Adriaan Fokker

Adriaan Daniël Fokker (Dutch pronunciation: [ˈaːdriaːn ˈdaːniɛl ˈfɔkər]; 17 August 1887 – 24 September 1972) was a Dutch physicist and musician. He was the inventor of the Fokker organ, a 31-tone equal-tempered organ.

Life and work

Adriaan Daniël Fokker was born on 17 August 1887 in Buitenzorg, Dutch East Indies (now Bogor, Indonesia). He was a cousin of the aeronautical engineer Anthony Fokker.

Fokker 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 made several contributions to special relativity, and some less well-known contributions to general relativity, particularly in the area of geodetic precession, the phenomena of precession of a freely falling gyroscope in a gravitational field.