Edward Appleton

Born on 6 September 1892 in Bradford, England, Edward Appleton was a physicist, Nobel laureate, and pioneer in radiophysics. He studied at St. John’s College at Cambridge University, where he worked at the Cavendish Laboratory under J. J. Thomson and Ernest Rutherford. He earned his BA in natural science in 1913 and MS in physics in 1914. It was while serving in the Corps of Royal Engineers during World War I that Appleton became interested in the propagation of radio waves. After the war, he returned to Cambridge, where he continued experimental studies in atmospheric physics. In 1924 he was appointed Wheatstone Professor of Physics at London University, where he conducted some of his most important research. Appleton used the BBC broadcasting station in Bournemouth to show that radio waves aimed up into the atmosphere were reflected back; he was also able to determine the time taken by the waves and the distance traveled. His measurements confirmed the existence of the ionosphere, which reflects radio waves and thus allows long-range radio communication and round-the-world broadcasting. The ionosphere’s upper layer, which has the highest electron density and is responsible for most radio-wave propagation, is often referred to as the Appleton layer. In 1936 Appleton returned to Cambridge as Jacksonian Professor of Natural Philosophy. In 1939 he became secretary of the UK’s department of scientific and industrial research, where he worked on radar during World War II. The importance of his work was recognized by numerous honors and awards, including the 1947 Nobel Prize in Physics. Also in 1947 he received the US’s highest civilian decoration—the Medal for Merit—and was made an officer of the French Legion of Honor. Over his career he served on many important scientific committees and helped plan the International Geophysical Year of 1957–58. In 1949 he became principal and vice chancellor of the University of Edinburgh, a position he held until his death in 1965 . (Photo credit: AIP Emilio Segrè Visual Archives, E. Scott Barr Collection)

Date in History: 6 September 1892