Bob Rosenberg received a PhD in History of Science and Technology from Johns Hopkins University. He spent two decades at Rutgers University on the staff of the Thomas A. Edison Papers, the last seven as director of the project. Since 2001 he has lived on the San Francisco Peninsula, working from 2005 to 2013 for John Wiley & Sons and otherwise as an independent scholar. Before undertaking his graduate studies he had worked briefly at the Psychical Research Foundation in Durham, N.C., and he has felt since that time that the epoch marked by the early empirical work of the Society for Psychical Research and its contemporaries has the potential to be as important as any watershed in the history of science — if we can figure out how to assign meaning or cause to the phenomena described by those researchers and their successors.
Too often, people who would like to cast psychical research into outer darkness start with a disparaging reference to the assumed desperate need of the researchers to believe in something “nonscientific,” something beyond the simple, material world. This “will to believe” is supposed to bias them to the extent that they cannot possibly be trusted as reliable witnesses or thinkers. And yet the history of science is full of episodes in which a discoverer only made advances because of a strongly held prior conviction — a conviction that might arise from experience, intuition, or philosophy. One such episode that is too little known outside professional history of science circles, and certainly deserving of more widespread acknowledgment, is that of Copernicus, Kepler, and the new heliocentric universe they championed.
The ideal, spherical geocentric universe.
When Copernicus published his De Revolutionibus in 1543, the cosmos — the geocentric world — was a place utterly alien to a modern person. The repercussions of Copernicus’s idea went far beyond a simple declaration that the planets went around the Sun, rather than having the Sun and the planets revolve around the Earth. He did not merely set the Earth in motion — he set in motion a new cosmology, a new physics, and a new theology.
What calculated geocentric planetary motions actually looked like.
The pre-Copernican universe was constructed using the ideas of Aristotle and the astronomer Claudius Ptolemy (2nd century C.E.). The Earth sat at the center, surrounded by nested, concentric spheres made of the “quintessence,” the fifth element — the first four being earth, water, air, and fire, which composed the Earth and did not exist elsewhere. The moon, sun, planets, stars, and the “crystalline” spheres that carried them in their motion around the Earth were all made of this quintessence. Because circular motion was considered the only appropriate motion for the heavens, and because the observed motion of the sun and planets is irregular, Ptolemaic astronomers had to construct astonishingly sophisticated geometrical combinations of circles to account for what they saw. Not every astronomer was happy with these constructions, but there was little choice. And while it was not easy to reconcile the astronomers’ mathematical gyrations with the idea of physical, rotating crystalline spheres, people can stand a lot of cognitive dissonance.
As this diagram of one orbital calculation shows, Copernicus’s system was not as simple as he might have liked.
Copernicus, too, objected to some of these constructions — one in particular, named the equant — and he wanted a system whose mathematics gave better results. He wasn’t looking at anomalous data demanding to be accommodated by a new theory; he was looking at a theory that felt makeshift. He was inspired to change it by his Neoplatonist philosophy: mathematics should be as simple as possible, and the sun belonged at the center of the universe. He got one of the two—the mathematics of his system was still horribly complicated, but the sun was placed properly.
“In the middle of all sits Sun enthroned. In this most beautiful temple could we place this luminary in any better position from which he can illuminate the whole at once? He is rightly called the Lamp, the Mind, the Ruler of the Universe; Hermes Trismegistus names him the Visible God, Sophocles’ Electra calls him the All-seeing. So the sun Sits as upon a royal throne ruling his children the planets which circle round him.”
What had Copernicus wrought? The Earth was now in the heavens, which meant that the old division of the universe into terrestrial and celestial elements no longer held. Furthermore, in the old physics heavy objects fell toward the center of the universe — that is, toward the center of the earth — while lighter elements (fire and air) rose above it. With the Earth no longer concentric with the center of the universe, that explanation went out the window. Finally, there were Scriptural contradictions and theological unease with removing Man from the center of the universe and placing him on one planet among many. All of this would have mattered more if anyone but mathematical astronomers had paid much attention to Copernicus for the next half-century, but in fact they didn’t.
Then, at the turn of the seventeenth century, Johannes Kepler showed up. Another Neoplatonist, he was delighted by the Copernican system. For him, the sun was
“a fountain of light, rich in fruitful heat, most fair, limpid, and pure to the sight, the source of vision, portrayer of all colors, though himself empty of color, called King of the planets for his motion, heart of the world for his power, it’s eye for his beauty, and which alone we should judge worthy of the Most High God, should he be pleased with a material domicile and choose a place in which to dwell with the blessed angels. … [Hence] by the highest right we return to the sun, who alone appears, by virtue of his dignity and power, suited for this motive duty and worthy to become the home of God himself, not to say the first mover.”
Unlike his predecessor, Kepler had new, remarkably accurate data to work with, and he set about working on the mathematics of a heliocentric system. The first large answer he arrived at was that the relative distances of the planets from the sun were dictated by nesting the five regular Platonic solids. It was brilliant, and it was completely wrong. His next conclusions about this new “solar system,” though, have proven more lasting — what became known as the law of equal areas; the relationship between a planet’s distance from the sun and its orbital period; and the hard-won, shocking realization, breaking free of ideas of circular motion, that the planets move in elliptical orbits. Through all this, Kepler was driven by his philosophical conviction that the sun not only was in the center by virtue of its importance, but that it also somehow provided the motive force for the planets (the “first mover”).
Kepler’s geometric model of planetary orbits.
His accomplishments, together with the contemporaneous astronomical observations of Galileo, were so powerful that the Copernican system suddenly became a cultural threat. It became more than a tool for astronomical calculations. Now natural philosophers and theologians had to acknowledge that cosmology, physics, and theology were under fire. Physics, particularly, was manifestly rootless, utterly without explanatory theory — and yet Galileo did his great descriptive work on motion regardless. (Modern investigators of psi phenomena have been similarly unable to provide a satisfactory mechanism. But good science does not necessarily need mechanism; it can advance on the strength of thoughtful, careful observation.)
Kepler’s work laid the essential astronomical ground for Isaac Newton’s fundamental synthesis of physics 60 years later. Kepler, like Copernicus, was a brilliant mathematician, fully the equal of any of his astronomical contemporaries; and his accomplishments, like those of Copernicus, sprang from deep belief that had nothing to do with observational or computational astronomy. The result — what we know as the Copernican revolution, certainly one of the greatest revolutions in human understanding — is a powerful reminder that the “will to believe,” far from being a hindrance to scientific advance, can be a positive and even necessary foundation for it.
Perhaps still the best description of the Copernican revolution is Thomas Kuhn’s Copernican Revolution (several editions), from which the translations of Copernicus and Kepler have been taken (p. 131).
© Robert Rosenberg