The Trans-Planckian Problem for Inflationary Cosmology Revisited
| dc.creator | Brandenberger, Robert | |
| dc.creator | Zhang, Xinmin | |
| dc.date | 2009-03-12 | |
| dc.date | 2009-03-15 | |
| dc.date.accessioned | 2026-07-07T12:52:09Z | |
| dc.date.available | 2026-07-07T12:52:09Z | |
| dc.description | We consider an inflationary universe model in which the phase of accelerated expansion was preceded by a non-singular bounce and a period of contraction which involves a phase of deceleration. We follow fluctuations which exit the Hubble radius in the radiation-dominated contracting phase as quantum vacuum fluctuations, re-enter the Hubble radius in the deflationary period and re-cross during the phase of inflationary expansion. Evolving the fluctuations using the general relativistic linear perturbation equations, we find that they exit the Hubble radius during inflation not with a scale-invariant spectrum, but with a highly red spectrum with index $n_s = -3$. We also show that the back-reaction of fluctuations limits the time interval of deflation. Our toy model demonstrates the importance for inflationary cosmology both of the trans-Planckian problem for cosmological perturbations and of back-reaction effects . Firstly, without understanding both Planck-scale physics and the phase which preceded inflation, it is a non-trivial assumption to take the perturbations to be in their local vacuum state when they exit the Hubble radius at late times. Secondly, the back-reaction effects of fluctuations can influence the background in an important way. | |
| dc.description | 8 pages, 2 figures, 2 references added | |
| dc.identifier | https://arxiv.org/abs/0903.2065 | |
| dc.identifier | http://arxiv.org/abs/0903.2065 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/223211 | |
| dc.subject | High Energy Physics - Theory | |
| dc.subject | Cosmology and Nongalactic Astrophysics | |
| dc.subject | General Relativity and Quantum Cosmology | |
| dc.subject | High Energy Physics - Phenomenology | |
| dc.title | The Trans-Planckian Problem for Inflationary Cosmology Revisited | |
| dc.type | text |