Mark Oliphant
(1901-2000)

Sir Marcus Laurence Elwin Oliphant, who died on 14 July, 2000, at the age of 98, was one of the "originals", a participant in the First Pugwash Conference in 1957; he probably was the oldest Pugwashite. He participated in a number of early Pugwash Conferences and in the South-East Asia Regional Pugwash Conference in Melbourne, in 1967.

Born in Adelaide, South Australia, he made his mark as a scientist in England, where he resided—on and off—from 1927 until 1950. The earlier part of that period was spent in Cambridge, as a member of the legendary team which-under the leadership of Lord Rutherford-produced the fundamental discoveries in nuclear physics that made the Cavendish Laboratory the Mecca for scientists during the years between the two World Wars. Oliphant's main contributions were the discovery of tritium, the third isotope of hydrogen, and the establishment of the reactions that take place at collisions between deuterons (the nuclei of the second isotope of hydrogen). Ironically for Oliphant—the later anti-nuclear campaigner—the main practical applications of his work were for military purposes: tritium is used as a booster in the fission bomb, and the fusion reactions are the basis of the hydrogen bomb.

During the War years, 1939-45, Oliphant made two vital contributions to the war effort. One was in radar. The resonant cavity magnetron, developed under his guidance, increased manifold the power of the radio beam transmitted at very short wavelengths, making radar into a practical tool to detect approaching enemy aircraft. It is the general opinion that this greatly contributed to the defeat of the Luftwaffe during the 1940 Battle of Britain, thus preventing Hitler's invasion of England. It was largely Oliphant's drive and indefatigability that made this possible.

A somewhat similar role was played by him in the development of the atom bomb. Some research on it had already begun, in England, in 1939, but the main impetus came after the calculations by Frisch and Peierls, early in 1940, which showed that the critical mass for a divergent chain reaction, propagated by fast neutrons in uranium-235, was only a few kilograms. It was Oliphant who brought the Frisch-Peierls Memorandum to the attention of government authorities. As a result, the MAUD Committee was set up, charged with the development of the atom bomb.

Most of the experimental research on the physics of the bomb was carried out in Liverpool, where Frisch joined Chadwick's team. By 1941 the scientific feasibility of the bomb had been established, but the separation of the uramnium-235 isotope was too difficult a task for Britain under wartime conditions.

While on a trip to the United States on radar business, in 1941, Oliphant discovered that no work was going on in the USA on the atom bomb, although the Report of the MAUD Committee had been sent to the relevant authorities. He immediately told a few friends about the British findings. The setting up of the Manhattan Project can be said to be the outcome of Oliphant's indiscretion!

Oliphant vehemently opposed the use of the atom bomb on the Japanese cities. He never overcame his feelings of guilt about the part he played in the Manhattan Project, and he frequently expressed his views publicly. He also took an active part in international campaigns against nuclear weapons, particularly in Pugwash. He fully shared the Pugwash precept that scientists have a moral duty to be concerned about the social impact of their work. Describing himself as a "belligerent pacifist"; he asserted his conviction that war itself is evil and should not be tolerated by humanity.

A figure larger than life with a booming laugh, Oliphant delighted in controversial discussions and was never shy of challenging authority. As a scientist he was imaginative and creative; as a public figure he abhorred secrecy and fought for openness in all walks of life. As a human being he had a strong belief in social values and—despite occasional scepticism—he deeply cared for humanity.

—Joseph Rotblat