>He concluded that the device was specifically designed to model "epicyclic" motion in keeping with the ancient Greek notion that celestial bodies moved in circular patterns, called epicycles. (This was pre-Copernicus, so the fixed point around which they moved was believed to be the Earth.)
Slightly tangential, but the whole pre/post-Copernicus narrative seems unlikely to be true to me. At least I find it difficult to believe it wasn't until the 16th century that someone worked this out and everyone prior was of some woefully mistaken (yet suspiciously Christian-aligned) view that the Earth was the center of the universe.
Some of the Ancient Greek philosophers believed that the Sun, and not the Earth, is in the center. For example Aristarchus of Samos and Seleucus of Seleucia.
However, the main problem with most of the achievements of the Ancient Greek Philosophy is that, unlike for logic and mathematics, for theories about natural objects they did not have good methods to determine which of several alternative theories is right.
So in the natural sciences there are a lot of questions about which some Ancient Greek philosophers have guessed the correct answer while others have guessed wrong.
Now we know who was right and who was wrong, but at that time this was non-obvious and in most cases the popularity of the alternative explanations was determined more by the rhetoric skill of their supporters than by their agreement with the observations of nature.
Even when the agreement with observations was actually checked, the methods of measurement were seldom precise enough to allow a non-ambiguous decision between 2 theories.
This also applies to the heliocentric theory and the geocentric theory. Both theories had their supporters, but in the end the geocentric theory became the main theory for almost 2 millennia because it happened to be the theory chosen by Hipparchus and then improved by Ptolemy.
Ptolemy made a more detailed kinematic model of the movements of the bodies in the Solar System, which agreed better with the observations of the planets than all the earlier models, so those were abandoned until Copernicus revived the heliocentric model.
Heliocentrist Aristarchus of Samos lived ~310-230 BCE. Archimedes ~287-212 BCE. They shared a lot of years in common. We know Archi knew about Ari, because of his work The Sand Reckoner [https://en.wikipedia.org/wiki/The_Sand_Reckoner]:
"Archimedes then estimated an upper bound for the number of grains of sand required to fill the Universe. To do this, he used the heliocentric model of Aristarchus of Samos. The original work by Aristarchus has been lost. This work by Archimedes however is one of the few surviving references to his theory...."
I was going to make a similar comment, but you phrased it better than I could have. It's easy to say in hindsight that X knew Y, but there's a big difference between knowing something and just suspecting it.
In fact, at the time the evidence for many models was equally strong. So, based on the limited available evidence of the day it actually would have been incorrect to believe too strongly in any model, even the one that we now know to be better than the others.
If I'm not mistaken, there is quite a bit of evidence that they knew the correct model was with the Sun in the center and they only used epicycles because it was easier to calculate with the tools they had (compass etc).
EDIT: I think the argument is at section "10.12 Seleucus and the Proof of Heliocentrism" of the book.
That's pretty funny, because a book I read about the Copernican revolution says that the prevailing attitude among astronomers during Copernicus' period was the exact opposite. Namely that Heliocentrism was not generally promoted or accepted as an accurate model of the heavens, but did gain acceptance as having a few computation advantages.
In particular, it removed the need for a particular type of epicycle called an Equant. Ironically, the Equant somewhat resembles Kepler's second law, meaning it arguably is a better approximation of reality than Copernicus' circles-only Heliocentric model.
There was no difference between heliocentric and geocentric models (except for philosophical arguments based on false premises) until Newton invented physics and the idea of planets spiraling around through space became clearly impossible due to inertia. Pre-F=ma there could not have been any way to know what was at the "center" because the conceptual tools for privileging a non-rotating frame of reference over rotating ones had not yet been developed.
Also, a heliocentric model still requires epicycles if the orbits in the model aren't elliptical.
I've wondered about that: Why privilege that frame of reference? It seems more intuitive and easier to work with, but do we have a better reason than that?
In a rotating frame of reference, forces appear in the equations that are proportional to the distance from the center. They are the forces necessary to make an object which is stationary in a non-rotating frame go in a circle in the rotating frame. Those forces do not correspond to springs, gravitating bodies or any physical phenomenon, and are called "fictitious forces." Non-rotating frames of references make those forces go away, and that is why they're special.
Russo's book may not be easy to get ahold of (thanks, interlibrary loan!), but it's interesting and solidly-reasoned reading. Ancient Greece did a lot of amazing stuff.
Earth being the center of the universe makes a lot of sense in a naive way, it doesn't feel like the earth is moving. Sat in this chair, I feel as though I am at rest, and when I look at the sky long enough, I see that the stars are moving.
And even with Copernicus's insight, he was still missing some key details which made it harder to believe he had the general idea right. Copernicus modeled the solar system using circular orbits, not elliptical orbits. To fit the observed data to this model, he needed epicycles, just as the geocentric model required.
We even have record of someone reasoning this out of simple observations nearly 2000 years prior. This suggests to me it was known (at least by intellectuals) for a very very long time.
What's funny about Copernicus not understanding that the planets orbits were elliptical is that it must have been clear that the moon's orbit around Earth is. The Antikythera mechanism models an elliptical orbit for it, so it must have been obvious. Now, it's not obvious that the moon's orbit around the Earth is like that of the planets around the Sun, but it doesn't take much imagination to think that orbits are similar in nature regardless of what is being orbited.
> At least I find it difficult to believe it wasn't until the 16th century that someone worked this out and everyone prior was of some woefully mistaken (yet suspiciously Christian-aligned) view that the Earth was the center of the universe.
That was because we do not perceive the Earth moving, but we see the stars move. Nobody could answer objections like why we don't go flying off the Earth if it's spinning. Yet any idiot could take a ball, put a rock or something on it, spin the ball and show you what happens. Why is the Earth itself somehow different? It's like how they knew that stellar parallax should exist, but nobody could measure it, which caused heliocentrism to be lacking evidence for quite a long time because the stars are just that far away that it's tiny.
If you go to the average person now, I think you'll find that most people who accept all this science can't even give full explanations for why.
There's actually a fairly simple explanation for why a heliocentric solar system wasn't superior in antiquity or when Copernicus introduced it: in both the Ptolemaic and Copernican models, the orbits are circular and require complex "epicyclic" motion to account for observation.
A heliocentric model wasn't simpler and more obvious until Kepler introduced elliptical orbits, doing away with epicycles in the heliocentric model. Crucially, elliptical orbits didn't work for the Ptolemaic model. Suddenly, a heliocentric solar system seemed much more elegant and likely.
The theory that the Earth was the center of the universe dates from at least the time of Ancient Greece and is probably more ancient. There's nothing Christian about it, in fact Christian scholars probably took the idea from Ancient Greeks, whom they revered (particularly the Platonists).
There were certainly heliocentric models of the universe proposed before Copernicus, but Copernicus' one was the more well-developed. In some cases we don't even have a model, as such, just some third-hand accounts mentioning that someone thought the sun must be in the center of the universe.
I suspect the most famous example of that is Aristarchos of Samos, for whose heliocentric theory we only know via a very brief and poorly detailed passage in Archimedes' The Sand Reckoner:
You [King Gelon] are aware that "universe" is the name given by most astronomers to the sphere, the centre of which is the centre of the earth, while its radius is equal to the straight line between the centre of the sun and the centre of the earth. This is the common account (τά γραφόμενα), as you have heard from astronomers. But Aristarchus brought out a book consisting of certain hypotheses, wherein it appears, as a consequence of the assumptions made, that the universe is many times greater than the "universe" just mentioned. His hypotheses are that the fixed stars and the sun remain unmoved, that the earth revolves about the sun on the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same centre as the sun, is so great that the circle in which he supposes the earth to revolve bears such a proportion to the distance of the fixed stars as the centre of the sphere bears to its surface.
> The theory that the Earth was the center of the universe dates from at least the time of Ancient Greece and is probably more ancient. There's nothing Christian about it, in fact Christian scholars probably took the idea from Ancient Greeks, whom they revered (particularly the Platonists).
It should be noted that the Ancient Greeks did consider the idea of the Earth moving, but there was no empirical evidence for it. Specifically no parallax as even Aristotle wrote in De Caelo (II.14):
> Again, everything that moves with the circular movement, except the first sphere, is observed to be passed, and to move with more than one motion. The earth, then, also, whether it move about the centre or as stationary at it, must necessarily move with two motions. But if this were so, there would have to be passings and turnings of the fixed stars. Yet no such thing is observed. The same stars always rise and set in the same parts of the earth.
In general, the way I understand it is that most of what the ancients believed about the universe was based on empirical observations. They didn't just come up with some arbitrary theory, they had observations and they were trying to explain them. The epicyclical model persisted all the way to Copernicus (whose model also had epicycles) just because it was so good at predicting future observations.
I think their main axiomatic assumption that was based on their metaphysical beliefs, rather than actual observations, was the assumption that the luminaries must move on circular orbits. Again, to my understanding, they had a mechanistic view of the universe that demanded order and symmetry, and they just couldn't imagine how a planet would move in any other orbit than a circle- hence why they were mystified by the apparent "retrograde" motion of the planets and had to come up with epicycles to model it.
The combination of their axiomatic belief in a mechanistic universe and the limited observations they could make with the naked eye conspired to keep them from a better model.
> The combination of their axiomatic belief in a mechanistic universe and the limited observations they could make with the naked eye conspired to keep them from a better model.
A mechanistic view of the universe, taken up later by Christianity, is what allowed science (in the modern sense) to be created. Contrast it with a worldview in which phenomena occurred because of the will(s) of deity(s).
My point was maybe this had something to do with why it "didn't really catch on." Given how viciously the idea was attacked by the Roman Inquisition as being heretical it was probably not the first time the church encountered the concept.
IIRC, monks were the predominant scribes in the western world pre-printing press. If intellectual ideas didn't conform to religious canon they could've theoretically been nearly completely erased via censorship only to be "newly discovered" by Copernicus etc.
It's more complicated than that. The Church didn't so much "attack" it, as not accept it as a proven fact, and not allow it to be presented as such. They favoured the mathematically equivalent model of Tycho Brahe (which is just a coordinate change from the Copernicus model, unlike earlier geocentric models). They did allow heliocentrism to be presented as an unproven hypothesis.
The heliocentrism model was only proven by the successive efforts of Kepler and Newton. Kepler made it more accurate by formulating his laws of motion (which allow for an elliptical motion and eliminate the last need for epicycles), and Newton showed how Kepler's laws of motion could be derived from F = GMm/d^2. Kepler was a contemporary of Galileo, and Newton came later.
Regarding the treatment of Galileo, Galileo was on very good terms with the Roman Church until he openly insulted geocentrism proponents in a book, and presented the heliocentrism theory as a proven fact. The book is also notable for presenting an incorrect theory of tides, not giving credit to his contemporaries, omitting the more accurate and profound theory of Kepler, and attacking a strawman that nobody was defending (in the sense that the favoured model of the time was Brahe's, and not the complicated epicycles model that Galileo was attacking).
Oh, sorry, I misunderstood. Yes, I think on that you're probably right. See what they did to Gallileo, after all (and maybe also Giordano Bruno, though that's not clear).
I don't reckon it was an easy job to be an astronomer in those days...
Right. So he would've been acutely aware of the implications of his work and how it might be received. Maybe that's why he didn't publish his book until 2 months prior to his death over a decade after completing the first manuscript. AFAIK Protestants are Christians.
The actual truth is not that heroic. But we want hero.
The path is the church did accept we watch from earth but every heaven body revolve around the sun except us. Catholic use this model and very accurately beat the Muslim and the Hans (do not want to use chinese as the fight started in yuan dynasty, Mongolian and Tibetan etc are not Hans) in the Far East precisely of these tables based on actual observation.
This comes from a guy x then his student called kepler pointed out … Newton use Kepler not just a Copernicus model only.
The key is Copernicus is only partially right as the orbit is NOT as he said. It is not circular. and in fact he did not have the details and hence might as well not exist and might not affect the history. That is why his book is ok for many decades after publishing. It is only of the models. And not exactly right like others. the actual path is those who have calculation and a detailed accurate projection which Copernicus did not have.
That revolve around the earth model worked. Not Epicircie.
In truth even today if you observe the sky from earth you cannot just have a solar model. You have the earth factor as well (like the earth minor movement around its axis abd hence North Star change from vega to polar then back to vega). Just solar modal is not right.
Now whilst the looking thru telescope did disturb the worldview. It does not matter.
And it is the attitude of Galileo that is more an issue. The pope is his friend you know well before he is a pope. Teasing him as a joker does not work in those days.
I am not saying C and G is totally wrong. I just say if they were more careful (like C publish his only after his death). And G accept the practical model of using sun as a centre based on actual observation and do not write satire … instead proposing a model that incorporates elliptical orbit, earth role etc but everything revolve around the sun except the earth (then do something about it gradually).
Anyway that is not the history of hero we read. We want drama. We want …
Epicycles were certainly a modelling technique for making predictions. They weren't much of a theory since there was nothing in epicycles about causation -- no explanation of why, just a model for what-where-when.
I'm sure it must have occurred to more than one back then that the planets go around the Sun in elliptical orbits. The Antikythera mechanism even models the elliptical orbit of the moon around the Earth, so it's not farfetched that they could have figured out the rest.
However, convincing all the right "authorities" of the copernican view back then would have been culturally very difficult.
One key element is that heliocentric models where just not as good at making predictions. It took new data for them to finally get to a dominating position.
I agree with you that heliocentrism was a known model in ancient Greece [1], but I believe that the reference was with respect to the functionality of the device, for which we know for certain that it places earth at the center.
Slightly tangential, but the whole pre/post-Copernicus narrative seems unlikely to be true to me. At least I find it difficult to believe it wasn't until the 16th century that someone worked this out and everyone prior was of some woefully mistaken (yet suspiciously Christian-aligned) view that the Earth was the center of the universe.