The development of quantum mechanics in the 1920s was truly remarkable. There were several centers for physics research in those days; Cambridge, Göttingen, München, Berlin, Copenhagen, Zurich and Leyden. After 1928, Leipzig became one of the centers, because Heisenberg and Debye moved there. In this study, more than 128 European physicists appear with their teacher-student relationship. Many of these scientists were born between 1900 and 1908. Consequently, they were in their twenties in the late 1920s. Pauli called quantum mechanics \"Knaben Physik\"(Boy\'s Physics). After Hitler came to power, many European physicists emigrated to the United States and Great Britain. And many of them worked on the Manhattan project. After 1933, the physics center of the world moved from Europe to the United States. As of the year 2000, the United States recevied 71 Nobel Prize in physics but 21 for Germany and 19 for Great Britain.