The Theory of Heliocentrism

Life at Benátky was not quite living up to Tycho Brahe’s fond imaginings of a return to his glory days. Holy Roman Emperor Rudolf II had promised him a generous monthly stipend to build a second incarnation of his sorcerer’s castle, but the actual payments were proving to be erratic.

The fact was that the imperial finances in general were in serious disarray, thanks to Rudolf’s longstanding habit of spending lavishly on pet projects like this one and neglecting the more plebeian aspects of running a government. Even when setting aside the vicissitudes of its individual monarchs, by this point the Holy Roman Empire itself, which was about to celebrate the 800th anniversary of its founding, was showing the signs of its age. If its wasn’t yet the impotent Medieval anachronism that would be so famously mocked by Voltaire in the eighteenth century as “neither holy nor Roman nor an empire,” neither did it smack all that much of the martial glory of its founder Charlemagne. The emperor was increasingly beholden to his ostensible subjects across greater Germany, a burgeoning network of burgher states who were able to express their approval or disapproval of his proclamations by deciding whether to pay or withhold their taxes. Even in the best of circumstances, the city-states of Germany rendered unto the emperor his share only after they had balanced their own books. What authority Rudolf did still possess arose more out of a lingering deference to tradition than anything else.

Financial disruptions at the top always roll downhill; thus the funding for Tycho’s second Uraniborg trickled in only in fits and starts. When Johannes Kepler arrived at Benátky on February 4, 1600, the place was still a construction site showing only desultory signs of progress, the master’s time taken up almost entirely with trying to wring the money he was owed out of Rudolf’s courtiers in Prague.

History does not record the details of the doubtless confusing scene that must have ensued just after Kepler turned up. One imagines that he and Tycho must have talked past one another for a while, what with the latter assuming the former to have come in response to an invitation which Kepler had never actually received. What is clear, however, is that the situation Kepler walked into wasn’t at all what he had expected. He had envisioned working in close harmony with the great astronomer in monkish isolation, probing the secrets of the heavens by his side, perhaps even slowly talking him round to a recognition of the superiority of Copernicus’s heliocentric cosmos. Instead the shy, awkward scholar found himself swept up into a swirling vortex of competing interests and enmities beyond his ken.

Tycho was now 53 years old, a far more advanced age in his time than it is in our own, and Kepler was far from the only man who sought to lay a claim to his legacy, to become the inheritor of his observational data and, even more importantly for most of the aspirants, his stipend and title from Emperor Rudolf. These aspirants had all assembled here on the scene to vie personally for the great man’s attention. Their ranks included among others Tycho’s own son Jørgen, whose seeming inside track to his father’s mantle was made more complicated by his native indolence and lack of mathematical talent; Franz Tengnagel von Camp, a German nobleman who thought his mostly likely route to becoming the next lord of Benátky lay not through astronomy, at which he wasn’t any more accomplished than Jørgen Brahe, but through marrying one of Tycho’s daughters; and Christian Severin Longomontanus, a Dane who had worked as Tycho’s faithful assistant for the past eight years. This gaggle of ambitious strivers reacted to the appearance of yet another rival for Tycho’s attention in predictable fashion. Kepler had a very hard time of it. Even Tycho’s court jester Jepp took a dislike to him, delighting in eviscerating every detail of his body, bearing, and behavior at the dysfunctional family’s cacophonous dinners. For his part, Tycho barely paid Kepler any attention at all, having seemingly forgotten his declaration of friendship in his letter of invitation; at dinner, Kepler sat near the foot of the table, and was seldom favored with even a passing glance or remark from the patriarch. What had become of the thoughtful natural philosopher with whom he had corresponded for the last several years? It seemed that Tycho Brahe contained multitudes, and Johannes Kepler didn’t like this incarnation of him one bit.

Tycho entrusted Kepler with only menial calculating tasks that any reasonably proficient man of numbers could have carried out, and never displayed a willingness to discuss his work in the expansive, egalitarian way he sometimes had in his letters. We can only speculate as to the reasons for his reticence and ambivalence. A man who wasn’t used to being contradicted, he probably found Kepler’s stubborn refusal to abandon heliocentrism and adopt his own hybrid geocentric model of the universe enormously frustrating. He may have decided to freeze the arrogant youngster out until he got with the program. Less pettily, as a dyed-in-the-wool empiricist, he may have been employing tough love to try to instill the same ethic in Kepler, to purge him of the sorts of flights of fancy that he had indulged in in his book so that he could live up to his real potential. (It must be understood that in Tycho’s mind the absence of stellar parallax proved heliocentrism to be every bit as absurd a flight of fancy as any of Kepler’s more explicitly mystical theories.)

Of course, Kepler was hardly a babe in the woods, no matter how vulnerable he may have looked to Jepp’s hawk-cruel gaze. In his way, he was as fiercely, selfishly ambitious as anyone at Benátky. Back in Graz, he had told Michael Mästlin in a letter “what I think of Tycho”: “He is very rich, but he does not make proper use of his riches, like most rich people. Therefore we must wrest his riches from him.”

What did make him unique among the flock of aspirants at Benátky was that by “riches” Kepler didn’t mean monetary wealth, but rather Tycho’s almost entirely unpublished observational data, the fruits of his decades of ceaseless star-gazing. Being not much of a stargazer himself — the watery eyes that Jepp so loved to mock precluded that — Kepler saw this data as the grist that his mill needed if he was to improve upon Copernicus and develop the first completely satisfactory, completely unassailable heliocentric model of the heavens. Even as he respected Tycho’s achievement in collecting all of this data, he was convinced that only he was capable of making proper use of it.

Tycho possesses the best observations, and thus, so to speak, the material for the building of the new edifice. He also has collaborators and everything he could wish for. He only lacks the architect who would put all this to use according to his own design. For although he has a happy disposition and real architectural skill, he is nevertheless obstructed in his progress by the multitude of the phenomena and by the fact that the truth is deeply hidden in them. Now old age is creeping upon him, enfeebling his spirit and his forces.

Kepler’s growing frustration at being cast in the role of a menial assistant instead of a proper protégé — much less a full-fledged partner — finally boiled over two months after his arrival in Benátky. He waylaid Tycho out of the blue one day, demanding, none too diplomatically, to have his status clarified. He wanted a formal position of his own, he said, complete with a stipend of his own from Emperor Rudolf, guaranteeing him a place here for at least the next two years. He was, after all, a married man, with all of the responsibilities attendant on that status. He needed to know where he stood, needed a measure of stability.

Kepler’s arguments were by no means entirely unreasonable, but Tycho was not a man who responded well to ultimatums. A screaming row followed, constituting by far the most extended communication the two men had indulged in since Kepler came to Benátky. When it was over, Kepler caught the next coach back to Prague, where he knocked on the door of Johann Friedrich Hoffman, the friendly baron who had effected his transport to Bohemia. He stayed in Hoffman’s house for three weeks, belatedly realizing over that period of time that it may have been unwise to make so many demands of his host when he had nowhere else to go. Dreading the prospect of returning to his tenuous existence as a Protestant in Catholic Graz, dreading perhaps most of all returning empty-handed to his hectoring wife, he reached for pen and paper to write the second cringing apology of his life to Tycho Brahe.

The criminal hand which, the other day, was quicker than the wind in inflicting injury hardly knows how to set about to make amends. What shall I mention first? My lack of self-control, which I can only remember with the greatest pain, or your benefactions, noblest Tycho, which can neither be enumerated nor valued according to merit? You have extended to me every friendliness; you have allowed me to share in your most cherished possession. Instead of thanking you, I displayed blind rage. Instead of showing you respect, I displayed the greatest insolence against your person, which by noble descent, prominent learning, and great fame deserves all respect…

The letter went on and on in that vein. It must have cost Kepler enormously to write it.

Nonetheless, this time Tycho was not quite so magnanimous as he had been the first time. He told Kepler to go home for the time being. Maybe at some point in the future he would invite him back, once he had paid the dues of his insolent temper.

So, Johannes Kepler returned to Graz and to his wife Barbara in June of 1600. There he found that the zealous young Archduke Ferdinand was more determined than ever to root out the remaining Protestants in his midst. On July 27, Ferdinand took the ultimate step. Over the coming weeks, it was announced, the head of each and every household in Graz would have to appear before a tribunal headed by Ferdinand himself and the local bishop. Each would be asked whether he recognized the God-given authority of the pope, and, if the answer was affirmative, required to parrot the Nicene Creed, the Catholic Church’s pledge of allegiance dating from before the fall of ancient Rome. (“We believe in… one holy Catholic and Apostolic Church…”) Then the citizen under examination must take Communion before the assembled witnesses. Those who refused would be expelled from the town forever. And this time, there would be no exceptions.

Kepler was one of the first to be called before this tribunal, on August 2. In his case, the proceedings didn’t last long. He may have been willing to prostrate himself before Tycho Brahe in the most abject fashion, but he was resolute when it came to the disposition of his immortal soul. Archduke Ferdinand, who was by all indications prepared to make him one of the leading lights of his court and solve all of his problems at a stroke if he would but convert, held no sway in this area. No, he was not willing to submit to the pope; no, he was not willing to swear by the Nicene Creed; no, he was not willing to take Catholic Communion. After that, there was nothing more to be said. He and his wife and stepdaughter were given five weeks to leave Graz forever.

Barbara Kepler’s father and her brothers proved less resolute than Johannes, agreeing to convert to Catholicism as the price for retaining their mill and their lives in Graz. Barbara would have preferred to do the same, thus adding one more bone of contention between her and her husband. As it was, Kepler’s refusal to swap his faith for another meant that the two of them were effectively disinherited. Kepler had lost his last source of income.

On September 10, 1600, the little family left Graz, adding their own one-horse wagon to a line of same leaving the town. They were now refugees, their situation acute. How were they to eat once they had spent the small quantity of coin in their pockets? Not knowing where else to go, they turned their wagon in the direction of Prague.

And so, a couple of weeks later, Kepler turned up yet again at the doorstep of Baron Hoffman, who must by this point have been wondering how long he would continue to be punished for his good deed of bringing this erratic fellow into Tycho’s orbit. This latest version of Kepler, however, was in a bad way: gaunt even in comparison to his usual appearance, looking every inch the impoverished refugee he was. Worse, he was shivering visibly and suffering from a wet, wracking cough of the kind that screamed danger to any European of this period — a period when about half of all children died from infectious diseases before reaching adulthood, when it was commonplace for entire cities to be shut down for months at a time in an attempt to minimize the terrible ravages of smallpox, tuberculous, scarlet fever, and the dreaded bubonic plague. Despite the dangers, Hoffman took Kepler and his family in, albeit whilst quarantining them for a time in one wing of the house. Truly he is one of the unsung heroes of science history.

It was touch and go for a while, but Kepler gradually recovered. As he did so, he learned that Tycho too had suffered a reversal of fortune in recent months. With the imperial finances more stretched than ever, Rudolf had been forced to ask him to give up on establishing a second Uraniborg in Benátky and join his court in Prague proper not that long after Kepler had left for Graz. Tycho was still in Prague when Kepler and his family straggled back into the imperial capital, being cooped up with his own, far larger family and the rest of his noisy retinue in one of the emperor’s spare mansions. Never anyone’s idea of a focused, hands-on ruler, Rudolf was retreating still further into abstractions and obsessions as he aged. He monopolized much of Tycho’s time in long, meandering conversations about astronomy, astrology, alchemy, or whatever else happened to have popped into his head that day. When Tycho was dismissed from the emperor’s presence, he often left with homework: Rudolf demanded that he cast his horoscope and those of his family and friends over and over again. This courtier’s life wasn’t at all the one that Tycho had imagined awaited him in Bohemia, but he saw no obvious way out of it. It was becoming clear that he was not going to get to play Prospero again in this life, on any real or metaphorical island of his own.

Tycho’s old nemesis Nicolaus Reimers died this year, not quite in disgrace but neither so widely respected as he had been ten years earlier. Far from taking this event as the last word on their feud, Tycho rushed to assert his own preeminence for all time. For he was moving into that phase of life when the cementing of one’s various legacies becomes more urgent than adding to them. He convinced Rudolf to ban the works of his former Imperial Mathematician throughout his realms as the scribblings of a dirty plagiarist (although in truth such proclamations from on-high counted for less and less in Rudolf’s empire of oft-wayward city-states).

Ironically, this final revenge campaign against Reimers became Tycho’s excuse for a rapprochement with Kepler, whose mind plainly continued to intrigue him even as his heart remained uneasy with the idea of friendship with this commoner who had insulted him so. Tycho asked Kepler to write a pamphlet refuting Reimers’s theories and asserting Tycho’s own claims to primacy when it came to a modified geocentric universe where only the Sun and Moon orbited the Earth. This was a delicate position for Kepler to be placed in, given that he himself didn’t believe in said universe. But he took the assignment on anyway, being desperate for a return to favor. As he had hoped, more assignments followed, for which Tycho appears to have paid him out of his own pocket. Kepler became a regular presence around Tycho’s mansion — in his sitting room, in his observatory, and sometimes in the alchemical laboratory he was constructing in the basement. The two seemed to get along better now that they had both been brought down a notch or two in the world. Then, too, with the prize of Benátky no longer being in Tycho’s remit, there were fewer fawners for Kepler to try to out-maneuver into the master’s favor. Tycho eventually invited Kepler and his family to move into his mansion, to the undoubted relief of Baron Hoffman.

In the spring of 1601, Barbara Kepler’s father died back in Graz, just nine months after bowing to necessity and converting to Catholicism. Tycho was kind enough to intercede with Emperor Rudolf, who in turned interceded with his zealous cousin Archduke Ferdinand, securing Johannes permission to go to Graz for a few months in order to try to reclaim his part of the Müller inheritance. He didn’t succeed against the rest of the family’s lawyers, returning to Prague as poor as ever in September of 1601. Little did he know that he was about to see a dramatic improvement in his situation anyway.

On October 13, Tycho was invited to dine with one Baron Rosenberg, yet another member of Rudolf’s extended court. The meal was typical of a noble feast, with more meat on the table than the average peasant family ate in the course of a year. Tycho partook with his standard gusto, but began to feel more and more unwell as the evening wore on. According to a doctor’s account that strained to turn gluttony into an act of heroism, “holding his urine longer than was his habit, Tycho remained seated. Although he drank a little overgenerously and experienced pressure on his bladder, he felt less concern for the state of his health than for etiquette. By the time he returned home, he could not urinate anymore.”

Tycho drifted back and forth across the border between lucidity and delirium over the next week and a half, while family, friends, and luminaries, among them Johannes Kepler, hovered around his bedside. At times, he seemed to be recovering, being able to sit up in bed and eat and talk quite calmly. But then he would slide back into the grip of a high fever that seemed fueled by a burning fire in his abdomen.

During the periods of calm, he talked most of all to Kepler. Most remaining traces of hostility between the two vanished, as Tycho addressed Kepler almost like a son, telling him over and over that he was destined to accomplish great things. The only hint of the old tensions came when he urged Kepler to give up his foolish insistence on heliocentrism in favor of a model of the universe that was supported by the empirical evidence — namely, the absence of stellar parallax.

During the periods of agony, Tycho withdrew deeply into himself. “Let me not have lived in vain!” he rasped through clenched teeth. At last, on October 24, the most famous astronomer since ancient times expired at the age of 54.

Two days later, one of Emperor Rudolf’s courtiers visited Johannes Kepler. In accordance with the terms of the great man’s will, he was told, he was to inherit Tycho’s post of Imperial Mathematician. It seemed that in his final months of life, Tycho had finally found it in himself to fully acknowledge the flickerings of genius he had long seen in Kepler — a genius that, as he may very well have recognized, in some ways exceeded his own. An empiricist to the last, he had chosen on the basis of Kepler’s self-evident abilities to elevate the ugly-duckling astronomer instead of his own son Jørgen or his much longer-serving assistant Christian Severin Longomontanus. (Franz Tengnagel von Camp, on the other hand, had at least managed to get the girl; he had married Elizabeth Brahe in June.) Tycho made just one final request from beyond the grave to Kepler: predictably, he begged him one last time to give up his silly allegiance to Copernicus’s heliocentrism. Touched and grateful though he was, Kepler would be unable to oblige his benefactor in this respect.

Before we continue with Kepler’s story, there is a bizarre postscript to that of Tycho that I can’t resist mentioning here. Right from the time of Tycho’s death, there were rumors and speculation about its cause. For, although he may have showed signs of mentally slowing, he had still given every appearance of being as physically robust as ever right up until the fateful evening of Baron Rosenberg’s dinner party. Some wondered darkly whether he had been poisoned, but that wasn’t an easy thing to prove or disprove in 1601.

Tycho had died a long way from Protestant Denmark; it would have been difficult to return his body to his homeland before it decayed even presuming that King Christian IV would have agreed to receive it. As a sort of compromise, he was buried beneath the flagstones of Prague’s Church of Our Lady Before Tyn. In a sense, this church was neither fully Catholic nor fully Protestant, being an artifact of a reforming movement led by one Jan Hus more than a century before Martin Luther, a movement with which an earlier generation of popes in Rome had found it in themselves to make accommodation by granting the Hussites a degree of autonomy. In 1630, however, the Hussites were forcibly and emphatically returned to the fold of mainstream orthodox Catholicism as yet another initiative of the slow-rolling Counter-Reformation. It was rumored for centuries afterward that some of the bodies buried in the church, among them that of Tycho Brahe, had been spirited away amidst the chaos and violence that accompanied this event.

In 1901, the Prague city council marked the 300th anniversary of Tycho’s death by opening his grave to see if he was still inside it. He was; the damage around the nose area of the skull demonstrated incontrovertibly that the corpse was truly his. The grave was sealed again, but the investigators kept some scraps of the clothing he wore and some strands of hair from his head and mustache.

Nine decades later, amidst the outpouring of pan-European bonhomie that followed the fall of the Berlin Wall, Prague’s National Museum presented the Danish ambassador to Czechoslovakia with some of these hairs. A group of Danish historians and scientists who called themselves “the Tycho gang” convinced their own government to turn over a few of the hairs to Bent Kæmpe, the Director of Forensic Chemistry at the Institute of Forensic Medicine of the University of Copenhagen. He found high levels of mercury therein. In 1993, he issued his tentative conclusion: that Tycho’s death “can probably be traced to mercury poisoning, most likely due to [his alchemical] experiments.”

Three years later, however, the plot was thickened by a Swedish pathologist named Jan Pallon who was also given access to the hairs. Using the most cutting-edge technology, Pallon announced that he had been able to turn a single stand of hair into a “study in time” of Tycho’s final 74 and a half hours: “The closer to the root, the closer to the time of death, when the hair stops growing.” An apparent sudden spike in the mercury level in the middle of that time line indicated to Pallon that the patient, already badly ill, had been administered another dose of mercury, at a time when he was most definitely not in any shape to be puttering about in his laboratory. Pallon’s conclusion? Murder. Someone at Tycho’s bedside had been deliberately poisoning him. This might explain why he had seemed to be getting better several times, only to relapse so violently.

There was only one leap left to take. In 2004, Joshua Gilder, a former speechwriter for the American presidents Ronald Reagan and George H.W. Bush, made the jump, in a book he co-authored with his wife Anne-Lee Gilder.

For 400 years, it was believed that Tycho Brahe died of natural causes. In fact, recent forensic analysis of remnants of his hair reveals that he was murdered, systematically poisoned. And all the answers as to motive, means, and opportunity point directly to one suspect: Johannes Kepler. Kepler’s brilliant mind had a dark side that was tormented by rage, fear, and jealousy — and obsessed with the desire to possess Tycho Brahe’s massive store of planetary observations as his own.

Kepler, the Gilders noted, had had enough knowledge of alchemy to use mercury as a poison, along with access to Tycho’s laboratory and regular access to the man himself, before and after Baron Rosenberg’s party. So much for means and opportunity. As for motive: he did so badly want Tycho’s observational data, didn’t he? In this light, Kepler’s one-time assertion that he “must wrest his riches from him” suddenly took on a darkly sinister cast. The Gilders’ book rode a wave of popular interest in historical true crime to become a minor sensation. Just imagine! One of the most important astronomers in history was a murderer, another one his victim! The story sold itself.

Of course, even if one assumed that Kepler knew that Tycho planned to make him his astronomical heir apparent — knowledge which Kepler never even hinted at having possessed before that visit from one of Emperor Rudolf’s courtiers — the case against him was, shall we say, highly circumstantial. Nevertheless, the excitement surrounding the Gilders’ book led to a second opening of Tycho’s grave in 2010, to collect samples of hair, bones, and teeth. These were then subjected to a thorough forensic examination by a consortium of Czech and Danish scientists.  They were not able to confirm Jan Pallon’s finding of a pattern of sudden high dosages of mercury. On the contrary, they “detected an accumulation of electron-dense granules [of mercury] of about ten nanometers inside the outer hair scales, but not in the hair shaft and roots.” Mercury, in other words, was found inside the hair, but not on its surface. This strongly reinforced the notion of low-grade exposure in a laboratory rather than a nefarious mercury poisoner. “The distribution of mercury does not support the murder hypothesis,” concluded the team, “but could be related to precipitation of mercury dust during long-term alchemistic activities.”

At the same time, the scientists concluded that Tycho had been morbidly obese, with all of the associated risk factors. His proximate cause of death was most likely a burst bladder. Although accidental mercury exposure may have contributed to his demise, the most probable ultimate cause is one with which we moderns are all too familiar: too much of the wrong kinds of food and nowhere near enough exercise. Not for nothing did the scientists name their study “Rich Table but Short Life.” Even a larger-than-life force of nature like Tycho Brahe, it seems, cannot defy the laws of nature forever.

Whatever else he may have been, then, we have no compelling reason to believe that Johannes Kepler was a murderer. Instead of a murder mystery, the months which he and Tycho spent in one another’s orbit at the end of the latter’s life must stand as one of the most fortuitous interactions in the history of science. Tycho Brahe had been an astronomical observer beyond parallel, assembling the most impressive body of astronomical data ever to appear in Europe, but he had been at heart a practitioner rather than a theorist. Now, his final gift act of generosity would allow his data to be used to its full potential by someone whose talents ran in a different direction. With it to hand, the tortured savant Johannes Kepler was about to resolve difficulties that had been dogging the study of the sky since before the time of the ancient Egyptians.

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(A full listing of print and online sources used will follow the final article in this series.)