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Jonathan_Lee comments on The Galileo affair: who was on the side of rationality? - Less Wrong
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Thank you for that informed account of the history.
You mention three times, without attributing it to any contemporary of Galileo, that the telescope "distorted the vision", which is a tendentious description. Given that the military application of the telescope was grasped as soon as the instrument became known, who at the time made this criticism? Did they similarly eschew its terrestrial use for the improvement of vision?
The precise phrasing is deliberately a little tendentious, but the issue of the epistemological status of the telescope was raised by loads of people at the time. For a modern review with heavy footnotes, see eg Galileo, Courtier: The Practice of Science in the Culture of Absolutism, pp 95-100, (though the whole chapter is good)
For example, the first anti-Galilean tract is by Horky in 1610 and focussed mostly on the lack of reliability of the telescope. For another, Magini's letters (confirmed in Kepler and Galileo) write of a "star party" in 1610 where Galileo attempted to convince a number of astronomers of the discovery of the Medician (now Galilean) moons; noone else could see the moons and additionally the telescope produced doubled images of everything more distant than the moon.
There wasn't much dispute about terrestial applications. Under Aristotle's physics everything above the moon is made of different stuff with different physics anyway, so any amount of accuracy when looking at stuff of the four elements doesn't allow one to induct to accuracy in observations of the heavens.
I think these words are rather telling (emphasis in the original, p.96):
And it goes on to show how the dispute was conducted on both sides in terms of status, Galileo getting princes on side by sending them telescopes, and his opponents attacking him because he was succeeding.
That sounds a rather odd argument to make, even at the time. Astronomy from antiquity was founded on accurate observations. Galileo's contemporaries could argue that the telescope wasn't good enough, but hardly that getting a better view of the heavens could reveal nothing new. They were arguing over what could be seen, not that seeing was the wrong thing to do.
Astronomy and epistemology aren't quite the same. Predicting where Saturn would be on a given date requires accurate observation, and nobody objected to Coperniucus as a calculational tool. For example, the Jesuits are teaching Copernicus in China in Chinese about 2 years after he publishes, which implies they translated and shipped it with some alacrity.
The heavens were classically held to be made of different stuff; quintessense (later called aether) was not like regular matter -- this is obvious from the inside, because it maintains perpetual motion where normal matter does not. A lot of optical phenomena (eg. twinkling stars, the surface of the moon) were not seen as properties of the objects in question but properties of regular 4-elements matter between us and them.
By a modern standard, the physics is weird and disjointed... but that is historically how it was seen.
I wonder how current physics will look like if/when GR and QM will be finally unified...
I'd lay my money on their both being recognizable, but QM coming through cleaner than GR. They both pull a lot of weight - a lot more than 16th century physics did.
It's worth noting that Copernicus' use of circular orbits required the use of epicycles to make the theory fit the observations.
Epicycles are sort of like Fourier analysis. Just like you can break down a non-sine function into sine waves, you can break down a non-circular orbit into a combination of circles.
But if you're going to use epicycles anyway, why prefer Copernicus to Ptolemy?
Fewer epicycles means easier calculations. Still, it isn't clear why you should prefer the Copernican system to the Tychonic (the other major contender in Galileo's time) when evaluating based on some mix of accuracy and ease of calculation (if your goal is to know "where Saturn would be on a given date").
Going by wiki, Copernicus' system had more epicycles.
Whoops, you're right. It seems as though Copernicus dropped an equant at the cost of adding even more epicycles. Hardly an unambiguously preferable trade-off.
According to Koestler (The Sleepwalkers) Copernicus just hated Ptolemy's "eccentrics" because a good Platonist God does not do ugly assymetrical work like that. http://en.wikipedia.org/wiki/Deferent_and_epicycle
Do you have a citation for that?
Added: No, this is false. The Jesuits were founded in 1540; Copernicus published in 1542. Francis Xavier proposed sending astronomers to Asia while in Japan in 1552. In the same year he died trying to reach China. I don't think Jesuits learned Chinese until about 1580. One of the first to do so, Matteo Ricci, again asked for astronomers in 1605, which suggests to me that he was not, himself, teaching Copernicus.