Niels Bohr

Bohr trained under J. J. Thomson and Ernest Rutherford, then in 1913 combined Rutherford's nuclear atom with quantum ideas to propose that electrons occupy fixed energy orbits and emit or absorb energy only in discrete jumps, explaining the hydrogen spectrum and founding modern atomic theory. He led the Copenhagen institute that shaped quantum mechanics for a generation. His mother, Ellen Adler, came from a prominent Danish Jewish family, and in 1943 his maternal Jewish ancestry forced him to flee occupied Denmark to Sweden and then Britain.