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Damped Perturbations in the No-Boundary State.
J Diaz Dorronsoro1, J J Halliwell2, J B Hartle3
1Institute for Theoretical Physics, KU Leuven, 3001 Leuven, Belgium.
Physical Review Letters
|September 8, 2018
Summary
We precisely evaluated the no-boundary path integral in a specific cosmological model. This approach confirms predictions of the original semiclassical no-boundary proposal, showing large perturbations are damped.
Area of Science:
- Cosmology
- Quantum Gravity
- Theoretical Physics
Background:
- The no-boundary proposal offers a potential solution to the initial singularity problem in cosmology.
- Bianchi type IX minisuperspace models provide a framework for studying early universe dynamics.
Purpose of the Study:
- To exactly evaluate the no-boundary path integral in a Bianchi type IX minisuperspace with two scale factors.
- To investigate the role of nonlinear perturbations and regularity conditions in implementing the no-boundary proposal.
Main Methods:
- Exact evaluation of the no-boundary path integral.
- Implementation of the proposal via specific initial conditions for scale factors and their conjugate momenta.
- Inclusion of nonlinear backreaction from perturbations.
Main Results:
- The study successfully implemented the no-boundary proposal within the chosen minisuperspace model.
- Predictions of the original semiclassical no-boundary proposal were recovered.
- Large perturbations were found to be strongly damped, aligning with vacuum state wave function characteristics.
Conclusions:
- The no-boundary path integral can be exactly evaluated in complex cosmological models.
- The findings support the validity and predictive power of the no-boundary proposal for the early universe.
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