In the Previous Postfound here, we saw that the geocentric/geostationary model of the world was not only not unreasonable, but was the best fit for the empirical data that was then available. Inter alia, you could see the stars and planets moving around the earth!
Oresme subverted that evidence in 1377 in his Livre du ciel et du monde, with an argument from relativity of inertial reference frames. Whether the Earth were turning and the heavens stood still or vice versa, everything would look the same. He also proposed "common motion" to counter the Argument of the Winds. None of these arguments were conclusive and Oresme lacked the sort of instrumentation that might have provided him with better information or the conceptual lumber (inertia, forces, ...) that would have let him frame the issue.
The main obstacle to the revolution of the Earth was the lack of stellar parallax. Copernicus (among others) proposed that the stars were really far away and thus the parallax would be too small to see with the naked eye. But this was saving one unproven hypothesis by throwing in a second unproven hypothesis. The stars could not possibly be as far away as Copernicanism required because then, given their visible disks, elementary geometry required the stars to be of such enormous size as to dwarf the solar system. Tycho (among others*) thought this absurd, as it would mean an entire class of new entities. The Copernicans answered by saying "Goddidit!" “Who cares how big the stars are?” wrote Christoph Rothmann, since an infinite Creator God is far bigger still.
"Father of..." this or that. Those who get credit are typically lucky, more astute in PR, or
standing on someone's shoulders. The best of them, like Newton, will tell you so.
Notice, en passant, that it was the Earth being stationary that mattered, not it's being 'in the center.' The ancients and [especially] the medievals, saw the Earth as being in the bottom of the world, the most ignoble place. That's why Copernicanism was supported by humanists but opposed by physicists. It elevated Earth (and humans) to a higher position in the universe.
1. The Magnificent Seven.
Now, in case you’re keeping tabs, there were by this time no less than seven models in play in the early 1600s:
- Heraclidean. Geo-heliocentric. Mercury and Venus circle the Sun; everything else circles the Earth.
- Ptolemaic. Geocentric, stationary Earth.
- Copernican. Heliocentric, pure circles with lots of epicycles.
- Gilbertian. Geocentric, rotating Earth. (proposed by William Gilbert in De magnete)
- Tychonic. Geo-heliocentric. Sun and Moon circle the Earth; everything else circles the Sun.
- Ursine. Tychonic, with rotating Earth.
- Keplerian. Heliocentric, with elliptical orbits.
|Physics deals with the abstracted properties |
of physical bodies; mathematics, with the
abstracted properties of ideal bodies.
Standing against all of these was Aristotelian physics, which saw no justification for the epicycles and other foo-foo in Ptolemaic and Copernican astronomy, for the spinning Earth of the Gilbertian and Ursine models, the sun-centeredness of the Copernican and Keplerian models, or for the gimcrackery of the Heraclidean, Tychonic, or Ursine models. Lofty physicists, who were, you know, scientists, looked down on mere astronomers, who were simply mathematicians.
At this point in our story, Ptolemy is still ahead. Tycho has few adherents. Copernicus has even fewer adherents (mainly humanists, not astronomers) and most of those who adopt it, do so on instrumentalist grounds. No one can make sense out of Kepler's math. Ursus and Gilbert seem stuck in the starting gate, since their spinning earths are a major stumbling block.
|In case you've forgotten: a comparison of the actual Ptolemaic and Copernican models.|
after drawings by Stahlman appearing in de Santillana (1955) pp 32-33.
Because astronomy was (along with optics and music) a specialized branch of mathematics, there was no compelling reason why a mathematical device like sun-centeredness or epicycles ought to be physically real. All that was necessary was that the math made accurate predictions. But with the rise of mystical Platonic woo-woo -- mathematical elegance implies physical reality -- even the Ptolemaics are beginning to think in physical terms.
The Aristotelians were aware of what we now call the Duhem-Quine Thesis, and knew that multiple, incompatible models can account for the very self-same data.
The Tychonic model, based as it was on spanking new data, blew away the Heraclidean model. One down, six to go! But to decide among the remainder required not simply new data, but new kinds of data.
2. The Far-Seeing Look-Glass
|Before telescopes. Science hating Catholic science-haters |
cleverly built their churches to include solar observatories.
These projected solar images onto 'meridian lines' like this one
showing a solar eclipse at S.Maria degli Angeli in Rome
(photo by Mario Catamo)
By 1608, people are playing with the new concave lenses, and toy look-glasses are showing up at fairs for the amusement of children. The delightfully-named Johann Philipp Fuchs von Bimbach, chief political advisor to Joachim-Ernst, Margrave of Ansbach, visits the autumn Fair in Frankfurt where a Dutch peddler offers to sell him a look-glass. (This is two weeks before Lipperhey will present his look-glass in Den Haag.) The instrument has a cracked lens and the price is exorbitant, so Fuchs von Bimbach declines purchase; but on his return to Ansbach he tells the court astronomer, Simon Mayr (a.k.a. "Marius") of the incident and sketches diagrams of the lenses. Unable to get suitable lenses ground in Nürnberg, they import a look-glass from Holland. (Later they purchased superior lenses from Venice and built their own telescope.)
July 1609. Galileo, a math professor in Padua, in the Republic of Venice, hears of these toy telescopes at a Venetian fair. He rushes to obtain one, but the vendor has gone. However, Galileo is a skilled lens-grinder who sells spectacles on the side, so he decides to 'roll his own' and the 'scopes he makes are among the best. (Kepler will later write to him asking for one, but Galileo in customary fashion never responds. Galileo does give a telescope to the Bavarian Elector; the Elector in turn lends it to Kepler in Prague. Kepler, also an expert in optics, eventually designs a superior model.)
People turn their look-glasses on the sky and the Gosh-Wow-Look! Era of astronomy begins.
|Tom Harriot and his Secret Diary|
One of the Jesuit astronomers in Rome, Giovan Paulo Lembo, independently notes the irregularity of the Moon's surface (and the starry composition of the Milky Way and the nebulae) using a telescope he has built himself.
|I'll be Doge-gone! Hoping for a government grant, |
Galileo demonstrates the look-glass to the Doge.
|Galileo sees a moon, and draws it with the eye of an artist.|
Seeing mountains on the moon was not as easy as just look-see. Telescopic images back then were not that clear, nor did they have a wide field of view. Wallace discusses Galileo’s reasoning process in The Modeling of Nature, (Wallace 1996) pp. 334-336.
Speaking of artists, Galileo's friend Lodovico Cigoli will portray the Moon as irregular and pockmarked in a fresco he paints the very next year. It is a painting of Mary robed in the Sun and standing upon a cratered Moon, and it is in the Pauline chapel in the Vatican.
Detail: Immacolata, by Cigoli, 1611. fresco.
Annus Mirabilis7 Jan. 1610. Galileo discovers the first three moons of Jupiter. One freaking day later, Simon Marius, court astronomer in Ansbach-Franconia, discovers them independently. (The fourth moon, which had been hiding, shows up shortly after.) This will later cause trouble. Wait for it.
Mar. 1610 While Marius continues to make painstaking observations, Galileo names the moons the Medician Stars after Grand Duke Cosimo di Medici and his brothers (Cosimo, Francesco, Carlo, and Lorenzo) and rushes his Sidereus Nuncius* into print with the His Serene Highness’ blessings. By some wild coincidence, this wins him a court appointment as the Duke's court philosopher and a salary from the Medicis. Go figure.
The appointment as 'philosopher' ticks off the real philosophers. Galileo is only a mathematicus, and holds no doctorate.
The book is a sensation.
|Johnny Kepler: Wish I had me|
one o' them look-glasses. Mebbe
I can make my own....
My dear Galileo, I must tell you what occurred the other day. My friend the [delightfully-named] Baron Wakher von Wachenfels drove up to my door and started shouting excitedly from his carriage: 'Is it true? Is it really true that he has found stars moving around stars?'
-- quoted in de Santillana, Grigorio. (1955) p. 10
Lunar mountains? Jovian moons? Hooray for Copernicus! Down with Ptolemy!
But that Jupiter has moons does not prove that the Earth circles the Sun. It only proves that not everything directly circles the Earth – and Tycho had already dealt with that. (When you think on it, the Jovian moons are on epicycles!) The physics problem is less about the Earth's position than it is about its motion.
|Chris Clavius. Thank him|
next time you use a calendar.
The Jesuits Odo van Maelcote and Giovanni Paolo Lembo have been making telescopic observation of their own even before Galileo had published his pamphlet. Lembo knows his telescope is not powerful enough either to confirm or to refute Galileo’s claims and tries to construct a more powerful one; but he fails in his attempt to grind and polish the necessary lenses -- a problem that will bedevil many of the telescopic pioneers.
Galileo's discoveries -- if confirmed -- are a punch in the Aristotelian nose, but do not lay a glove on Ptolemaic astronomy. But try telling that to Galileo.
The Last Hurrah of Claude Ptolemy.
|Ptolemy sez: Awshit. But I|
had a good run of attaboys!
Oct. 1610. Kepler tells Galileo that many looking through the look-glass (e.g. Martin Horky) have not seen the Medicean stars. Is Galileo pranking everyone? But other astronomers are already making the same discoveries. Harriot in England sees the Jovian moons in October, as does Kepler using his borrowed instrument. Kepler publishes his own telescopic observations of the moons in Narratio de Jovis Satellitibus, calling them 'satellites.'
Nov. 1610. De La Vette and de Peiresc see the moons in different regions of France.
Dec. 1610. Christoph Grienberger,* the senior mathematician at the Collegio after Clavius (and soon to be his successor) had been absent at the time of Galileo’s publication. Now he returns to Rome and he and Lembo construct a suitable instrument with which they confirm all of Galileo’s claims. Fr. Clavius writes his friend immediately to inform him of this vital corroboration.
stars can be tracked over time by making adjustments on only one axis.
Dec. 1610. In a letter to his former student Castelli, Galileo writes that those not convinced of the truth of Copernicus -- even before the discovery of the phases of Venus -- are bookish philosophers who care only for the empty applause of the vulgar crowds.* He was a charmer, all right. Lacking empirical evidence, he wants Copernicanism accepted on faith.
|The phases of Venus (bottom)|
also: Saturn has handles.
The Ptolemaic model does predict phases for Venus, but not this phase! The Ptolemaic model has been decisively falsified and immediately goes down for the count, dragging the Gilbertian model with it. Two thousand years of scientific consensus is tossed on the ash heap of history.
But the phases of Venus are also predicted by the Tychonic/Ursine models.
Three down, four to go.
1611. Galileo parties hearty.Galileo did not like to leave his villa, except to go to his townhouse in Florence. He suffered from a form of rheumatism that often had him bed-ridden. In his whole life, he made only six trips to Rome. His first, as a youth of 23, was made in 1587 to put his name about and meet the movers and shakers in mathematics. Among those he met were Christoph Clavius and Roberto Bellarmino. The latter, while lecturing on cosmology at the University of Louvain, had trashed the notion of the 'crystaline spheres' and proposed that space was a liquid. Both men took a liking to the young math teacher and his first papers, and Clavius in particular boosted him, becoming a friend and mentor.
Now at age 47, an accomplished mathematicus, Galileo asks permission(*) of the Grand Duke to visit Rome a second time to flog his book about the Medicean Stars (hint-hint). The Duke is assured that both the head of the Roman College (Clavius) and the Imperial Mathematician (Kepler) have endorsed the findings and that the trip will no doubt enhance the Grand Duke's stature. Permission is duly granted.
courtier and couldn't travel without Ducal permission.
26 March. Galileo arrives in Rome, calls on his friend Cardinal de Monte, and presents his bona fides from the Grand Duke.
30 March. Galileo drops in at the Roman College to shmooze with Clavius, Lembo, Grienberger, Maelcote and the others Jesuits, whom he finds entirely supportive. They had begun regular observations of the Medicean stars two months earlier and, comparing notes, found them in complete agreement with Galileo’s observations. Grienberger had done optical calculations that indicated the telescopic lenses might distort the images, but improved lenses had dispelled his doubts.
2 April. Galileo meets with Cardinal Maffeo Barberini, who writes to the Medici immediately afterward that he would be delighted to help Galileo in any way in his power. Keep an eye on Maffeo.
14 April. Federico Cesi throws a party in Galileo’s honor in the vineyard of Monsignor Malvasia high atop the Janiculum, the tallest of the Roman hills. The guests include Fr. Johann Schreck from the Swiss, Jan van Eyk from the Low Countries, and Joannes Demisiani from Greece, and others. Van Eyk and Cesi are Lynceans. Galileo and Schreck will be before the year is out. Before dinner, they use a look-glass to spy the Lateran Palace across the Tiber, reading the inscriptions and counting the windows. After dinner, they observe the moons of Jupiter. In between, either Demisiani or Cesi himself suggest a Greek name for the look-glass: telescope. It caught on.
Aristotelian physicists refusing to look through the scopes.
I know that Your Reverences are aware of the new celestial observations by a worthy mathematician using an instrument called a canone or ochiale. By means of this instrument even I have seen some very marvelous things concerning the Moon and Venus, but I wish that you would do me the pleasure of telling your sincere opinion of these things.... I hear various opinions spoken about these matters and Your Reverences, versed as you are in the mathematical sciences, will easily be able to tell me if these new discoveries are well-founded, or if they are rather appearances and not real.There is room for doubt. The lenses then in use have a restricted field of view, can not always be aimed or focused well, and (due to impurities in the glass) give the images a greenish tint. (Hence, the Moon looks like green cheese! WTF?) Some astronomers [like Horky] can see no Jovian moons, lunar mountains, or sunspots. Others [like Cremonini] refuse to look. Remember, these are the first instrument-mediated observations in history, the first time an observation cannot be directly verified by the senses. The true telescopic revolution was to convert the planets from lights in the sky to objects about which physical discoveries could be made. Astronomy began to transition from the math department to the physics department.
-- Bellarmino to Clavius
The Jesuits respond to Bellamino a few days later. Clavius is in his seventies and his eyes were not up to it, but his younger assistants, Grienberger, Maelcote, et al. have been making meticulous observations with their own telescopes and these have confirmed all of Galileo’s observations, if not all of his interpretations. Clavius wonders if the lunar mountains may be differences in density of a pellucid surface. Cigoli, Galileo's booster among the artists, thinks this is proof that all mathematicians need to learn drawing. But Clavius is, by God, a scientist, and eventually changes his mind as the evidence accumulates.
22 April. Galileo receives an audience with Pope Paul V, in which he is much honored. He writes to his friend Salviati that the Pope would not let him kneel, but told him to stand. He also mentions some back-biting letters received in Rome from Florence, but with the Pope's good wishes and the Jesuits' support he regards them as unimportant. (Paul V had made the decision in 1607 to tear down Constantine's dilapidated basilica and build the St. Peter's we know today. It was nearing completion when Galileo visited.)
25 April. Galileo is inducted as the sixth member of Cesi’s Lyncean Academy. (Later that same year, Fr. Schreck will be inducted as the seventh member. Schreck will take a telescope with him on his mission to China, where it will have almost no impact on Chinese astronomy.) Cesi will be made a Prince in 1613, and will agree to underwrite Galileo’s future books. Had he not died before the Dialogo was written, it is likely that many of the difficulties that followed would have been avoided.
13 May. On Friday the 13th, the Jesuits throw a big shindig for Galileo at the Roman College, where they give him the equivalent of an honorary doctorate. Fr. Maelcote reads an address about The Sidereal Message in the presence of the entire College, as well as several cardinals and notables (including Cesi). It is the highpoint of the Roman visit and as a result Galileo can now refer to himself as a "celebrated" astronomer.* Clavius, a friend of Galileo’s for many decades, will publish these discoveries and his institution’s confirmations of them in the final edition of his Sphaera , the most important textbook for astronomy in Europe, shortly before his death in 1612.
4 June 1611. Galileo leaves Rome on Saturday, pleased with himself and his successes. Cardinal Francesco del Monte has prepared a glowing report to the Grand Duke.
"During his stay in Rome, Galileo has given great pleasure and, I believe, received as much. He showed off his discoveries so well that those who are competent here all agreed that they were not only true and well founded but simply marvellous. Were we still living in the ancient Roman Republic, I am certain that a statue would be erected in his honour on the Capitol."
-- Francesco Maria del Monte to Cosimo II, 31 May 1611
Kepler, Harriot, Marius, Lembo, Maelcote, Grienberger, Fabricius, Scheiner? Who dey? Galileo is on top of the freaking world!
What could possibly go wrong?
- TOF. The Grest Ptolemaic Smackdown
- Aslaksen, Helmer. Myths about the Copernican Revolution
- Christie, Thony. The Renaissance Mathematicus. A treasure trove! Some items used above:
- Galileo's Great Bluff .
- One Day Later
- The Starry Messenger What it Said and What that Really Meant!
- Teleskopos: How the telescope got its name.
- A small spot in front of the sun, a small step down the road to heliocentricity.
- Extracting the Stopper.
- De Santillana, Giorgio. The Crime of Galileo. Chicago: University of Chicago Press, 1955.
- Heilbron, J.L. The Sun in the Church: Cathedrals as Solar Observatories
- Huff, Toby. Intellectual Curiosity and the Scientific Revolution. Cambridge: Cambridge University Press, 2011
- princeton.edu The Partnership of Art and Science: The Moon of Cigoli and Galileo
- Rowland, Wade. Galileo's Mistake. New York: Arcade Publishing, 2003.
Shea, William R. & Mariano Artigas. Galileo in Rome. Oxford: Oxford University Press, 2003
- Sant, Joseph (2012). Jesuits and the Early Telescope:Scheiner and Grienberger. Retrieved from scientus.org