Date:
21. September 2018 - 11:30
Speaker:
Sebastien Zell (Max-Planck-Institut für Physik & Ludwig-Maximilians-Universität, Munich, Germany)
The quantum break-time is the timescale after which a system can no longer be described classically. In this talk, I will first use a simple example of a scalar field to show that the quantum break-time generically depends on three universal parameters [1, 2]. Subsequently, I will discuss quantum breaking for de Sitter [1]. We show that the spacetime itself can be understood as expectation value of an underlying quantum state, which is able to reproduce all known semiclassical properties. In this picture, backreaction on the quantum state of de Sitter leads to a finite quantum break-time, after which the description in terms of a classical metric ceases to be valid. For inflation, this results in a model-independent lower bound on the gradient of the potential.
Based on:
[1] Gia Dvali, Cesar Gomez and S. Z., Quantum Break-Time of de Sitter, J. Cosmol. Astropart. Phys. 2017 no. 06, 028, arXiv:1701.08776.
[2] Gia Dvali and S. Z., Classicality and Quantum Break-Time for Cosmic Axions, J. Cosmol. Astropart. Phys. 2018 no. 07, 064, arXiv:1710.00835.