Werner Heinrich Gustav Kolhörster (28 December 1887 – 5 August 1946) 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 a pioneer of research into

cosmic ray Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the ...

s. Kolhörster was born in Schwiebus (Świebodzin), Brandenburg Province of

Prussia Prussia (; ; Old Prussian: ''Prūsija'') was a Germans, German state centred on the North European Plain that originated from the 1525 secularization of the Prussia (region), Prussian part of the State of the Teutonic Order. For centuries, ...

. While attending the

University of Halle Martin Luther University Halle-Wittenberg (), also referred to as MLU, is a public research university in the cities of Halle and Wittenberg. It is the largest and oldest university in the German state of Saxony-Anhalt. MLU offers German and i ...

, he studied physics under

Friedrich Ernst Dorn Friedrich Ernst Dorn (27 July 1848 – 16 December 1916) was a German physicist. He is best remembered for his discovery that radium emits a radioactive substance, later named radon. Life and work Dorn was born in Guttstadt (Dobre Miasto), ...

. Repeating the

experiments of Victor Hess, in 1913-14 Kolhörster ascended by balloon to an altitude of 9 km, where he confirmed Hess' result that the ionization rate from cosmic rays was greater at that altitude than at sea level. This was evidence that the source for these ionizing rays came from above the Earth's atmosphere. Kolhörster continued his physics studies at the '' Physikalisch-Technische Reichsanstalt'' in

Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...

, beginning in 1914. During

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

he made measurements of atmospheric electricity in Turkey. Following the war he became a teacher. He joined the ''Physikalisch-Technische Reichsanstalt'' in 1922. In 1928–29, Walter Bothe and Kolhörster used the Geiger-Muller detector to demonstrate that

s were actually charged particles. The ability of these particles to penetrate the Earth's atmosphere meant that they must be highly energetic. In 1930, Kolhörster started the first institute for the study of cosmic rays in

Potsdam Potsdam () is the capital and largest city of the Germany, German States of Germany, state of Brandenburg. It is part of the Berlin/Brandenburg Metropolitan Region. Potsdam sits on the Havel, River Havel, a tributary of the Elbe, downstream of B ...

, with financial assistance from the

Prussian Academy of Sciences The Royal Prussian Academy of Sciences () was an academy established in Berlin, Germany on 11 July 1700, four years after the Prussian Academy of Arts, or "Arts Academy," to which "Berlin Academy" may also refer. In the 18th century, when Frenc ...

. He became director of the ''Institut für Hohenstrahlungsforschung'' in Berlin-Dahlem in 1935, where he was appointed an ordinary professor. Kolhörster was killed in a car crash in

Munich Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...

. The crater Kolhörster on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

is named in his memory.

References

1887 births 1946 deaths 20th-century German physicists Scientists from the Province of Brandenburg Martin Luther University of Halle-Wittenberg alumni People from Świebodzin Cosmic ray physicists {{Germany-physicist-stub