Coming of Age in the Milky Way (10 page)

Tycho, however, was an observer and not a theorist. His chief contribution to theoretical cosmology—a compromise geocentric model in which the planets orbit the sun, which in turn orbits the earth—created as many problems as it solved. Needed was someone with the ingenuity and perservance to compose Tycho’s tables into a single, accurate and simple theory.

Tycho proposed a compromise between the Copernican and Ptolemaic models in which the sun orbited the earth, and was in turn orbited by the other planets. (Not to scale.)

Amazingly, just such a man turned up. He was Johannes Kepler, and on February 4, 1600, he arrived at Benatek Castle near Prague, where Tycho had moved his observatory and retinue after his benefactor King Frederick drank himself to death. Tycho and Kepler made for unlikely collaborators, with each other or anybody else. Tycho was an expansive, despotic giant of a man, who sported a belly of Jovian proportions and a gleaming, metal-alloy nose (the bridge of his original nose having been cut off in a youthful duel). Heroically passionate and wildly eccentric, he dressed like a prince and ruled his domain like a king, tossing scraps to a dwarf named Jepp who huddled beneath the dinner table. Kepler, for his part, was a prototypical outsider. Myopic, sickly, and “doglike” in appearance (his words) he came from the antipodes of nobility. His father was a mercenary soldier and a dipsomaniac wife-beater. His mother had been raised by an aunt who was burned alive as a witch, and she herself narrowly escaped the stake. (Among her other objectionable habits, she enjoyed spiking people’s drinks with psychedelic drugs.)

Neurotic, self-loathing, arrogant, and vociferous, Kepler was drubbed with tiresome regularity by his classmates. He fared little better once out in the world, where he tried but failed to become a Lutheran minister. He sought solicitude in marriage, but his wife, he said with the bleak objectivity of a born observer, was “simple of mind and fat of body … stupid, sulking, lonely, melancholy.”
¹⁹
Kepler tried to make a living casting horoscopes, but was seldom paid; he spent much of his time trekking from one court to another to plead for his fee, drawing titters from the flunkies when he appeared, in his baggy, food-stained suit, tripping over himself with apologies and explanations, getting nowhere. His lifetime earnings could not have purchased the star-globe in Tycho’s library.

Kepler’s initial scientific endeavors amounted to a comedy of errors and absurdities. He tried to sight the stars using only a wooden staff suspended from a rope: “Hold your laughter, friends, who are admitted to this spectacle,” he wrote of his makeshift observatory.
²⁰
His first great theoretical idea—which came to him with the force of revelation, halting him in mid-sentence while he was delivering a soporific lecture on mathematics in a high school in Graz, Austria—was that the intervals between the orbits of the planets describe a nest of concentric Platonic solids. They do not.

Yet this was the man who would discern the architecture of
the solar system and discover the phenomenological laws that govern the motions of the planets, thus curing the Copernican cosmology of its pathologies and flinging open the door to the depths of cosmic space. An extraordinarily perspicacious theorist—no less exacting a critic than Immanuel Kant called him “the most acute thinker ever born”
²¹
—Kepler was blessed with an ecstatic conviction that the world that had treated him so harshly was, nonetheless, fundamentally beautiful. He never lost either this faith or the clearheaded empiricism with which it was tempered, and the combination eventually rewarded him with some of the most splendid insights into the workings of the universe ever granted a mortal mind.

Kepler’s chief source of inspiration was the Pythagorean doctrine of celestial harmony, which he had encountered in Plato. “As our eyes are framed for astronomy, so our ears are framed for the movements of harmony,” Plato wrote, “and these two sciences are sisters, as the Pythagoreans say and we agree.”
²²
In the final book of the
Republic
, Plato portrays with great beauty a voyage into space, where the motion of each planet is attended to by a Siren singing

Aristotle found all this a bit much. “The theory that the movement of the stars produces a harmony, i.e., that the sounds they make are concordant, in spite of the grace and originality with which it has been stated, is nevertheless untrue,” he wrote.
²⁴
Kepler sided with Plato. The muddy tumult of the world, he felt, was built upon harmonious and symmetrical law; if the motions of the planets seem discordant, that is because we have not yet learned how to hear their song. Kepler wanted to hear it before he died. At this he succeeded, and the sunlight of his success banished the gloom of his many failures.

The doctrine of celestial harmony was, literally, in the air, in
the new music and poetry of Kepler’s generation and those that immediately followed it. Milton, who was always ransacking science for promising themes, celebrated it in verses like this one:

Even Shakespeare, who was rather unsympathetic toward astronomy, found room in the
Merchant of Venice
for a nod to Pythagoras:

The churches of the day rang with approximations of the music of the spheres. The plainsongs and chants of the medieval cathedrals were being supplanted by polyphony, the music of many voices that would reach an epiphany in the fugues—the word
fugue
means “flight”—of Johann Sebastian Bach. For Kepler, polyphony in music was a model for the voices sung by the planets as they spun out their Pythagorean harmonies: “The ratio of plainsong or monody … to polyphony,” he wrote,

Kepler’s interest in astronomy, like Tycho’s, dated from his boyhood, when his mother took him out in the evening to see the great comet of 1577 and, three years later, to behold the sanguine face of the eclipsed moon. He was introduced to heliocentric cosmology at the University of Tübingen, by Michael Mastlin, one of the few Copernican academics of his day. Attracted to it partly out of mystical, Neoplatonic motives like those that had inspired Copernicus himself, Kepler wrote of sunlight in terms that would have brought a smile to the countenance of Marsilio Ficino:

But Kepler’s penchant for Platonic ecstasy was wedded to an acid skepticism about the validity of all theories, his own included. He mocked no thinker more than himself, tested no ideas more rigorously than his own. If, as he avowed in 1608, he was to “interweave Copernicus into the revised astronomy and physics, so that either both will perish or both be kept alive,” he would need more accurate observational data than were available to Ptolemy or to Copernicus. Tycho had those data. “Tycho possesses the best observations,” Kepler mused. “… He only lacks the architect who would put all this to use according to his own design.”
²⁹
Tycho was “superlatively rich, but he knows not how to make proper use of it as is the case with most rich people. Therefore, one must try
to wrest his riches from him.”
³⁰
Suiting action to intention, Kepler wrote adoring letters to Tycho, who in reply praised his theories as “ingenious” if rather too a priori, and invited him to come and join the staff at Benatek Castle.

There the two quarreled constantly. Tycho, justly fearful that the younger and more incisive Kepler would eclipse him, played his cards close to his chest. “Tycho did not give me the chance to share his practical knowledge,” Kepler recalled, “except in conversation during meals, today something about the apogee, tomorrow something about the nodes of another planet.”
³¹
Kepler threw fits and threatened to leave; at one point he had packed his bags and boarded a stage before Tycho finally summoned him back.

Realizing that he would have to give his young colleague something of substance to work on if he wanted to keep him on staff, Tycho devised a scheme redolent with the enmity that Kepler seemed to attract like lightning to a summit pine. “When he saw that I possess a daring mind,” Kepler wrote, “he thought the best way to deal with me would be to give me my head, to let me choose the observations of one single planet, Mars.”
³²
Mars, as Tycho knew and Kepler did not, presented an almost impossible challenge. As Mars lies near the earth, its position in the sky had been ascertained with great exactitude; for no planet were the inadequacies of both the Ptolemaic and Copernican models rendered more starkly. Kepler, who did not at first appreciate the difficulties involved, brashly prophesied that he would solve the problem of determining the orbit of Mars in eight days. Tycho must have been cheerful at dinner that night. Let the Platonist take on Mars. Kepler was still working on the problem eight years later.

Tycho, though, was out of time. He died on October 24, 1601, as the result of a burst bladder suffered while drinking too much beer at a royal dinner party from which he felt constrained by protocol from excusing himself. “Let me not seem to have died in vain,” he cried repeatedly that night.
³³

Kepler was to grant his dying wish. Named Tycho’s successor as imperial mathematician (albeit, as befitting his lesser status, at a much reduced stipend), he pressed on in his search for a single, straightforward theory to account for the motion of Mars. If every great achievement calls for the sacrifice of something one loves, Kepler’s sacrifice was the perfect circle. “My first mistake was in having assumed that the orbit on which planets move is a circle,”
he recalled. “This mistake showed itself to be all the more baneful in that it had been supported by the authority of all the philosophers, and especially as it was quite acceptable metaphysically.”
³⁴
In all, Kepler tested
seventy
circular orbits against Tycho’s Mars data, all to no avail. At one point, performing a leap of the imagination like Leonardo’s to the moon, he imagined himself on Mars, and sought to reconstruct the path the
earth’s
motion would trace out across the skies of a Martian observatory; this effort consumed nine hundred pages of calculations, but still failed to solve the major problem. He tried imagining what the motion of Mars would look like from the sun. At last, his calculations yielded up their result: “I have the answer,” Kepler wrote to his friend the astronomer David Fabricius. “… The orbit of the planet is a perfect ellipse.”