Robert Christy
Robert Christy

PASADENA — Caltech physicist Robert F. Christy, one of the last of the Manhattan Project scientists who built the world's first atomic bomb, died Wednesday at his home in Pasadena.

Christy, who was 96, died of natural causes, surrounded by his family, said Juliana Christy-Sackmann, his wife of 39 years.

In an interview with the Pasadena Star-News in August 1995, on the 50th anniversary of the Hiroshima atomic bomb, Christy said he had no regrets about his part in events that ended World War II and ultimately changed the world forever.

"I'm comfortable with the work we did. I feel we did make a significant contribution to ending the war," he said. The price was "major loss of life in Japan," he said. "But I firmly believe the price to Japan would have been worse if he hadn't finished the war with the bomb."

Christy-Sackmann described her husband as a "humble, generous man who never looked for or wanted fame," and who became "very, very active in stopping nuclear proliferation," starting in the 1950s.

"He was at peace with it," Christy-Sackmann said of her husband's work with the team at the Los Alamos Laboratory, where he helped design the trigger mechanism for the atomic bomb.

"But he was not willing to work ... to build more killing machines," she said. "He was hoping for diplomacy and humanitarian ways to resolve conflicts."

In 1990, Christy visited Hiroshima and Nagasaki, where the second atomic bomb was dropped, as part of his work with the joint U.S.-Japan Radiation Effects Research Foundation, and in the 1980s he worked on the National Research Council's Committee on Dosimetry, investigating the effects of radiation.

Although the Manhattan Project was an important part of her husband's life, Christy- Sackmann said Thursday, he went on to become involved in several branches of physics, notably astrophysics, taught a "tremendous load" of students, and was both provost and interim president of Caltech during his 40 years as a professor there.

In his 1995 interview, Christy said his post-war work in astrophysics was more "scientifically refined" than his contributions to the Manhattan Project. He called that "engineering more than discovery."

Thomas Soifer, chair of Caltech's division of physics, mathematics and astronomy, was one of Christy's undergraduate students, but didn't know of his Manhattan Project connection until returning as a colleague in the 1970s.

Christy, who retired in 1986, was a familiar figure on campus and still had an office where the theoretical physics offices are, Soifer said. Until recent months, he was a regular at the legendary "Round Table" at Caltech's Athenaeum.

"He was one of the giants of of theoretical physics, and may well be the last living person" who worked on the Manhattan Project's core team, Soifer said.

Christy was born in Vancouver, Canada, on May 14, 1916, lost his parents early in life, and "grew up poor," his wife said.

In a series of interviews for Caltech's Oral History Archives he recalled that he "didn't do anything special in elementary school, except that he found mathematics "very easy," wasn't so good at "essay-type questions" and developed an interest in physics — which led to some "unusual" questions.

On the topic of refracted light, he said, "I came up with a question that the class thought was very naive, which it was. I said, 'Oh, is that the reason that if you're sitting in the bathtub and your big toe sticks up out of the water, the part that sticks up appears so much bigger than the part that's down below the surface?' And he says, 'Yes.' And the whole class burst into laughter. ... But I was interested in the physics of it. That turned me on."

He studied physics at the University of British Columbia in the 1930s, in the early days of quantum physics, and was later accepted as a graduate student at UC Berkeley by J. Robert Oppenheimer, then the nation's leading theoretical physicist.

After his Ph.D., Christy joined the Illinois Institute of Technology, and was recruited by Enrico Fermi at the University of Chicago to join the effort to build the first reactor; Oppenheimer later asked him to join the Manhattan Project.

In 1946, Christy came to Caltech as an associate professor, officials said, working on the application of theory to cosmic-ray experiments in particle physics. He later moved into nuclear physics and astrophysics, his work earning him the Eddington Medal of the Royal Astronomical Society in 1967.

Christy's interviews can be accessed at Christy_R.pdf.

He is survived by his wife, two daughters and two sons.

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