2018/12/31 by Alexander Vilenkin, Masaki Yamada · 49 citations
Physics and Astronomy · #Amplitude #Black Holes and Theoretical Physics #Cosmology #Cosmology and Gravitation Theories #Dark energy #De Sitter universe #Mathematical physics #Metric expansion of space #Minisuperspace #Particle physics theoretical and experimental studies #Path integral formulation #Physics #Quantum #Quantum cosmology #Quantum electrodynamics #Quantum field theory #Quantum gravity #Quantum mechanics #Quantum tunnelling #Scalar field #Scale factor (cosmology) #Universe #Vacuum energy #Wave function #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.99.066010
published in Physical review. D/Physical review. D. 99(6) (American Physical Society) · 9 pages; v2: Path integral analysis is extended to a massive scalar field
arxiv created 2019/02/20 · openalex publication_date 2019/03/26 · arxiv updated 2019/04/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The tunneling wave function of the Universe is calculated exactly for a de Sitter minisuperspace model with a massless conformally coupled scalar field, both by solving the Wheeler-DeWitt equation and by evaluating the Lorentzian path integral. The same wave function is found in both approaches. The backreaction of quantum field fluctuations on the scale factor amounts to a constant renormalization of the vacuum energy density. This is in contrast to the recent suggestion of Feldbrugge et al. that the backreaction should diverge when the scale factor gets small, a\ensuremath→0. Similar results are found for a massive scalar field in the limit of a large mass. We also verified that the tunneling wave function can be expressed as a transition amplitude from a universe of vanishing size with the scalar field in the state of Euclidean vacuum, as was suggested in our earlier work.