David Fryberger, 95, a physicist at the Stanford Linear Accelerator Center (SLAC), died peacefully at his home in Palo Alto, California, on May 3rd, 2026, in the presence of his wife Betsy and son Mark.
During his SLAC career (1967 to 1998), David contributed significantly to its programs as an experimental physicist and later as a senior administrator and theorist. With a colleague in 1973, he devised a touch-panel screen that was a precursor to the modern touchscreen. He was a collaborator on the 1974 discovery of the J/psi particle, which revolutionized modern physics and earned SLAC a Nobel Prize. In later years, he pursued his own theoretical work postulating the existence of a subatomic particle that he named the vorton, a second solution to Maxwell’s symmetrized equations. David then spent significant time during his remaining professional work life and in retirement searching for manifestations or other evidence of either the vorton or its close relative, the magneticon (a magnetic monopole), to support his theory.
David was born in Duluth, Minnesota, on February 22, 1931. His father, William B. Fryberger, met his mother, Kathleen O’Brien, while they were students at Dartmouth College and Smith College. Their marriage was short-lived, and David was their only child. He lived with his mother in Daytona Beach, Florida, during the school year and with his father, grandparents, and the larger Fryberger family in Duluth during the summers. From an early age, he enjoyed taking objects apart to figure out how they worked and subscribed to magazines like Popular Science and Popular Mechanics. David attended Phillips Exeter Academy, thrived in its atmosphere, won several science prizes, and then went on to Yale University, graduating with a degree in Electrical Engineering in 1953.
In his last year at Yale, he met Betsy Geraghty, a freshman at Bryn Mawr College, through a chance encounter at a mutual family friend’s apartment the day after Thanksgiving in New York City. Upon graduation, he joined the Navy and served for four years on active duty, followed by another 21 years in the Navy Reserve. He served as a flight navigator on two six-month cruises in the Pacific, where he participated in hundreds of carrier landings. Throughout his military service, he corresponded with Betsy, and in January of 1957, they married in Chicago.
In the fall of 1957, he enrolled in the Harvard Business School. He soon realized business school wasn’t his calling, and took a leave of absence, never to return. After a yearlong sojourn to the Upper Peninsula of Michigan, where he worked in electrical sales, they moved to Chicago in 1959. Betsy joined the staff of the Art Institute of Chicago. David worked as an electrical engineer at the Illinois Institute of Technology, from which he also earned a master’s degree in 1962. His never-ending yearning to understand how things worked finally led him to focus his studies in physics. He was admitted to the University of Chicago to study physics in a department made famous by Enrico Fermi, who had won a Nobel Prize a few years earlier. David’s thesis advisor was Valentine Telegdi, who pioneered the use of spark chambers to detect subatomic particles. Years later, at the Smithsonian Museum in Washington, D.C., David saw the spark chamber he had worked on, labeled “first experimental use”. In 1967, he was awarded his PhD, and he and Betsy moved to Palo Alto, where they made their home for the next 59 years.
In retirement, David interwove travel and research as he continued to search for evidence to verify his vorton theory. He spent more than a month at Langmuir Laboratory for Atmospheric Research in New Mexico, where appearances of strange transitory lights had been seen. He traveled to Popocatepetl, Mexico, to learn more about the lights seen during volcanic eruptions there, and to Hessdalen, Norway, to better understand earthlights. In the early 2000s, he made several trips to Jefferson Laboratory in Virginia to study moving lights observed in a superconducting RF cavity. These moving balls of light in the cavity looked like small versions of ball lightning. For the past 20 years, David collaborated with Michael Sullivan on refining his theories and conducting experiments to detect his theorized particles. Mike plans to continue this effort.
Outside of physics, David’s interests were focused on two areas: singing and playing soccer. As an adult, he sang in several church choruses. Then, in the late 1980s, he joined a Russian chorus named Slavyanka. He sang in many concerts throughout the Bay Area and traveled twice to Russia to perform there. An avid soccer player (he was on Yale’s varsity team), he played recreationally for 50 years and coached his son Mark’s teams from first grade through high school. He was one of the founders of the SLACers soccer club in 1998, which continues to this day. He and Betsy also played tennis for many years and, in later years, avidly followed professional tennis on TV.
David enjoyed traveling with his family, spending summer vacations in Duluth and New England with Betsy and his extended families. A highlight for many years was the annual Fryberger family soccer game. Thanksgivings were often shared with his half-sister Liz’s family in Vermont. Betsy’s long career as a museum curator and her love of gardening took them to Europe several times, where they visited historic churches, museums, villas, and gardens. They also found time to enjoy lavish meals with matching wines, often finishing with a chocolate dessert. In the Bay Area, they attended the San Francisco Opera for over 50 years and later were patrons of Music@Menlo.
David will be remembered by many for his patient, gentle soul, his graciousness and dignity, the twinkle in his eye, and his kindness to all he encountered. Free of body, his spirit will continue to explore the fundamental building blocks of the cosmos that he spent his lifetime studying.
