Frank Oppenheimer (1912–1985) was born in New York on August 14, the younger brother of J. Robert Oppenheimer. Like his brother he became a physicist, but with a focus on experimental work rather than theory. As a physicist he contributed to the development of the atomic bomb, and then in 1969 became a leader in science education by founding the interactive San Francisco Exploratorium. He died of lung cancer in Sausalito, California, on February 3.

After earning a B.S. in physics from Johns Hopkins University in 1933 he studied for a time in Europe before going to the California Institute of Technology where he earned his PhD in 1939. In 1941 he began work at Oak Ridge, Tennessee, on separating Uranium–235, the fissile isotope, from the more common Uranium–238, then subsequently became special assistant to his older brother at the Los Alamos National Laboratory where the atomic bomb was being designed and...