Frank Oppenheimer

Frank Friedman Oppenheimer (14 August 1912 – 3 February 1985) was an American particle physicist, cattle rancher, professor of physics at the University of Colorado, and the founder of the Exploratorium in San Francisco.

A younger brother of renowned physicist J. Robert Oppenheimer, Frank Oppenheimer conducted research on aspects of nuclear physics during the time of the Manhattan Project, and made contributions to uranium enrichment.

After the war, Oppenheimer's earlier involvement with the American Communist Party placed him under scrutiny, and he resigned from his physics position at the University of Minnesota.

Frank Friedman Oppenheimer was born in 1912 in New York City to a Jewish family.

His parents were Ella (née Friedman), a painter, and Julius Seligmann Oppenheimer, a successful textile importer from Hanau in the Kingdom of Prussia.

During his childhood, he studied painting.

He also studied the flute under nationally known teacher George Barrera, becoming competent enough at the instrument to consider a career as a flautist.

Oppenheimer began his schooling at the Ethical Culture School, where he attended until seventh grade.

The remainder of his high school education was completed at Fieldston School in Riverdale, a school operated by the Ethical Culture Society.

Following the advice of his older brother Robert, he became a professional physicist.

In 1930 he began his studies at Johns Hopkins University, graduating three years later with a BS in physics.

He then studied for a further 18 months at the Cavendish Laboratory in Cambridge, England.

While in England he earned a pilot's license.

In 1935, he worked on the development of nuclear particle counters at the Institute di Arcetri in Florence, Italy.

While completing his PhD at the California Institute of Technology, Oppenheimer became engaged to Jacquenette Quann, an economics student at the University of California, Berkeley; she was also active in the Young Communist League.

In spite of his brother Robert's advice, Oppenheimer and Jackie were married in 1936 and they both joined the American Communist Party, also against the older brother's advice.

Oppenheimer and his wife were atheists.

In 1937 they had been involved in local attempts to desegregate the Pasadena public swimming pool, which was open to non-white people only on Wednesday, after which the pool was drained and the water replaced.

Oppenheimer said he and his wife had joined at a time when they sought answers to the high unemployment experienced in the United States during the later part of the Great Depression.

He refused to name others he knew to be members.

This caused a media sensation—that J. Robert Oppenheimer's brother was a former member of the Communist Party—and led to Oppenheimer resigning his post at the University of Minnesota.

After being branded a Communist, Oppenheimer could no longer find work in physics in the United States, and he was also denied a passport, preventing him from working abroad.

Oppenheimer received his PhD in 1939 and completed two postdoctoral years at Stanford University.

During World War II, Oppenheimer's older brother Robert became the director of the Los Alamos Laboratory, part of the Manhattan Project, the Allied effort to produce the first atomic weapons.

From 1941 to 1945 Oppenheimer worked at the University of California Radiation Laboratory on the problem of uranium isotope separation under the direction of his brother's friend, Ernest O. Lawrence.

In late 1943 he arrived at the Los Alamos Laboratory, working directly under Kenneth T. Bainbridge.

His responsibilities included the instrumentation for the Trinity test site, in New Mexico.

In 1945 he was sent to the enrichment facility at Oak Ridge, Tennessee, to help monitor the equipment.

Oppenheimer was involved in the founding of the Association of Los Alamos Scientists, on August 30, 1945.

This organization promoted international peaceful control of nuclear power.

He later also joined the Federation of American Scientists, and was a member of the American Physical Society.

After the war, Oppenheimer returned to Berkeley, working with Luis Alvarez and Wolfgang Panofsky to develop the proton linear accelerator.

In 1947 he took a position as assistant professor of physics at the University of Minnesota, where he participated in the discovery of heavy cosmic ray nuclei.

On July 12, 1947, the Washington Times Herald reported that Oppenheimer had been a member of the Communist Party during the years 1937–1939.

At first, he denied these reports, but later said they were true.

In June 1949, as part of a larger investigation on the possible mishandling of "atomic secrets" during the war, he was called before the United States Congress House Un-American Activities Committee (HUAC).

Before the committee, he testified that he and his wife had been members of the Communist Party for about three and a half years.

Oppenheimer was a target of McCarthyism and was blacklisted from finding any physics teaching position in the United States until 1957, when he was allowed to teach science at a high school in Colorado.

This rehabilitation allowed him to gain a position at the University of Colorado teaching physics.

In 1969, Oppenheimer founded the Exploratorium in San Francisco, and he served as its first director until his death in 1985.