# The exponential expansion of the universe from unrenormalised energy momentum tensor

### APA

Unruh, B. (2017). The exponential expansion of the universe from unrenormalised energy momentum tensor. Perimeter Institute. https://pirsa.org/17080016

### MLA

Unruh, Bill. The exponential expansion of the universe from unrenormalised energy momentum tensor. Perimeter Institute, Aug. 03, 2017, https://pirsa.org/17080016

### BibTex

@misc{ pirsa_PIRSA:17080016, doi = {10.48660/17080016}, url = {https://pirsa.org/17080016}, author = {Unruh, Bill}, keywords = {Cosmology}, language = {en}, title = {The exponential expansion of the universe from unrenormalised energy momentum tensor}, publisher = {Perimeter Institute}, year = {2017}, month = {aug}, note = {PIRSA:17080016 see, \url{https://pirsa.org}} }

Bill Unruh University of British Columbia

## Abstract

The unrenormalised energy momentum tensor is both huge and fluctuating from point to point. Taking this seriously we (Qingdi Wang, Zhen Zhu, and myself) argue that the slow exponential expansion of the universe (on time scales of 10^10 years) comes from a very weak parametric resonance induced by the fluctuating energy mementum tensor on the rapidly fluctuating scale factor (on time scales much shorter than the Planck scale). We see only the slow exponential growth because we avarage over the scale factor squared.