Problem of Time: Facets and Machian Strategy
arXiv:1306.5816 · doi:10.1111/nyas.12510
Abstract
The Problem of Time is that `time' in each of ordinary quantum theory and general relativity are mutually incompatible notions. This causes difficulties in trying to put these two theories together to form a theory of Quantum Gravity. The Problem of Time has 8 facets in canonical approaches. I clarify that all but one of these facets already occur at the classical level, and reconceptualize and re-name some of these facets as follows.The Frozen Formalism Problem becomes Temporal Relationalism, the Thin Sandwich Problem becomes Configurational Relationalism, via the notion of Best Matching. The Problem of Observables becomes the Problem of Beables, and the Functional Evolution Problem becomes the Constraint Closure Problem. I also outline how each of the Global and Multiple-Choice Problems of Time have their own plurality of facets. This article additionally contains a local resolution to the Problem of Time at the conceptual level and which is actually realizable for the relational triangle and minisuperspace models. This resolution is, moreover, Machian, and has three levels: classical, semiclassical and a combined semiclassical-histories-timeless records scheme. I end by delineating the current frontiers of this program toward resolution of the Problem of Time in the cases of full GR and of slightly inhomogeneous cosmology.
Longer version (more introductory explanations of problem of time's terminology, more references), as Accepted by `Annals of the New York Academy of Sciences'
References in corpus (18)
- Revisiting observables in generally covariant theories in the light of gauge fixing methods
- Beables/Observables in Classical and Quantum Gravity
- A First Class Constraint Generates Not a Gauge Transformation, But a Bad Physical Change: The Case of Electromagnetism
- The Quantum Measurement Problem: State of Play
- New interpretation of variational principles for gauge theories. I. Cyclic coordinate alternative to ADM split
- Classical Machian Resolution of the Spacetime Reconstruction Problem
- Can effects of quantum gravity be observed in the cosmic microwave background?
- Records Theory
- Machian Time Is To Be Abstracted From What Change?
- Consciousness and the Quantum
- Seminar on Records Theory
- On Background Independence
- Shape dynamics and Mach's principles: Gravity from conformal geometrodynamics
- Kendall's Shape Statistics as a Classical Realization of Barbour-type Timeless Records Theory approach to Quantum Gravity
- Minisuperspace model of Machian Resolution of Problem of Time. I. Isotropic Case
- Machian Classical and Semiclassical Emergent Time
- Quantum Cosmology will need to become a Numerical Subject
- Quantum Cosmological Relational Model of Shape and Scale in 1-d