Martin Knudsen

Martin Hans Christian Knudsen ( * February 15, 1871 in Hasmark, † May 27, 1949 in Copenhagen) was a Danish physicist and oceanographer. He was the inventor of the radiometer and the associated calculation equation.

Knudsen was from 1912 to 1941 as the successor to Christian Christiansen professor at the University of Copenhagen. In the academic year 1927/28, he served as rector of the university.

In 1909 he became a member of the Royal Danish Academy of Sciences and served from 1917 to 1945 as its secretary. He was also appointed to numerous other academies, including of Göttingen, Berlin, Uppsala and Lund. In 1935 he was awarded the Alexander Agassiz Medal of the National Academy of Sciences.

After him were named: the Knudsen diffusion, the Knudsen gas, Knudsen flow, the Knudsen number and the Knudsen cell.