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Loop quantum cosmology and singularities. [PDF]
Sci Rep, 2017 Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of so-called loop quantum cosmology which concerns symmetry-reduced models of quantum gravity. In this paper, the
Struyve W.
europepmc +4 more sources
Living Rev Relativ, 2008 Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a ...
Bojowald M.
europepmc +14 more sources
Hybrid Loop Quantum Cosmology: An Overview [PDF]
Frontiers in Astronomy and Space Sciences, 2021 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 ...
Beatriz Elizaga Navascués +1 more
doaj +2 more sources
Some conceptual issues in loop quantum cosmology [PDF]
, 2016 Loop quantum gravity is a mature theory. To proceed to explicit calculations in cosmology, it is necessary to make assumptions and simplifications based on the symmetries of the cosmological setting. Symmetry reduction is especially critical when dealing with cosmological perturbations.
A. Barrau, B. Bolliet
arxiv +3 more sources
Quantum Reduced Loop Gravity and the foundation of Loop Quantum Cosmology [PDF]
, 2016 Quantum Reduced Loop Gravity is a promising framework for linking Loop Quantum Gravity and the effective semiclassical dynamics of Loop Quantum Cosmology. We review its basic achievements and its main perspectives, outlining how it provides a quantum description of the Universe in terms of a cuboidal graph which constitutes the proper framework for ...
Emanuele Alesci, F. Cianfrani
arxiv +3 more sources
Living Rev Relativ, 2005 Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical
Bojowald M.
europepmc +2 more sources
Primordial black holes in loop quantum cosmology: the effect on the threshold [PDF]
Classical and quantum gravity, 2023 Primordial black holes form in the early Universe and constitute one of the most viable candidates for dark matter. The study of their formation process requires the determination of a critical energy density perturbation threshold δc , which in general ...
T. Papanikolaou
semanticscholar +1 more source
Quantum cosmology in f(Q) theory [PDF]
Classical and quantum gravity, 2021 We use Dirac’s method for the quantization of constrained systems in order to quantize a spatially flat Friedmann–Lemaître–Robertson–Walker spacetime in the context of f(Q) cosmology.
N. Dimakis +2 more
semanticscholar +1 more source
Unitarity, clock dependence and quantum recollapse in quantum cosmology [PDF]
Classical and quantum gravity, 2021 We continue our analysis of a quantum cosmology model describing a flat Friedmann–Lemaître–Robertson–Walker Universe filled with a (free) massless scalar field and an arbitrary perfect fluid.
Steffen Gielen, Luc'ia Men'endez-Pidal
semanticscholar +1 more source
Lorentzian quantum cosmology goes simplicial [PDF]
Classical and quantum gravity, 2021 We employ the methods of discrete (Lorentzian) Regge calculus for analysing Lorentzian quantum cosmology models with a special focus on discrete analogues of the no-boundary proposal for the early universe.
B. Dittrich, Steffen Gielen, S. Schander
semanticscholar +1 more source