Philosophy Beyond Spacetime: Implications from Quantum Gravity

✍ Scribed by Christian Wüthrich (editor), Baptiste Le Bihan (editor), Nick Huggett (editor)

• Publisher: Oxford University Press
• Year: 2021
• Tongue: English
• Leaves: 305
• Category: Library

✦ Synopsis

Quantum gravity seeks a unified theory in which quantum matter is dynamically related to generally relativistic spacetime. Although a continuing work in progress, research programmes in the field such as string theory, loop quantum gravity, and causal set theory make it clear that a successful theory of quantum gravity will raise important challenges to our conceptions of space, time, and matter-perhaps abolishing them altogether as fundamental entities. But just as important, there is good reason to think that some of the problems in finding a theory of quantum gravity are themselves conceptual, in need of philosophical analysis.

Philosophy Beyond Spacetime: Implications from Quantum Gravity assembles original papers from philosophers (and one physicist), establishing a definitive statement of the current state of play, on which future research into this area can build. Aiming to expand knowledge and understanding of the philosophy of quantum gravity, it emphasizes how debates in metaphysics--regarding emergence, composition, or grounding for example--shed light on the conceptual questions of quantum gravity. And conversely, how quantum theories of space and time call into question philosophical views grounded in classical spacetime. Furthermore, the philosophy of quantum gravity raises methodological questions, for instance concerning the relation between physics and metaphysics. The essays have been chosen to demonstrate to a wide range of philosophers the significance of the subject, as well as making novel contributions to it.

✦ Table of Contents

Cover
Philosophy Beyond Spacetime: Implications from Quantum Gravity
Copright
Contents
Acknowledgements
List of Figures
List of Contributors
1:
Introduction
Abstract
1.1 Searching for Spacetime
1.2 The Metaphysics of Spacetime Emergence
1.3 Methodological Issues
References
2: Levels of Spacetime Emergence
in Quantum Gravity
Abstract
2.1 Introduction
2.2 Level 0: Classical and Quantum (Modified)
General Relativity
2.3 Level 1: New Degrees of Freedom—Geometry
and Spacetime as Emergent Entities
2.4 Level 2: Non-Geometric Phases—The Atoms of Space(time)
Are Really Not Spatiotemporal
2.5 Level 3: Geometrogenesis—The Emergence of Spacetime
via a Phase Transition as a Physical Process
2.6 An Analogy: From the Atoms to the Hydrodynamics
of (Super)fluids
2.7 Conclusions
References
3: On Dualities and Equivalences between
Physical Theories
Abstract
3.1 Introduction
3.1.1 Prospectus: The Remark and the Implication
3.1.2 Relations to Other Work
3.2 A Schema for Duality
3.3 Interpreting Physical Theories
3.3.1 Intensional Semantics
3.3.2 Subject-Matters: (Contr) and (Diff)
3.3.3 Credo
3.4 Examples in Classical and Quantum Physics
3.4.1 (1): Newtonian Mechanics with Different Standards of Rest
3.4.2 (2): Position-Momentum Duality in
Elementary Quantum Mechanics
3.5 An Implication about Theoretical Equivalence
3.5.1 A Warning about Jargon
3.5.2 The Implication: For Logical Equivalence
3.5.3 The Implication: For Weaker Notions of Equivalence
3.6 Envoi
References
4: From Quantum Entanglement to
Spatiotemporal Distance
Abstract
4.1 Introduction
4.2 Constructing the Metric from Entanglement Entropy
in the AdS/CFT Context
4.3 The Entanglement Entropy-Distance Link Beyond
AdS/CFT: Area Laws
4.4 From Correspondence to Emergence?
4.5 Gluing with Entanglement?
4.6 Back to Ryu–Takayanagi and Black Hole Thermodynamics
4.7 No Support for Emergence
4.8 Conclusion
References
5: Taking Up Superspace:
The Spacetime Setting for Supersymmetric Field Theory
Abstract
5.1 Introduction
5.2 Arriving at Spacetime Structure
5.2.1 Earman’s Principle
5.2.1.1 Earman on Absolute Objects
5.2.1.2 Spacetime Symmetries from External Symmetries
5.2.2 The Geometrical Approach
5.2.3 The Dynamical Approach
5.2.4 Spacetime Functionalism
5.2.5 How to Do Things with Spacetime
5.3 Supersymmetric Field Theory and Superspace
5.3.1 What Is Supersymmetry?
5.3.2 Supernumbers and Superspace
5.3.2.1 Supernumbers
5.3.2.2 Superspace
5.4 On the Spatiotemporality of Superspace
5.4.1 The Three Approaches to Spacetime
5.4.1.1 Earman’s Principle
5.4.1.2 The Dynamical Approach
5.4.1.3 Spacetime Functionalism
5.4.2 Chronometry in Superspace
5.4.2.1 What Is It to Be Spatial?
5.5 Conclusion
References
6:
Thinking about Spacetime
Abstract
6.1 Introduction
6.1.1 The Problem of Empirical Coherence
6.1.2 Realist and Antirealist Solutions
6.2 Spacetime Antirealism
6.2.1 Transparent vs. Non-Transparent Concepts
6.2.2 Phenomenal Realizer Functionalism
6.2.3 Theoretical Realizer Functionalism
6.3 Spacetime Realism
6.3.1 Role Spacetime Functionalism
6.3.2 Grounded or Caused?
6.4 Conclusion
References
7:
Finding Space in a Non-Spatial World
Abstract
7.1 The Two Images
7.2 Primitivism and Functionalism about Color
7.3 Primitivism and Functionalism about Space
7.4 Spatial Functionalism and Explanatory Gaps
7.5 What Is the Space Role?
7.6 Virtual Reality and Cartesian Skepticism
7.7 Spatial Functionalism and Spacetime Functionalism
7.8 The Emergence of Spacetime
References
8:
Explanations of and in Time
Abstract
8.1 Introduction
8.2 Demarcation Criteria
8.3 The Mediation Criterion in Loop Quantum Gravity
8.4 Spacetime Functionalism
8.5 Grounding the Spatiotemporal in the Many-Instant Landscape
8.6 Conclusion
References
9: Do You See Space? How to Recover the Visible and Tangible Reality of Space
(Without Space)
Abstract
9.1 Introduction
9.1.1 Quantum Gravity
9.2 Part 1
9.2.1 Mach on the Construction of Phenomenological Space
9.2.2 Coordination
9.2.3 Phenomenology
9.2.4 The Upshot
9.3 Part 2
9.3.1 Maudlin’s Warning: Stay Away from the Observer
9.3.2 Putting the Observer Back In
9.4 Conclusion
References
10: The Measurement Problem for Emergent
Spacetime in Loop Quantum Gravity
Abstract
10.1 Introduction
10.2 Rovelli’s Relational Quantum Mechanics
10.2.1 What Is a State?
10.2.2 Systems, Interactions, and Processes: Quantum Mechanics
10.2.3 Systems, Interactions, and Processes: Quantum Field Theory
10.3 Loop Quantum Gravity
10.4 The Measurement Problem
10.5 Relational Loop Quantum Gravity
10.6 The Measurement Problem in Relational Loop
Quantum Gravity
10.7 Morals of the Story
References
11: The ‘Philosopher’s Stone’:
Physics, Metaphysics, and the Value of a Final Theory
Abstract
11.1 Introduction
11.2 What Is ‘Naturalistic Fundamentality Metaphysics’?
11.3 Theory Change in Metaphysics
11.4 The Problem of Theory Change in Science
11.5 The Problem of Progress in Metaphysics
11.6 Conclusion
References
12: Problems with the Cosmological
Constant Problem
Abstract
12.1 Introduction: What’s the Problem?
12.1.1 Multiple CCPs
12.2 The Steps Required to Accept a CCP
12.2.1 Is the Vacuum Energy Real?
12.2.2 How Much Energy Is in the Vacuum?
12.2.3 How Should the Vacuum Energy Enter
Einstein’s Field Equations?
12.2.4 Does Anything Else Act Like Λ?
12.3 Plausibility of Attempted Solutions
12.3.1 ’t Hooft Naturalness
12.3.2 Violate Equivalence Principle
12.3.3 Statistical Solutions
12.4 Conclusions
References
Index