May 6 – 10, 2024
US/Eastern timezone

The problems of time, normalizability and classical limit in canonical quantum gravity: A pilot-wave approach

May 9, 2024, 4:10 PM
15m
FAU FTL Room 131

FAU FTL Room 131

Quantum Foundations and QG Quantum Foundations and QG

Speaker

Indrajit Sen

Description

Abstract: Quantum gravitational theories generically suffer from issues such as the problems of normalizability, time and classical limit. Despite decades of technically sophisticated efforts, based on the orthodox quantum formulation, there remains a lack of consensus on these issues. In this talk, I will develop the viewpoint that these issues are not technical but conceptual, rooted in interpretational questions. In particular, I will show how the conceptual structure of pilot-wave theory (deBroglie-Bohm) provides a natural resolution of these issues in non-perturbative quantum gravity using recent work.

I will first illustrate some key ideas using non-normalizable solutions of the quantum harmonic oscillator in pilot-wave theory. I will then reformulate the discussion in a holomorphic representation, which will make clear the connection to non-perturbative quantum gravity in terms of Ashtekar variables. I will then apply the pilot-wave formulation to the interacting fermionic-gravitational system in (Phys. Rev. D 106.10 (2022): 106012). I will show how a real global time is obtained without semiclassical approximations by parameterizing the variation of the fermionic field. I will then discuss the classical limit in this approach using guidance equation for the Ashtekar connection. Lastly, I will show the existence of unitary states in minisuperspace.

Based on:
1. Sen, I. Physical interpretation of non-normalizable harmonic oscillator states and relaxation to pilot-wave equilibrium. Nat. Sci. Rep. 14, 669 (2024).
2. Sen, I., Alexander, S., & Dressel, J. A Realist Interpretation of Unitarity in Quantum Gravity. arXiv:2310.15157 (2023).

Author

Co-authors

Dr Justin Dressel (Chapman University) Prof. Stephon Alexander (Brown University)

Presentation materials