ABSTRACT
The foundations of modern physics-in contrast to those of classical physics-were laid in the first half of the twentieth century. In theoretical physics, the decisive developments were the establishment of relativity and quantum physics, while experimental physics contributed a secure knowledge of the atomic structure of matter as well as the internal structure of atoms. Nearly all fields of modern science, from astrophysics to medical diagnostics, have been strongly influenced by the methods and concepts developed during this period.
