18 November 1897, London (United Kingdom) - 13 July 1974, London (United Kindom)
Patrick Maynard Stuart Blackett, originally trained as a naval officer at Dartmouth in 1912.
In August 1914, at the outbreak of the First World War, he was appointed to active service as a midshipman.
At the end of the war, he resigned as a lieutenant and went to study physics with Ernest Rutherford at Cambridge, graduating from Magdalene College in 1921.
He then spent 10 years working at the Cavendish Laboratory, directed by Rutherford, and began his research with cloud chambers, which resulted in 1924 in the first photographs showing the transmutation of nitrogen into an oxygen isotope, produced by bombarding atomic nuclei with alpha particles.
In 1932, together with the Italian scientist Occhialini, he designed a counter-controlled fog chamber, a brilliant invention with which they made cosmic rays take their pictures. By this method, the fog chamber is set in motion only when the impulses from two Geiger-Muller tubes, placed one above and one below Wilson's vertical chamber, coincide as a result of the passage of an electrically charged particle through both.
In 1933 they not only confirmed Anderson's discovery of the positive electron, but also demonstrated the existence of "showers" of positive and negative electrons, both in approximately equal amounts. This fact, and the knowledge that positive particles (positrons) do not normally exist as normal constituents of matter on Earth, formed the basis of their conception that gamma rays can be transformed into two material particles (positrons and electrons) plus a certain amount of kinetic energy, a phenomenon usually called pair production.
The reverse process, a collision between a positron and an electron in which both are transformed into gamma radiation (so-called annihilation radiation) was also verified experimentally.
In interpreting these experiments, Blackett and Occhialini were guided by the electron theory of the physicist Paul Dirac.
In 1933, Blackett became a professor of physics at Birkbeck College in London, where he continued his research work on cosmic rays, thus creating a cosmopolitan school of researchers.
In 1937, he succeeded Sir Lawrence Bragg at the University of Manchester, where Bragg had succeeded Rutherford, as chairman of the physics department and his school of cosmic research continued to develop and, since the war, the Manchester laboratory has expanded its field of activity, particularly in the investigation of radar meteor trails, under the direction of Dr. Lovell.
At the outbreak of the Second World War, Blackett joined the Instrument Section of the Royal Aircraft Establishment and, in 1940, became scientific advisor to Air Marshal Joubert in Coastal Command.
In 1945, after the end of the Second World War, he resumed cosmic ray research at the University of Manchester and, in particular, continued the study of cosmic ray particles employing the counterweight-controlled fog chamber in a strong magnetic field, built and used before the war.
In 1947 he introduced the theory of paleomagnetism which helped prove continental drift and, a year later, his work was awarded the Nobel Prize in Physics for his discoveries in the fields of nuclear physics and cosmic rays.
After teaching at various institutions, from 1953 to 1965, Blackett was a Professor of Physics at the Imperial College of Science and Technology, University of London. He was President of the Royal Society in London from 1965 to 1970.
Blackett was awarded the Royal Medal of the Royal Society in 1940 and the American Medal of Merit, for operational research work in connection with the submarine campaign, in 1946. He is the author of Military and Political Consequences of Atomic Energy (1948; revised edition 1949; American edition Fear, War, and the Bomb, 1949).
