'Do not be put off by its length … this is one of those rare volumes where quantity is matched by quality … this is a remarkable volume.' Nature

• Foreword John A. Wheeler; Editor's preface John D. Barrow, Paul Davies and Charles Harper, Jr.; Preface Freeman J. Dyson; Part I. An Overview of the Contributions of John Archibald Wheeler: 1. John Archibald Wheeler and the clash of ideas Paul C. W. Davies; Part II. An Historian's Tribute to John Archibald Wheeler and Scientific Speculation Through the Ages: 2. The heritage of Heraclitus: John Archibald Wheeler and the itch to speculate Jaroslav Pelikan; Part III. Quantum Reality - Theory: 3. Why is nature described by quantum theory? Lucien Hardy; 4. Thought experiments in honor of John Wheeler Freeman J. Dyson; 5. It from qubit David Deutsch; 6. The wave function: it or bit? H. Dieter Zeh; 7. Quantum Darwinism and envariance Wojciech H. Zurek; 8. Using qubits to learn about it Juan Pablo Paz; 9. Quantum gravity as an ordinary gauge theory Juan M. Maldacena; 10. The Everett interpretation of quantum mechanics Bryce S. DeWitt; Part IV. Quantum Reality - Experiment: 11. Why the quantum? It from bit? A participatory universe? Three far-reaching, visionary questions from John Archibald Wheeler and how they inspired a quantum experimentalist Anton Zeilinger; 12. Speakable and unspeakable, past and future Aephraim M. Steinberg; 13. Conceptual tensions between quantum mechanics and general relativity: are there experimental consequences? Raymond Y. Chiao; 14. Breeding non-local Schrödinger cats: a thought experiment to explore the quantum classical boundary Serge Haroche; 15. Quantum erasing the nature of reality - or, perhaps, the reality of nature? Paul G. Kwiat and Berthold-Georg Englert; 16. Quantum feedback and the quantum-classical transition Hideo Mabuchi; 17. What quantum computers may tell us about quantum mechanics Christopher R. Monroe; Part V. Big Questions in Cosmology: 18. Cosmic inflation and the arrow of time Andreas Albrecht; 19. Cosmology and immutability John D. Barrow; 20. Quantum cosmology, inflation, and the anthropic principle Andrei Linde; 21. Parallel universes Max Tegmark; 22. Quantum theories of gravity: results and prospects Lee Smolin; 23. A genuinely evolving universe Joao Magueijo; 24. Planck-scale models of the universe Fotini G. Markopoulou; 25. Implications of additional spatial dimensions to questions in cosmology Lisa Randall; Part VI. Emergence, Life, and Related Topics: 26. Emergence: us from it Philip D. Clayton; 27. True complexity and its associated ontology George F. R. Ellis; 28. The three origins: cosmos, life and mind Marcelo Gleiser; 29. Autonomous agents Stuart A. Kauffman; 30. To see a world in a grain of sand Shou-Cheng Zhang; Appendix A. Science and ultimate reality program committees; Appendix B. Young researchers competition in honor of John Archibald Wheeler for physics graduate students, post-doctoral fellows, and young faculty.