y did not completely satisfy him because it did not include electromagnetism. Beginning in the late 1920's, he tried to combine electromagnetic and gravitational phenomena in a single theory, called a unified field theory (see Electromagnetism; Gravitation). Einstein failed to establish a unified field theory, though he spent the last 25 years of his life working on it. Toward the end of his life, he remarked that it would be worthwhile to show that such a theory did not exist. He worried that if he neither produced a theory nor showed that one was impossible, perhaps no one ever would. Einstein in the United States. In 1933, Einstein left Germany because of the political unrest there. He gave up his German citizenship and moved to the United States, where he had been invited to become a member of the staff of the newly created Institute for Advanced Study in Princeton, New Jersey. Einstein accepted this position for life, and settled down in Princeton. He lived there until his death. In 1940, Einstein became an American citizen. He died on April 18, 1955. His personal life. Although he lived a quiet personal life, Einstein maintained a vital interest in human affairs. He was fond of classical music, and played the violin. He had a deep compassion for people who were politically or economically oppressed. He supported Zionism, and was offered the presidency of the state of Israel in 1952 (see Zionism). But he declined this honor, insisting that he was not fitted for such a position. Until the rise of Nazism in the 1930's, Einstein was an ardent pacifist. After the war, he became an equally determined supporter of world government. He insisted that peace among nations could be maintained in the atomic age only by bringing all people together under a system of world law. Although not well-to-do, Einstein was never concerned about money. Publishers and editors from all parts of the world offered him huge sums for an autobiography. He never...
