This book is based on an in-depth conversation between Howard Burton and Physics Nobel Laureate Tony Leggett. The basis of this conversation is Tony Leggett’s book The Problems of Physics and further explores the insightful plain-speaking itemization that he developed of the physics landscape according to four basic categories—the very small (particle physics), the very large (cosmology), the very complex (condensed matter physics) and the very unclear (foundations of quantum theory)—while providing a thoughtful follow-up analysis from a contemporary perspective to assess how much progress we’ve made and which mysteries remain or have come on the scene since the book was published.This carefully-edited book includes an introduction, The Gentleman Laureate, and questions for discussion at the end of each chapter:I. Back to the Future - Setting the StageII. The Very Small - Much the sameIII. The Very Large - CosmologyIV. A Glassy Digression - The perils of affirming the consequentV. The Very Complex - Condensed matter physics meets quantum informationVI. Understanding - What it actually meansVII. Different Regimes - Nature’s ScalesVIII. Schrödinger’s Cat - Different domains?IX. The Slings and Arrows of Time - Irreversible?X. The Anthropic Principle - Better left unsaid?XI. The Future of Physics - From Louis Armstrong to topological quantum computingAbout Ideas Roadshow Conversations Series: This book is part of a series of 100 Ideas Roadshow Conversations. Presented in an accessible, conversational format, Ideas Roadshow books not only explore frontline academic research featuring world-leading researchers, including 3 Nobel Laureates, but also reveal the inspirations and personal journeys behind the research.