Emil Wiechert (26.12.1861-19.03.1928) was a German physicist and geophysicist and a corresponding member of the Berlin Academy of Sciences (1911). He was born in Tilsit. In 1889 he received the degree of Doctor of Philosophy at the University of Königsberg, where he also worked. From 1897 he worked at the University of Göttingen (professor from 1898) and from 1899 he was director of the Institute of Geophysics at the university.
His research was in the fields of electrodynamics, the study of X-rays and cathode rays, geophysics and relativity. Independently of G. Stokes he gave the first theoretical account of the origin of X-rays (1896). He developed a method of determining the velocity of the particles of cathode rays directly and determined their specific charge (Wiechert's experiment). Independently of J. J. Thomson he discovered the electron. He studied the distribution of masses inside the Earth, the shape of the Earth, terrestrial magnetism, earthquakes and the propagation of seismic waves during earthquakes. He developed the theory of automatic seismographs and the theory of microseismic phenomena. In 1897 he established the existence of the Earth's core.
A corresponding member of the St Petersburg Academy of Sciences (1912).