Completar frases Einstein in AmericaVersión en línea What did Einstein do in America after immigration from Germany? por Peter Feher 1 Adolf Princeton Manhattan D 1933 Franklin 1955 Project Institute Study bombs nuclear Roosevelt for 1940 Hitler Advanced He was visiting the United States when came to power in and did not go back to Germany , where he had been a professor at the Berlin Academy of Sciences . He settled in the U . S . , becoming an American citizen in . [ 7 ] On the eve of World War II , he endorsed a letter to President . alerting him to the potential developing of " extremely powerful of a new type " and recommending that the U . S . begin similar research . This eventually led to what would become the . Einstein was in support of defending the Allied forces , but largely denounced using the new discovery of nuclear fission as a weapon . Later , with the British philosopher Bertrand Russell , Einstein signed the Russell ? Einstein Manifesto , which highlighted the danger of weapons . Einstein was affiliated with the in , New Jersey , until his death in .