This article discusses density perturbations in inflationary models, offering a pedagogical description of how these perturbations are generated by quantum fluctuations in the early universe. A key feature of inflation is that that rapid expansion can stretch microscopic fluctuations to cosmological proportions. I discuss also another important conseqence of quantum fluctuations: the fact that almost all inflationary models become eternal, so that once inflation starts, it never stops.
- Pub Date:
- December 2013
- High Energy Physics - Theory;
- General Relativity and Quantum Cosmology
- 23 pages, 4 figures. Published in the Proceedings of the 25th Solvay Conference on Physics, "The Theory of the Quantum World," Brussels, 19--22 October 2011, edited by D. Gross, M. Henneaux, and A. Sevrin (World Scientific, 2013)