THE MYSTERIOUS MAJOR FRANK THOMPSON

I rarely pay attention to street names unless I am lost. Although I learned the Cyrillic alphabet early on, I tended to navigate my way around Sofia, the capital city of Bulgaria, by landmark. I must have walked up and down Major Thompson Street a hundred times because it was in the neighborhood where my in-laws lived. I assumed this Thompson was not a Bulgarian, but it never occurred to me to ask who he was. Not until a decade later, in a conversation with an octogenarian British physicist in Princeton, New Jersey, would I learn the identity of the mysterious major. This revelation would more or less consume the next six years of my life.

In 2007, Freeman Dyson was eighty-two years old, forty-five years my senior. He was an emeritus professor in the School of Natural Sciences at the Institute for Advanced Study in Princeton, New Jersey. I was a junior professor, a member in the School of Social Sciences for the academic year 2006–2007. I often saw Professor Dyson at the three o'clock tea held each day in Fuld Hall. I was too shy to approach him, for he was the academic equivalent of a rock star, a lead singer for the global scientific community. He was also a known contrarian and had recently outraged his colleagues by saying that the problem of global warming had been grossly exaggerated. In addition to his scholarly fame, Dyson enjoyed the adulation of the wider Star Trek geekiverse for the inclusion of a "Dyson sphere" in the 130th episode of The Next Generation. He seemed to me a god among mortals.

After six months of crippling intimidation, I found myself right behind him in the lunch line at the institute cafeteria. He seemed so unassuming as he considered the choice between the blackened haddock and the baked acorn squash stuffed with quinoa.

"Uh ... Professor Dyson?" I said.

"Yes," he said, looking back.

I hesitated. He kept his eyes fixed on me.

"It is an honor to meet you," I said. "My name is Kristen Ghodsee. I'm a member here this year. In social sciences."

"I see," he said. "Are you an economist?" I shook my head. "No, I am an ethnographer. I work in Bulgaria. I'm writing a book about Bulgaria."

"Bulgaria?" His eyes widened. "Are you Bulgarian?" I told him I wasn't.

"Do you speak Bulgarian?" he said.

"Yes," I said. "I've been doing fieldwork there for the last ten years."

"Well, then," he said. "You must come and see me. I have a dear friend who died in Bulgaria many years ago. Maybe you can help me with something."

"I'd love to," I said, my heart thudding. It was perhaps the first time in the United States that I told someone that I worked on Bulgaria and received genuine interest in return.

I made my appointment with Professor Dyson's assistant. I met him in his office on the second floor of Bloomberg Hall. I was very nervous. Our conversation was casual and friendly; he slowly put me at ease by regaling me with stories of his early days at the institute, the one thing we had in common. He had first come to Princeton in 1953 when Robert Oppenheimer was the director and Albert Einstein was still in residence.

"I don't remember much about Einstein, but I do remember seeing T. S. Eliot in Fuld Hall. I was too shy to speak with him," he said.

"Yes," I said. "I can imagine."

We spoke for a while about science and science fiction, a genre of which we were both great fans. Our conversation flowed to Charles Simonyi, the president of the institute's board of trustees. He had just returned from a two-week trip to the International Space Station. For the mere sum of $25 million, Simonyi had become the world's fifth space tourist.

"So what do you think of space tourism?" I said. "Is this where we'll all be spending our holidays in the future?"

"I have the feeling that this sort of extravagant space exploring by private citizens does have a future," Dyson said. "But, of course, I was brought up as a socialist and the idea of extravagant wealth is evil in itself."

I looked around his spacious office. Along the walls stood floor-to-ceiling bookshelves, crammed full of volumes on physics, biology, mathematics, philosophy, history, and literature. The surface of his desk was piled high with papers, files, and books that he was going to review for the New York Review of Books.

"Where I work in Bulgaria," I said, "there are still a lot of people who think that extravagant private wealth is evil."

Professor Dyson tilted his head. He smiled at me. It seemed to me a conspiratorial smile, as if we were now going to share secrets. I was amazed at how comfortable I felt in his office. He was so soft-spoken and modest, and I could not believe how intimidated I was by him just one week earlier. Perhaps he knew that. Perhaps he told me that story about T. S. Eliot on purpose.

"Yes, we see that in Germany very strongly," he said, leaning back in his chair. "I don't know whether you are familiar with Germany, because my wife is German, and we still have family there. And, of course, the Easterners and Westerners are still very different. She is an Easterner. I used to visit the village where her family lived. And in those times, during the communist times, it was actually a happy place. The system worked. The Germans were very proud of it. And they said, 'After all, we invented communism. The Russians messed it up, but we can actually make it work.'"

I was surprised to learn that Professor Dyson knew so much about Eastern Europe. Many of the scientists of my generation are a narrowly focused lot. There are geniuses to be sure, but not always the sort of genius that extended beyond their subject area. Dyson was of a generation that still cultivated the idea of the Renaissance man: a scholar who was widely read and conversant in many disciplines. I also knew that Dyson had served in the British Bomber Command during World War II. Though his mind was dedicated to mathematics, his life had been bound up with politics.

"And they did make it work in a sense," Dyson said. "That society was a very humane society, unless you wanted to be a politician. Of course they were brutal if you got involved in any sort of political activity....