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"The Great Ptolemaic Smackdown" pops up often on the web, but it is completely dishonest. Its arguments are “it was not proven then” and „Galileo wasn‘t skilfu

by acqq 7y ago

"The Great Ptolemaic Smackdown" pops up often on the web, but it is completely dishonest. Its arguments are “it was not proven then” and „Galileo wasn‘t skilful enough not to insult the pope.” It also intentionally misleadingly avoids to show to the readers the actual papers and sentence made by inquisition which are preserved and completely disprove the quasi-arguments.

throw0101a 7y ago
How was the Copernicus' model any better than Ptolemy's? Over the course of 1500 years after Ptolemy's publication there were more accurate measurements, so Copernicus threw in more epicycles to have the model better match observations, but that's just another layer of indirection. But how are C's epicycles any less 'ad hoc' than P's? They hardly look any different, at least to a layman: * http://astro-andy.eu//img/the_solar_system_of_mlp_ptolemaic.jpg http://astro-andy.eu//img/the_solar_system_of_mlp_ptolemaic.... * https://casswww.ucsd.edu/archive/public/tutorial/images/history/epicycles.gif https://casswww.ucsd.edu/archive/public/tutorial/images/hist...
- mannykannot 7y ago
  You have a point, but the most useful answer is that science does not work that way, in practice. By the time the textbooks are written, a clear answer has emerged, but science happens in the time when there are competing theories. The significance of Copernicus was that he was on the right track to a greater understanding than any refinements to epicyclic heliocentric models would likely achieve.
  - throw0101a 7y ago
    Copernicus' shift in think was certainly his major contribution to the field (IMHO). And Galileo was certainly gifted in many things (being a bit of a poly-math, as many were at that time: art, medicine, optics), but I'm not sure what value he added to the cosmological conversation. Kepler published his defense of the Copernican system in 1596. He then published his first two laws in 1609 using Brahe's (pre-telescopic?) observations; the first patent for the telescope was in 1608. So even by then things were moving toward what 'reality' actually is. More generally, I think that the 'Galileo affair' is portrayed as being a bigger deal than it actually was. I also think that people underestimate how much "politics" was a blood sport at that time.
    - Symmetry 7y ago
      The discovery of moons orbiting Jupiter was certainly a strong piece of evidence that Jupiter and Earth were the same sort of thing, planets.
    - mannykannot 7y ago
      The popular story has cetainly inverted the significance of Galileo and Kepler to the scientific story. The rise in prominence of Galieo's story is partly due to its use in anti-clerical, and often specifically anti-catholic, rhetoric in the 18th. and 19th. centuries.
- acqq 7y ago
  > They hardly look any different, at least to a layman: That is argument for what exactly? That only "proves" that the layman can't understand something that is "hard". "Math is hard, lets go shopping" argument. Galileo didn't have to simply "believe" Copernicus, he was physically the first man ever to see the moons of Jupiter with this own eyes, using the telescope he made with this own hands. The mere existence of these moons was completely against the church doctrine, explicitly stated by the Inquisition in the official sentence with which he was sentenced: "the above-mentioned Galileo, because of the things deduced in the trial and confessed by you as above, have rendered yourself according to this Holy Office vehemently suspected of heresy, namely of having held and believed a doctrine which is false and contrary to the divine and Holy Scripture: that the sun is the center of the world and does not move from east to west, and the earth moves and is not the center of the world, and that one may hold and defend as probable an opinion after it has been declared and defined contrary to Holy Scripture."
- DiogenesKynikos 7y ago
  There are several important reasons why Galileo found Copernicus' heliocentrism more compelling than Ptolemy's geocentrism. First off, you have to understand the intellectual background. Aristotelian physics dominated Europe at the time. Aristotle held the Earth to be separate from the heavens, with the heavens being the realm of perfect forms. All imperfect objects seek to move to the center of the Universe, which is the center of the Earth, while perfect objects move in circles in the heavens. This was the intellectual foundation of geocentrism. Galileo was the first human in history to point a telescope at the sky, and what he saw fundamentally undermined Aristotelian physics. The Moon is not a perfect form: it has mountains, just like the Earth. Not everything revolves around the Earth: Jupiter has its own moons that orbit it. The Sun is also not perfect: it has spots. Galileo also did mechanical experiments that demonstrated the principle of inertia (Newton's first law), which further undermined Aristotelian physics. With Aristotelian physics out the window, the strong intellectual bias towards geocentrism was also gone. Until Galileo's telescopic observations, he himself had been a geocentrist, like most people. If you then look at geocentrism and heliocentrism with fresh eyes, there are a lot of appealing aspects of heliocentrism. * Geocentrism needs epicycles to explain even the most basic elements of planetary motion (retrograde motion). Heliocentrism already explains retrograde motion without any epicycles. Not only that, but heliocentrism correctly predicts exactly where (in relation to the Sun) retrograde motion occurs. In the geocentric model, retrograde motion could occur anywhere, but in the heliocentric model, it has to occur when planets are opposite the Sun, and lo and behold, that's exactly where it occurs. * The Jovian system and the Earth-Moon system also suggest that small objects orbit larger objects, according to some as-of-yet (at Galileo's time) undiscovered principle. Why would the Sun (which was then known to be much larger than the Earth) orbit the Earth? * The phases of Venus decisively rule out Ptolemy's model. In order to save geocentrism, you have to invent some weird geo-heliocentric hybrid model (Tycho's model). To many people, a pure heliocentric model was much more appealing, and the hybrid model appeared to be an awkward attempt to save some of geocentrism.

by acqq 7y ago

throw0101a 7y ago

How was the Copernicus' model any better than Ptolemy's? Over the course of 1500 years after Ptolemy's publication there were more accurate measurements, so Copernicus threw in more epicycles to have the model better match observations, but that's just another layer of indirection. But how are C's epicycles any less 'ad hoc' than P's? They hardly look any different, at least to a layman: * http://astro-andy.eu//img/the_solar_system_of_mlp_ptolemaic.jpg http://astro-andy.eu//img/the_solar_system_of_mlp_ptolemaic.... * https://casswww.ucsd.edu/archive/public/tutorial/images/history/epicycles.gif https://casswww.ucsd.edu/archive/public/tutorial/images/hist...

mannykannot 7y ago
You have a point, but the most useful answer is that science does not work that way, in practice. By the time the textbooks are written, a clear answer has emerged, but science happens in the time when there are competing theories. The significance of Copernicus was that he was on the right track to a greater understanding than any refinements to epicyclic heliocentric models would likely achieve.
- throw0101a 7y ago
  Copernicus' shift in think was certainly his major contribution to the field (IMHO). And Galileo was certainly gifted in many things (being a bit of a poly-math, as many were at that time: art, medicine, optics), but I'm not sure what value he added to the cosmological conversation. Kepler published his defense of the Copernican system in 1596. He then published his first two laws in 1609 using Brahe's (pre-telescopic?) observations; the first patent for the telescope was in 1608. So even by then things were moving toward what 'reality' actually is. More generally, I think that the 'Galileo affair' is portrayed as being a bigger deal than it actually was. I also think that people underestimate how much "politics" was a blood sport at that time.
  - Symmetry 7y ago
    The discovery of moons orbiting Jupiter was certainly a strong piece of evidence that Jupiter and Earth were the same sort of thing, planets.
  - mannykannot 7y ago
    The popular story has cetainly inverted the significance of Galileo and Kepler to the scientific story. The rise in prominence of Galieo's story is partly due to its use in anti-clerical, and often specifically anti-catholic, rhetoric in the 18th. and 19th. centuries.
acqq 7y ago
> They hardly look any different, at least to a layman: That is argument for what exactly? That only "proves" that the layman can't understand something that is "hard". "Math is hard, lets go shopping" argument. Galileo didn't have to simply "believe" Copernicus, he was physically the first man ever to see the moons of Jupiter with this own eyes, using the telescope he made with this own hands. The mere existence of these moons was completely against the church doctrine, explicitly stated by the Inquisition in the official sentence with which he was sentenced: "the above-mentioned Galileo, because of the things deduced in the trial and confessed by you as above, have rendered yourself according to this Holy Office vehemently suspected of heresy, namely of having held and believed a doctrine which is false and contrary to the divine and Holy Scripture: that the sun is the center of the world and does not move from east to west, and the earth moves and is not the center of the world, and that one may hold and defend as probable an opinion after it has been declared and defined contrary to Holy Scripture."
DiogenesKynikos 7y ago
There are several important reasons why Galileo found Copernicus' heliocentrism more compelling than Ptolemy's geocentrism. First off, you have to understand the intellectual background. Aristotelian physics dominated Europe at the time. Aristotle held the Earth to be separate from the heavens, with the heavens being the realm of perfect forms. All imperfect objects seek to move to the center of the Universe, which is the center of the Earth, while perfect objects move in circles in the heavens. This was the intellectual foundation of geocentrism. Galileo was the first human in history to point a telescope at the sky, and what he saw fundamentally undermined Aristotelian physics. The Moon is not a perfect form: it has mountains, just like the Earth. Not everything revolves around the Earth: Jupiter has its own moons that orbit it. The Sun is also not perfect: it has spots. Galileo also did mechanical experiments that demonstrated the principle of inertia (Newton's first law), which further undermined Aristotelian physics. With Aristotelian physics out the window, the strong intellectual bias towards geocentrism was also gone. Until Galileo's telescopic observations, he himself had been a geocentrist, like most people. If you then look at geocentrism and heliocentrism with fresh eyes, there are a lot of appealing aspects of heliocentrism. * Geocentrism needs epicycles to explain even the most basic elements of planetary motion (retrograde motion). Heliocentrism already explains retrograde motion without any epicycles. Not only that, but heliocentrism correctly predicts exactly where (in relation to the Sun) retrograde motion occurs. In the geocentric model, retrograde motion could occur anywhere, but in the heliocentric model, it has to occur when planets are opposite the Sun, and lo and behold, that's exactly where it occurs. * The Jovian system and the Earth-Moon system also suggest that small objects orbit larger objects, according to some as-of-yet (at Galileo's time) undiscovered principle. Why would the Sun (which was then known to be much larger than the Earth) orbit the Earth? * The phases of Venus decisively rule out Ptolemy's model. In order to save geocentrism, you have to invent some weird geo-heliocentric hybrid model (Tycho's model). To many people, a pure heliocentric model was much more appealing, and the hybrid model appeared to be an awkward attempt to save some of geocentrism.