Joseph John Thomson

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Sir Joseph John Thomson
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Sir Joseph John Thomson OM (often also JJ Thomson; born December 18, 1856 in Cheetham Hill near Manchester , †  August 30, 1940 in Cambridge ) was a British physicist and Nobel Prize laureate in physics . He discovered  the electron in 1897 - around the same time as the German physicist Emil Wiechert .


Joseph John Thomson was born near Manchester in 1856 to Scottish parents . His father had a second-hand bookshop. From 1870 he attended Owen College in Manchester, which gave him a good scientific education. His parents wanted him to become an engineer and study in a locomotive factory. After his father's death in 1873, Thomson became a half-orphan and these plans failed because the financial means were lacking. From 1876 he studied at the College Trinity of the University of Cambridge mathematics and physics, graduating as Second Wrangler in the Tripos examinations in mathematics in 1880 (according to the bachelor's degree). He also finished second in the competition for the Smith Prize , which he received in 1880. In 1883 the master’s degree followed, at the same time he won the Adams Prize in 1882 . In 1884 he received the prestigious Cavendish Professorship in Physics at Cambridge, which previously John William Strutt, 3rd Baron Rayleigh , held. On January 22, 1890, he married Rose Elizabeth Paget, one of the earliest researchers at the Cavendish Laboratory . They had two children, Joan Paget Thomson and George Paget Thomson , another Nobel Prize winner . Thomson himself has been described as clumsy. He supervised the experiments and gave instructions. However, his assistants and students tried to keep him away from conducting the experiments. One of his students was Ernest Rutherford , who would later receive a Nobel Prize in Chemistry .

He was director of Trinity College from 1918 until his death in 1940 and President of the Royal Society from 1916 to 1920 . Thomson's ashes were buried in Westminster Abbey (near Sir Isaac Newton ).


A cathode ray tube with which Thomson succeeded in proving the electron experimentally

Thomson was (together with John Henry Poynting , George Francis FitzGerald , Oliver Heaviside and Joseph Larmor ) one of those who further developed the electrodynamics of James Clerk Maxwell . In 1880 he derived (but only approximately) the Lorentz force . In 1881 he investigated the behavior of moving charges and introduced the concept of electromagnetic mass ; d. that is, he discovered that electromagnetic energy behaves as if it increases the mass of a body. And in 1893 Thomson was able to derive the impulse associated with electromagnetic energy.

By examining the cathode radiation in 1897, Thomson succeeded in experimentally demonstrating the existence of the electron as predicted by George Johnstone Stoney in 1874 (the electron played a fundamental role in the theories of Hendrik Antoon Lorentz and Joseph Larmor as early as 1892 ). Thomson was also able to prove that moving electrons could be deflected by a magnetic field, which Heinrich Hertz had previously denied. However, Thomson now had better vacuum pumps so that he could work with significantly lower pressure in his cathode ray tube.

This was the first discovery of a subatomic particle , and Thomson was honored with the 1906 Nobel Prize in Physics. Based on this, Thomson developed Thomson 's atomic model (also known as the “raisin cake” or “plum pudding model”), according to which the very small and light electrons inside the atoms are embedded like raisins in cake dough. In 1906 Thomson was able to show that the hydrogen atom contains exactly one electron. However, this atomic model was later refuted by Ernest Rutherford ( Rutherford scattering experiment ) and replaced by Rutherford's atomic model, in which a small, heavy nucleus with a positive charge is surrounded by a light shell with a negative charge.

In 1913, Thomson was able to prove in experiments with canal rays that the chemical element neon is a mixture of atoms of different weights (in this case 20 Ne and 22 Ne). From this, u. a. Frederick Soddy developed the theory of isotopy . Thomson also made important contributions to the subsequent development of mass spectrometry .


In 1884 Thomson was elected as a member (" Fellow ") in the Royal Society , which awarded him the Royal Medal in 1894 , the Hughes Medal in 1902 and the Copley Medal in 1914 . In 1902 he was elected to the American Academy of Arts and Sciences , in 1903 to the National Academy of Sciences and in 1905 to the Royal Society of Edinburgh . In 1906 he was awarded the Nobel Prize in Physics for his research on the electrical conductivity of gases . Thomson was promoted to Knight Bachelor in 1908 and accepted into the Order of Merit in 1912 . From 1907 he was a corresponding member of the Bavarian Academy of Sciences . In 1911 he was elected a foreign member of the Göttingen Academy of Sciences . Since 1911 he was a corresponding member of the Académie des sciences and a foreign member since 1919 . Mount JJ ​​Thomson , a mountain in East Antarctic Victoria Land, bears his name.


  • Recollections and Reflections . G. Bell, London 1936 ( online ).


See also

Web links

Commons : Joseph John Thomson  - album with pictures, videos and audio files

Individual evidence

  1. ^ Fellows Directory. Biographical Index: Former RSE Fellows 1783–2002. (PDF file) Royal Society of Edinburgh, accessed April 16, 2020 .
  2. Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= Treatises of the Academy of Sciences in Göttingen, Philological-Historical Class. Volume 3, Vol. 246 = Treatises of the Academy of Sciences in Göttingen, Mathematical-Physical Class. Episode 3, vol. 50). Vandenhoeck & Ruprecht, Göttingen 2001, ISBN 3-525-82516-1 , p. 239.