Unitarily inequivalent quantum cosmological bouncing models

Abstract

By quantising the background as well as the perturbations in a simple one fluid model, we show that there exists an ambiguity in the choice of relevant variables, potentially leading to incompatible observational physical predictions. In a classical or quantum inflationary background, the exact same canonical transformations lead to unique predictions, so the ambiguity we put forward demands a semiclassical background with a sufficiently strong departure from classical evolution. The latter condition happens to be satisfied in bouncing scenarios, which may thus be having predictability issues. Inflationary models could evade such a problem because of the monotonic behavior of their scale factor; they do, however, initiate from a singular state which bouncing scenarios aim at solving.

13 pages, 7 figures

References in corpus (5)

• A Critical Review of Classical Bouncing Cosmologies
• Inflationary Perturbations: the Cosmological Schwinger Effect
• Unitarity of quantum-gravitational corrections to primordial fluctuations in the Born-Oppenheimer approach
• Quantum empty Bianchi I spacetime with internal time
• Dynamics of primordial fields in quantum cosmological spacetimes