1616

by Christensen, Thomas

  Rudolf II, Holy Roman Emperor, as Vertumnus, the Roman God of the Seasons, about 1590, by Giuseppe Arcimboldo. Oil on panel, 57 × 70 cm. Skokloster Castle, Sweden.

  Tycho Brahe and Johannes Kepler each served as imperial mathematician to Rudolf II of Bavaria. Rudolf, renowned as a patron of the arts and the occult sciences, was also famous for such eccentricities as withdrawing from contact with his court for weeks on end and speaking at an inaudible volume. This portrait of him by Giuseppe Arcimboldo was among his favorites. It was acquired by Sweden when the Swedish army sacked Prague during the Thirty Years War.

  At about the same time, Kepler too had to flee from his home. He had been living in Gratz, in Eastern Austria, where he was employed as a teacher of mathematics at subsistence pay. (He was not an exceptional teacher. His mind tended to wander. In his first year a few students signed up for mathematics; in his second year not a single one took the course.) A crackdown on Protestants in the region forced him to look for a new situation, as he refused to renounce Lutheranism and convert to Catholicism. A similar stubbornness later in his life, when he rejected the concept of “ubiquity” — the idea that God’s body is ubiquitous in the world and not just his spirit, as Kepler held — caused him to be excommunicated from the Lutheran church. From the distance of the twenty-first century it can be difficult to understand how such distinctions could be so important as to expel a person who subscribed to all of the other official church doctrines from its community, or why it was so important to Kepler to maintain this position despite the serious consequences, but within a few years, in the Thirty Years War, a great many people would die for just such fine distinctions (ironically, the Lutheran church itself would abandon the doctrine of ubiquity within a few years).

  Kepler and Tycho had corresponded, and the result was his moving to Prague to serve as Tycho’s assistant. The two were an odd couple. Tycho was aristocratic, rich, outgoing, and robust. He loved banquets and celebrations; Danes at this time had a reputation as the heaviest drinkers in Europe and Tycho was no exception. (He had been raised by an uncle who had kidnapped him as a young boy from his parents; the uncle died of pneumonia after fishing the drunken King Frederick out of the icy Copenhagen waters into which he had toppled.) Kepler, on the other hand, could barely tolerate alcohol because of his perpetual poor health. Something of a tortured soul, he was solitary and inward-looking, and he shrank from social situations. Secretly believing himself the better astronomer, Kepler resented Tycho’s wealth and popularity. He also coveted Tycho’s data, which he needed to figure out why the planetary orbits refused to properly conform to his theories, but Tycho was not ready to share the information in more than a limited way. He had previously had his work stolen — a man calling himself Ursus (“Bear”) had obtained some of his work and passed it off as his own; in fact, this is the man Tycho had now replaced as Rudolf’s royal astronomer.

  Tycho Brahe, 19th century engraving by Johann-Leonhard Appold (1809–1858) after portraits by Jacob de Gheyn (1565–1629).

  Tycho’s prosthetic nose is evident in this portrait.

  Brahe was a flamboyant figure, who combined his astronomical observations with alchemical experiments. Having lost part of his nose in a duel, he wore a prosthetic metal one. He is said to have kept a pet moose that died when it got drunk on beer and fell down the stairs. Among his household was a dwarf who was supposed to be clairvoyant: he would make portentous pronouncements from a position underneath the dining table during parties. Despite his personal eccentricities Tycho had compiled decades of data from his celestial observations that were far more meticulous and precise than anything previously available. His elevation of observation over speculation was one of the key developments leading to the modern concept of inductive scientific investigation. Kepler, though appreciative of the benefit of accurate data, was less capable of obtaining it directly. A bout of smallpox in childhood had left him frail and sickly, with a severe visual handicap: he was short-sighted and had double vision in one eye. Nor did he have the means to construct a large observatory like Tycho’s Uraniborg. So he depended on Tycho for the data he needed to elaborate his theories of celestial harmony. How far would he go to obtain that data? In an odd echo of the case against his mother, Kepler was accused, nearly four hundred years after the fact, in a 2004 book by Joshua and Anne-Lee Gilder, of poisoning his mentor.

  Traditionally, Tycho was said to have died of bladder failure after a banquet, because etiquette required him not to leave the table in the presence of royalty. Even today some Czechs who need to leave the table for a bathroom break may say “Excuse me, please. I don’t want to end up like Tycho Brahe.” This explanation never made much sense: Tycho was completely at ease with royalty and could have found some means of handling the situation. The Gilders’ attempt to build a case against Kepler was based on then-recent forensic analysis of Tycho Brahe’s hair that suggested he had ingested a potent dose of mercury shortly before his sudden, unexpected death in Prague in 1601. From this they deduce that he was murdered, and they go on to paint Kepler as a sociopath who would stop at nothing to obtain Tycho’s data. With the case gone more than four hundred years cold, Kepler, like a number of others, cannot be ruled out as a suspect in the murder, if there was one. But the Guilders’ case is speculative in the extreme. The mercury could have been administered as a form of euthanasia, or it could have been taken inadvertently. Mercury was used to treat various diseases, and an accidental overdose is a possibility championed by, among others, an archaeologist who exhumed Tycho’s remains and a historian of science at Johns Hopkins University. The mercury could have been taken by Tycho himself or administered by his wife or any number of people other than Kepler.

  A Danish scholar, Peter Andersen, has proposed that Tycho was killed by a visiting cousin in a plot concocted by the Danish king Christian IV. (Contentious cousins bedeviled Tycho — it was another cousin who had removed the bridge of his nose in a duel. Four more of his cousins died in other duels, one killed by yet another cousin.) This particular cousin arrived in Prague from Denmark not long before the alleged murder, and Andersen says his diaries tend to implicate him. He also suggests that Christian resented Tycho for having had an affair with his mother, Queen Sophie. And, to add a bizarre Oedipal complication to the theory, he goes on to suggest that Christian could have been Tycho’s son, and he has called for DNA testing of the king’s remains to test this theory.

  Finally, the conclusion reached by the forensic analysis has itself been challenged by a professor of pharmacy and medicine at the University of Toronto. This point at least should soon be settled. In November 2010 Tycho’s body was once again exhumed, and new tests were made; the results of those tests are unknown at this writing — perhaps they will shed some light on the Danish astronomer’s death, although whether he was murdered and, if so, by whom, will almost certainly remain a mystery.

  Kepler may not have been a murderer, but he was in many respects an unpleasant personality. Despite his talents he suffered from feelings of inadequacy, which made him by turns resentful, suspicious, calculating, fawning, and obsequious; he was opportunistic, duplicitous, and deceitful. As a young man he kept an enemies list, on which it seemed nearly everyone he associated with appeared — he never forgot slights but would not hesitate to shower praise on the offending party when it was beneficial to him to do so (while criticizing him behind his back). His correspondence with Tycho is marked by alternating fits of rage and cringing apologies. He did not believe in washing and bathing, and perhaps as a result complained constantly about boils and sores, as well as a variety of other ailments and afflictions; sitting was painful for him, so that he would often walk in preference to riding a horse. In a horoscope he cast for himself as a young man he compared himself to an annoying little dog that imitates the behavior of others, fawns on its masters but snaps at everyone else, and snarls when things are taken from it; like a dog, he liked to gnaw on bones and hard dry bread. “He is malicious,” wrote
Kepler of himself, “and bites people with his sarcasms.”

  And yet, he was more generous with the results of his work than were Tycho or Galileo with theirs. He would not bend his religious principles, even when faced with excommunication. He was inspired by beauty and motivated by the desire to understand the workings of God. He was relentless in pursuing a problem to its final solution. He combined brilliant intuition with a willingness for inexhaustible labor when needed.

  When the published version of The Cosmographic Mystery appeared, Kepler was still convinced that his connection of the planetary orbits to the five regular solids was a fundamental breakthrough toward discovering God’s plan for the universe. With great enthusiasm he mailed copies to all of the influential people he could think of who had an interest in astronomical topics or might assist him in his career, but the results of these mailings would be disappointing. Still, among the recipients was a thirty-three-year-old professor of mathematics at the University of Padua, who wrote back to confess that he too was a Copernican, subscribing to the radical notion that the earth orbited around the sun. But he was afraid, he said, to state that belief publicly. Kepler responded by urging him to speak out, but Galileo did not acknowledge this second letter — in fact, he would not be in touch with Kepler again for thirteen years. The reason, according to Albert Einstein, was vanity, which he considered a failing of many great scientists. “It has always hurt me to think,” he wrote in a letter to a friend, “that Galileo did not acknowledge the work of Kepler.”

  Galileo was the son of a musician, Vicenzo Galilei, who was an early advocate of what is called “equal temperament” in music theory, in which octaves or other intervals are divided into mathematically equal steps. This idea was in the air, as it was championed around the same time by Zhu Zaiyu in China and Simon Stevin in Flanders; wherever it originated, it may have spread through East-West trade channels. Kepler took Galileo’s father’s book, The Dialogue on Ancient and Modern Music, with him in 1616 when he traveled to assist his mother’s defense in her witchcraft case. In questioning traditional music theory, Vincenzo Galilei had made experiments with strings of different lengths to determine the mathematical relations among notes of varying pitch. In writing about this he said, “It appears to me that they who in proof of anything rely simply on the weight of authority, without adducing any argument in support of it, act very absurdly. I, on the contrary, wish to raise questions freely … as becomes those who are truly in search of the truth.” Rejection of authority in favor of empirical research would likewise be the hallmark of Galileo’s scientific methodology. Of course, experimentation in itself was nothing spectacularly new, and to yield really innovative results it needed to be combined with thinking beyond the bounds of convention.

  Galileo’s mother, like Kepler’s, was a source of aggravation. Galileo had taken a Venetian woman as his mistress, with whom he had three children. (One of these, Virginia, who took the apropos name Sister Maria Celeste when she entered a convent in 1616, would be a particular solace to him in his later life. Her birth, in 1600, had been announced in the parish registry as “Virginia, daughter of Marina of Venice, born of fornication.”) His mother, who seems to have been difficult and disagreeable, disapproved of this relationship, and her visits to Padua from Galileo’s childhood home of Florence (where the family had moved from Pisa when Galileo was ten) were known to degenerate into shrieking bouts of hair pulling.

  As a student at the University of Pisa Galileo developed a reputation for questioning authority and contradicting his professors. The famous demonstration of dropping balls of different sizes from the Leaning Tower began with his questioning of the accepted idea, based on Aristotle, that the speed of falling bodies was proportional to their sizes. (Many scholars are convinced this incident is apocryphal since there is no contemporaneous documentation of it. It first appears in a biography of Galileo written by a young man who lived and studied with him in his old age. Still, the showy demonstration fits Galileo’s style. His biographer may well have heard the story from him, and Galileo’s own writings do contain suggestive passages on the topic of dropped objects.) Galileo may have questioned accepted wisdom about falling bodies after observing that hailstones of different sizes reach the ground around the same time: if larger bodies fell faster, shouldn’t hail descend in waves of diminishing sizes?

  Observation was the essence of Galileo’s approach to science. His investigation of the rate of motion of falling bodies was typical. The conventional belief (odd as it seems today) was that acceleration was not at all a continuous process but rather a series of successive, uniform rates of speed, each faster than the one before — not like a continuous incline but like the series of steps of a stairway. Initially Galileo worked from that assumption, but the evidence soon led him to abandon it. To discover the truth he constructed a gently sloping ramp down which he allowed a ball to roll. Using musical beats as a timing device, he marked the position of the ball at regular intervals. He found that speed increased by odd numbers — as 1, 3, 5, 7 — and therefore distance from the beginning point by the sequence 1, 4, 9, 16 (1+3 = 4, 4+5 = 9, 9+7 = 16) with each successive beat. From this he derived the law of falling bodies, that distances from rest are as the square of the elapsed times (1, 4, 9, 16 = 12, 22, 32, 42).

  Phases of the Moon, about 1610, probably by Galileo Galilei. Watercolor or sepia ink on paper.

  Two developments in the early seventeenth century enabled the gathering of highly accurate astronomical data. The first was Danish astronomer Tycho Brahe’s construction of elaborate observatories and his systematic accumulation of detailed data from them. The other was Galileo’s refinements of the technology of the telescope and the celestial discoveries they enabled. This depiction of the phases of the moon was pasted into a printing of The Starry Messenger (1610), Galileo’s report on his celestial discoveries based on observations by telescope; the book caused a sensation.

  Galileo was not only a scientist but also an accomplished musician and artist, and a friend of artists. It is generally supposed (though on scant evidence) that this is his own work, perhaps the original images that served as models for some of the engravings in The Starry Messenger.

  Galileo’s depictions of the moon might seem beautiful today, but they struck some at the time as an affront: surely God’s heavenly objects must be perfect, they thought, not pocked and roughened with craters and protuberances like some ordinary rock of the earthly realm.

  Unlike Kepler, Galileo was not trying to lay bare God’s perfect plan for the universe. He did not expect observation to yield flawless results, because he knew that the conditions of experimentation were almost never ideal, measurement was accurate only to a certain level of precision, and data could be subtly corrupted by any number of real-world factors. He merely wanted scientific theory to generally correspond with actual observation. Because of this basic difference in their attitudes, Galileo was not sympathetic to some of the directions of Kepler’s work.

  Kepler had begun to recognize that astronomical bodies exert forces on each other. He posited a force of the earth that governs the orbit of the moon and a force of the sun that governs the orbits of the planets, in this way explaining their varying velocities by their proximity to the sun in elliptical orbits (he thought the force might be a kind of magnetism; in fact, it is gravitation). Galileo thought that all of this was hokum. He rejected the notion that heavenly bodies can influence each other, or even terrestrial phenomena such as tides, from afar. To Galileo such notions smacked of the occult. “Among the great people discussing this phenomenon of nature,” he wrote, “the one who surprises me the most is Kepler, who, possessing a free and sharp mind and being quite familiar with the motions ascribed to the earth, admits a fundamental power of the moon on water, hidden properties, and such similar childishness.” Galileo’s skepticism is understandable but, as it turns out, Kepler was right.