Frisch-Peierls memorandum

The Frisch–Peierls memorandum was the first technical exposition of a practical nuclear weapon. It was written by expatriate German physicists Otto Frisch and Rudolf Peierls in March 1940 while they were both working for Mark Oliphant at the University of Birmingham in England during World War II.

The memorandum contained the first calculations about the size of the critical mass of fissile material needed for an atomic bomb. It revealed for the first time that the amount required might be small enough to incorporate into a bomb that could be delivered by air. It also anticipated the strategic and moral implications of nuclear weapons.

It helped send both Britain and America down a path which led to the MAUD Committee, the Tube Alloys project, the Manhattan Project, and ultimately the atomic bombings of Hiroshima and Nagasaki.

Rudolf Peierls was born in Berlin in 1907. He studied physics at the University of Berlin, at the University of Munich under Arnold Sommerfeld, the University of Leipzig under Werner Heisenberg, and ETH Zurich under Wolfgang Pauli. After receiving his DPhil from Leipzig in 1929, he became an assistant to Pauli in Zurich. In 1932, he was awarded a Rockefeller Fellowship, which he used to study in Rome under Enrico Fermi, and then at the Cavendish Laboratory at the University of Cambridge under Ralph H. Fowler. Due to Adolf Hitler's rise to power in Germany, he elected to not return home in 1933, but to remain in Britain. He worked with Hans Bethe at the University of Manchester, then at the Mond Laboratory at Cambridge. In 1937, Mark Oliphant, the Australian, newly appointed professor of physics at the University of Birmingham recruited him for a new chair there in applied mathematics.

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