Just over 400 years ago in Prague, a tempestuous collaboration between two astronomers resulted in the birth of modern science: Tycho Brahe, royal astronomer of the Holy Roman Empire, invited Johannes Kepler to help him map the heavens. When Brahe died suddenly of a burst bladder, Kepler supplanted him as royal astronomer. Then, using Brahe’s stockpile of astronomical observations, he worked out his three famous laws of planetary motion, the foundation for Sir Isaac Newton’s work on universal gravitation. The rest, as they say, is history.

Or it is to most of us. But to 50-year-old Bethesda resident Joshua Gilder and his wife, Anne-Lee Gilder, it was a trail leading to a mystery. “The whole story surrounding Brahe’s death was a little murky,” says Anne-Lee. “The rumor that he died of a burst bladder because he was too polite to excuse himself during a long, drawn-out banquet is total nonsense. Any doctor will tell you that the bladder is incredibly elastic, and you would need to be kicked by a horse to burst it.”

A former investigative reporter for German television, the Lübeck, Germany–born Anne-Lee, 38, first started thinking about Brahe’s death in the summer of 2001, when she was helping Joshua do research for a proposed book about the transition from medieval to modern science centered on the two astronomers. Fresh off a well-received medical thriller titled Ghost Image, Joshua was following the advice of his literary agent, who thought that the writer’s gift for finding simple ways to describe complicated concepts could be applied to nonfictional narratives about scientific history.

“We knew they were fascinating characters,” he says, “and we knew that it was a stormy relationship.”

Just how stormy, the Gilders had yet to discover. But Joshua, who was reading everything he could find on Kepler, had noticed something odd, too. “Nobody quoted from the original documents,” he says. “As I followed the references backward, they all converged on one guy—Max Caspar.”

In 1935, Caspar founded the Commission for the Publication of the Works of Johannes Kepler, whose purpose to this day is to publish—and thus profit from—definitive editions of Kepler’s work. “Caspar’s translations are hardly objective accounts,” says Joshua. “He simply couldn’t pass muster as a scholar today.” The Kepler Commission declined to speak to the Gilders for their research, but by then, Anne-Lee’s investigative instincts had already kicked in. “Something didn’t fit,” she recalls.

The Gilders also came across some recent research on hair taken from Brahe’s beard early in the 20th century. Two independent analyses found massive quantities of mercury, suggesting that the astronomer died not of a burst bladder, but of poisoning.

“Murder has always been dismissed as an explanation, because Brahe was an alchemist who made his own mercury drugs,” says Anne-Lee. “It was a logical assumption to think that he had an accident while he was trying to treat himself for some existing problem. But if you want to get to the bottom of things, you need to look at the mercury drug he made. So we found an expert who could translate Brahe’s recipe, and we learned that his drug wasn’t meant to treat the [urological] symptoms that we know he suffered from.”

“We also found out that Brahe wasn’t just some guy who was mixing potions and taking a swig every now and then to see what happened,” adds Joshua. “He was very sophisticated and had a detailed knowledge about which substances were poisonous.”

“So we concluded that Brahe was killed,” says Anne-Lee. “And if you have a murder, then you investigate the case. You look for motive, means, opportunity, and psychological profile. And the only person who could answer all these questions was Kepler.”

Carl Sagan once said that extraordinary claims require extraordinary proof. In the case of two extraordinary scientists who helped set modern physics on its course—one a poor German boy obsessed with unraveling God’s design, the other a Danish nobleman who had the bridge of his nose hacked off in a broadsword duel—the burden of proof seemed unbearable. So the Gilders spent the next two and a half years building their case, which was published last month as Heavenly Intrigue: Johannes Kepler, Tycho Brahe, and the Murder Behind One of History’s Greatest Scientific Discoveries.

“It was a tremendously intense, full-time job, seven days a week,” recalls Anne-Lee. The pair set up camp in the Library of Congress’ European Reading Room; made research trips to the Czech Republic, Denmark, and Germany; and looked high and low for experts to translate Kepler’s and Brahe’s papers, written in difficult Renaissance Latin and full of arcane astronomical and alchemical terms.

“If you want to write about these two people,” says Anne-Lee, “you’ve got to dig up every single letter that was ever written. Much of it had never been translated before, and those that had been were often mistranslated. All of the letters that the Kepler Commission published had synopses at the beginning, but they were so wrong. They didn’t reflect the content of the letters at all.”

One crucial document was Kepler’s Self-Analysis of 1597, which the Gilders had retranslated from scratch. “We all know Kepler as others have written about him—a very driven mathematical genius,” says Joshua. “But his Self-Analysis, written when he was 26, sheds an incredibly harsh light on himself. What emerges is an angry, jealous, vengeful man with a tremendous thirst for glory.”

By the time Kepler arrived in Prague, in 1600, he desperately wanted to get his hands on Brahe’s research. After all, explains Joshua, the elder astronomer has “spent over 40 years making detailed astronomical observations, building enormous, precise instruments while others were still eyeballing distances with a piece of string. It took over a century after Galileo invented the telescope to match the accuracy of Brahe’s observations.”

“When you go through all of their correspondence, you see how Kepler never, ever lost sight of this,” says Anne-Lee. “The frustration over getting Brahe’s data drove him insane, and what struck us was that he showed no moral baseline.

“Everything fits,” she suggests. “Kepler had the motive, the means, the opportunity to get close to Brahe; the knowledge about this very particular murder weapon; and this very disturbing psychological portrait.”

Not surprisingly, many in the scientific community are skeptical of the Gilders’ accusation that one of their gods was a cold-blooded murderer. “Oh my,” says Claudio Pellegrini, chair of UCLA’s Department of Physics and Astronomy. “I cannot imagine Kepler doing something like that. I’m not familiar with the new forensic studies, and what the Gilders are saying about Kepler trying to get Brahe’s data is not inconceivable. But that’s pushing it to the extreme.

“I think of my own colleagues,” he laughs, “and while things can get difficult, no one I know has gotten to that point.”

Claus Thykier, a curator at Denmark’s Ole Rømer Museum, agrees. Thykier was the one who first suggested that Brahe’s beard be examined for evidence of mercury poisoning, after a small box containing samples of his facial hair was donated to the museum by the Czech government in 1991. The hair had been removed 90 years earlier, during the tricentennial restoration of Brahe’s tomb in Prague, where city officials were worried about another mystery having to do with Brahe: that the Protestant astronomer’s body had been disinterred by vengeful Catholics when they took control of Bohemia in 1620.

It hadn’t, and some thoughtful grave-opener took the beard clippings that Thykier later had analyzed at university laboratories in Denmark and Sweden. The curator introduced the Gilders to the evidence of mercury poisoning when they began their project, but he has a different interpretation of the data. “I think it is very unpleasant to accuse any person, living or dead, of murder if it cannot be proved,” he says. “My theory is that Brahe died by his own medicine. That Kepler is supposed to have murdered Brahe is pure fantasy.”

“We never pretended we were scholars,” reminds Joshua. “That wasn’t the point. The point was to explore the field and examine the facts and talk to the experts until we understood everything, in order to give an unbifurcated view of the facts.”

Happily, the Gilders’ collaboration didn’t mirror Brahe and Kepler’s—although, as Anne-Lee points out, their research was sometimes maddening. “I can’t tell you how many conversations we had around the dinner table with Josh’s urologist,” she jokes, “asking him about urinary tracts and bladders and blockages.”

“When we told our friends that we were going to write a book together, they said, ‘Are you out of your minds? Do you want to ruin your marriage?’” she adds. “There were times when we were short with each other, but we never fought. We respected each other’s strengths and acknowledged our own weaknesses and, knock on wood, we’re still happily married.”

“Anne-Lee had been my primary editor and reader for my novel, so I knew we would work well,” says Joshua. “And she’s got the instincts of a journalist. She was the one who said that things didn’t add up and that we needed to look further, while I had been content with the idea of ‘Kepler, troubled genius.’”

Anne-Lee did much of the initial research and translating from the German for Heavenly Intrigue. Joshua wrote the first draft and then turned it over to his wife for a read-through. As Anne-Lee edited and organized Joshua’s draft, she began rewriting certain passages. But the Gilders simply say that they wrote the book together. “After a while, you forget who wrote what, because it doesn’t matter,” says Anne-Lee. “We didn’t bother keeping tabs.”

The couple is considering writing another book together, though they aren’t quite ready for another adventure. “I need some intellectual rest,” says Anne-Lee. “It’s nice to have a weekend again, and I regret having to tell my son for the last two years that I didn’t have time.”

For now, they’re waiting for the reviews to come in. So far, they say, the response from the European media has been surprisingly positive—except for the Kepler Commission, which has been noticeably silent.

“We think that our case is watertight,” says Joshua. “If somebody wants to go back to the source material and come up with a different conclusion, like a good defense lawyer would, that would be great. We would actually welcome somebody to challenge us. But no one has done that. Everyone has relied on very imperfect, selective, and highly distorted translations like the Caspar histories.

“Certainly people are going to respond negatively, because they’ll think it’s just another debunking book. People have always wanted to present Kepler as this secular saint of science, and we don’t take anything away from him as one of the greatest creative minds in history. But he also had a very dark side.”

“Of course,” adds Anne-Lee, “after 400 years, there’s no confession, no picture, no video. There’s no famous glove, and that doesn’t even get you anywhere sometimes. The jury is the reader, and it’s up to them to decide.” CP