Historical and Experimental Foundations

Abstract

In spite of the multitude of phenomena described by classical mechanics and electrodynamics, a large group of natural phenomena remains unexplained by classical physics. It is possible to find examples in various branches of physics, for example, in the physics of atomic shells, which provide a foundation for the structure of electron shells of atoms and for the occurrence of discrete energy levels and of homopolar and Van der Waals bonding. The physics of macroscopic bodies (solids, liquids, and gases) is not able to give — on the basis of classical mechanics — consistent explanations for the structure and stability of condensed matter, for the energy of cohesion of solids, for electrical and thermal conductivity, specific heat of molecular gases and solids at low temperatures, and for phenomena such as superconductivity, ferromagnetism, superfluidity, quantum crystals, and neutron stars. Nuclear physics and elementary particle physics require absolutely new theoretical foundations in order to describe the structure of atomic nuclei, nuclear spectra, nuclear reactions (interaction of particles with nuclei, nuclear fission, and nuclear fusion), and the stability of nuclei, and similarly in order to make predictions concerning the size and structure of elementary particles, their mechanical and electromagnetic properties (mass, angular momentum (spin), charge, magnetic moment, isospin), and their interactions (scattering, decay, and production). Even in electrodynamics and optics there are effects which cannot be understood classically, for example, blackbody radiation and the photoelectric effect.