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 Schrö

dinger 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 Kalmara

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.