Introduction

Abstract

Atomic and quantum physics, which are introduced in this book, are essentially products of the first third of this century. The division of classical physics into branches such as mechanics, acoustics, thermodynamics, electricity, and optics had to be enlarged when — as a consequence of the increasing knowledge of the structure of matter — atoms and quanta became the objects of physical research. Thus, in the twentieth century, classical physics has been complemented by atomic physics and the physics of light or energy quanta. The goal of atomic physics is an understanding of the structure of atoms and their interactions with one another and with electric and magnetic fields. Atoms are made up of positively charged nuclei and negatively charged electrons. The electromagnetic forces through which these particles interact are well known in classical physics.