Otto Robert Frisch collaborated with his maternal aunt, the noted physicist lise meitner, in deducing the process of nuclear fission, a term coined by Frisch to describe the splitting of the uranium nucleus. It was Frisch who confirmed the feasibility of using nuclear fission to induce a chain reaction capable of detonating a nuclear bomb, and thus he is primarily responsible for ushering in the atomic age whereby humans discovered the means to effect our own destruction.
Otto Robert Frisch collaborated with his maternal aunt, the noted physicist Lise Meitner, in deducing the process of nuclear fission, a term coined by Frisch to describe the splitting of the uranium nucleus.
Frisch was born on October 1, 1904, in Vienna, Austria. His father, Justinian Frisch, held a doctorate in law but worked as a publisher, and his mother, Auguste Meitner, was a retired pianist, composer, and conductor. Frisch graduated from high school in 1922 and matriculated at the University of Vienna, majoring in physics and minoring in mathematics. He wrote his doctoral dissertation on the discoloration of rock salts by cathode rays to earn his D.Phil. in 1926, at the age of 22.
Frisch first secured a job at an X-ray dosimeters manufacturing firm, but after a year, he moved to Berlin to accept a position in Carl Muller’s optics laboratory at the Physikalisch Technische Reischsanstalt (PTR) developing a new measurement of brightness to replace can-dlepower. After three years there, he accepted a concurrent part-time position in the physics department at the University of Berlin helping Peter Pringsheim design a mercury-vapor detector. In 1930, he moved to the University of Hamburg to take up an assistantship under Otto Stern; together, the pair proved that beams of atoms act like waves (as do beams of electrons), and on his own, he conducted research on particle-like qualities of light.
After Hitler became chancellor of Germany in 1933, the university fired Frisch due to his Judaism, prompting him to immigrate to England. Stern recommended Frisch for an Academic Assistance Council grant supporting work on gamma ray emissions and cloud chamber construction under Patrick Blackett at Birkbeck College in London. He subsequently built an instrument on which he detected radioactive emissions from phosphorous and sodium.
In 1934, Frisch accepted Niels Bohr’s invitation to work at Copenhagen’s Institute of Theoretical Physics, where he worked with Czech physicist George Placzek measuring the absorption of slow-moving neutrons by cadmium, boron, and gold (using Nobel medals left with Bohr by German scientists fleeing Hitler).
In 1940, the Nazi invasion of Denmark forced Frisch to return to England, where the Australian physicist Marcus Oliphant offered him an auxiliary lectureship at the University of Birmingham. On his way there, he spent Christmas in Sweden with his aunt, Lise Meitner. The two physicists discussed the perplexing results of an experiment by Meitner’s former colleague, Otto Hahn, and Fritz Strassmann—the inexplicable production of an isotope of barium resulting from the bombardment of the uranium nucleus with slow-moving neutrons. At first, Frisch considered Hahn’s observations flawed, but after Meitner defended her former colleague’s precision as an experimentalist, aunt and nephew struck upon the only explanation: the uranium nucleus must have been split in two. Frisch coined the term nuclear "fission" for this cleavage.
Accompanied by Meitner, Frisch hastily returned to Copenhagen to confirm their hypothesis experimentally before making his way back to England. In Birmingham, he collaborated with Rudolf Peierls pursuing Bohr’s suggestion that uranium-235 would catalyze a chain reaction better than any other radioactive element or isotope. They not only confirmed Bohr’s hunch, but they also discovered that it would require a mere few pounds of the radioactive material, not a few tons as was supposed, to start a chain reaction to detonate a nuclear bomb. Frisch reported this finding to Sir Henry Tizard, the British government’s scientific adviser, which set in motion the forming of the Maud Committee to investigate the development of a nuclear bomb. Frisch could thus be identified as one of the first instigators of the process that resulted in the construction and detonation of the first nuclear weapon.
In August 1940, James Chadwick invited Frisch to Liverpool, where the Austrian oversaw the construction of a pulse height analyzer, or a "kicksorter," which analyzes uranium’s alpha ray spectrum to determine its isotopic composition. In 1943, the British government granted him citizenship to facilitate his participation in the Manhattan Project, the secret atomic bomb building initiative taking place in Los Alamos, New Mexico. There, he led the Critical Assembly Group, in charge of the "dragon experiment," the trial run of a nuclear explosion, which he witnessed from a distance of merely 25 miles in order to conduct experiments.
After World War II, Frisch returned to England to serve as a deputy chief scientific officer and head of the Nuclear Physics Division of the Atomic Energy Research Establishment from 1945 through 1947. Cambridge University then named him Jacksonian Professor of Natural Philosophy and director of the nuclear physics department of the Cavendish Laboratory, a position he retained for the remainder of his career. In 1951, he married graphic designer Ulla Blau, a fellow Austrian, and together the couple had two children—Tony, who became a physicist, and Monica.
Frisch retired from Cambridge in 1972 but continued to work as chairman of Laserscan Ltd., the company founded to manufacture the "Sweepnik," the instrument he invented to track the path of charged particles passing through the liquid of a bubble chamber. He died on September 22, 1979, after sustaining injuries in a fall.
