Claudius Ptolemy (ancient Greek: κ λ α _ δ ι ο λ ε μ α _ ο _; Latin: ClaudiusPtolemaeus, about 90- 168), is a Greek mathematician, astronomer, geographer and astrologer. He lives in Alexandria, and he has a Latin name, which some historians think implies that he is also a Roman citizen. He quoted the words of the Greek philosopher and used the observation results of Babylon and Babylon's moon theory. /kloc-Theodore Melitinitz, an astronomer in the 0/4th century, said that his birthplace was the Greek city Hermiou (Greek: π ο ο λ ε μ α _ "ε ο μ ε _ ο ο) in Thebaid. But it is too old, and there is no other evidence to prove or refute it. He died in Alexandria around 168.
Ptolemy wrote several scientific papers, three of which were important to the later Byzantine, Islamic and Western European science. The first one is an astronomical paper now called Almagest, although it was originally called a mathematical paper (M α θ ι κ _ σ _ νι _, Math ♀гггггггггgrammar), and later it was called a big paper. The third is a paper on astrology. He tried to adapt his model of the universe to Aristotle's natural philosophy at that time. This is sometimes called ApoTelesimatika (_ π ο π∩ λ ε σ μ α π ο ο π ω ο _ β ι σ ο _), but it is more commonly called the four books of astrology, which means "four books" or Latin tetralogy.
Chinese name: Claudius Ptolemy.
Mbth: ClaudiusPtolemy
Nationality: Roman Empire
Ethnic group: Greek
Place of birth: Tolemade, Egypt
Date of birth: 90 AD
Date of death: A.D. 168.
Occupation: mathematician, astronomer, geographer, astrologer.
Main achievements: master of geocentric theory
Representative works: astronomy, geography, astronomy, optics.
outline
Claudius Ptolemy, a geocentric master, was born in Egypt to Greek parents. In A.D. 127, the young Ptolemy was sent to Alexandria to study. There, he read a lot of books and studied astronomy and geodesy. He lived in Alexandria for a long time until 15 1. There are few records about his life in the history books.
Born in Ptolemy, Egypt in about 90 AD, he lived and worked in Alexandria and died in 168. I have written a lot in my life. Among them, Astronomical Masterpieces (volume 13) is an encyclopedia of western classical astronomy based on the research results of hipparchus, which mainly discusses the geocentric system of the universe, and holds that the earth is the center and the sun, moon, planets and stars revolve around the earth. This book was regarded as the standard work of astronomy in the Middle Ages, and the geocentric theory was not overthrown until it was published by Heliocentrism of Copernicus in the middle of16th century. Another important work, Geography Guide (8 volumes), is a summary of the knowledge of mathematical geography in ancient Greece, which is mainly based on Marinus' works and refers to the information of Alexandria Library. 1 is an overview of the general theory, which expounds his geographical system and corrects Marinus' drawing method. Volumes 2 to 7 list 8 100 locations in Europe, Asia and Africa. The circumference is divided into 360 parts by using the latitude and longitude network established by Hipachas, and the latitude and longitude coordinates of each location are marked. The eighth volume consists of 27 maps of the world and 26 maps of local areas, and has been published many times since then, which is called Ptolemy Map.
Ptolemy believes that geography is a linear description of the whole known area of the earth and everything related to it, that is, drawing graphics and replacing geographical description with place names and survey lists. He used Percy donis's wrong map of the circumference of the earth in the Geographic Guide, and added errors when drawing the eastward extension of land. Imagine the inhabited world as a continuous land mass surrounded by some basins, and show on the map that there is an unknown southern continent south of the Indian Ocean (see Geography of Ancient Greece and Rome). It was not until the expedition of British explorer J Cook in the18th century that this mistake was eliminated. In the Geographic Guide, he also proposed two new map projections: conic projection and spherical projection.
Life exploration
From 127 to 15 1, he made astronomical observations in Alexandria. Little is known about Ptolemy's life so far. The main information comes from the relevant records in his handed down works, followed by some statements handed down by writers in the Roman Empire and Byzantine era-usually quite suspicious. In Ptolemy's most important book "Astronomy Masterpiece" (the ancient Arabic translation of astronomy), some astronomical observations made by himself are recorded, which is the most reliable information to determine his life age and work place. The earliest date of Ptolemy astronomical observation recorded in Da Lun is 65438+March 26th, 2027, and the latest date is 14 1 February 2nd. It can be seen that Ptolemy was active in the Roman emperors Hadrian (1 17- 138) and Antoninus (138- 1). The Great Theory is Ptolemy's early work, and he has written many works since then. It can be inferred from these works that Ptolemy was very active in the era of Emperor Hadrian, and he lived until Emperor Marcus (16 1- 180 reigned).
According to the observation records left by Ptolemy, all his astronomical observations were made in Alexandria, Egypt (then under the rule of the Roman Empire). There is a saying that he was born in Ptolemy in Upper Egypt, which may be correct, but this is from later generations (about 1360 at the latest), and there is no circumstantial evidence.
Ptolemy's name contains some speculative information. Ptolemy showed that he was an Egyptian resident and his ancestors were Greeks or Greeks. Claudius showed that he had Roman citizenship, which was probably given to his ancestors by the Roman emperor Claudius (4 1-54) or Nero (54-68).
Ptolemy's works are a collection of ancient Greek astronomical cities, but so far he knows almost nothing about his personal knowledge. Theon's planetary observation data are used in great theories. Some people think that Theon may be his teacher, but this is just a guess. Many of Ptolemy's works are dedicated to a Syrus who doesn't know who he is. Others think that Marinus Fortier of Tyre was Ptolemy's teacher, and Ptolemy used and revised many materials of Marinus in his book Gography. All these circumstances are not enough to determine Ptolemy's successor.
Academic viewpoint
astronomy
In ancient cosmology, people regarded the sky as a lid and the earth as a flat plate supported by pillars.
From the 4th century to the 3rd century BC, the Greeks had two different views on the motion of celestial bodies: one was represented by eudoxus, who explained the motion of celestial bodies from a geometric point of view and decomposed the complex periodic phenomena in the sky into several simple periodic motions; He also designated a circular orbit or a spherical shell for each simple periodic motion. He believes that all celestial bodies move in a uniform circle around the earth, and explains the movement of celestial bodies with 27 spheres. By Aristotle, the number of spheres had increased to 56. The other is represented by Alistair, who thinks that the earth rotates on its own axis every day and revolves around the sun once a year. The sun and stars are stationary, while the planets move around the sun. But Alistair's point of view was not understood or accepted at that time, because it was different from what people saw with the naked eye.
Ptolemy put forward his own theory of cosmic structure in the second century AD, 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 limited sphere, which is divided into two layers: heaven and earth. The earth is in the center of the universe, so the sun and the moon go around the earth and objects always fall to the ground. There are nine equidistant celestial bodies outside the earth, and the order from inside to outside is: Moon Day, Mercury Day, Venus Day, Sun Day, Mars Day, Jupiter Day, Saturn Day, sidereal day Day, Motive Force Day. There is nothing in outer space. Each celestial layer does not move by itself. God drives the celestial sphere, which drives all celestial bodies. The earth where human beings live stands quietly in the center of the universe. Ptolemy inherited Aristotle's geocentric theory in an all-round way, and made use of the accumulated data of predecessors and his long-term observation to write an eight-volume On Greatness. In the book, he expanded Aristotle's nine-story sky to 1 1, changed the dynamic sky into a crystal clear sky, and added the highest sky and clear fire sky outside. Ptolemy imagined that all the planets move around a small circle, and the center of each circle moves on a circle centered on the earth. He called the circle around the earth "even wheel" and each small circle "current wheel". At the same time, it is assumed that the earth is not completely in the center of the even wheel, but at a certain distance, and the even wheel is some eccentric circles; In addition to the above orbits, the sun, moon and planets also go around the earth once a day with the stars. Ptolemy, a mathematical picture that does not reflect the actual structure of the universe, perfectly explained the planetary motion observed at that time, and gained practical value in navigation, which was widely believed by people.
Ptolemy's celestial model has been popular for thousands of years because of its advantages and historical reasons. Its main features are:
1. The uniform angular velocity motion around a center conforms to Plato's hypothesis, which was the dominant idea at that time and also applied to Aristotle's physics, and was easily accepted.
2. The motion position of the planet is predicted by several different combinations of circular orbits, which is quite different from the actual situation. Compared with the previous system, it is improved and can explain the brightness change of the planet.
3. The idea that the earth does not move is a comforting assumption for people's life at that time, and it is also in line with the Christian belief.
Under the historical conditions at that time, Ptolemy's planetary system theory was of progressive significance. First of all, it affirms that the earth is a suspended sphere without columns. Secondly, it is a key step to distinguish the planets, the sun and the moon from the stars, which are a group of celestial bodies close to us.
Ptolemy himself claimed that his system did not have physical authenticity, but was only a mathematical scheme to calculate the position of celestial bodies. As for the church's use and maintenance of geocentric theory, it was more than 1000 years after Ptolemy's death. The reason why the church maintains the geocentric theory is only to distort it to prove the image of heaven and hell on earth depicted in the doctrine. If other doctrines are popular when compiling doctrines, maybe the church will also use them. Therefore, Ptolemy's theory of the universe is not necessarily related to religion.
Ptolemy's astronomical works remained influential in Europe for a long time after they were known to Arab scholars, at least until16th century. Before that, there was no western ephemeris that was not calculated according to Ptolemy theory. Although the precision of ephemeris is improving, the ancient Greek current _ even gear train used by Ptolemy has a function similar to series expansion, that is, in order to increase the calculation accuracy, a small wheel can be added to this current wheel, so that the center of this small wheel can revolve around this current wheel, and celestial bodies can also revolve around this current wheel. As long as the radius, detour direction and speed of the wheels are properly adjusted, the requirements can be met. In theory, the number of small wheels can be continuously increased to achieve higher accuracy, as some astronomers do. But its shortcoming is also obvious, that is, it is too cumbersome. Later, Copernicus abandoned this representation in On the Movement of Celestial Bodies and adopted a more concise Heliocentrism.
geography
In addition to his achievements in astronomy, Ptolemy also made outstanding achievements in geography. He believes that the research object of geography should be the whole earth, mainly studying its shape, size, determination of latitude and longitude and map projection method. He made an astrolabe-like instrument for measuring latitude and longitude (astrolabe) and an angular distance measuring instrument, which is very famous in Europe. Ptolemy has eight volumes of geographical works, six of which are lists of places and locations marked by latitude and longitude. Most of his position seems to be calculated according to the distance between his prime meridian and the horizontal circle expressed in radians, because none of his longitude is determined from astronomy, only a few latitudes are so determined. Ptolemy used the smaller value of the circumference of the earth measured by Bosidoni, which made all his land distances expressed in radians exaggerated, because he set the distance of each radian as 500 Greek miles instead of 600 Greek miles. As a result, the distance between Europe and Asia across the Atlantic seems to be much smaller than Eratosthenes's calculation, which eventually led to Columbus's attempt to sail from the west to Asia. Ptolemy knew the world better than his predecessors. Eratosthenes's map only reached the Ganges River in the east, but Ptolemy knew that there was the Malay Peninsula and the "Silk Country", namely China.
other
Mathematically, he explained the apparent motion of celestial bodies with the combination of circular motions, which was considered absolutely accurate at that time. He also demonstrated the characteristics of quadrilateral, that is, the famous Ptolemy theorem. He also studied optics and thought that when light is refracted, the incident angle of light is proportional to the refraction angle.
Personality assessment
When discussing Ptolemy's historical achievements and influence, we have to talk about some preconceptions that are easy to lead people astray. These prejudices are not the result of academic research, but closely combined with the propaganda activities in some specific periods. So it is widely circulated, and the following two are more important.
The first stereotype is that Ptolemy was just an editor of some ancient scientific documents. By extension, there will naturally be extreme theories such as "big theory", but it is not from hipparchus, and "geography" is just a copy of Marinus' works. According to the research, the origin of this prejudice is probably1The History written by delambre, a French mathematician and historian of astronomy in the early 9th century. This view has long been denied by scholars' research, but it can still be seen in some non-academic reading materials.
The second prejudice is to confuse Ptolemy and Aristotle's different cosmic systems, and then regard them as historical sinners who hinder the development of astronomy. In the works of contemporary history of science, J.Needham's statement that "the concept of rigid concentric crystal ball of Aristotle and Ptolemy has bound European astronomical thought for more than a thousand years" is still repeatedly quoted by many China works. This statement is actually obviously contrary to historical facts. Aristotle did advocate a concentric crystal ball universe system, but Ptolemy didn't use this universe system at all in his works, and he never said that he agreed with this system. On the other hand, Aristotle's theory, which was mainly preserved and handed down by Greek-Arab scholars, was still regarded as a heresy by the Roman church until 13 century and was banned from teaching in universities many times. So Ptolemy or Aristotle could not "fetter European astronomy for more than a thousand years". By 1323, the Pope declared Thomas Aquinas a "saint", and Aquinas' huge scholastic philosophy system was officially recognized by the church and became king James Doctrine. This theory is the synthesis of Aristotle's theory and Christian theology by Aquinas and his teacher AlbertusMagnus. Aquinas used Ptolemy's works to demonstrate geocentric theory and statism when demonstrating the crystal ball universe system. Since then, Aristotle's crystal ball universe has indeed bound European astronomical thought for about two or three hundred years, but this obviously cannot constitute any charges of Ptolemy.
Ptolemy's Motto soon became the standard textbook for studying astronomy in the ancient western world. In the 4th century, Pappus's critical literature and TheonofAlexandria's critical literature appeared. Arabic translation appeared around 800 AD. Later, a more perfect version appeared, which was closely related to Al_Ma'mun, the caliph of Abbasid dynasty who strongly sponsored astronomy. 1 175, the Latin translation of cremona's GerardofCremona from Arabic appeared, and the great theory began to be recognized by western European scholars again. Shortly before this, there was a Latin translation of Greek in Sicily around 1 160, but it may not be well known. These translations, together with some new works based on supremacism from Arabia, greatly improved the level of western astronomy in the13rd century, while in the long Middle Ages, the progress of astronomy in the western world mainly appeared in the Arab world. However, Arab astronomers benefited a lot from Ptolemy's astronomical works.
Engineering overview
Ptolemy wrote four important works: Astronomy, Geography, Four Bibles and Optics. In addition, there are works on chronology and astrology.
almagest
Ptolemy summed up the achievements of ancient Greek astronomy and wrote thirteen volumes of astronomical works. The duration of one year is determined, the catalogue is compiled, the correction caused by precession and refraction is explained, and the calculation method of solar eclipse is given. He used a large number of observations and research results of Greek astronomers, especially Hipparchus (also translated as Iba Valley), and systematically demonstrated various geocentric systems that explained the motion of celestial bodies with eccentric circles or small wheel trains. Later generations named this geocentric system after him, calling it Ptolemaic geocentric system. This masterpiece was an encyclopedia of astronomy at that time, and it was a must-read book for astronomers before Kepler's era.
Astronomical masterpiece, the peak of Greek astronomy and cosmology in the past 500 years, ruled the astronomical world for 13 centuries. Such a book with complicated knowledge cannot be completed by one person. There is no need to hide Ptolemy's dependence on his pioneers, especially Hippocrates. The basic problem he faces is to try to explain the motion of celestial bodies on the premise that the universe is centered on the earth and all celestial bodies run in a completely circular orbit at a uniform speed. Because the actual celestial body moves around the center outside the earth in a variable-speed elliptical orbit, in order to maintain the original basic assumption, some very complicated geometries must be considered. Ptolemy used three complicated original ideas: current wheel, eccentric circle and even wheel. He can give reasonable descriptions of the orbits of Mars, Venus and Mercury respectively, but if they are put in a model, their scales and periods will conflict. But no matter what shortcomings this system has, it still prevailed for 1300 years, and it was not overthrown by Copernicus until 15 century.
Geographical guide
Ptolemy wrote an eight-volume Geographic Guide, which described his map of the world and discussed the principles of astronomy.
In the book Geographic Guide, Ptolemy fully explained how to determine the longitude and latitude lines by mathematical methods. But no meridian is determined by astronomical method, only a few parallels are calculated in this way. He reduced the distance measured on land to 10 degrees and determined the location of the area on this uncertain grid. The distance on the sea is simply a guess. He put Canary Islands 7 east of their real position, so the whole grid positioning can only be wrong. The influence of Geographical Guide on the western world outlook is almost as great and lasting as that of astronomical masterpieces.
The book Geographic Guide was translated into Arabic at the beginning of the 9th century. The inaccuracies recorded in various parts of the Islamic Empire were quickly discovered and replaced by more accurate accounts. The original Arabic translation has been lost, but the direct and indirect influence of this book on Islamic geography is worth noting. The Latin version of Geographic Guide appeared in about 1406, which was translated from Greek by J. Angelus. Because this book even at that time (after publication 1200 years! ) is still the best guide to know the general situation of the world geography, so it quickly became popular. Until16th century,16th century, many advances in cartography provided powerful stimulation. Ptolemy's projector was criticized, which led to the emergence of various new projection methods. The first projection method in geography was criticized in the Map of Europe of Mercator 1554, and the second projection method was criticized more from 15 1 1. But in any case, Ptolemy's Geography Guide provided the world's earliest map projection method with mathematical foundation for future generations.
Modern scholars' detailed research shows that C. Columbus (145 1- 1506) carefully read at least five books before his voyage to change human history, one of which was Ptolemy's Geographic Guide, and the other four were not of the same category. Thus, Columbus's geographical thoughts mainly came from Ptolemy. Ptolemy's position in Asia is closer to the west than it actually is, and the cartographer in Columbus's time inherited his wrong view, otherwise Columbus might not have sailed. Columbus believed that he could reach the east coast of the Asian continent through a short sea crossing route, and as a result, he discovered the new American continent on the east coast of Asia in his vision-although until his death, he still thought that he had discovered the Asian continent painted on the Ptolemy map.
optics
Ptolemy wrote five volumes of Optics, in which the first volume tells about the relationship between eyes and light, the second volume explains the visual conditions and binocular effect, the third volume tells about the reflection of plane and curved mirrors and the apparent diameter of the sun at noon and in the morning and evening, and the fifth volume tries to find out the law of refraction, describes his experiments and discusses atmospheric refraction.
List of works