Wolfgang Gaede (25.05.1878-24.06.1945) was a German physicist. He was born in Bremerhaven (now Germany). In 1900 he received the degree of Doctor of Philosophy at the University of Freiburg, where he was an assistant until 1907; in 1907—18 he worked at the university's Institute of Technical Physics, in 1919 —34 he was professor at the Higher Technical School in Karlsruhe, and later he worked in private laboratories in Karlsruhe and Munich.
His research was in the field of technical physics and vacuum technology. In 1905 he constructed the rotary mercury pump, which was long used in industry for evacuating lighting lamps and X-ray tubes, and a little later the rotary oil pump, used to produce the preliminary vacuum in the rotary mercury pump. In 1913 he invented the molecular pump, which made it possible to obtain considerably lower pressures at much higher pumping speeds and so set a new direction in the design of vacuum pumps, and in 1915 the diffusion pump, which brought still greater progress in vacuum technology. Gaede's mercury vapour pumps gave pressures of about 10-4 mm Hg. He studied the laws of the flow of gases at low pressures. In 1934 he constructed a vacuum gauge for measuring pressures down to 10-7 mm Hg.