What If…?
Just meditate about it for a few minutes: what if the approach of Cardinal Bellarmine had won the day in 1633, and the Catholic Churchmen had stuck to their guns with a “Proof, please”, challenging generation after generation of astronomers to provide it? “For”, as Osiander had put it in his foreword to Copernicus’ book, “these hypotheses need not to be true nor even probable; if they provide a calculus consistent with the observations, that alone is sufficient… the astronomer will accept above all others the one which is the easiest to grasp. The philosopher will perhaps seek the semblance of truth. But neither of them will understand or state anything certain, unless it has been divinely revealed to him…So far as hypotheses are concerned, let no one accept anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than when he entered it.”(130) To which words I cannot but add Hoyle’s appraisal that they “agree remarkably well with the outlook of modern theoretical physics, and are not at all inept, as earlier generations have supposed.”(121)
What if Tycho Brahe’s view had been more strenuously adhered to? His system “had the merit of being theoretically equivalent to the Copernican, without the apparent defect of ascribing motion to the Earth; it made possible a scientifically adequate geostatic astronomy, irrefutable by any test of observation that Galileo or anyone else could impose on it.”(122) To object that Newtonian kinematics and Kepler’s laws decidedly put an end to its tenability is not warranted. Jupiter’s many moons circle, obedient to all these generalizing laws, their wandering star whilst that planet in its turn just as law-abidingly describes steady orbits around the Sun. Until we have found a firm hold on space, and consequently can pinpoint absolute motion, we may put the fulcrum of the Solar System wheresoever it pleases us. Newton, fully aware of the difficulty, thought to have solved it for his mechanomorphic model by means of his well-known whirling water-filled bucket. However – as is now generally admitted – Bishop Berkeley, preempting so to say Mach and Einstein, convincingly showed that this demonstration did not settle the issue. The most and best we can do when positing a Sun immovably fixed in space is to demonstrate the Earth’s 30 km/sec motion while revolving around it. So long as that has not been accomplished, Galileo may get a hearing, but no one is compelled to take him seriously.
To argue that Bradley’s discovery and his accounting for it would have provided Tychonian theorists clear evidence for that motion of the Earth is, as I have shown, an overhasty conclusion. More: if then and there after 1727 Boscovich’ water-filled telescope had been utilized to test Bradley’s contention, that contention would have been found wanting. The only change in the geocentric model necessitated by the outcome of the experiment would have been the one advocated in the present essay: a starry dome not hinged on the Earth but on the Sun. Any stringent reason to exchange the proven cosmic structure for an unproven heliocentric guess nobody could have postulated. Let me quote a knowledgeable, almost two centuries after Galileo not yet by the general opinion browbeaten, witness for the true theoretical situation in his days: Alexander von Humboldt (1769-1859) still declared: “I have already known a long time that we do not yet have proof for the system of Copernicus, but I shall not take the risk to be the first one attacking it.(123)
Even when a good hundred years after Bradley, three astronomers – Bessel, Henderson and Struve -detected the first parallaxes, their findings could, as is done in this essay, without difficulty be accommodated to the geocentric model. And surely the last devotees of Copernicus would have been disconcerted after à la Michelson and Morley, in vain having tried to vindicate their prophet. To be sure, they would have been rescued again by the ingenious ad hoc of Poincaré’s “principle of relativity”, as – utilizing Lorentz’ equations – elaborated by Einstein. However, and no mistake: every logician will agree with me: that principle – and that to the detriment of its extrapolations – is no more than an ad hoc, not to be taken too seriously, for it explains something by means of the very phenomenon it was invented to explain. That is: by taking, all three-dimensional data to the contrary, a whirlabout Earth for granted.
In the wistful “what if” scientific fantasia I have myself allowed the Tychonian astronomical establishment would, I envisage, have treated those erring Copernicans better than in the harsh climate of today’s blinkered secularism the stargazers treat the geocentrists.
My convinced geocentrists would have been epistemologically prudent enough to forego the use of the qualification “unthinkable”. They would have allowed a Sun-centered Universe, adrift or not adrift in a – let us admit it! – strict definition eluding spatiality, a logical possibility. Therefore, wanting to be true, unbiased scientists, they would have been on the lookout for any chance to test the truth of their theory. And diehard Copernicans suggesting an experiment capable of overthrowing the Earth-centered paradigm, would have immediately been granted a serious hearing and enthusiastic cooperation in performing it.
A year before and a year after Einstein burst upon the scene in 1905, a Lutheran pastor, F.E. Pasche, published books in defence of the pre-Copernican view.(124) Whether the Germania Publishing Company of Milwaukee found it a bad bargain to market these books I do not know, but that no second printing became necessary stands to reason. Yet, I find the coincidence remarkable. Geocentricity was apparently, at least among scientifically mal-adjusted German immigrant circles in Wisconsin, still alive and well on planet Earth when a German in Switzerland published a theory aimed at destroying the last shreds of its credibility. What careful experiments had not been able to accomplish this “Zur Elektrodynamik bewegter Körper”,(52) would once and for all do. For the “unthinkable” spectre, by test-results threateningly again conjured up out of the murky medieval depths of superstition, the special theory of relativity effectively, it seemed, would exorcise. Small wonder that physicists in general and astronomers in particular took to this proposal as ducks to the water. However, I doubt whether many of them sufficiently realized how this undertaking, welcomed as a panacea par excellence for physical theory, in fact would move the basic problem back to square one. That is to say: to the alternatives outlined by Cardinal Bellarmine in his Foscarini letter. To declare that from Einstein’s point of view both Tycho Brahe’s and Copernicus’ models are “as good as anybody else’s – but no better” is one thing – to substantiate this is another. I appreciate Hoyle’s confession that after all Tychonians cannot be labeled outright fools, but it is not good enough. Before I accept Sir Fred’s judgement and am constrained to pronounce myself satisfied with such an insubstantial equality, I want what is called “proof”. On the prerequisites for such a proof I agree with a creationist like Robert Kofahl.(125) With him I concur that the quest has to be conducted in, and confined to, the empirically approachable natural world. Do I then ask too much when on these terms I challenge Hoyle, et al., to authenticate their claim? By urging, nay: beseeching, them to perform the common sense extra-terrestrial, but still sublunary, measurements of the speed of light suggested in this paper? Measurements of which the theoretical considerations suggesting them rest on a modus tollendo tollens that will make the outcome logically binding? And if this outcome is found to be squarely contradicting Poincaré’s principle of relativity -will it not have to be admitted already a century ago to have been attested by Airy’s failure?