Would Copernicus have been more convincing if he’d been more accurate?

copernicus
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As a follow-up to yesterday’s post, I was won­der­ing if Copernicus would have been more con­vin­cing if he’d used ellipses in his model instead of circles. By using circles Copernicus had to use epi­cycles like Ptolemy, though not so many. Still, it gave the impres­sion that epi­cycles were neces­sary. If that’s the case then why not have a sta­tion­ary Earth as well? The dis­cov­ery that plan­et­ary motion would be bet­ter described by ellipses didn’t come about till Kepler’s work almost a cen­tury later. As far as the post title goes, I think Dr* T’s Theory #1 applies here: Any tabloid head­ing that starts ‘Is this.…’, ‘Could this be…’ etc. can be safely answered ‘No’

So my post title is a bit of a cliché, but the reason I’ve used it is that if the answer is no, then some­thing strange is hap­pen­ing. More accur­ate is less convincing?

The reason I think that is that Copernicus’ model wasn’t isol­ated from the rest of thought for that period. It used and built on a num­ber of assump­tions of the time. One of those ideas was the cre­ation of the uni­verse by a per­fect being. Another was the idea that a circle was a per­fect shape, derived from clas­sical geo­metry. By telling people the Sun was at the centre of the uni­verse and not the Earth, Copernicus was ask­ing people to make a big shift in their think­ing. A lot of people thought it non­sense. If he’d made the orbits ellipt­ical as well then many people who would have been will­ing to listen to Copernicus’ ideas would have balked at that, redu­cing his poten­tial audi­ence fur­ther. In terms of num­bers, the pop­u­la­tion of math­em­at­ic­ally minded people who could exam­ine his work was small enough already.

If he’d reduced the num­ber of ini­tial read­ers fur­ther, would his ideas have spread enough for oth­ers to pick them 50 years later? It’s impossible to say, but if Copernicus hadn’t given Kepler the idea of a put­ting the Sun at the centre of uni­verse, could Kepler have dis­covered it inde­pend­ently? It’s hard to say but, given how Kepler struggled with let­ting go of circles and using ellipses, I think it’s unlikely.

This is why I’m wary of his­tor­ies of sci­ence that are purely about who got it right and who got it wrong. Copernicus’ use of circles isn’t ‘right’, but it was neces­sary at the time.

I’ve «cough» bor­rowed the por­trait of Copernicus from Prof Reike’s page on Copernicus. It’s well worth vis­it­ing if you want to find out more about the astronomer.

You can read more about Kepler’s dis­cov­ery of the ellipt­ical path of plan­ets at:
Boccaletti 2001. From the epi­cycles of the Greeks to Keplerʼs ellipse — The break­down of the circle paradigm

Copernicus and the Star that was bigger than the Universe

The constellation Delphinus
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I’ve been try­ing to watch Cosmos by Carl Sagan. I’ve never seen it and it’s prov­ing to be a bit of a struggle. He def­in­itely can write. Some of the sequences are fant­astic, but some of it is badly dated. The thing that really grates to me is his dis­missal of Ptolemy and his geo­centric uni­verse. For Sagan at best Ptolemy’s sys­tem held back astro­nomy by 1,500 years. At worst he’s only worth men­tion­ing to say he’s dead wrong, like in the first episode.

It’s not really fair to lay into Sagan for his atti­tude to Ptolemy. His work is a product of its time and it was writ­ten over thirty years ago. But the idea that Ptolemy was clearly wrong seems to the pop­u­lar under­stand­ing of Renaissance astro­nomy. The ques­tion here is Why did some people oppose the helio­centric the­ory of the uni­verse? not Who in their right mind would accept it? It over­looks the power of the Ptolemaic sys­tem. If you fol­lowed Ptolemy’s work you could pre­dict where the plan­ets would be with enough accur­acy for naked-eye astro­nomy. If Copernicus had only used simple circles, then his model might have seemed bet­ter, but he too needed to add epi­cycles and fudges to make his sys­tem match the observ­able sky. It needed fewer epi­cycles, but it was hardly perfect.

Popular belief is that the prob­lem was solved when Galileo picked up his tele­scope and proved the helio­centric the­ory. In fact a recently pub­lished paper by Christopher Graney, The Telescope Against Copernicus: Star Observations by Riccioli Supporting a Geocentric Universe in the Journal for the History of Astronomy shows that the tele­scope could have dealt a ser­i­ous blow to the Copernican model of the uni­verse.
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Sun Symbolism and Cosmology in “Michelangelo’s Last Judgment” by Valerie Shrimplin

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[Cross-posted to Revise & Dissent]

Valerie Shrimplin’s Sun Symbolism and Cosmology in “Michelangelo’s Last Judgment” is a dif­fi­cult book to write about. I like it, but it tackles such a var­ied range of sources that it raises a lot of intriguing ques­tions. Certainly more than can be covered in one blog post so, for now, I’ll leave them for a later post. For now I’ll start from the pop­u­lar, if incor­rect, view of the arrival of Copernicanism.

Sometime in the 16th cen­tury Nicolaus Copernicus dis­covered that con­trary to the teach­ings of the church, the Earth went round the Sun. Fearing con­dem­na­tion by the Church he refused to pub­lish his the­ory until his death. The next day Galileo buys a copy of the book and is inspired to dis­cover Jupiter’s moons with a tele­scope. This proves Copernicus’s the­ory and he tells the world about it. In the Vatican all hell breaks loose, fig­ur­at­ively speak­ing. The Inquistion is sent to deal with Galileo, much to his sur­prise, and so the church becomes an army of dark­ness in the War for Enlightenment.

The above is non­sense, but per­haps a fair ste­reo­type of the Science vs. Religion battle that con­tin­ues to this day. So what would it mean if there was a depic­tion of a helio­centric uni­verse in the Sistene chapel dat­ing from the six­teenth cen­tury in full view of everyone?

The Last Judgement
The Last Judgement: Image from Wikipedia.

In the midst of all assuredly dwells the Sun. For in this most beau­ti­ful who would place this luminary in any other or bet­ter pos­i­tion from which he can illu­min­ate the whole at once? Indeed, some rightly call Him the Light of the World, oth­ers, the Mind or ruler of the Universe: Trismegistus names him the vis­ible God, Sophocles’ Electra calls him the all-seeing. So indeed the Sun remains, as if in his kingly domin­ion, gov­ern­ing the fam­ily of Heavenly bod­ies which circles around him.

Shrimplin begins her book with this quote which could be read as a descrip­tion of Michelangelo’s Last Judgement. It’s not. It’s from De revolu­tionibus orbium coe­les­tium. Ok, so Michelangelo could have been inspired by Copernicus. The prob­lem is that Michelangelo fin­ished his paint­ing in 1541 and De Revolutionibus was not pub­lished until 1543.
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The Michelangelo Code

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The Last Judgement - Michelangelo
Last Judgement. Fresco in the Sistene Chapel by Michelangelo.

IN THE MIDST OF ALL assuredly dwells the Sun. For in this most beau­ti­ful who would place this luminary in any other or bet­ter pos­i­tion from which he can illu­min­ate the whole at once? Indeed, some rightly call Him the Light of the World, oth­ers, the Mind or ruler of the Universe: Trismegistus names him the vis­ible God, Sophocles’ Electra calls him the all-seeing. So indeed the Sun remains, as if in his kingly domin­ion, gov­ern­ing the fam­ily of Heavenly bod­ies which circles around him.

The most inter­est­ing talk of the NAM his­tor­ical ses­sion was the excel­lently titled Michelangelo Code. Valerie Shrimplin based her talk on part of her PhD thesis Sun Symbolism and Cosmology in Michelangelo’s ‘Last Judgement’ avail­able from Truman State University Press. It tackles some­thing that ini­tially doesn’t seem to be a prob­lem. She also cov­ers this in her paper of the same title in the Sixteenth Century Journal (Vol 21.4 1990 pp 607–44 JSTOR) which I’ve lif­ted the above quote from. The text above seems a reas­on­able descrip­tion of Michelangelo’s Last Judgement. In fact it’s from De Revolutionibus, by Nicholas Copernicus describ­ing his helio­centric cos­mo­logy. Did Michelangelo paint Copernicus’s heav­ens in the Sistine Chapel?

It seems unlikely. De Revolutionibus was pub­lished two years after Michelangelo fin­ished the chapel. After Copernicus’s death helio­centri­cism became con­tro­ver­sial. It could be accep­ted as a math­em­at­ical device, but as a rep­res­ent­a­tion of real­ity, which is how Michelangelo uses it, it would later be seen as heresy. The accep­ted explan­a­tion is that Michelangelo came to place Christ in a cent­ral pos­i­tion inde­pend­ently, but this is an odd explan­a­tion when you look at other depic­tions of the Last Judgement and what it is sup­posed to do.
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