Walther Bothe - Physicists, Career and Family

Walther Wilhelm Georg Bothe was born on January 8, 1891, in Oranienburg, near Berlin, Germany, to Charlotte Hartung and Fredrich Bothe

Growing up, he showed a great interest in Physics. Between 1908 and 1912 Bothe studied at the Friedrich-Wilhelms-Universität (now known as the Humboldt University of Berlin).

He studied under the tutelage of the famous physicist, Max Planck and excelled in mathematics, physics, and chemistry. He became Planck’s teaching assistant in 1913. Just before the First World War broke out, he obtained his doctorate, in 1914, under Planck.

In 1913, he was offered a job at the Physikalische-Technische Reichsanstalt (presently known as Physikalisch-Technische Bundesanstalt). He served there as a ‘Professor Extraordinary’ until 1930.

In 1914, after obtaining his doctorate, he proceeded to join the German cavalry. He was captured by the Russians and imprisoned for over 5 years in Siberia. During his captivity, he chose to study mathematics and also learnt to read and write Russian. He was released in 1920 and he returned to Germany.

Walther Bothe was an active theoretical and experimental physicist. He worked on the scattering of alpha and beta rays and devised a theory involving scattering at small angles.

He and Hans Geiger, in 1924, performed an experiment involving the wavelike properties of radiation. Both of them formulated a new quantum theory of radiation. He published his coincidence method and applied it to the study of nuclear reactions, the “Compton Effect”, and the wave-particle duality of light.

In 1925, while still at Physikalische-Technische Reichsanstalt, he became a ‘Privatdozent’ (denotes an ability to teach independently at university level. Later on in 1929, he became an ‘ausserordentlicher Professor’ (extraordinarius professor) there 1929.

In 1929, he began another study focusing on cosmic rays. This subject would go on to become his lifelong muse. For this study, he collaborated with guest professors at the university, Werner Kolhörster and Bruno Rossi.

In 1930, he became an ‘ordentlicher Professor’ (ordinarius professor) and was appointed ‘Director of the Institute of Physics’ at the Justus Liebig-Universität Gießen (University of Giessen). In 1930, he discovered an unusual radiation emitted by beryllium when it is bombarded with alpha particles. This would later lead to the discovery of the neutron in 1932 by Sir James Chadwick.

Walther Bothe was appointed the Director of the ‘Physikalische und Radiologische Institut’ (Physical and Radiological Institute) at the University of Heidelberg, in 1932.

With the rise of Hitler, the concept of Deutsche Physik [German Physics] or Aryan Physics started gaining momentum. It was a political concept that was against theoretical, modern, atomic, and nuclear physics as well as against quantum mechanics. This led to a number of violent attacks on theoretical physicists. Under the influence of Philipp Lenard, he was able to move on to the Directorial position at Institut für Physik (Institute for Physics) at ‘Kaiser-Wilhelm-Institut für medizinische Forschung’ (the Max-Planck-Institut für medizinische Forschung).

At Heidelberg, he set up a cyclotron from funds obtained from various research groups. During World War II, he was able to work on the diffusion theory of neutrons and related measurements.

His research paper, ‘Atlas of Typical Cloud Chamber Images’ was published in 1940. It contained images gathered from a cloud chamber built by Heinz Maier-Leibnitz. It depicts scattered particles and means to identify them.

He became an ‘ordentlicher Professor’ at the University of Heidelberg between 1946 and 1957. He was a member of the ‘Arbeitskreis Kernphysik’ (Nuclear Physics Working Group) of the ‘Deutschen Atomkommission’ [German Atomic Energy Commission) during 1956 and 1957.

His most famous work is the ‘Coincidence Circuit’ that works on the coincidence principle. Walther Bothe used two Geiger counters and studied the coincidences between scattered X-rays and recoiling electrons. The observations indicated a small scale conservation of energy and momentum. He also used this principle to show that cosmic rays act like particles.

For his coincidence method and the discoveries made therewith, Walther Bothe was co-awarded the “Nobel Prize in Physics” in 1954. The other recipient of the award was Max Born. The coincidence method and its circuits are widely used in many particle physics experiments and various other areas of science and technology.

In 1952, he was awarded Knight of the Order of Merit for Sciences and the Arts.

In 1953, he was honored with the Max-Planck-Medaille of the Deutsche Physikalische Gesellschaft..

During his incarceration in Russia, Walther Bothe met Barbara Below. She was from Moscow and returned with him to Germany after their wedding in 1920. They sired two children.

Though he was a busy man, he took time off to paint. His inspirations were the mountains and he dabbled in oil and watercolor pieces. He discussed French impressionists with the same enthusiasm with which he discussed physics.

He was also a music lover, listening to pieces by Beethoven and Bach. He used to attend many concerts and learnt to play the piano.

At work, he was a highly difficult and strict teacher with a gift of concentration and speed. At home, however, he was a gracious and hospitable man with a lot of ease and happiness.

He died in Heidelberg, West Germany, on February 8, 1957, at the age of 66.