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

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

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 The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...

.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 Sovetsk (russian: Сове́тск; german: Tilsit; Old Prussian: ''Tilzi''; lt, Tilžė; pl, Tylża) is a town in Kaliningrad Oblast, Russia, located on the south bank of the Neman River which forms the border with Lithuania. Geography S ...

Province of Prussia The Province of Prussia (; ; pl, Prowincja Prusy; csb, Prowincjô Prësë) was a province of Prussia from 1829 to 1878. Prussia was established as a province of the Kingdom of Prussia in 1829 from the provinces of East Prussia and West Prussia ...

, the son of Johann and Emilie Wiechert. After his father died, his mother, Emilie, moved to

Königsberg Königsberg (, ) was the historic Prussian city that is now Kaliningrad, Russia. Königsberg was founded in 1255 on the site of the ancient Old Prussian settlement ''Twangste'' by the Teutonic Knights during the Northern Crusades, and was ...

so that Emil could study at the

University of Königsberg The University of Königsberg (german: Albertus-Universität Königsberg) was the university of Königsberg in East Prussia. It was founded in 1544 as the world's second Protestant academy (after the University of Marburg) by Duke Albert of Pruss ...

. 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 ...

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

Career

Whilst at Königsberg, Wiechert was investigating the nature of X-rays and became one of the first to discover that

cathode ray Cathode rays or electron beam (e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to el ...

s 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 electr ...

of these particles but failed to take the final step and explain that these particles were a new type of elementary particle - the

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...

. 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 Christian Felix Klein (; 25 April 1849 – 22 June 1925) was a German mathematician and mathematics educator, known for his work with group theory, complex analysis, non-Euclidean geometry, and on the associations between geometry and grou ...

's efforts to re-establish the University of Göttingen as a world leading research centre, Wiechert's tutor,

Woldemar Voigt Woldemar Voigt (; 2 September 1850 – 13 December 1919) was a German physicist, who taught at the Georg August University of Göttingen. Voigt eventually went on to head the Mathematical Physics Department at Göttingen and was succeeded in ...

, 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 Karl Bernhard Zoeppritz (22 October 1881 – 20 July 1908) was a German geophysicist who made important contributions to seismology, in particular the formulation of the Zoeppritz equations. These equations relate the amplitudes of P-waves and S- ...

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 wave A seismic wave is a wave of acoustic energy that travels through the Earth. It can result from an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic ener ...

s 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 outpu ...

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 The German Academy of Sciences at Berlin, german: Deutsche Akademie der Wissenschaften zu Berlin (DAW), in 1972 renamed the Academy of Sciences of the GDR (''Akademie der Wissenschaften der DDR (AdW)''), was the most eminent research institution ...

, 1912. * The crater Wiechert on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

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