I was born at Ulm, in Württemberg, Germany, on March 14, 1879. Six weeks later, my family and I moved to Munich and I began going to school there at the Luitpold Gymnasium. Later, we moved to Italy and I continued my education at Aarau, Switzerland and in 1896 I entered the Swiss Federal Polytechnic School in Zurich to be trained as a teacher in physics and mathematics. In 1901, the year I gained my diploma, I acquired Swiss citizenship and, as I was unable to find a teaching post, I accepted a position as technical assistant in the Swiss Patent Office. In 1905 I obtained my doctor's degree.During my stay at the Patent Office, and in my spare time, I produced much of my work and in 1908 I was appointed Privatdozent in Berne. In 1909 I became Professor Extraordinary at Zurich, in 1911 Professor of Theoretical Physics at Prague, returning to Zurich in the following year to fill a similar post. In 1914 I was appointed Director of the Kaiser Wilhelm Physical Institute and Professor in the University of Berlin. I became a German citizen in 1914 and remained in Berlin until 1933 when I renounced my citizenship for political reasons and emigrated to America to take the position of Professor of Theoretical Physics at Princeton. I became a United States citizen in 1940 and retired from my post in 1945.
