Contents -- The International Solvay Institutes -- In Memoriam Jacques Solvay (1920-2010) -- 25th Solvay Conference on Physics -- Opening Session -- Session 1: History and Reflections Chair: M. Henneaux -- John L. Heilbron: The First Solvay Council "A sort of private conference"a -- 1. Introduction -- 2. Soda and Energy -- 3. Positivism and Progress -- 4. International Connections -- 5. The Council of 1911 -- Works Cited -- References -- Murray Gell-Mann: From Solvay 1961 to Solvay 2011 -- Session 2: Foundations of Quantum Mechanics and Quantum Computation Chair: A. Aspect -- Rapporteur talk by A. Leggett: The Structure of a World Described by Quantum Mechanics -- References -- Prepared comments -- Discussion -- Prepared comments -- Discussion -- Rapporteur talk by J. Preskill: Quantum Entanglement and Quantum Computing -- 1. Introduction: Toward Quantum Supremacy -- 2. Quantum Entanglement and the Vastness of Hilbert Space -- 3. Separating Classical from Quantum -- 4. Easiness and Hardness -- 5. Local Hamiltonians -- 6. Quantum Error Correction -- 7. Scalable Quantum Computing -- 8. Topological Quantum Computing -- 9. Quantum Computing vs. Quantum Simulation -- 10. Conclusions and Questions -- Acknowledgments -- References -- Prepared comment -- Discussion -- Session 3: Control of Quantum Systems Chair: P. Zoller -- Rapporteur talk by I. Cirac: Quantum Computing and Simulation with Atoms and Photons -- 1. Introduction -- 2. Bottom-up Approach: Quantum Information -- 3. Top-down Approach: Quantum Simulations -- 4. Conclusions -- References -- Prepared comments -- Discussion -- Rapporteur talk by S. Girvin: Quantum Machines: Coherent Control of Mesoscopic Solid-State Systems -- 1. Introduction -- 2. Superconducting Qubits and Quantum Microwave Circuits -- 2.1. Quantum Limited Amplification, Measurement and Feedback.

2.2. Future Directions for Superconducting Qubits -- 3. Quantum Optomechanics -- 4. Summary -- Acknowledgments -- References -- Prepared comment -- Discussion -- Prepared comments -- Discussion -- Prepared comments -- Discussion -- Session 4: Quantum Condensed Matter Chair: B. Halperin -- Rapporteur talk by S. Sachdev: The Quantum Phases of Matter -- 1. Introduction -- 2. Gapped Quantum Matter -- 3. Conformal Quantum Matter -- 4. Compressible Quantum Matter -- 5. Connections to String Theory -- Acknowledgments -- References -- Discussion -- Prepared comments -- Discussion -- Prepared comments -- Discussion -- Prepared comments -- Discussion -- Session 5: Particles and Fields Chair: H. Georgi -- Rapporteur talk by F. Wilczek: A Long View of Particle Physics -- 1. Origins: Understanding Matter -- 2. Phenomena: New Questions and Surprising Answers -- 3. Questions That the Standard Model Begs -- 3.1. Questions from the Core -- 3.2. Loose Ends -- 3.3. Gravity -- 4. Approaches: "Modest" Improvements -- 4.1. Unification and Supersymmetry -- 4.2. Θ Problem and Axions -- 5. Experimental Frontiers -- 6. Cosmic Questions: Way Beyond the Standard Model -- 6.1. Kinematics and Dynamics -- 6.2. Dynamics and Initial Values -- 6.3. The Ubiquity of Spinors -- 6.4. Information as Foundation? -- Acknowledgments -- Discussion -- Prepared comments -- Discussion -- Prepared comments -- Discussion -- Session 6: Quantum Gravity and String Theory Chair: J. Polchinski -- Rapporteur talk by J. Maldacena: The Quantum Spacetime -- 1. Classical Spacetime Dynamics -- 2. Quantum Spacetime -- 3. Two Surprising Predictions -- 4. Quantization at Low Energies -- 5. UV Completion in Field Theory -- 6. UV Completion in Gravity? -- 7. Perturbative String Theory -- 8. Unification -- 9. Beyond Perturbation Theory? -- 10. Beyond Perturbation Theory -- 11. Non Perturbative Quantum Spacetimes.

12. Hyperbolic Space -- 13. Quantum Hyperbolic Space -- 14. Emergent Space -- 15. Black Holes in AdS -- 16. The Information Problem -- 17. The Information Problem -- 18. Lessons -- 19. String Theory and the Real World -- 20. Some Unsolved Problems -- Acknowledgments -- References -- Discussion -- Prepared comments -- Discussion -- Rapporteur talk by A. Guth: Quantum Fluctuations in Cosmology and How they Lead to a Multiverse -- 1. Introduction -- 2. Origin of Density Perturbations During the Inflationary Era -- 3. Evolution of the Density Perturbations Through the End of Inflation -- 4. Simplifying the Description -- 5. Deducing the Consequences, Comparing with Observation -- 6. Outstanding Questions About Density Perturbations -- 7. Fluctuations on Larger Scales: Eternal Inflation? -- References -- Prepared comments -- Discussion -- Session 7: General Discussion and Conclusions Chair: D. Gross -- Alain Aspect: Foundations of Quantum Mechanics and Quantum Computation -- Peter Zoller: Control of Quantum Systems -- Bertrand Halperin: Quantum Condensed Matter -- Howard Georgi: Particles and Fields -- Joseph Polchinski: Quantum Gravity and String Theory -- David Gross: Conclusions -- Closing Session Chair of the Conference David Gross -- Address by the Director of the International Solvay Institutes Marc Henneaux.