2014/03/26 by Martin Bojowald, David Simpson
Physics and Astronomy · #Big Bounce #Black Holes and Theoretical Physics #Classical mechanics #Cosmology #Cosmology and Gravitation Theories #Curvature #De Sitter universe #Equations of motion #Hamiltonian (control theory) #Hamiltonian constraint #Initial singularity #Loop quantum cosmology #Loop quantum gravity #Massless particle #Mathematical physics #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum cosmology #Quantum gravity #Quantum mechanics #Scalar field #Semiclassical physics #Singularity #Theoretical physics #Universe #gr-qc #hep-th
paper · pdf · doi:10.1088/0264-9381/31/18/185016
published as Class. Quantum Grav. 31 (2014) 185016 · 27 pages, 3 figures
arxiv created 2014/03/26 · openalex publication_date 2014/09/05 · arxiv updated 2014/09/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Quantum cosmology implies corrections to the classical equations of motion which may lead to significant departures from the classical trajectory, especially at high curvature near the big-bang singularity. Corrections could in principle be significant even in certain low-curvature regimes, provided that they add up during long cosmic evolution. The analysis of such terms is therefore an important problem to make sure that the theory shows acceptable semiclassical behavior. This paper presents a general search for terms of this type as corrections in effective equations for a k=0 isotropic quantum cosmological model with a free, massless scalar field. Specifically, the question of whether such models can show a collapse by quantum effects is studied, and it turns out that factor-ordering choices in the Hamiltonian constraint are especially relevant in this regard. A systematic analysis of factor-ordering ambiguities in effective equations is therefore developed.