Stuart Jay Freedman, a world-renowned nuclear physicist at the Lawrence Berkeley National Laboratory and a UC Berkeley professor, died Nov. 9 while at a scientific conference in New Mexico. He was 68.

Freedman was born in Los Angeles on Jan. 13, 1944. He graduated with a Bachelor of Science degree in engineering physics from UC Berkeley in 1965 and eventually returned to the campus to take up a joint position as a professor in the campus physics department and a senior scientist in Berkeley lab’s Nuclear Science Division.

He is known for research he did ruling out the existence of naked quarks — which are single subatomic particles — and faster-than-light particles as well as work he did as a graduate student at UC Berkeley studying quantum mechanics.

Freedman was also at the forefront of nuclear physics study at the national level. He worked for the National Academy of Sciences beginning in 2001 and also advised the U.S. Department of Energy on which industries the nation should focus its resources on.

“He was one of the leaders in the physics community and in the area of very difficult, important experiments where you look for new laws of nature,” said Roberto Peccei, formerly UCLA’s vice chancellor for research and an assistant professor at Stanford University when Freedman was there in the late 1970s. “We’ve lost an enormous ability to do that, and we’ve lost a great man.”

Freedman was known for an interest in unconventional theories.

“He did a lot of experiments that were unorthodox — things that people did not expect,” said Berkeley lab researcher Robert Cahn. “He did a number of experiments that found a lot of surprising results.”

One of Freedman’s experiments showed that heavy neutrinos, subatomic particles, weigh 100,000 times less than previously believed, according to Cahn.

“He was always looking far into the future,” said Spencer Klein, a deputy director of Berkeley lab’s Nuclear Sciences Division and Freedman’s colleague since 1994. “He worked extremely hard. He was able to juggle an impressively large number of projects and keep up with them.”

Besides being a talented scientist, Freedman was known for his encouragement of new researchers and students.

“He liked human company very much, especially the company of young people, and was always willing to take the time to encourage his undergraduate and graduate students,” said James Symons, a colleague of Freedman’s at Berkeley lab. “He was happiest when two or three people had dropped in to discuss quite different things and could learn from each other.”

Outside of the lab, Freedman had a passion for flying, sailing and motor vehicles. He loved the thrill of piloting, skydiving, riding motorcycles and driving sports cars, according to his wife, Joyce Freedman.

“He was a man of great integrity, had a fabulous wit and always a twinkle in his eyes,” she said. “He was devoted to his students, postdocs and any young person coming up through the sciences that he felt needed the support and mentoring.”