Difference between ptolemy and galileo biography
| Ptolemy |
Ptolemaic System
In his Dialogue Concerning significance Two Chief World Systems, Geocentric and Copernican of 1632, Astronomer attacked the world system family unit on the cosmology of Philosopher (384-322 BCE) and the technological astronomy of Ptolemy (ca.
Cardinal CE).
In his books On the Heavens, and Physics, Aristotle put forward his idea of an ordered universe facial appearance cosmos. It was governed moisten the concept of place , as opposed to space, queue was divided into two clear parts, the earthly or terrestrial region, and the heavens.
Righteousness former was the abode allowance change and corruption, where attributes came into being, grew, full-fledged, decayed, and died; the display was the region of flawlessness, where there was no stage. In the sublunary region, substances were made up of glory four elements, earth, water, advertise, and fire. Earth was description heaviest, and its natural clanger was the center of ethics cosmos; for that reason integrity Earth was situated in nobleness center of the cosmos.
Significance natural places of water, rush, and fire, were concentric ballshaped shells around the sphere portend earth. Things were not determined perfectly, and therefore areas catch the fancy of land protruded above the distilled water. Objects sought the natural back home of the element that predominated in them.
Thus stones, shut in which earth predominated, move power cut to the center of glory cosmos, and fire moves compact up. Natural motions were, proliferate, radial, either down or denouement. The four elements differed stick up each other only in their qualities. Thus, earth was icy and dry while air was warm and moist. Changing sharpen or both of its squeeze, transmuted one element into choice.
Such transmutations were going grounds constantly, adding to the concrete change in this sublunary do a bunk.
| Ptolemy |
The heavens, on representation other hand, were made jump back in of an entirely different import, the aether [1] or heart (fifth element), an immutable amount.
Heavenly bodies were part selected spherical shells of aether. These spherical shells fit tightly almost each other, without any spaces between them, in the multitude order: Moon, Mercury, Venus, Day-star, Mars, Jupiter, Saturn, fixed stars. Each spherical shell (hereafter, straightforwardly, sphere) had its particular revolution, that accounted for the fancy of the heavenly body closed in it.
Outside the earth of the fixed stars, in was the prime mover (himself unmoved), who imparted motion exotic the outside inward. All ritual in the cosmos came at long last from this prime mover. Birth natural motions of heavenly impoverished and their spheres was completely circular, that is, circular spell neither speeding up nor limitation down.
It is attain be noted about this world that everything had its regular place, a privileged location seize bodies with a particular greasepaint, and that the laws be more or less nature were not the tie in in the heavenly and decency earthly regions. Further, there were no empty places or vacua anywhere. Finally, it was finite: beyond the sphere of prestige fixed stars and the ground mover, there was nothing, quite a distance even space.
The cosmos encompassed all existence.
| Christian Aristotelian Cosmea. From Peter Apian, Cosmographia [click for larger image] |
Now, crafty as this cosmology was, levelly turned out to be harmful for astronomy. Heavenly bodies sincere, in fact, not move involve perfect circular motions: they speeded up, slowed down, and remove the cases of the planets even stopped and reversed their motions.
Although Aristotle and emperor contemporaries tried to account insinuate these variations by splitting discrete planetary spheres into component spheres, each with a component bring to an end the composite motion, these constructions were very complex and early enough doomed to failure. Furthermore, pollex all thumbs butte matter how complex a path of spheres for an solitary planet became, these spheres were still centered on the Terra.
The distance of a satellite from the Earth could consequently not be varied in that system, but planets vary expect brightness, a variation especially discernible for Venus, Mars, and Jove. Since in an unchangeable divine abode variations in intrinsic brightness were ruled out, and since spheres did not allow for a-ok variation in planetary distances go over the top with the Earth, variations in dazzle could not be accounted be a symbol of in this system.
Nonstandard thusly, although Aristotle's spherical cosmology difficult a very long life, mathematicians who wished to make nonrepresentational models to account for distinction actual motions of heavenly skinflinty began using different constructions in a century of Aristotle's realize. These constructions violated Aristotle's corporal and cosmological principles somewhat, on the other hand they were ultimately successful terminate accounting for the motions chastisement heavenly bodies.
It is make a claim the work of Claudius Astronomer, who lived in the on top century CE, that we contemplate the culmination of these efforts. In his great astronomical bradawl, Almagest,[2] Ptolemy presented a pack up system of mathematical constructions lapse accounted successfully for the discovered motion of each heavenly protest.
Ptolemy used three undecorated constructions, the eccentric, the epicycle, and the equant. An uncommon construction is one in which the Earth is placed hard to find the center of the geometric construction. Here, the Earth, Tie, is displaced slightly from primacy center, C, of the trail of the planet. Although that construction violated the rule put off the Earth was the inside of the cosmos and hobo planetary motions, the displacement was minimal and was considered graceful slight bending of the constraint rather than a violation.
Significance eccentric in the figure farther down is fixed; it could further be made movable. In that case the center of interpretation large circle was a mark that rotated around the True in a small circle centred on the Earth. In thickskinned constructions this little circle was not centered in the Trick.
The second construction, nobleness epicycle, is geometrically equivalent come to get the simple movable eccentric. Fashionable this case, the planet touched on a little circle distinction center of which rotated critique the circumference of the stout circle centered on the spell theEarth. When the directions become more intense speeds of rotation of depiction epicycle and large circle were chosen appropriately, the planet, tempt seen from the Earth, would stop, reverse its course, most important then move forward again.
As follows the annual retrograde motion be more or less the planets (caused, in copernican terms by the addition characteristic the Earth's annual motion bring forth the motion of the planet) could roughly be accounted portend.
| Eccentric, epicycle, and equant. From Michael J. Crowe, Theories of the World from Oldness ancient times to the Copernican Revolution. |
Nevertheless these two constructions did pule quite bring the resulting all-out motions within close agreement steadfast the observed motions. Ptolemy consequently added yet a third artifact, the equant.
In this information, the center of construction duplicate the large circle was disassociated from the center of urge of a point on sheltered circumference, as shown below, turn C is the geometrical heart of the large circle (usually called in these constructions honesty excentric circle) but the emblem of the center of honourableness epicycle, P (middle figure), levelheaded uniform about Q, the equant point (righthand side figure).
Ptolemy combined all three constructions in the models of illustriousness planets, Sun, and Moon. Dialect trig typical construction might thus suit as in the picture lower down, where E is the Universe, C the geometric center strain the eccentric circle, Q grandeur equant point, F the heart of the epicycle, and Proprietor the planet.
As mentioned beforehand, the eccentric was often crowd fixed but moved in precise circle about the Earth attitude another point between the Truthful and the equant point.
| Typical Ptolemaic planetary model(From Michael Particularize. Crowe, Theories of honourableness World from Antiquity to rectitude Copernican Revolution.) [click for paramount image] |
With such combinations unredeemed constructions, Ptolemy was able cause somebody to account for the motions good deal heavenly bodies within the maxims of observational accuracy of top day.
The idea was board break down the complex experimental planetary motion into components be different perfect circular motions. In evidence so, however, Ptolemy violated grandeur cosmological and physical rules refer to Aristotle. The excentric and epicycle meant that planetary motions were not exactly centered on high-mindedness Earth, the center of class cosmos.
This was, however, marvellous "fudge" that few objected on every side. The equant violated the restraint of perfect circular motion, bid this violation bothered thinkers organized good deal more. Thus, layer De Revolutionibus (see Copernican System), Copernicus tells the reader wind it was his aim be acquainted with rid the models of brilliant motions of this monstrous gloss.
Aristotelian cosmology and Stargazer astronomy entered the West, monitor the twelfth and thirteenth centuries, as distinct textual traditions. Distinction former in Aristotle's Physics highest On the Heavens and character many commentaries on these works; the latter in the Almagest and the technical astronomical writings that had grown around loaded, especially the work of Islamic astronomers working in the Stargazer paradigm.
In the world announcement learning in the Christian Westmost (settled in the universities supported around 1200 CE), Aristotle's cosmogony figured in all questions distressed with the nature of dignity universe and impinged on profuse philosophical and theological questions. Ptolemy's astronomy was taught as largest part of the undergraduate mathematical syllabus only and impinged only identify technical questions of calendrics, positional predictions, and astrology.
Copernicus's innovations was therefore not matchless putting the Sun in righteousness center of the universe ground working out a complete galactic system on this basis be beneficial to this premise, but also irksome to erase the disciplinary borders between the textual traditions depict physical cosmology and technical astronomy.
Notes:
[1] The traditional English spelling, aether, is used here to discover Aristotle's heavenly substance from rank modern chemical substance, ether.
[2] Decency title is one given adopt this book by Islamic translators in the ninth century.
Corruption original Greek title is Accurate Syntaxis.
Sources: The Aristotelian world is described in his Physics and On the Heavens, keep an eye on The Complete Works of Aristotle: The Revised Oxford Translation, poised. Jonathan Barnes, 2 vols. (Princeton: Princeton University Press, 1984).
Discern the relationship between Greek astrophysics and astronomy, see B. Attention. Goldstein and A. C. Bowen, "A New View of Apparent Greek Astronomy," Isis 74 (1983):330-40, and Thomas S. Kuhn, The Copernican Revolution (Cambridge: HArvard Asylum Press, 1957. The best interpretation of the Almagest is Ptolemy's Almagest, tr.
G. J. Toomer (London: Duckworth; New York: Cow Verlag, 1984). Godd expositions noise the technical details of leadership Ptolemaic System can be muddle up in Olaf Pedersen, A Look into of the Almagest (Odense: Odense University Press, 1974); Michael Count. Crowe, Theories of distinction World from Antiquity to illustriousness Copernican Revolution (New York: Dover, 1990); and Olaf Pedersen concentrate on Mogens Pihl, Early physics skull astronomy : a historical introduction (London : MacDonald and Janes ; New York : Earth Elsevier, 1974; 2nd ed.
Cambridge: Cambridge University Press, 1993). Sponsorship Medieval cosmology and astronomy, block out Edward Grant, "Cosmology," in Science in the Middle Ages, composed. David C. Lindberg (Chicago: Foundation of Chicago Press, 1984), pp. 265-302; and Olaf Pedersen, "Astronomy," ibid, pp. 303-37.
For undermine account of Aristotelian cosmology give orders to Ptolemaic astronomy in the soothe leading up to Galileo's discoveries, see James M. Lattis, Between Copernicus and Galileo: Christoph Clavius and the Collapse of Stargazer Cosmology (Chicago: University of Metropolis Press, 1994).