2008/03/31 by Tomi Koivisto · 162 citations
Mathematics · Physics and Astronomy · #Acceleration #Black Holes and Theoretical Physics #Classical mechanics #Cosmology #Cosmology and Gravitation Theories #De Sitter universe #Einstein #Initial singularity #Loop quantum cosmology #Mathematical analysis #Mathematical physics #Mathematics #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum cosmology #Quantum gravity #Quantum mechanics #Scalar (mathematics) #Singularity #Theoretical physics #Universe #astro-ph #gr-qc
paper · pdf · doi:10.1103/physrevd.77.123513
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 77(12) (American Physical Society) · 14 pages, 3 figures. V2: minor corrections
arxiv created 2008/06/06 · openalex publication_date 2008/06/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Nonlocal quantum corrections to gravity have been recently proposed as a possible solution to the cosmological fine-tuning problems. We study the dynamics of a class of nonlocal actions defined by the function of the inverse d'Alembertian of the Ricci scalar. Power-law and exponential functions are considered in detail, but we also show a method to reconstruct a nonlocal correction that generates a given background expansion. We find that even the simplest terms can, while involving only Planck scale constants, drive the late time acceleration without changing early cosmology. This leads to a sudden future singularity which, however, may be avoided by regularizing the d'Alembertian. We also consider the Einstein frame versions of these models.