Renormalizability, Fundamentality, and a Final Theory: The Role of UV-Completion in the Search for Quantum Gravity
Abstract
Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity (QG), where novel empirical data are lacking. One principle widely adopted in the search for QG is ultraviolet (UV) completion: the idea that a theory should (formally) hold up to all possible high energies. We argue—contra standard scientific practice—that UV-completion is poorly motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore the reasons for expecting, or desiring, a UV-complete theory, as well as analyse how UV-completion is used, and how it should be used, in various specific approaches to QG.
1. Introduction
1.1. Principles in theory development and evaluation
2. Primer on UV-Completion, Renormalizability, and All That
2.1. Renormalizability and UV-completion
2.2. Other forms of UV-completion
3. Why Should QG Be UV-Complete?
3.1. UV-completion and fundamentality
3.2. UV-completion and minimal length
4. UV-Completion in Different Approaches to QG
4.1. String theory
4.2. Asymptotic safety
4.3. Causal dynamical triangulation
4.4. Higher derivative approaches
4.5. Supergravity
4.6. Causal set theory
4.7. Canonical QG
4.8. Loop quantum gravity
4.9. Approaches based on alternative gravitational theories
4.10. Emergent gravity approaches
5. UV-Completion as a Guiding Principle in QG
6. Conclusion
