Frequent Renaissance Mathematicus commentator (comment-writer, commenter, commentor), Phillip Helbig, sent me an interesting email in response to my previous blog post. In skewering the Nadlers’ comic book I didn’t actually comment on every single detail of everything that was wrong with it, one of the things I left out was Galileo saying:
It is not the center of the cosmos it is a planet just like the others and they all orbit the sun.
As Phillip correctly pointed out in the Ptolemaic-Aristotelian geocentric model of the cosmos the Earth was not viewed as the centre of the cosmos but rather as the bottom. I wrote a brief post long ago quoting a wonderful passage by Otto von Guericke, the inventor of the vacuum pump on exactly this topic:
Since, however, almost everyone has been of the conviction that the earth is immobile since it is a heavy body, the dregs, as it were, of the universe and for this reason situated in the middle or the lowest region of the heaven…
Otto von Guericke; The New (So-Called) Magdeburg Experiments of Otto von Guericke, trans. with pref. by Margaret Glover Foley Ames. Kluwer Academic Publishers, Dordrecht/Boston/London, 1994, pp. 15 – 16. (my emphasis)
Phillip then asks, “So what was the “shock” of the Copernican Revolution (how many even get that pun?)? Was it demoting humanity from the centre of the universe, or promoting the Earth to be on par with the other heavenly bodies?”
Before I answer his question I would point out that the idea that Copernicus had demoted the Earth from the centre of the cosmos first emerged much later, sometime in the late eighteenth or early nineteenth century, as an explanation for the supposed irrational rejection of the heliocentric hypothesis. Of course as is now well known, or at least should be, the initial rejection of the heliocentric hypothesis was not irrational but was based on solid common sense and the available empirical scientific evidence nearly all of which spoke against it. For a lot, but by no means all, of the astronomical arguments read Chris Graney’s excellent Setting Aside All Authority.
So back to Phillip’s question, what was the real Copernican shock? The answer is as simple as it is surprising, there wasn’t one. The acknowledgement and acceptance of the heliocentric hypothesis was so gradual and spread out over such a long period of time that it caused almost no waves at all.
First up, there was nothing very new in Copernicus suggesting a heliocentric cosmos. As should be well known it had already been proposed by Aristarchus of Samos in the third century BCE and Ptolemaeus’ Syntaxis Mathematiké (Almagest) contains a long section detailing the counter arguments to it, which were well known to all renaissance and medieval astronomers. Also in the centuries prior to Copernicus various scholars such as Nicholas of Cusa had extensively discussed both geocentric models with diurnal rotation and full heliocentric ones. All that was new with Copernicus was an extensive mathematical model for a heliocentric cosmos.
At first this was greeted with some enthusiasm as a purely hypothetical model with the hope that it would deliver better predictions of the heavenly movements than the geocentric models for use in astrology, cartography, navigation etc. However it soon became apparent that Copernicus was not really any better than the older models, as it was based on the same inaccurate and oft corrupted data as Ptolemaeus, so the interest waned, although it was these inaccuracies in both model that inspired Tycho Brahe to undertake his very extensive programme of new astronomical observations on which Kepler would base his models.
As Robert Westman pointed out, in a now legendary footnote, between the publication of De revolutionibus in 1543 and 1600 there were only ten people in the whole world, who accepted Copernicus’ heliocentric cosmology, not exactly earth shattering. Even after 1600 the acceptance of a heliocentric worldview only increased very slowly and in gradual increments as the evidence for it accumulated.
The first two factors are the work of Kepler and the early telescopic discoveries. Because Kepler couldn’t or rather didn’t deal with the physical problems of a moving earth his work initially fell on deaf ears. The early telescopic discoveries only refuted a pure Ptolemaic geocentric model but were consistent with a Tychonic geo-heliocentric one and as this had a stationary earth, it became the model of choice. Of interest, and I think up till now not adequately explained, a Tychonic model with diurnal rotation, i.e. a spinning earth, became the preferred variation. A partial step in the right direction. Kepler’s publication of the Rudolphine Tables in 1627 led to an acceptance of his elliptical astronomy at least for calculations if not cosmologically. Then Cassini, with the help of Riccioli, demonstrated with a heliometer in the San Petronio Basilica in Bologna that the sun’s orbit around the earth or the earth’s orbit around the sun was indeed a Keplerian ellipse, but couldn’t determine which of the two possibilities was the right one. Another partial step in the right direction.
Both Kepler’s first and third laws, solidly empirical, were now accepted but his second law still caused problems. Around 1670 Nicholas Mercator provided a new solid proof of Kepler’s second law and it is about then that the majority of European astronomers finally accepted heliocentricity, although it was Kepler’s elliptical astronomy and not Copernicus’ model; the two models were regarded as competitors; also there was still a distinct lack of empirical proof for a heliocentric cosmos.
The developments in physics over the seventeenth century combined with the discovery of the physical reality of the atmosphere and Newton’s gravitation law finally solved the problems of why, if the earth is moving various disasters don’t occur: high winds, atmosphere blowing away etc., all of those arguments already listed by Ptolemaeus. The final empirical proofs of the annual orbit, Bradley and stellar aberration in 1727, and diurnal rotation, measuring the shape of the earth, around 1750, were delivered in the eighteenth century.
As can been seen by this very brief outline of the acceptance and confirmation of heliocentrism it was a process that took nearly two hundred years and proceeded in small increments so there was never anything that could possibly be described as a shock. As already stated above the concept that the ‘Copernican Revolution’ caused consternation or was a shock is a myth created sometime in the late eighteenth or early nineteenth century to explain something that never took place. One might even call it fake news!
Addendum: A lot of the themes touched on here are dealt with in greater detail in my The transition to heliocentricity: The Rough Guides series of blog posts