In his Philosophical Essays: From Ancient Creed to Technological Man, Hans Jonas has an essay titled “Seventeenth Century and After: The Meaning of the Scientific and Technological Revolution”. In part of this essay, he writes about the radical shift in the change from an Aristotelian and Ptolemaic cosmology to a Copernican and post-Copernican one, and what this meant for the early moderns.
It was a shift in our modern cosmic imaginary, not merely about the objects in the sky (and not merely from a geocentric to a heliocentric planetary system), but about the universe as a whole.
There were three implications that the new theory brought about that “were not at all in its inventor’s mind, but which inevitably led to a new physical cosmology far beyond any merely mathematical reinterpretation of astronomical data”. These were:
(1) the necessarily implied proposition of the homogeneity of nature throughout the universe; (2) the absence of a solid architecture of the universe to account for its orderliness; and (3) its probable infinity, by which it ceased to be a “whole” or a “cosmos” in the sense of a determinate entity. [Jonas, 52]
The first point asserts that everything everywhere in the universe is made out of the same kind of matter, the same kind of “stuff”. This suggests that the stars are not made of purer substances, which is difficult to imagine for us:
To us, who have long been accustomed to thinking of “heavenly” bodies in no other way and have actually seen men walking on the moon, it is not easy to appreciate the spectacular impact which this first ocular display of physical detail had not only on the direct issue, vi&., the material nature of the stars, but on the verification of the total world-hypothesis from which it was but one marginal inference […]. [Jonas, 53]
The homogeneity of nature means that the mechanical laws by which things on earth operate become the laws by which the heavens and things in the heavens operate, too. (Indeed, I would add, the significance of “the heavens” as a phrase, changes — by being obliterated as having any qualitative or ontological significance.)
The second point is harder to help people understand, because of how far removed we are from this revolution in thought. There was a “solid cosmic architecture which had guaranteed the orderly working of the Aristotelian-Ptolemaic universe”. [Jonas, 53] These heavenly spheres began as an observation of the circular movement of the stars around the pole, and then “gained the quality of a metaphysical principle” [Jonas, 54]. Force, in this system, accounts
for the fact of motion and not for its shape: the latter followed simply from the shape of movable structures, endowed with just one “degree of freedom.” Whatever rides on the circumference of a wheel or axially rotating sphere cannot but describe a circular path. [Jonas, 55]
There is a “spatial order” to things in this older system, and there is an impulse, which goes from the First Mover down through the system of things, that moves all along their paths. Everything has a proper place; “place” is not a homogeneous idea. Thus, in this earlier system, “no dynamics of interacting forces was called for, merely a geometry of constraining forms.” In the wake of the death of this cosmology, it became obvious that the circular motion of the fixed stars was merely apparent, and not real. Thus, the death of the circle as a heavenly form, as the form of higher perfection. The “immobilized Great Sphere” that generated motion became redundant. In Kepler, planets were “independent bodies” and “attached to nothing”, “moving freely through empty, featureless space”. [Jonas, 56]
The third “unpremeditated consequence from Copernican doctrine […] was the extension of the world to infinity.” [Jonas, 56] In order to account for the fact that the stars appear to remain in fixed positions, despite the assertion of a moving Earth which would suggest that their positions would also appear to move, an obscene increase in the magnitude of the distance between the earth and the stars was needed, in order to refute the anti-Copernican objection that there was no parallax, so the stars must be in a fixed sphere. “But this is a case where quantity turns into quality.” [Jonas, 56] The size of the universe was formerly thought to be enormous, but now it was beyond any sense of scale, and without a border at all — it went “from the closed to the open universe”. [Jonas, 57] (Here, Jonas recommends Koyré’s From the Closed World to the Infinite Universe as a more expansive guide.) It was Giordano Bruno who was the evangelist for this, the infinity of the world heralded by him as the befitting expression of the divine infinity that was fully expressed in it. As a further change to the imagined cosmos: there was no center, said Bruno; the multiplicity of worlds was held together by a unity of dynamics across them. Bruno thought of this as a liberation: he was a “burning spirit [who] greeted the opening of the universe like the crumbling of prison walls, as an outer infinity congenial to the infinity in man.” [Jonas, 58] This is only one possible reaction to the new cosmology, however: figures like Pascal felt not Bruno’s kindred sympathy, but a horrifying alienation.
Header image found here.