Emil Johann Wiechert (26 December 1861 – 19 March 1928) was a German physicist and

geophysicist Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ...

who made many contributions to both fields, including presenting the first verifiable model of a layered

structure of the Earth The internal structure of Earth is the solid portion of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core whos ...

and being among the first to discover the electron. He went on to become the world's first Professor of Geophysics at the University of Göttingen.Bormann, P. (Ed.). (2012). Dedication to the 150th birthday of Emil WIECHERT (1861-1928). In P. Bormann (Ed.), New Manual of Seismological Observatory Practice 2 (NMSOP 2) (pp. 1-2). Potsdam: Deutsches GeoForschungsZentrum GFZ.

Early years

Wiechert was born in Tilsit, Province of Prussia, the son of Johann and Emilie Wiechert. After his father died, his mother, Emilie, moved to Königsberg so that Emil could study at the University of Königsberg. Owing to financial difficulties, he took longer than normal to complete his education and was finally awarded a Ph.D. on 1 February 1889.Emil Wiechert (1861 – 1928). Joachim R. R. Ritter & Johannes Schweitzer. In October 1890 he received his

Habilitation Habilitation is the highest university degree, or the procedure by which it is achieved, in many European countries. The candidate fulfills a university's set criteria of excellence in research, teaching and further education, usually including a ...

in Physics and by 1896, he had achieved the title of Professor. In 1898, he was appointed to the world's first Chair of Geophysics at the University of Göttingen.

Career

Whilst at Königsberg, Wiechert was investigating the nature of X-rays and became one of the first to discover that cathode rays are made up of particle streams. He correctly measured the

Mass-to-charge ratio The mass-to-charge ratio (''m''/''Q'') is a physical quantity relating the ''mass'' (quantity of matter) and the ''electric charge'' of a given particle, expressed in units of kilograms per coulomb (kg/C). It is most widely used in the electrody ...

of these particles but failed to take the final step and explain that these particles were a new type of elementary particle - the electron. Wiechert was also interested in fields outside of fundamental physics and in 1896, he published the first verifiable model of the Earth's interior as a series of shells. Here he concluded that the difference between the density of the Earth's surface rocks and the mean density of the Earth meant that the Earth must have a heavy iron core.Some Aspects in Emil Wiechert's Scientific Work. Wilfried Schroeder. http://verplant.org/history-geophysics/Wiechert.htm These were the foundations that one of Wiechert's students, Beno Gutenberg, used to discover the three-layered Earth in 1914. As part of Felix Klein's efforts to re-establish the University of Göttingen as a world leading research centre, Wiechert's tutor, Woldemar Voigt, was lured away from Königsberg and took Wiechert with him. He had initially hoped to become a Professor of theoretical physics but was eventually invited by Klein to found the world's first Institute of Geophysics, becoming the world's first Professor of Geophysics in 1898. He would remain there for the rest of his career, mentoring many students who became world-leading geophysicists and seismologists, including Karl Bernhard Zoeppritz and Beno Gutenberg.

Contributions and influence

During his career he made many other important contributions, writing a number of scientific papers, including a pioneering work on how seismic waves propagate through the Earth. He also devised an improved

seismograph A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output ...

and created the field of geological prospecting using small, artificially-created earthquakes. Wiechert was also interested in theoretical physics, such as the theory by Albert Einstein. He discussed the role of the ether and related questions with Hendrik Antoon Lorentz and others. He married Helene Ziebarth, a lawyer's daughter, in 1908, but the couple did not have children.

Awards and honors

* Corresponding member of the Berlin Academy of Science, 1912. * The crater

Wiechert Wiechert is a German surname. Notable people with the surname include: * Emil Wiechert (1861–1928), German physicist and geophysicist * Ernst Wiechert (1887–1950), German teacher, poet, and writer See also * Weichert (surname) Weichert is a ...

on the Moon is named after him.

References

*Angenheister, G.H., (1928). Emil Wiechert. Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Geschäftliche Mitteilungen, 53–62.

External links

* *
Emil Wiechert (1861–1928): Esteemed seismologist, forgotten physicist

Photographs of the Wiechert Seismograph used in the Lick Observatory from the Lick Observatory Records Digital Archive, UC Santa Cruz Library's Digital Collections
* {{DEFAULTSORT:Wiechert, Emil 1861 births 1928 deaths German geophysicists People from the Province of Prussia People from Tilsit Seismologists University of Göttingen faculty University of Königsberg alumni