Adriaan Fokker

Infobox_Scientist
name = Adriaan Fokker


caption = Adriaan Daniël Fokker
birth_date = birth date|1887|8|17|mf=y
birth_place = Buitenzorg, Dutch East Indies
death_date = death date and age|1972|9|24|1887|8|17|mf=y
death_place = Beekbergen, Netherlands
residence =
nationality =
field = Physicist
work_institution = University of Leiden
Teylers Museum
alma_mater = Delft University of Technology
University of Leiden
doctoral_advisor = Hendrik Lorentz
doctoral_students =
known_for = Fokker-Planck equation
Fokker periodicity block
prizes =
religion =
footnotes =

Adriaan Daniël Fokker (August 17, 1887 – September 24, 1972), was a Dutch physicist and musician.

Fokker was born in Buitenzorg, Dutch East Indies (now Bogor, Indonesia); he was a cousin of the aeronautical engineer Anthony Fokker. He studied mining engineering at the Delft University of Technology and physics at the University of Leiden with Hendrik Lorentz, where he earned his doctorate in 1913. He continued his studies with Albert Einstein, Ernest Rutherford and William Bragg. In his 1913 thesis, he derived the Fokker-Planck equation along with Max Planck. After his military service during World War I he returned to Leiden as Lorentz' and Ehrenfest's assistant.In 1928 Fokker succeeded Hendrik Lorentz as director of research at Teylers Museum in Haarlem.

Fokker began to study music theory during the Second World War, when the University of Leiden was closed; partly this was due to a desire to convince the Nazis he would be of no use to the war effort, and partly it was a response to reading the work of Christiaan Huygens on the 31 equal temperament. The year 1942 consequently marked a turning point in his life; after then he wrote many pieces in 31-equal, which are notable for using the 7th harmonic as a consonant interval (31-equal has a much better approximation of the 7th harmonic than the ubiquitous 12-equal). He also made notable contributions to music theory, such as the Fokker periodicity block.

He died at Beekbergen (near Apeldoorn).

Musical instruments

Fokker designed and had built a number of keyboard instruments capable of playing microtonal scales via a generalized keyboard. The best-known of these is his 31-tone equal-tempered organ, which was installed in Teyler's Museum in Haarlem in 1951. It is commonly called the Fokker organ.

ee also

* Fokker-Planck equation
* Fokker periodicity blocks
* Euler-Fokker genus

External links

* [http://www.xs4all.nl/~huygensf/english/fokker.html Short biography from the Huygens-Fokker Foundation]
* [http://www.teylersmuseum.nl/museum/collectionitems.jsp?view=%2Fxsl%2Fhtml&pageName=museum_collection_areas_item&lang=nl&id=3337 Fokker's Euler organ at the Teylers Museum]