When Bettina Hoerlin, formerly an adjunct professor at Penn for 16 years, was a teenager, she met Italian physicist and Nobel Prize-winner Enrico Fermi on a Sunday hike with her father, Hermann Hoerlin, a physicist at Los Alamos National Laboratory in New Mexico.

Little did she know that many years later she would  join forces with her husband, Gino Segrè, an emeritus professor of physics at Penn, to write a biography on Fermi titled “The Pope of Physics: Enrico Fermi and the Birth of the Atomic Age.”

Entirely self-educated, Fermi was the only physicist to reach the peak of his profession as both a theorist and experimentalist. Born in Rome in 1901, he emigrated to the United States in 1938, the same year he received the Nobel Prize in Physics. Segrè says in America, Fermi was the “go to guy” on the Manhattan Project, which ushered in nuclear weapons and the atomic age.

Even though Fermi is considered a hero in Italy, Hoerlin and Segrè say he doesn’t get the recognition he deserves in the United States. They hope that their book will change that.

“I think one of the things about him is that he really shaped our future in a way that not many scientists do,” Hoerlin says. “Everybody has heard of Einstein and Heisenberg, but Fermi is relatively unsung in the country. We wanted to do that singing.”

Segrè started writing the book about five years ago. He, too, had a connection with Fermi. He is the nephew of Emilio Segrè, Fermi’s first student in Rome who also went on to receive the Nobel Prize in Physics. As a physicist himself, Gino Segrè also had an appreciation for what Hoerlin calls the “elegance and the scope of Fermi’s accomplishments.”

Segrè set out to write a biography of Fermi, but at a certain point he realized he was getting too tied to the physics and losing the big picture of Fermi’s life. Hoerlin, a one-time health commissioner of Philadelphia who taught health care disparities at Penn, was less connected to the science, and helped Segrè take the book in a new direction.

“We became co-authors,” Segrè says. “The book was restructured, rewritten, and became very much of a joint project. We included perspectives about Fermi’s personal life, his family, and the political climate that shaped him.”

A few years ago, Hoerlin published a book about her parents leaving Nazi Germany and Segrè has published three other books about scientific topics. But this was the couple’s first time collaborating on a book.

“It’s very unusual that a couple does a book together,” Segrè says. “Married couples often don’t play doubles in tennis because they get mad at each other.”

According to Hoerlin, who has always been her husband’s first reader and critic, they each brought different, yet very complementary tools to the collaboration.

Segrè’s experiences growing up in Italy were vital, as many of the sources on Fermi are only available in Italy. Together, they traveled to the archives in Rome and Pisa to gather information, and also visited the extensive Fermi archives at the University of Chicago.

Beyond their familial connections to Fermi, Hoerlin and Segrè also share a similar history with him. In 1939, Fermi and his wife, who was Jewish, immigrated to the United States to escape fascist Italy. Segrè’s father was Jewish and his parents emigrated from Italy that same year. Hoerlin’s mother was Jewish and her parents emigrated from Germany the year before.

“We’re familiar with the world of physics, but we’re also familiar with the world of having to flee fascism and coming to the United States,” Segrè says.

Hoerlin says that the struggles in the book that were part of Fermi’s life are still present today.

“One of those fancy German words is ‘Weltanschauung’: Our world view,” Segrè says. “It fits in nicely with our concerns particularly now about politics, about nuclear proliferation, and about immigrants.”