How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution by Rick Doble Copyright © 2015 Rick Doble From Doble's blog, DeconstructingTime, deconstructingtime.blogspot.com All pictures and photos are from commons.wikimedia.org How Ptolemy's Geocentric Astronomy Helped Build the Modern World If you took the standard required western history course in college as I did, you learned that about 400 years ago astronomers Copernicus, Galileo and Kepler along with Isaac Newton were key players in the scientific revolution that overturned the cumbersome system of geocentric astronomy. In this outdated system the Sun, moon and stars went around the stationary Earth. Instead these early scientists proved that the Earth and the planets went around the Sun. Known as the Copernican Revolution, it is considered the beginning of the scientific revolution, a new way of thinking which continues to this day and has created our modern world and our modern hi-tech marvels. Well, that story is sort of true, but in hindsight it greatly simplifies the complex path that the scientific revolution took, the path that ultimately led to today's scientific and technological wonders. Specifically it leaves out the fact that the geometry of a geocentric universe and its foremost astronomer, Ptolemy, who perfected the geocentric system, were key players in this new scientific outlook. In fact the discredited geocentric theory was, oddly, essential for building our new scientific/technological world. Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 1 of 11 BACKGROUND OF THE GEOCENTRIC/PTOLEMAIC SYSTEM Over hundreds of years the early ancient Greeks put together a concept of the Solar System as a coherent system of concentric circles -- which was a major advance for Western thought. Later in the 4th century BCE, Plato and then Aristotle decided that the Earth was stationary and at the center of the universe, while the Sun, moon, planets and stars moved in perfect circles -- thought of as concentric spheres -- around the Earth. In the ancient Greek view of the cosmos, the orbits had to be perfect circles since all things in Heaven were considered 'perfect'. Each heavenly object moved with its own uniform motion. http://abyss.uoregon.edu/~js/ast121/lectures/lec02.html Ancient Greek view of the cosmos. However, "the geocentric model of Plato could not explain the retrograde motion of the planets. Around 140 A.D. Ptolemy proposed his refined geocentric model. In the Ptolemaic universe, a planet moves in a small circle called an epicycle, and the center of the epicycle moves along a larger circle around the Earth." http://www.hyperhistory.com/online_n2/people_n2/science_n2/geocentric.html Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 2 of 11 "A simple illustration showing the basic elements of Ptolemaic astronomy. It shows a planet rotating on an epicycle which is itself rotating around a deferent inside a crystalline sphere." Quoted from: http://en.wikipedia.org/wiki/File:Ptolemaic_elements.svg Claudius Ptolemy in his book the Almagest (published around 150 CE) laid out his refined geometry for the movement of the heavenly bodies, based on earlier Greek science and the work of the Greek astronomer Hipparchus. His revised system was quite accurate and this view of the universe lasted for almost 1500 years. Ptolemaic Model Of The Solar System Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 3 of 11 From NASA's Cosmos: By selecting suitable radii and speeds of motion, Ptolemy could use this system of uniform motion around two [ED: perfect] circles to reproduce the apparent motions of the planets with remarkable accuracy. He succeeded so well that his model was still being used to predict the locations of the planets in the sky more than a thousand years after his death. http://ase.tufts.edu/cosmos/view_chapter.asp?id=1&page=1 The problem people had with Ptolemy's cosmology was that it was complicated:The resultant system...seems unwieldy to modern astronomers; each planet required an epicycle revolving on a deferent, offset by an equant which was different for each planet. http://en.wikipedia.org/wiki/Geocentric_model Eventually the new heliocentric science advanced by Copernicus, observed by Galileo, perfected by Kepler and then explained by Newton was easier to calculate. It was accepted in part because it was a more elegant and simpler mathematical solution and once refined was more accurate than the predictions of Ptolemy's system. So what is my argument with all of this you might ask? Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 4 of 11 HOW PTOLEMY'S GEOMETRY WAS A KEY FACTOR IN THE SCIENTIFIC REVOLUTION Ptolemy's system had a large but hidden benefit. The perfect circles that were the key component of his system meant that man-made machines -- first clocks and later engines -- could be easily constructed with circular gears. Ptolemy's system mapped out how mechanical models could be made of the solar system and these machines eventually led to the building of clocks. Yet even before the first astronomical clock was made, the idea of a mechanical universe based on Ptolemy's ideas was widely known. Page from De sphaera mundi The Sphere of the Cosmos (De sphaera mundi) is a medieval introduction to the basic elements of astronomy written by Johannes de Sacrobosco (John of Holywood) [ED: publication date] c. 1230. Based heavily on Ptolemy's Almagest, and drawing additional ideas from Islamic astronomy, it was one of the most influential works of pre-Copernican astronomy in Europe. Sacrobosco's De sphaera mundi was the most successful of several competing thirteenth-century textbooks on this topic. It was used in universities for hundreds of years. Sacrobosco spoke of the universe as the machina mundi, the machine of the world... This concept is similar to the clockwork universe analogy that became very popular centuries later, during the Enlightenment. [ED: my emphasis] http://en.wikipedia.org/wiki/De_sphaera_mundi Around 1264 Campanus of Novara, an Italian astronomer, "wrote a Theorica Planetarum [which] ... included instructions on building a planetary equatorium as well as its geometrical description. The data on planets are drawn from the Almagest [by Ptolemy] and the Toledan Tables of the Arab astronomer Arzachel. Campanus gave precise instructions on using the tables, and made detailed calculations of the distances to the planets and their sizes." http://en.wikipedia.org/wiki/Campanus_of_Novara Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 5 of 11 The Theorica Planetarum has been called "the first detailed account of the Ptolemaic astronomical system... to be written in the Latin-speaking West." Benjamin, Francis Seymour; Toomer, G. J. (1971). Campanus of Novara and medieval planetary theory: Theorica planetarum. Thus, the ancestors of Western clocks were early planetaria, and forerunners of what later became known as astronomical clocks. Fraser, J.T. (1978). Time as Conflict: A Scientific and Humanistic Study. In the middle ages starting in 1364 CE, many astronomical clocks were made throughout Europe. They were both timekeeping instruments and devices that showed the movement of the Sun, moon, planets and the zodiac. See a list here: http://en.wikipedia.org/wiki/Category:Astronomical_clocks Most of the first clocks were not so much chronometers as exhibitions of the pattern of the cosmos ... Clearly the origins of the mechanical clock lie in a complex realm of monumental planetariums... White, Lynn Jr. (1966). Medieval Technology and Social Change. The first documented astrarium clock was completed in 1364 by Giovanni de' Dondi (1318–1388)... The original clock, consisting of 107 wheels and pinions, was lost..., but de' Dondi left detailed descriptions which have survived, enabling the reconstruction of the clock. It displays the mean time, sidereal, or star, time and the motions of the Sun, moon and the five then known planets Venus, Mars, Saturn, Mercury, and Jupiter. It was conceived according to a Ptolemaic conception of the solar system.[ED: my emphasis] http://en.wikipedia.org/wiki/Astrarium Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 6 of 11 "The Prague astronomical clock [above] was installed in 1410...and is the oldest functioning Astronomical clock in the world." Quoted from: http://commons.wikimedia.org/wiki/File:Czech-2013-Prague-Astronomical_clock_face.jpg The Prague clock was built more than 130 years before Copernicus published On the Revolutions of the Celestial Spheres in 1543. The publication of Copernicus' book is considered by some to be the beginning of the modern age, yet was preceded by astronomical clocks starting in 1364 (see above) -- almost 180 years earlier. Explanation of the information on the Prague astronomical clock. Doble, Rick How the Discredited Geocentric Cosmos Was a Critical Component of the Scientific Revolution Page 7 of 11 The design of these mechanical clocks, a huge technological advance for the age, was largely based on Ptolemy's geometry. Clocks eventually became the symbol for the Newtonian age -- the age of the scientific revolution. They helped spawn the idea that God was the great watchmaker. In the history of science, the clockwork universe compares the universe to a mechanical clock. It continues ticking along, as a perfect machine, with its gears governed by the laws of physics, making every aspect of the machine predictable. http://en.wikipedia.org/wiki/Clockwork_universe René Descartes saw "the cosmos as a great time machine operating according to fixed laws, a watch created and wound up by the great watchmaker." http://en.wikipedia.org/wiki/Watchmaker_analogy Gears in a pocket watch.