Fritz Zwicky, Swiss-American physicist and astronomer (died 1974)

Fritz Zwicky was a Swiss astronomer. He worked most of his life at the California Institute of Technology in the United States of America, where he made many important contributions in theoretical and observational astronomy. He was the first to propose supernovas as giant explosions at the end of a star's life, and neutron stars as the remnants left over after supernovas. In 1933, Zwicky was the first to use the virial theorem to postulate the existence of unseen dark matter, describing it as "dunkle Materie".