2020/11/30 by Beatriz Elizaga Navascués, Guillermo A. Mena Marugán · 46 citations
Physics and Astronomy · #Advanced Mathematical Theories and Applications #Cosmology #Cosmology and Gravitation Theories #Gravitation #Loop quantum cosmology #Loop quantum gravity #Noncommutative and Quantum Gravity Theories #Quantization (signal processing) #Quantum #Quantum cosmology #Quantum gravity #gr-qc
paper · pdf · doi:10.3389/fspas.2021.624824
published in Frontiers in Astronomy and Space Sciences 8 (Frontiers Media) · 39 pages
openalex created_date 2020/11/23 · openalex publication_date 2021/06/03 · arxiv created 2021/09/10 · arxiv updated 2021/09/13 · openalex updated_date 2026/08/05
Loop Quantum Gravity is a nonperturbative and background independent program for the quantization of General Relativity. Its underlying formalism has been applied successfully to the study of cosmological spacetimes, both to test the principles and techniques of the theory and to discuss its physical consequences. These applications have opened a new area of research known as Loop Quantum Cosmology. The hybrid approach addresses the quantization of cosmological systems that include fields. This proposal combines the description of a finite number of degrees of freedom using Loop Quantum Cosmology, typically corresponding to a homogeneous background, and a Fock quantization of the field content of the model. In this review we first present a summary of the foundations of homogeneous Loop Quantum Cosmology and we then revisit the hybrid quantization approach, applying it to the study of Gowdy spacetimes with linearly polarized gravitational waves on toroidal spatial sections, and to the analysis of cosmological perturbations in preinflationary and inflationary stages of the Universe. The main challenge is to extract predictions about quantum geometry effects that eventually might be confronted with cosmological observations. This is the first extensive review of the hybrid approach in the literature on Loop Quantum Cosmology.