Euan Squires brings the best selling ^IMystery of the Quantum World up to date with the inclusion of a new chapter which introduces the reader to the most important of the recent developments in quantum theory. His authoritative selection of topics ensures that interested readers extend their knowledge of quantum theory, and that those readers with no previous knowledge acquire an insight into this fascinating world. Some of the material now included is at a more advanced level, and will be certain to stimulate those readers already familiar with the first edition of the book.Quantum mechanics stands as one of the most remarkable achievements of the 20th century - at once a new and startling insight into the nature of matter and a spectacularly successful predicitve theory. However, while the predictive ability of the quantum theory has been rigorously tested time and again, so that it now satisfies any criterion of reliability as a tool of scientific inquiry, surprisingly fundamental difficulties remain with its interpretation.This book introduces the general reader to the philosophical issues raised by the success of the quantum theory and lucidly outlines the different points of view adopted by various schools of physicists striving to understand the meaning underlying the theories they use every day. The reader is encouraged to see how this most successful of physical theories is relevant to issues outside physics.