Society: Arts and Science – July 13


The Nobel Prize is bestowed annually in categories as selected by Swedish and Norwegian committees in recognition of cultural or scientific advances. The 1895 will of Swedish inventor Alfred Nobel established the prizes.
Jonas Ferdinand Gabriel Lippmann died on this date in 1921. He was a Franco-Luxembourgish physicist and inventor. Above all, Lippmann is remembered as the inventor of a method for reproducing colours by photography, based on the interference phenomenon, which earned him the Nobel Prize in Physics for 1908.
Patrick Maynard Stuart Blackett, Baron Blackett OM CH FRS died on this date in 1974. He was an English experimental physicist known for his work on cloud chambers, cosmic rays, and paleomagnetism. He also made a major contribution in World War II advising on military strategy and developing operational research. His left-wing views saw an outlet in third world development and in influencing policy in the Labour Government of the sixtiess. After graduating from Magdalene College in 1921, Blackett spent ten years working at the Cavendish Laboratory as an experimental physicist with Professor Rutherford and in 1923 became a fellow of King’s College, Cambridge, a position he held until 1933. Rutherford had found out that the nucleus of the nitrogen atom could be disintegrated by firing fast alpha particles into nitrogen. He asked Blackett to use a cloud chamber to find visible tracks of this disintegration, and by 1924, he had taken 23,000 photographs showing 415,000 tracks of ionized particles. Eight of these were forked, and this showed that the nitrogen atom-alpha particle combination had formed an atom of fluorine, which then disintegrated into an isotope of oxygen and a proton. Blackett spent some time in 1924–1925 at Göttingen, Germany working with James Franck on atomic spectra. In 1932, working with Giuseppe Occhialini, he devised a system of geiger counters which only took photographs when a cosmic ray particle traversed the chamber. They found 500 tracks of high energy cosmic ray particles in 700 automatic exposures. In 1933, Blackett discovered fourteen tracks which confirmed the existence of the positron and revealed the now instantly recognisable opposing spiral traces of positron/electron pair production. This work and that on annihilation radiation made him one of the first and leading experts on anti-matter. That same year he moved to Birkbeck College, University of London as Professor of Physics for four years. Then in 1937 he went to the Victoria University of Manchester where he was elected to the Langworthy Professorship and created a major international research laboratory. The Blackett Memorial Hall and Blackett lecture theatre at the University of Manchester were named after him. In 1947, Blackett introduced a theory to account for the Earth’s magnetic field as a function of its rotation, with the hope that it would unify both the electromagnetic force and the force of gravity. He spent a number of years developing high-quality magnetometers to test his theory, and eventually found it to be without merit. His work on the subject, however, led him into the field of geophysics, where he eventually helped process data relating to paleomagnetism and helped to provide strong evidence for continental drift. In 1948 he was awarded the Nobel Prize in Physics, for his investigation of cosmic rays using his invention of the counter-controlled cloud chamber. Professor Blackett was appointed Head of the Physics Department of Imperial College London in 1953 and retired in July 1963. The current Physics department building of Imperial College is named the Blackett Laboratory. In 1957 Blackett gave the presidential address (Technology and World Advancement) to the British Association meeting in Dublin. In 1965 he was invited to deliver his “Continental Drift” talk for the MacMillan Memorial Lecture to the Institution of Engineers and Shipbuilders in Scotland.