2015/04/20 by S. P. de Alwis, de Alwis, S. P.
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th) #Relativity and Gravitational Theory
paper · pdf · doi:10.48550/arxiv.1504.05211
openalex publication_date 2015/04/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The theory of cosmological fluctuations assumes that the pre-inflationary state of the universe was the quantum vacuum of a scalar field(s) coupled to gravity. The observed cosmic microwave background fluctuations are then interpreted as quantum fluctuations. Here we consider alternate interpretations of the classic calculations of scalar and tensor power spectra by replacing the Bunch-Davies quantum vacuum with a classical statistical distribution, which may have been the consequence of a pre-inflationary process of decoherence as in the quantum cosmology literature. Mathematically they are essentially identical calculations. However if one takes the latter interpretation then one might replace the Planck length by for instance the fundamental length scale of string theory. In particular this changes the relation between the scale of inflation and the scalar power spectrum but leaves the parameter(s) characterizing the bi-spectrum unchanged at leading order. Differences will occur however at higher order in the loop expansion. We also discuss the relation to theories with low sound speed and/or a period of dissipation during inflation (warm inflation).