Oskar Benjamin Klein was a Swedish theoretical physicist now best remembered for the Klein-Gordon equation of relativistic quantum mechanics, the Kaluza-Klein theory, a unified field theory of gravita
Oskar Benjamin Klein (1894–1977).
Oskar Klein (first row, fifth right) at the commemoration meeting for Niels Bohr in Copenhagen in 1963
Yoshio Nishina was a Japanese physicist who was called "the founding father of modern physics research in Japan". He led the efforts of Japan to develop an atomic bomb during World War II.
Yoshio Nishina, Llewellyn Thomas and Friedrich Hund, in Copenhagen in 1926