I am free to give myself up to the sacred madness, I am free to taunt mortals with the frank confession that I am stealing the golden vessels of the Egyptians, in order to build of them a temple for my God, far from the territory of Egypt. If you pardon me, I shall rejoice; if you are enraged, I shall bear up. The die is cast.35
And so on. The cause of his celebration was his discovery of what are known today as Kepler’s laws. The first contained the news he had communicated to Fabricius—that each planet orbits the sun in an ellipse with the sun at one of its two foci. The second law revealed something even more astonishing, a Bach fugue in the sky. Kepler found that while a planet’s velocity changes during its year, so that it moves more rapidly when close to the sun and more slowly when distant from the sun, its motion obeys a simple mathematical rule: Each planet sweeps out equal areas in equal times. The third law came ten years later. It stated that the cube of the mean distance of each planet from the sun is proportional to the square of the time it takes to complete one orbit. Archimedes would have liked that one. Newton was to employ it in formulating his law of universal gravitation.
Kepler’s first law: The orbit of each planet describes an ellipse, with the sun at one of its foci.
Kepler’s second law: If time AB = time CD, area ABSun = area CDSun.
Kepler’s third law: The cube of the distance of each planet from the sun is proportional to the square of its orbital period.
Here at last was “the principal thing” of which Copernicus had dreamed, the naked kinematics of the sun and its planets. “I contemplate its beauty with incredible and ravishing delight,” Kepler wrote.36 Scientists have been contemplating it ever since, and Kepler’s laws today are utilized in studying everything from binary star systems to the orbits of galaxies across clusters of galaxies. The intricate etchings of Saturn’s rings, photographed by the Twin Voyager spacecraft in 1980 and 1981, offer a gaudy display of Keplerian harmonies, and the Voyager phonograph record, carried aboard the spacecraft as an artifact of human civilization, includes a set of computer-generated tones representing the relative velocities of the planets—the music of the spheres made audible at last.
But the sun of learning is paired with a dark star, and Kepler’s life remained as vexed with tumult as his thoughts were suffused with harmony. His friend David Fabricius was murdered. Smallpox carried by soldiers fighting the Thirty Years’ War killed his favorite son, Friedrich, at age six. Kepler’s wife grew despondent —“numbed,” he said, “by the horrors committed by the soldiers”—and died soon thereafter, of typhus.37 His mother was threatened with torture and was barely acquitted of witchcraft (due, the court records noted, to the “unfortunate” intervention of her son the imperial mathematician as attorney for the defense) and died six months after her release from prison. “Let us despise the barbaric neighings which echo through these noble lands,” Kepler wrote, “and awaken our understanding and longing for the harmonies.”38
He moved his dwindling family to Sagan, an outback. “I am a guest and a stranger here. … I feel confined by loneliness,” he wrote.39 There he annotated his Somnium, a dream of a trip to the moon. In it he describes looking back from the moon to discern the continent of Africa, which, he thought, resembled a severed head, and Europe, which looked like a girl bending down to kiss that head. The moon itself was divided between bright days and cold dark nights, like Earth a world half darkness and half light.
Dismissed from his last official post, as astrologer to Duke Albrecht von Wallenstein, Kepler left Sagan, alone, on horseback, searching for funds to feed his children. The roads were full of wandering prophets declaring that the end of the world was at hand. Kepler arrived in Ratisbon, hoping to collect some fraction of the twelve thousand florins owed him by the emperor. There he fell ill with a fever and died, on November IS, 1630, at the age of forty-eight. On his deathbed, it was reported, he “did not talk, but pointed his index finger now at his head, now at the sky above him.”40 His epitaph was of his own composition:
Mensus eram coelos, nunc terrae metior umbras
Mens coelestis erat, corporis umbra iacet.
I measured the skies, now I measure the shadows
Skybound was the mind, the body rests in the earth.
The grave has vanished, trampled under in the war.
*One could write a plausible intellectual history in which the decline of sun worship, the religion abandoned by the Roman emperor Constantine when he converted to Christianity, was said to have produced the Dark Ages, while its subsequent resurrection gave rise to the Renaissance.
*Modern myth to the contrary, little of the ecclesiastical opposition to Copernicanism appears to have derived from fear that the theory would “dethrone” humanity from a privileged position at the center of the universe. The center of the universe in Christian cosmology was hell, and few mortals would have felt dis-accommodated at being informed that they did not live there. Heaven was the place of distinction, for Christian and pagan thinkers alike. As Aristotle put it, “The superior glory of … nature is proportional to its distance from this world of ours.” When Leonardo da Vinci suggested that the earth “is not in the center of the universe,” he intended no slander of Earth, but was suggesting that our planet is due the same dignity—noblesse—as are the stars.
*Comets are chunks of ice and dirt that fall in from the outer solar system, sprouting long, glowing “tails” of vapor and dust blown off by the sun’s heat and by solar wind. The appearance of new comets cannot be predicted even today; they appear to originate in a cloud that lies near the outer reaches of the solar system, about which little is understood. Their orbits, altered by encounters with the planets and by the kick of their own vapor jets, remain difficult to predict as well.
*The cometary stigma persisted into the early twentieth century, when millions bought patent medicines to protect themselves from the evil effects of comet Halley during its 1910 visitation. Several fatalities were reported, among them a man who died of pneumonia after jumping into a frozen creek to escape the ethereal vapors. A deputation of sheriffs intervened to prevent the sacrifice of a virgin, in Oklahoma, by a sect called the Sacred Followers who were out to appease the comet god.
* Twentieth-century radio astronomers using Renaissance star charts have located the wreckage of both Tycho’s supernova, now designated 3C 10 in the Cambridge catalog of radio sources, and of Kepler’s, known as 3C 358. Also located is the remnant of the Vela supernova, which blazed forth in the southern skies some six to eight thousand years ago, casting long shadows across the plains of Eden. (The word Eden is Sumerian for “flatland,” and is thought to refer to the fertile, rock-free plains of the Tigris-Euphrates.) The Sumerians identified that supernova with the god Ea (in Egypt, Seshat), whom they credited with the invention of writing and agriculture. The Ea myth thus suggests that the creation of agriculture and the written word were attributed by the ancients to the incentive provided by the sight of an exploding star.
5
THE WORLD IN RETROGRADE
Pure logical thinking cannot yield us any knowledge of the empirical world; all knowledge of reality starts from experience and ends in it…. Because Galileo saw this, and particularly because he drummed it into the scientific world, he is the father of modern physics—indeed, of modern science altogether.
—Einstein
What if the Sun
Be Center to the World, and …
The Planet Earth, so stedfast though she seem,
Insensibly three different Motions move?
—Milton, Paradise Lost
History plays on the great the trick of calcifying them into symbols; their legend becomes like the big house on the hill, whose owner is much talked about but seldom seen. For no scientist has this been more true than for Galileo Galilei. Galileo dropping a cannonball and a musket ball from atop the Leaning Tower of Pisa, thus demonstrating that objects of unequal weight fall at the same rate of acceleration, has come to symbolize the grow
ing importance of observation and experiment in the Renaissance. Galileo fashioning the first telescope symbolizes the importance of technology in opening human eyes to nature on the large scale. Galileo on his knees before the Inquisition symbolizes the conflict between science and religion.
Such mental snapshots, though useful as cultural mnemonic devices, extract their price in accuracy. The story of Galileo at the Leaning Tower is almost certainly apocryphal. It appears in a romantic biography written by his student Vincenzio Viciani, but Galileo himself makes no mention of it, and in any event the experiment would not have worked: Owing to air resistance, the heavier object would have hit the ground first. Nor did Galileo invent the telescope, though he improved it, and applied it to astronomy. And, while Galileo was indeed persecuted by the Roman Catholic Church, and on trumped-up charges at that, he did as much as anyone outside of a few hard-core Vatican extremists to lay his body across the tracks of martyrdom.
Still, these distortions in the popular conception of Galileo work to his favor, and that would have pleased him. A devoted careerist with a genius for public relations, he was ahead of his time in more ways than one. His mission, as he put it, was “to win some fame.”1
Galileo was born in Pisa, on February 15, 1564, twenty years after the publication of Copernicus’s On the Revolutions. From his father, Vincenzo Galilei, a professional lute player and amateur mathematician, Galileo inherited a biting wit, a penchant for the dialogue form of argument, and a vehement distrust of authority. Vincenzo had written a book, Dialogue of Ancient and Modern Music, that encouraged Kepler in his search for Pythagorean harmonies. One of the characters in it utters a declaration that could have been the motto of the younger Galileo:
It appears to me that they who in proof of any assertion rely simply on the weight of authority, without adducing any argument in support of it, act very absurdly. I, on the contrary, wish to be allowed freely to question and freely to answer you without any sort of adulation, as well becomes those who are in search of truth.2
Galileo prospered so long as he remained true to that independent creed. Disaster beset him once he neglected it and began demanding that questions be decided on the pronouncements of his own authority.
As a young man, however, Galileo waged glorious campaigns against those who, as he was to write, “think that our intellect should be enslaved to that of some other man.”3 An incandescent speaker and pamphleteer, he was known during his student days at the University of Pisa as “the wrangler” for the sarcastic aplomb with which he skewered the Scholastic professors.
At his parents’ behest Galileo studied medicine, but he found little there to gratify his appetite for empirical knowledge. Medical lecturers typically taught from a volume of Galen, who had been dead for fifteen hundred years, and their laboratory sessions were hindered by a Church prohibition against dissection of human bodies. Galileo soon dropped out. He then spent four irresponsible, productive years lazing about at home, reading Virgil and Ovid, building little machines, and studying mathematics with a tutor, Ostilio Ricci, with whom he shared a devotion to the works of Archimedes.
Galileo was twenty-five years old when a scientifically inclined nobleman, Francesco Cardinal del Monte, took an interest in his abilities and got him appointed professor of mathematics at Pisa. There he lectured on astronomy, poetry, and mathematics and resumed his hectoring of the Aristotelians, at one point circulating a satirical poem poking fun at the Scholastics’ habit of coming to school in togas, like little wax Aristotles. The students were delighted but the Scholastics were in the majority on the faculty, and when Galileo’s contract expired he was let go.
He then managed to gain an appointment to the chair of mathematics at the University of Padua, in the free Republic of Venice.* (Another applicant for the post was Giordano Bruno, but he was in chains by the time Galileo arrived at the university in September 1592 and was burned alive eight years later for refusing to abjure many heresies, among them his insistence that the stars are suns.) Galileo remained at Padua for eighteen years, writing, lecturing, conducting experiments, and inventing scientific instruments, among them the thermometer.
During this time his financial troubles, always onerous, became insupportable. His father had died in 1591, leaving Galileo to pay his two sisters’ dowries, each of which equaled several years’ worth of his university salary. In addition he was obliged to send money to his brother Michelangelo, a wandering musician who demonstrated his contempt for cash by squandering it as rapidly as he could get his hands on it. By the age of forty-five, Galileo was a respected scientist and teacher with a couple of books to his credit, but his contract was coming up for renewal, his debts were mounting, and he needed something to elevate his career from the creditable to the extraordinary. It came to him in 1609. It was the telescope.
During one of his frequent visits to nearby Venice, Galileo learned that telescopes were being constructed in Holland. Quick to grasp the principles involved, he returned home to Padua and built a telescope for himself. “Placing my eye near the concave lens,” he recalled, “I perceived objects satisfactorily large and near, for they appeared three times closer and nine times larger than when seen with the naked eye alone. Next I constructed another one, more accurate, which represented objects as enlarged more than sixty times.”4
Galileo did not need to be told that the telescope would have great practical value. Venice was an unwalled city, and its citizens depended for their defense upon their ability to spot approaching enemy ships in time to dispatch a fleet to engage them while they were still at sea; the telescope would greatly improve this early-warning system. The Venetians, furthermore, made their living from sea trade, and frequently kept an anxious watch, from the lookout towers (campanili) that dotted the city, for galleys returning with their holds full of cornmeal from the Levant, spices from Constantinople, and silver from Spain; an investor might be ruined if his ship were lost, or double his money once “his ship came in.” A lookout using a telescope could spot the flag flying from an incoming trading ship much sooner than with the unaided eye.
Galileo accordingly arranged a demonstration for the authorities. On August 25, 1609, he led a procession of Venetian senators across the Piazza San Marco and up the Campanile for their first look through his first telescope. As he recalled the scene:
Very many were the patricians and senators who, although aged, have more than once climbed the stairs of the highest campanili of Venice, to detect sails and vessels on the sea, so far away that coming under full sail toward the harbor, two hours or more passed before they could be seen without my eyeglass; because in fact the effect of this instrument is to represent an object that is, for example, fifty miles off, as large and near as if it were only five miles away.5
The senators, suitably impressed, doubled Galileo’s salary and granted him a lifelong appointment at Padua; as we would say today, Galileo got tenure. But his triumph was darkened by a cloud of deception. He permitted the senators to assume that he had invented the telescope. This was not strictly true, and his silence as to the stimulus of his greatest invention became embarrassing once telescopes produced by Dutch and Italian spectacle-makers began turning up in the marketplaces of Venice. In Bertolt Brecht’s play Galileo, Priuli the Venetian curator upbraids Galileo for his guile:
CURATOR: There it is—your “miraculous optical tube.” Do you know that this invention he so picturesquely termed “the fruit of seventeen years’ research” will be on sale tomorrow for two scudi apiece at every street corner in Venice? A shipload of them has just arrived from Holland.
SAGREDO: Oh, dear! Galileo turns his back and adjusts the telescope.
CURATOR: When I think of the poor gentlemen of the Senate who believed they were getting an invention they could monopolize for their own profit…. Why, when they took their first look through the glass, it was only by the merest chance that they didn’t see a peddler, seven times enlarged, selling tubes exactly like it at the corner of
the street.6
But while the senators trained their telescopes on the horizon, Galileo trained his on the night skies. He was the first scientist to do so (or one of the first; Thomas Harriot in England observed the moon through a telescope that same summer) and what he saw spelled the beginning of the end of the closed, geocentric cosmos, and the opening up of the depths of space.
As beginning observers have done ever since, Galileo looked first at the moon, and the sight of its mountains and craters immediately impressed him with the fact that it was not a wafer composed of heavenly aether, but a rocky, dusty, sovereign world. Aristotle to the contrary, the moon is “not robed in a smooth and polished surface,” wrote Galileo, but is “… rough and uneven, covered everywhere, just like the earth’s surface, with huge prominences, deep valleys, and chasms.”7
Turning his telescope to Jupiter, Galileo discovered four moons orbiting that giant planet, their positions changing perceptibly in the course of just a few hours’ observation. Jupiter, he was to conclude, constituted a Copernican solar system in miniature, and proof as well that the earth is not unique in having a moon. Galileo called it
a fine and elegant argument for quieting the doubts of those who, while accepting with tranquil mind the revolutions of the planets about the sun in the Copernican system, are mightily disturbed to have the moon alone revolve about the earth and accompany it in an annual rotation about the sun. Some have believed that this structure of the universe should be rejected as impossible. But now we have not just one planet rotating about another while both run through a great orbit around the sun; our own eyes show us the four stars [i.e., satellites, a term coined by Kepler] which wander around Jupiter as does the moon around the earth, while all together trace out a grand revolution about the sun in the space of twelve years.8
Coming of Age in the Milky Way Page 8