How this book came about

This book is the outcome of a long cherished ambition to write a follow-up to my book Theoretical Concepts in Physics (TCP2) (Longair, 2003). In that book, I took the story of the development of theoretical concepts in physics up to the discovery of quanta and the acceptance by the physics community that quanta and quantisation are essential features of the new physics of the early twentieth century. There was neither space nor scope to take that story further – it was just too complicated and would have required more advanced mathematics than I wished to include in that volume.

This book is my attempt to do for quantum mechanics what I did for classical physics and relativity in TCP2. The objective is to try to reconstruct as closely as possible the way in which quantum mechanics was created out of a mass of diverse experimental data and mathematical analyses through the period from about 1900 to 1930. In my view, quantisation and quanta are the greatest discoveries in the physics of the twentieth century. The phenomena of quantum mechanics have no direct impact upon our consciousness which to all intents and purposes is a world dominated by classical physics. But quantum mechanics underlies all the phenomena of matter and radiation and is the basis of essentially all aspects of civilisation in the twenty-first century.