Introduction

Abstract

Quantum theory is perhaps the theory with the greatest predictive and explanatory success in all the history of physics. To name just a few of its countless achievements: it explains the stability of the stable atoms and nuclei and predicts the decay rates of the unstable ones; it accounts for the different manifestations of matter such as gaseous, liquid and solid, metallic and insulating, magnetic, superfluid and superconducting; it forms the basis of our chemical knowledge; and it provides the conceptual framework of all contemporary models for the fundamental constituents of matter. In addition, some of its predictions, for example that of the ‘electron spin g-factor’ in quantum electrodynamics, are perhaps the most accurate ones ever made in the history of science. Some of its predictions concern matter at extremely high energy and interactions between bits of matter at extremely short distances; others are about matter at extremely low energy and close to the zero of absolute temperature. As far as its technological applications are concerned, its insights are at the heart of the overwhelming technological progress in information technology in the past few decades, it explains why nuclear fission and fusion work as they do, and it forms the basis of the rapidly growing field of nanotechnology.