When he was visiting the United States, Adolf Hitler came to power in 1933, so he did not return to Germany, where he was a professor at the Berlin Academy of Sciences. He settled in the United States and officially became a US citizen in 1940. All i need today is a little bit of camping and a whole lot of Jesus shirt. At the time of the Second World War, he signed a letter warning President Franklin D. Roosevelt that the Nazis might be studying the development of a “very dangerous new bomb” and promotion. The US report should have similar studies. Indeed, it led to the birth of the Manhattan Project later. Einstein supported the Allied forces, but was generally against the use of new innovations in nuclear fission. Later, along with British philosopher Bertrand Russell, he signed the Russell – Einstein Declaration, highlighting the danger of nuclear weapons. Einstein worked at the Institute for Advanced Studies in Princeton, New Jersey until his death in 1955.