This new edition has been revised throughout to take into account developments in this field over the past fifteen years.

Preface to the second edition; Preface to the first edition; 1. Quantum physics; 2. Which way are the photons pointing?; 3. What can be hidden in a pair of photons?; 4. Wonderful Copenhagen?; 5. Is it all in the mind?; 6. Many worlds; 7. Is it a matter of size?; 8. Backwards and forwards; 9. Only one way forward?; 10. Can we be consistent?; 11. Illusion or reality?; Further reading.