, one of which is Ptolemy's《Guide to Geography》The other four books are not of the same kind, so it can be seen that Columbus's geographical thought mainly came from Ptolemy.PtolemyAsiaThe location is closer than it actually is (to the west), and the map maker of Columbus's contemporary inherited his wrong view, otherwise Columbus might not have sailed.Columbus believed that the east coast of the Asian continent could be reached through a short sea crossing route, but he found it on the east coast of Asia he imaginedAmericaNew World - although he still believed that what he discovered was the Asian continent painted on Ptolemy's map until his death.[2]
optics
Ptolemy wrote five volumes of Optics, of which the first volume describes the relationship between the eye and light, and the second volume describes the visible conditionsBinocular effect, Volume IIIPlane mirrorAndCurved mirrorThe reflection of the sun and the size of the apparent diameter of the sun at noon and in the morning and evening. Volume 5 attempts to find outLaw of refractionAnd describes his experiment and discusses the phenomenon of atmospheric refraction.[2]
List of works
《Astronomy》（Almagest）Thirteen volumes (also known as The Great Theory, The Great Theory, The Great Collection Theory, The Great Synthesis Theory)
When discussing Ptolemy's historical achievements and influence, we must first talk about some prejudices that are easily misleading.These stereotypes are not the results of academic research, but closely combined with propaganda activities in certain specific periods.As a result, it is widely spread, of which the following two are more important.
The first stereotype is to regard Ptolemy as just some ancient peoplescientific literatureBy extension, the editors of "The Greatest Theory" naturally have extreme theories such as "The Greatest Theory" is only borrowed from Hipparchus, and "Geography" is just a copy of Marinus' works.According to research, the origin of this stereotype is probably J. B., a French mathematician and astronomer historian in the early 19th century·DrambolThe book Histoire de I'astronomie Ancienne by Delambre has long been denied by scholars, but it can still be seen in some non academic reading materials.
The second stereotype is to connect Ptolemy withAristotle(Aristotle) The two people's different cosmic systems were confused, and they were regarded as historical criminals who hindered the development of astronomy.In contemporary timesHistory of ScienceIn writingJoseph Needham(J. Needham) "The rigid concentric crystal ball concept of Aristotle and Ptolemy has bound European astronomical thought for more than a thousand years", which is still quoted repeatedly in many Chinese works.In fact, this statement is obviously contrary to historical facts.Aristotle did advocate a kind of concentric overlapping crystal spheres universe system, but Ptolemy did not adopt this kind of universe system in his works, and he never expressed his approval of this kind of system.On the other hand, Aristotle's theory, which was mainly preserved and handed down by Greek Arab scholars, was still used until the 13th centurythe roman catholic churchIt is regarded as heresy and is forbidden to teach in universities for many times.Therefore, neither Ptolemy nor Aristotle could "shackle European astronomical thought for more than a thousand years". By 1323, the Pope announced thatthomas aquinas (T. Aquinas) as a "saint", AquinasScholastic philosophyThe system was officially recognized by the church and became the official doctrine.This theory is that Aquinas and his teacher, Albertus Magnus, combined Aristotle's theory withChristian theologyIt is a comprehensive combination.When demonstrating the system of the crystal ball universe, Aquinas once cited Ptolemy's works to demonstrate the theory of geocentricity and geostationary.Since then, Aristotle's crystal ball universe has indeed bound European astronomy for about two or three hundred years, but this obviously cannot constitute any crime of Ptolemy.
Ptolemy's The Great Theory soon became an ancient bookwestern worldStandard textbook for studying astronomy.In the 4th century, Pappus's commentary literature and Theon of Alexandria's commentary appeared.An Arabic translation appeared around 800 AD.Then came a more complete translation, which was related toAbbasid caliphate Al – Ma'mun's strong sponsorship of astronomy is closely linked.In 1175, the Latin translation of Gerard of Cremona from Arabic appeared, and The Great Theory began to beWestern EuropeScholars understand.Not long before that, around 1160, a Latin translation from the Greek text appeared in Sicily, but it may not be known.These translations, together with some new works from Arabia based on The Supreme Theory, greatly improved the level of western astronomy in the 13th century. In the long medieval period before that, the progress of astronomy in the western world mainly occurred inArab World；But ArabastronomerHe also greatly benefited from Ptolemy's astronomical works.
