Emil Wiechert

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Emil Wiechert

Emil Wiechert (born December 26, 1861 in Tilsit , East Prussia, † March 19, 1928 in Göttingen ; also: Johann Emil Wiechert ) was a German physicist and seismologist .

Life

Emil Wiechert was the only child of the Tilsit merchant Johann Wiechert and his wife Emilie. After the early death of his father, he grew up in Königsberg i. Pr. On. He attended the Löbenichtsche Realgymnasium and, after graduating from high school in 1881, studied physics at the Albertus University in Königsberg . In 1889 he received his doctorate with a doctoral thesis under Paul Volkmann . The following year he completed his habilitation in physics. His research in Königsberg dealt with the structure of matter, experiments with cathode rays and theoretical work on electricity. Little is known that he succeeded in doing one of the first determinations of the ratio of charge to mass of the electron.

At about the same time as Joseph John Thomson (who is usually called the discoverer) he discovered the particle that is now called "electron". In April 1896, in a lecture to the Koenigsberger Physikalisch-Ökonomische Gesellschaft, he pointed out the existence of a particle whose mass must be much smaller than that of the hydrogen atom. On January 7, 1897, in a lecture to the same company, he reported that he had proven the particle and experimentally determined its mass to be about 2000 to 4000 times smaller than that of the hydrogen atom. In September 1897 he announced a more precise value: The mass of the particle is about 1 / (1500 ± 500) the mass of the hydrogen atom (today's value 1/1838). Thomson's lecture to the Royal Society was on April 30, 1897.

Independently of Alfred-Marie Liénard (1898), Wiechert introduced the Liénard-Wiechert potentials of a moving charge, named after both, in an article in 1900 .

Memorial plaque in the Göttingen earthquake station

After Göttingen physicists became aware of Emil Wiechert, he worked at the University of Göttingen from 1897, where he was appointed to the world's first chair in geophysics in 1898 . After completion of the newly established Institute for Geophysics on the Hainberg above Göttingen, Wiechert began in 1901 with the construction of the Wiechert earthquake station, which is still in operation there today .

The construction of the air-damped Wiechert seismograph with high magnification, which was to remain the model for most of the instruments used in earthquake monitoring stations around the world for decades, made it possible for the first time to continuously record global earthquake activity. With the diagrams of the ground movement recorded by these seismographs, the propagation of the earthquake waves and the structure of the earth's interior were researched. In addition, geomagnetic and air-electric phenomena were investigated. In 1902 a geophysical observatory was founded on Samoa at Wiechert's instigation , which was operated from Göttingen until after the First World War . Behind this was the realization that answering the big questions of geophysics requires a worldwide observation network.

In 1903 Emil Wiechert was one of the founders of the Association Internationale de Séismologie, from which today's International Association of Seismology and Physics of the Earth's Interior (IASPEI) emerged. In the same year he was elected a full member of the Göttingen Academy of Sciences . In 1911 he was accepted as a corresponding member of the Bavarian Academy of Sciences and in 1912 of the Russian Academy of Sciences in Saint Petersburg .

Many of Emil Wiechert's Göttingen students later became important geophysicists and made decisive progress in certain areas of science, for example Beno Gutenberg and Ludger Mintrop as well as Hans Haalck . Wiechert himself received numerous honors, was in constant exchange with the leading physicists of his time (such as Arnold Sommerfeld , Hendrik Antoon Lorentz , Albert Einstein , Max Planck ) and took an active part in the rapid developments in many fields of physics, including the development of Theory of relativity. This was expressed, among other things, in his contributions on the subject of ethers in physics, about which Wilfried Schroeder brought a compilation, who also published the Sommerfeld-Wiechert and Lorentz-Wiechert correspondence. His most important field of work, however, remained seismology, which he continued to advance in practical and theoretical fields. Consequently, in 1922, he initiated the founding of the German Seismological Society, of which he was elected first chairman in Leipzig. In 1924 the German Geophysical Society (DGG) emerged, which named its highest award for outstanding work in the field of geophysics after Emil Wiechert.

Grave site in Göttingen
Special postage stamp for the 150th birthday in 2011

Emil Wiechert turned down several calls to renowned professorships. In 1908 he had married Helene Ziebarth, the daughter of a well-known Göttingen lawyer; the marriage remained childless. He lived with her and his mother in a secluded life and concentrated very much on his scientific work, which he continued unabated until immediately before his death in 1928 at the age of 66.

Emil Wiechert is also recognized internationally as the founding father of the geophysics department. Even today he is considered one of the most important seismologists in Germany, if not worldwide. The seismic observatory he founded in Göttingen is still in operation today with its historical instruments as a scientific monument. It is the only facility that enables a direct comparison of major earthquakes in the past, such as San Francisco in 1906, with earthquakes today.

A crater on the back of the moon is named after Emil Wiechert.

On November 10, 2011, Deutsche Post issued a special stamp (worth 90 cents) on the occasion of Emil Wiechert's 150th birthday.

Quote

"The swaying rock brings you distant news -: interpret the signs!"

- Emil Wiechert, 1902 : Inscription above the earthquake house of the Göttingen earthquake station

See also

literature

  • Wilfried Schröder: Emil Wiechert: Physicist - Geophysicist - Science Organizer. History Commission of the German Geophysical Society, Bremen-Roennebeck 2000 (communications from the Working Group on the History of Geophysics; Jg. 19, H. 1/2).
  • Wilfried Schroeder: The ether in physics with Albert Einstein, Gustav Mie and Emil Wiechert . Science Edition, Bremen 2006.
  • Wilfried Schroeder Hendrik Antoon Lorentz and Emil Wiechert (correspondence and relationship between the two physicists) , Archive for History Exact Sciences, Volume 30, 1984, pp. 167–187.
  • Wilfried Schroeder: Emil Wiechert and its importance for the development of geophysics into exact science , Archive for History of Exact Sciences, Volume 27, No. 4 (1982), pp. 369-389.
  • In memory of Emil Wiechert on the occasion of the 100th anniversary of his birthday. Akademie-Verlag, Berlin 1962 (publications by the Institute for Soil Dynamics and Earthquake Research in Jena; issue 72).
  • Joseph F. Mulligan: Emil Wiechert (1861–1928): Esteemed seismologist, forgotten physicist. American Journal of Physics, Volume 69, 2001, pp. 277-287.

Web links

Individual evidence

  1. ↑ Dissertation: About elastic aftereffects .
  2. ↑ Two Means of Facilitating the Observation of Electrodynamic Waves .
  3. ^ Wiechert E. // Writings d. phys.-econom. Companion zu Königsberg in Pr. 1897. Volume 38 № 1. Meeting report. Pp. 3-16.
  4. ^ Wiechert, Archives Néerlandaises des Sciences Exactes et Naturelles, Series 2, Volume 5, 1900, p. 549 (online)
  5. ↑ 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. 258.
  6. ^ Foreign members of the Russian Academy of Sciences since 1724. Johann Emil Wiechert. Russian Academy of Sciences, accessed August 12, 2015 .
personal data
SURNAME Wiechert, Emil
ALTERNATIVE NAMES Wiechert, Johann Emil
BRIEF DESCRIPTION German physicist and seismologist
DATE OF BIRTH December 26, 1861
PLACE OF BIRTH Tilsit
DATE OF DEATH March 19, 1928
Place of death Goettingen