in spring of 1914, he moved back to germany, and became ordinary member of the prussian academy and director of a newly established institute for physics of the kaiser-wilhelm-gesellschaft. he lived in berlin and finished the general theory of relativity in november 1915. in the weimar republic, he was politically active for socialism and zionism. in 1922, he received the nobel prize for physics for his explanation of the photoelectric effect in 1905. he then tried to formulate a general field theory uniting gravitation and electromagnetism, without success. he had reservations about the quantum mechanics invented by heisenberg (1925) and schrödinger (1926). in spring of 1933, einstein and elsa were traveling in the usa when the nazi party came to power. the nazis were violently antisemitic. they einstein's relativity theory "jewish physics," and some german physicists started polemics against his theories. others, like planck and heisenberg, defended einstein.