Ptolemy | Copernicus | Kepler

by Ptolemy, Mikołaj Kopernik, Johannes Kepler

Ptolemy (C. 100-C. 178)
The Almagest

Copernicus (1473–1543)
On the Revolutions of the Heavenly Spheres

Kepler (1571-1630)
Epitome of Copernican IV – V
The Harmonies of the V

Genres: Science, Nonfiction, History, Classics

1085 pages, Hardcover

First published January 1, 1952

About the author

Geocentric model of Greek astronomer and geographer Ptolemy, who flourished in 2nd century at Alexandria, for the universe dominated cosmological theory until the Renaissance.

Ptolemy compiled Almagest , a comprehensive treatise on astronomy, geography, and mathematics, about 150.

The Ptolemaic system dominated medieval cosmology until Nicolaus Copernicus contradicted it.

Claudius Ptolemy (circa 90 – circa 168), a Roman citizen of Egypt, wrote. As a poet, he composed a single epigram in the Anthology. He lived in Egypt under Roman rule. Theodore Meliteniotes proposed possibly correct but late and unsupported birthplace in the town of Ptolemais Hermiou in the Thebaid circa 1360. No reason exists to suppose that he ever lived anywhere else.

Ptolemy authored at least three works of continuing importance to later Islamic and European science. People first knew originally Μαθηματικὴ Σύνταξις, "Mathematical Treatise"). The second Geography thoroughly discusses the knowledge of the Roman world. In the third, known sometimes as the Apotelesmatika (Ἀποτελεσματικά), more commonly as the Tetrabiblos (Τετράβιβλος, and in Latin as the Quadripartitum or four books, he attempted to adapt horoscopes to the Aristotelian natural philosophy of his day.

Reviews

[Jim · Rating 4 out of 5]

I am grateful for the opportunity to read these three classical works on astronomy, one of the seven essentials fields of study of the Trivium and the Quadrivium. I hadn't been exposed to the heavenly bodies since I was a Physics and Math major in the late 60's and early 70's. One of the best things I learned from this reading, is how Copernicus seems to have developed trigonometric results simply using Geometry; wow! But of course, I never was much of a geometrist. So for me, wow! Easy to read, much to learn, I recommend this book.

[Darwin Ross · Rating 3 out of 5]

This volume contains nothing but math problems (geometry, algebra, trigonometry) and, therefore, is unreadable. If one is a mathematician, there are innumerable problems to try and work out, but without working them out, there is little to gain from reading Ptolemy, Copernicus and Kepler, as laid out here.

Still, I gained an overall familiarity with the obstacles faced in formulating a proper understanding of our universe. I also learned that Ptolemy began his treatise by confessing that the heliocentric universe offered a simpler theory than did the geocentric one. Although the principle of "Occam's Razor" was unknown to him, he, nevertheless intuited the principle of parsimony. Had he followed it, he would have saved himself and Copernicus a lot of trouble.

There is a problem revealed, too, in the thinking of the ancients that the heavens were perfect and, so, the planets had to travel paths that were in perfect circles, circles being the perfect geometric shape - unless you count the sphere. This created untold useless effort to conform celestial observations of what heavenly bodies actually did, as opposed to what they ought to have been doing. Copernicus, though realizing that planets moved around the sun, wasted incalculable time and energy trying to fit it all together, with circles upon circles upon circles.

Kepler rescued the whole effort by breaking away from this notion of perfection of the heavens, hitting upon the fact that planetary orbits are elliptical around the sun. Nonetheless, his notions about the planets being placed in their order, due to the ratios of geometric shapes that can fit within one another, and the planets relating to each other, according to musical harmonies (based upon ratios of string lengths, rather than the vibrations that we use today) are erroneous though valiant attempts to prove the heliocentrism of the six (then) known planets.

I don't recommend reading this volume, unless you are a mathematician or an astronomer. Still, I give it high marks for the human intelligence displayed within. Astronomy has come a long way since Ptolemy, Copernicus and Kepler. I now appreciate better what it took to get to where we are. These guys were amazing!

[William Crosby]

Going through my set of "Great Books" although I mostly skimmed this one (lots of formulas and tables of data).

[Dylan · Rating 2 out of 5]

Ptolemy's math checks out, but he assumes bodies of heaven are subject to the same euclidean laws of geometry as objects on earth. dont know why he would do that. Copernicus concedes that his math only works assuming the movements of the celestial bodies to be regular, but fails in ground work that Ptolemy didnt need to cover considering Pltolemy subscribes to an Aristotelian geocentric unmoving earth view. Ptolemy did remark that treating the earth as something that moves would be no more than "a convenient device for computation". Honestly was too bored to finish Kepler.