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 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 Solar System in our own ...

s. Kolhörster was born in Schwiebus (Świebodzin),

Brandenburg Province The Province of Brandenburg (german: Provinz Brandenburg) was a province of Prussia from 1815 to 1945. Brandenburg was established in 1815 from the Kingdom of Prussia's core territory, comprised the bulk of the historic Margraviate of Brandenburg ...

Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an ...

. While attending the

University of Halle Martin Luther University of Halle-Wittenberg (german: Martin-Luther-Universität Halle-Wittenberg), also referred to as MLU, is a public, research-oriented university in the cities of Halle and Wittenberg and the largest and oldest university in ...

, he studied physics under Friedrich Ernst Dorn. Repeating the

experiments of

Victor Hess Victor Franz Hess (; 24 June 188317 December 1964) was an Austrian- American physicist, and Nobel laureate in physics, who discovered cosmic rays. Biography He was born to Vinzenz Hess and Serafine Edle von Grossbauer-Waldstätt, in Waldstei ...

, 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 and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...

, beginning in 1914. During

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

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 Walther Wilhelm Georg Bothe (; 8 January 1891 – 8 February 1957) was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born. In 1913, he joined the newly created Laboratory for Radioactivity at the Reich Physi ...

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, with around 183,000 inhabitants, largest city of the German state of Brandenburg. It is part of the Berlin/Brandenburg Metropolitan Region. Potsdam sits on the River Havel, a tributary of the Elbe, downstream o ...

, with financial assistance from the

Prussian Academy of Sciences The Royal Prussian Academy of Sciences (german: Königlich-Preußische Akademie der Wissenschaften) 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 ...

. 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 ( ; german: München ; bar, Minga ) is the capital and most populous city of the German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the third-largest city in Germany, after Berlin and Ha ...

. The crater Kolhörster 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 in his memory.

References

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