Read Online Tycho and Kepler by Kitty Ferguson - Free Book Online

he proceeded to explore the possibility that Copernican theory could be interpreted in such a way as to allow Earth to stand still. In Tycho’s words, Copernican theory might be “adapted to the stability of the Earth.” A decade would have to pass before he would realize this early hope in his “Tychonic system,” but Galileo’snemesis was waiting in the wings.
    Tycho’s attitude toward Copernicus—deep respect that fell short of acceptance of a moving Earth—would not have seemed a startling departure to the more well informed among his audience. Although Copernicus’s book
De Revolutionibus
, which had been published a month before that astronomer’s death in the spring of 1543 (about thirty years before Tycho’s lectures),departed radically from the prevailing Ptolemaic worldview, neither the scholarly nor the religious world had reacted negatively to it. Galileo’s clash with the pope did not occur until well after Tycho’s death. Meanwhile, a great deal of time was elapsing, and no overt, dramatic conflict was occurring among scholars or theologians about how the universe was arranged.
    Copernicus himself undoubtedlybelieved that his Sun-centered astronomy represented literal truth—what really was going on in the universe. He did not regard it as only a mathematical scheme that made the prediction of planetary movement simpler and more accurate. However, it was not in the mind-set of his contemporaries to assume or even to recognize that he had made any such truth claim in
De Revolutionibus
. Aristotle haddone ancient and medieval astronomers a considerable service by drawing a line between physics and the mathematical sciences, including astronomy, in a way that could be interpreted to mean that astronomers need not search for Aristotelian “causes” for celestial motions. By Ptolemy’s day, it had become routine to invent devices such as the epicycle and equant that yielded reliable predictions, withoutany need to explain what might cause the planets to move in the manner prescribed by those devices. In fact, to declare that Ptolemy either did or did not think the planets literally move in the way these mechanisms had them moving would be to misunderstand him. In the absence of any remote chance of conclusive direct evidence one way or the other, there was much to be said for not belaboringthat question—maybe for not even realizing the possibility of such a question. A man who worried about whether his mathematical system represented literal reality was an exception. This was not an intellectual situation confined to the ancients. A similar mind-set exists today at the leading edge of theoretical physics.
    Copernicus had no better view of the skies than Ptolemy, and his fortewas not observational astronomy: Most of his observations were less accurate than those of Hellenistic and Islamic astronomers. However, Copernicus accepted the neo-Platonic idea that underlying all the complication of nature there are simple, harmonious patterns. Nothing so complexly convoluted as Ptolemaic astronomy and the mathematical wilderness needed to support it could represent truth. Copernicus’sown system, which potentially explained planetary movement in a much more spare and simple way, must, he believed, therefore be a clearer insight into reality.
    However much Copernicus was motivated by a desire for greater simplicity,
De Revolutionibus
was not an easy book, and not many had the expertise to wade through it, but skilled mathematicians soon found that Copernicus’s math was brilliantand extremely useful. Long before controversy arose about whether or not Earth really moved and whether it or the Sun was in the center, Copernicus’s math and astronomy had proved too valuable to discard. The Copernican Prutenic Tables, which Tycho had found a little more reliable than the antiquated Alfonsine Tables based on Ptolemaic astronomy, were drawn up in Protestant Wittenberg by Melanchthon’syounger colleague, Erasmus