Science in Christian Perspective
Galileo and the Church: Tensions with a Message for Today Part II
T. H. LEITH
Toronto, Ontario, Canada
From: JASA 25 (June 1973): 64-66.
[ The year of 1973 has been designated Copernican Year in honor of the 500th of the birth of Copernicus in 1473. In keeping with this commeration, the Journal ASA offers a four-part publication of a paperr presented by T. H. Leith at the 1972 Convention of the American Scientific Affiliation at York University. Part 1 appeared in journal ASA 25, 21-24, March 1973.]
Copernicus' vindication of his system took two tacks, a critique of earlier views defending a stationary Earth and a presentation of alternative arguments for the mobility of our planet. Each was, in turn, a combination of kinematic and dynamic reasoning. The former rested upon a simple description of observed motions in the heavens and the latter was based upon theories as to the nature of motion.
In treating his geostatic competitors kinematically, Copernicus argued that what we observe of the motions of the stars and the bodies which wander across them may equally well he described by means of his heliocentric scheme. Indeed it did rather better, for Copernicus was able to employ contemporary observations to correct varied errors in Ptolemy's predictions and to make improved forecasts in refining the geometry, of his own scheme. That was, however, no more than a historical accident, for presumably the Ptolemaic system could be revised in order to account for the newer information. Thus we can explain how Reinhold, in deriving his Prussian Tables of 1551, could utilize Copernicus' data and applaud his technical abilities while retaining the essentials of the geocentric method in his calculations. At best, then, Copernicus' argument here served merely to undermine confidence in the Ptolemaic prejudice by offering an alternative; at worst, it left the debate at the sceptical level of Nicolas of Cusa.
The dynamic arguments in favor of a geostatic position were met in an even less satisfying manner. The critique tended to take the form of esthetic judgments or to resort to suggestions for a physics rather different from Aristotle's. The first, unfortunately, reduced the mobility or stability of the Earth to a matter of taste. The second introduced various quite speculative ideas such as the assumption that the rotation of the Earth sas natural and unforced and the argument that heavy objects fall toward the center of the Earth because of a natural affinity rather than because it lies at the middle of the universe. The whole was rather poorly thought out and would certainly carry little conviction by the time of Newton. Apparently Copernicus, convinced as he was on other grounds of the correctness of his system, was aware that this required that the old dynamic dogmas be in error. Unable to foresee the new physics suited to his own scheme, he could do no more than make rather gratuitous and fragmentary suggestions as to its nature.
On what basis did he found his convictions? It was the interdependence and coherent simplicity which his model gave to the available observational data. In the Ptolemic scheme, motions on the deferents of the inferior planets and motions on the epicycles of the superior planets took place in a period of a year. The Copernican scheme replaced these by the single annual revolution of the Earth about the Sun. Now the relative size of the deferent and the epicycle for any planet in the Ptolemaic scheme could be fixed by observation. Placing this fact beside his replacement just mentioned, Copernicus was enabled to fix the relative sizes of the epicycles of the inferior planets and the deferents of Mars, Jupiter, and Saturn by employing the circles which represent the movement of the Earth at the same scale when dealing with each planet. The result, of course, is that once these relative sizes were known they became the orbits of these planets and the order of the planets was established properly about the Sun. After several thousand years of debate about the ordering of the planets and about their relative distances, an insight into what a single circle apparently meant in the separate planetary devices used by Ptolemy seemed to resolve the problem in one short step! 'Where tradition left these matters on a speculative, arbitrary, and erroneous level, the Copernican system pulled them so tightly together that to change any part was to make the whole unintelligible9.
Certainly the Copernican scheme now begins to sound worthy of belief. Belief, however, is often a complex psychological matter and thus a function of an idea's agreement with familiar concepts and theories. Many were too astounded by the relative emptiness of Copernicus' universe, by the immensity which it required to explain the lack of observed stellar parallax (it was first found in the fourth decade of the Nineteenth Century), and by Copernicus' disdain for the logic of the two-level cosmos of the past, to find the new scheme credible. And, of course, Biblical scholars could point out its apparent incoherence with the traditional understanding of passages such as Psalm 93:1, Psalm 104:5, Psalm 75:3, Psalm 119:90, Psalm 19:4-6, Joshua 10:12-14, Eeclesiastes 1:4-5, Job 26:7, and 2nd Kings 20:9-il and the theologian could ask how man's important role in creation was to be reconciled with his position on a more planet rather than centrally in creation. Clearly an acceptance of Copernicus' understanding would not he widespread in the short term.
Tycho and Kepler
In its ability to predict the motions of the heavenly bodies the Copernican scheme was flaw (-,,d by the fact that the data which it employed were only very partially an improvement upon those available to Ptolemy. Consequently, tables such as those of Reinhold contained serious errors and modern observations made with accuracy and over a long term were required if the deficiency were to be corrected. It is on Tycho Brahe (1546-1601), the diligent and eccentric Danish astronomer, that the task fell although his motivation was scarcely to strengthen the Copernican system. Rather, Tycho's ambition was to provide the foundations for a model in which the Sun circled a stationary Earth, lying in the center of a spherical cosmos, carrying with it the five known planets. Thereby he hoped both to reconcile astronomy with Scriptural teaching as commonly understood and to remove the necessity of placing the stars far beyond the outermost planet as was required by the heliocentric scheme. His careful observations revealed no measurable stellar parallax, thus either the Earth did not move about the Sun in an immense circle or the stellar regions were at even greater distances than had been thought necessary' in Copernicus' day. He preferred the former.
Because his suggested model also retained a non-rotating Earth, it was necessary, as it was in all geocentric systems in which the Earth lacks a daily rotation, to move the planets and Sun and Moon as well as the stars around the Earth once each clay. The individual motions of the bodies moving within the starry heavens of course caused these also to drift at various rates across the stars. Tycho was apparently' willing to retain this long-standing complexity in spite of the fact that lie took his model to be true to what was actually occurring, rather than to he a useful fiction, and in spite of the absence of any physical explanation. However, he did not live to see his data applied in a detailed technical manner to his scheme; his colleague in the short period before his death, Kepler, was to use them to quite different ends. They provided instead the foundation of a Copernican picture of a novel sort, a picture he had intended to avoid.
Tycho contributed too, we must mention, to the downfall of certain aspects of the Aristotelian worldview, something lie did intend. His careful studies removed the comets from their traditional place above the
atmosphere and beneath the Moon and placed them in paths at distances previously reserved for the planets. Aristotle's transparent shells were shattered thereby. Again, his observations of the new star of 1572, because they failed to show any parallax over the eighteen month period in which it was visible, led him to conclude that it lay' in the regions beyond the planets. The supposedly changeless starry heavens exhibited an unforeseen novelty and decay; another facet of the Aristotelian cosmos had been destroyed10.
Upon Tycho's death, Johann Kepler (1571-1630), his successor as Imperial Mathematician to the Holy Roman Emperor in Prague, obtained Tycho's massive collection of data on stellar positions and the apparent movements of the heavenly bodies. Kepler was already a Copernican, tutored in the system by one of its few astronomical adherents, Maestlin, while Kepler ,vas his student at Tuhingen, and the author in 1597 of a small book defending a heliocentric scheme entitled The Cosmographic Mystery. As is well-known, Kepler employed the information to develop a revised Copernican model in which the traditional circles and epicycles of its founder were replaced by elliptical orbits. His conclusions appear in 1609 in the New Astronomy, the same year that Galileo began his equally revolutionary studies with the telescope".
What is less commonly realized is the extent to which Kepler challenged another tradition, the received attitude on Biblical teaching regarding the Earth's motion. When his volume of 1597 had appeared, while he was still a high-school teacher, he had withdrawn a chapter on the subject to avoid setting off a serious dispute and lest the Tubigen faculty might not approve the work as his printer had requested they do. Later, as Imperial Mathematician he could better afford to treat this contentious question which he did in the New Astronomy, in his Epitome of Copernican Astronomy of 1618, and in the second edition of the Cosmographic Mystery of 1621. Let me quote briefly from the second of these.
Astronomy discloses the causes of natural phenomena and takes within its purview the investigation of optical illusions. Much loftier subjects are treated by Holy Writ, which employs popular speech in order to be understood . . . Not even astronomers cultivate astronomy with the intention of altering popular speeds. Yet while it remains unchanged, we seek to open the doors of truth his is all the more reason not to require divinely inspired Scripture to abandons the popular style of speech, weigh its words no the precision balance of natural science, confuse Gods simple people with unfamiliar and inappropriate utterances about matters which are beyond the comprehension of those will) are to he instructed, and thereby block their access to the far more elevated authentic goal of Scripture.
In our days all the most outstanding philosophers and astronomers agree with Copernicus . . . Yet the authorities are cast aside by most educated people, whose knowledge is on a level not much higher than the uneducated. Acting by themselves and blinded by ignorance, first they condemn a discordant and unfamilar doctrine as false. After deciding that it must be completely rejected and destroyed, they look around for authorities, with whom they protect and arm themselves. On the other hand they would make an exception of these same authorities, sacred and secular alike ... if they found them aligned on the side if the unconventional doctrine. They show this attitude in connection with, the book of Job, chapter 38, when anybody proves by means of it that the earth is flat, stretched to the tautness of a line, and resting on certain foundations, according to the literal meaning.12
I quote from the third source.
Who would deny that God's word is attuned to its subject matter and for that reason to the popular speech of mankind? Hence, every deeply religious man will most carefully refrain from twisting God's word in the most obvious matters so that it denies God's handiwork in nature. When he has understood the most delicately harmonious coordination of the celestial motions , let him ask himself whether sufficiently correct and sufficiently productive reasons have been discovered for the agreement between the word of God and the hand of God, or whether there is any advantage in rejecting this agreement and by means of censorship destroying this glorification of the boundless beauty of the divine handiwork. The ignorant refuse to have respect for authority; they rush recklessly into a fight, relying on their numbers and the protection of tradition, which is impervious to the weapons of truth. But after the edge of the ax has been struck against iron, it does not cut wood any longer either. Let this be understood by anyone who is interested.13
Two aspects of Kepler's comments deserve special note here. The
of Copernician astronomy and the discovery of a mathematical
regularity in nature
enunciated in Kepler's famed three laws of planetary motion (the third appeared
in 1619 in his Harmony of the World, the first two in the New
Astronomy a decade
earlier), together with a welter of speculative musical analogies, astrological
theory, and mystical theology had convinced Kepler that he had indeed uncovered
in part the true handiwork of deity. His choice of the most eminent
and astronomers, all Copernicans, was colored by this belief. We assume that he
included Galileo, unaware
likely of Gahleo's distaste for Kepler's approach, but he clearly ignored his
Aristotelian and Oekhamist philosophical opponents, those who found the lack of
a physical basis for his system disturbing, and astronomers for whom a Tychonie
scheme more readily fitted their predilections. Also 'authority' in
was not only handed to Copernican sympathizers but removed from its traditional
tenure by Biblical exegetes, Aristotle, and those who espoused a
belief that astronomical
work must resort to fictions. His point that tradition was employed only when
convenient to current opinion was a worthy one but most of his contemporaries
were unprepared to recognize it; novel ideas, even if founded upon
have to await a new mind-set before they are accepted and only then
are the short-comings
of traditional authorities comprehended.
(To be continued)
9Further information may be found in The World of Copernicus, A. Armitage, New York, 1947; Des Revolutions des Orbes Celestes, N. Copernicus, Paris, 1970; La Revolution Astrooonisque, A. Koyrc, Paris, 1961; The Copernician Revolution, T.S. Kuhn, New York, 1959; and Three Coperni can Treatises, E. Rosen, New York, 1959.
10See Tycho Brahe, J.L.E. Dreyer, New York, 1963 for details.
11 On Kepler's life and work see Kepler, M. Gasper, New York, 1962.
12Translation by E. Rosen in his paper "Kepler and the Lutheran attitude toward Copernicanism at the Kepler Colloquium, Line, Austria, 1971.