Coming of Age in the Milky Way (8 page)
Read Coming of Age in the Milky Way Online
Authors: Timothy Ferris
Tags: #Science, #Philosophy, #Space and time, #Cosmology, #Science - History, #Astronomy, #Metaphysics, #History
More importantly though less distinctly, the great explorations opened up the human imagination, encouraging Western thinkers to regard not only the continents and seas but the entire planet from a more generous perspective. The dimensions of the known world had doubled by the year 1600, prompting a corresponding expansion in the cosmos of the mind. Heartened by the decline of the old authorities and by the adventuresome spirit of Columbus and the other explorers, the scholars of what would become the Renaissance began to imagine themselves traveling not only across the surface of the earth but also up into space. As Leon Frobenius was to write in a later century, “Our view is confined no longer to a spot of space on the surface of this earth. It surveys the whole of the planet…. This lack of horizon is something new.” Nicholas of Cusa pointed out that “up” and “down” are relative terms, postulated that each star might be its own center of gravity, and suggested that if we lived on another planet we might assume that we occupied the center of the universe. Leonardo da Vinci was forty years old when Columbus reached the continent to which Leonardo’s friend Amerigo Vespucci would lend his name, and he was a friend as well to Paolo Toscanelli, the astronomer who urged Columbus on his way. Imbued with an explorer’s vision, Leonardo cast his mind’s eye out into space and imagined that the earth from a distance would look like the moon:
If you were where the moon is, it would appear to you that the sun was reflected over as much of the sea as it illumines in its daily course, and the land would appear amid this water like the dark spots that are upon the moon, which when looked at from the earth presents to mankind the same appearance that our earth would present to men dwelling in the moon.
22
Copernicus was a student at the University of Cracow when Columbus landed in the Indies. He was forty-nine years old when Magellan’s ship completed its circumnavigation of the globe. He sent
his
mind’s eye journeying to the sun, and what he saw turned the earth into a ship under sail, assaying oceanic reaches of space undreamed of since the days of Aristarchus of Samos.
*
The myth that Columbus was out to prove the world round was invented 130 years after the fact, and subsequently was popularized by Washington Irving.
*
The circumnavigation of the earth by Ferdinand Magellan would prove the geographers right. In the course of that grueling, three-year voyage Magellan was killed, most of his men died, and his collaborator, the cosmographer Rui Faleiro, went insane. Wrote Magellan’s shipmate Antonio Pigafetta of the privations suffered during their crossing of the Pacific, “I believe that nevermore will any man undertake to make such a voyage.”
14
†
As Columbus was a practical, unbookish man and not (yet) insane, presumably he had some reason other than the old geographies to think his voyage would succeed. We do not know what this was, but can speculate that he heard sailors’ tales of sighting the coast of South America when driven west by winds while trying to round the Cape of Good Hope, or knew that the Gulf Stream, which flows east, carries fresh horsebeans and other signs of a reasonably proximate landmass. The explorer Thor Heyerdahl even proposes that Columbus heard of Leif Erikson’s discovery of America, either from Vatican sources or during a visit to Iceland that Columbus is said by his son to have made at the age of twenty-six.
16
T
HE
S
UN
W
ORSHIPERS
There is no new thing under the sun.
—Ecclesiastes
Amazed, and as if astonished and stupefied, I stood still, gazing for a certain length of time with my eyes fixed intently upon it…. When I had satisfied myself that no star of that kind had ever shone forth before, I was led into such perplexity by the unbelievability of the thing that I began to doubt the faith of my own eyes.
—Tycho, on the supernova of 1572
M
ikolai Kopernik, though rightly esteemed as a great astronomer, was never much of a stargazer. He did some observing in his student days, assisting his astronomy professor at Bologna, Domenico Maria de Novara, in watching an occultation of the star Aldebaran by the moon, and he later took numerous sightings of the sun, using an instrument of his own devising that reflected the solar disk onto a series of graph lines etched into a wall outside his study. But these excursions served mainly to confirm what Kopernik and everybody else already knew, that the Ptolemaic
system was inaccurate, making predictions that often proved to be wrong by hours or even days.
Kopernik drew inspiration less from stars than from books. In this he was very much a man of his time. The printing press—invented just thirty years before he was born—had touched off a communications revolution comparable in its impact to the changes wrought in the latter half of the twentieth century by the electronic computer. To be sure, Greek and Roman classics had been making their way from the Islamic world to Europe for centuries, and with enlightening effect—the first universities had been founded principally to house the books and study their contents—but the books themselves, each laboriously copied out by hand, were rare and expensive, and frequently were marred by transcription errors. All this changed with the advent of cheap, high-quality paper (a gift of Chinese technology) and the press. Now a single competent edition of Plato or Aristotle or Archimedes or Ptolemy could be reproduced in considerable quantities; every library could have one, and so could many individual scholars and more than a few farmers and housewives and tradespeople. As books spread so did literacy, and as the number of literate people increased, so did the market for books. By the time Kopernik was thirty years old (and printing itself but sixty years old), some six to nine million printed copies of more than thirty-five thousand titles had been published, and the print shops were working overtime trying to satisfy the demand for more.
Kopernik was as voracious a reader as any, at home in law, literature, and medicine as well as natural philosophy. Born in 1473 in northern Poland, he had come under the sponsorship of his powerful and calculating uncle Lucas Waczenrode, later bishop of Warmia, who gave him books and sent him to the best schools. He attended the University of Cracow, then ventured south into the Renaissance heartland to study at the universities of Bologna and Padua. He read Aristotle, Plato, Plutarch, Ovid, Virgil, Euclid, Archimedes, and Cicero, the restorer of Archimedes’ grave. Steeped in the literature and science of the ancients, he returned home with a Latinized name, as Nicolaus Copernicus.
Like Aristotle, Copernicus collected books; unlike Aristotle, he did not have to be wealthy to do so. Thanks to the printing press, a scholar who was only moderately well off could afford to read widely, at home, without having to beg admission to distant
institutions of learning where the books were kept chained to the reading desks. Copernicus was one of the first scholars to study printed books in his own library, and he studied none more closely than Ptolemy’s
Almagest
. Great was his admiration for Ptolemy, whom he admired as a thoroughly professional astronomer, mathematically sophisticated and dedicated to fitting his cosmological model to the observed phenomena. Indeed, Copernicus’s
De Revolutionibus (On the Revolutions)
, the book that would set the earth into motion around the sun and bring about Ptolemy’s downfall, otherwise reads like nothing so much as a sustained imitation of Ptolemy’s
Almagest
.
It is widely assumed that Copernicus proposed his heliocentric theory in order to repair the inaccuracies of the Ptolemaic model. Certainly it must have become evident to him, in his adulthood if not in his student days, that the Ptolemaic system did not work very well: “The mathematicians are so unsure of the movements of the sun and moon,” notes the preface to
De Revolutionibus
, “that they cannot even explain or observe the constant length of the seasonal year.”
1
Prior to the advent of the printing press, the failings of Ptolemy’s
Almagest
could be attributed to errors in transcription or translation, but once reasonably accurate printed editions of the book had been published, this excuse began to evaporate. Copernicus owned at least two editions of
Almagest
, and had read others in libraries, and the more clearly he came to understand Ptolemy’s model, the more readily he could see that its deficiencies were inherent, not incidental, to the theory. So considerations of accuracy may indeed have helped convince him that a new approach was required.
But by “new,” Copernicus the Renaissance man most often meant the rediscovery of something old.
Renaissance
, after all, means “re-birth,” and Renaissance art and science in general sprang more from classical tradition than from innovation. The young Michelangelo’s first accomplished piece of sculpture—executed in the classical style—was made marketable by rubbing dirt into it and palming it off, in Paris, as a Greek relic. Petrarch, called the founder of the Renaissance, dreamed not of the future but of the day when “our grandsons will be able to walk
back
into the pure radiance
of the past”
2
(emphasis added); when Petrarch was found dead, at the age of seventy, slumped at his desk after an all-night study session, his head was resting not on a contemporary volume but on a Latin
edition of his favorite poet, Virgil, who had lived fourteen centuries earlier. Copernicus similarly worked in awe of the ancients, and his efforts, like so much of natural philosophy then and since, can be read as a continuation of the academic dialogues of Plato and Aristotle.
Aristotle, the first of the Greeks to have been rediscovered in the West, was so widely revered that he was routinely referred to as “the philosopher,” much as lovers of Shakespeare were to call him “the poet.” Much of his philosophy had been incorporated into the world view of the Roman Catholic Church. (Most notably by Thomas Aquinas—at least until the morning of December 6, 1273, when, while saying mass in Naples, Thomas became enlightened and declared that “I can do no more; such things have been revealed to me that all I have written seems as straw, and I now await the end of my life.”) From Aristotle, Copernicus acquired an enthusiasm for the universe of crystalline spheres—although, like Aristotle, Copernicus never could decide whether the spheres actually existed or were but a useful abstraction.
Copernicus also read Plato, as well as many of the Neoplatonic philosophers whose work ornaments and obfuscates medieval thought, and from them absorbed the Platonic conviction that there must be a simple underlying structure to the universe. It was just this unitary beauty that the Ptolemaic cosmology lacked. “A system of this sort seemed neither sufficiently absolute nor sufficiently pleasing to the mind,” Copernicus wrote.
3
He was after a grasp of the more central truth. He called it “the principal thing—namely the shape of the universe and the unchangeable symmetry of its parts.”
4
Rather early on, perhaps during his student days in sunny Italy, Copernicus decided that the “principal thing” was to place the sun at the center of the universe. He may have drawn encouragement from reading, in Plutarch’s
Morals
, that Aristarchus of Samos “supposed that the heavens remained immobile and that the earth moved through an oblique circle, at the same time turning about its own axis.”
5
(He mentions Aristarchus in
De Revolutionibus
, though not in this context.) Possibly he encountered more recent speculations about the motion of the earth, as in Nicole Oresme, the fourteenth-century Parisian scholar who pointed out that
if a man in the heavens, moved and carried along by their daily motion, could see the earth distinctly and its mountains, valleys,
rivers, cities, and castles, it would appear to him that the earth was moving in daily motion, just as to us on earth it seems as though the heavens are moving…. One could then believe that the earth moves and not the heavens.
6
Copernicus was influenced by Neoplatonic sun worship as well. This was a popular view at the time—even Christ was being modeled by Renaissance painters on busts of Apollo the sun god—and decades later, back in the rainy north, Copernicus remained effusive on the subject of the sun.
*
In
De Revolutionibus
he invokes the authority of none other than Hermes Trismegistus, “the thrice-great Hermes,” a fantastical figure in astrology and alchemy who had become the patron saint of the new sun-worshipers: “Trismegistus calls [the sun] a ‘visible god,’ Sophocles’ Electra, ‘that which gazes upon all things.’”
7
He quotes the Neoplatonist mystic Marsilio Ficino’s declaration that “the sun can signify God himself to you, and who shall dare to say the sun is false?”
8
Finally, Copernicus tries his hand at a solar paean of his own:
In this most beautiful temple, who would place this lamp in another or better position than that from which it can light up everything at the same time? For the sun is not inappropriately called by some people the lantern of the universe, its mind by others, and its ruler by still others.
9
Trouble arose not in the incentive for the Copernican cosmology, but in its execution. (The devil, like God, is in the details.) When Copernicus, after considerable toil, managed to complete a fully realized model of the universe based upon the heliocentric hypothesis—the model set forth, eventually, in
De Revolutionibus
—he found that it worked little better than the Ptolemaic model. One difficulty was that Copernicus, like Aristotle and Eudoxus before him, was enthralled by the Platonic beauty of the sphere—“The sphere,” he wrote, echoing Plato, “is the most perfect… the most capacious of figures … wherein neither beginning nor end can be found”
10
—and he assumed, accordingly, that the planets move in
circular orbits at constant velocities. Actually, as Kepler would establish, the orbits of the planets are elliptical, and planets move more rapidly when close to the sun than when distant from it. Nor was the Copernican universe less intricate than Ptolemy’s: Copernicus found it necessary to introduce Ptolemaic epicycles into his model and to move the center of the universe to a point a little away from the sun. Nor did it make consistently more accurate predictions, even in its wretchedly compromised form; for many applications it was less useful.