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Loop quantum cosmology (LQC) is used to provide concrete evidence in support of the general paradigm underlying spin foam models (SFMs). Specifically, it is shown that: i) the physical inner product in the timeless framework equals the…

General Relativity and Quantum Cosmology · Physics 2009-12-10 Abhay Ashtekar , Miguel Campiglia , Adam Henderson

We study FLRW cosmology, taking into account quantum gravitational corrections in the formalism of the exact renormalization group flow of the effective action for gravity. We calculate the quantum corrected scale factor, energy density,…

General Relativity and Quantum Cosmology · Physics 2022-10-26 Rituparna Mandal , Sunandan Gangopadhyay , Amitabha Lahiri

In contrast to previous work in the field, we construct the Loop Quantum Cosmology (LQC) of the flat isotropic model with a massless scalar field in the absence of higher order curvature corrections to the gravitational part of the…

General Relativity and Quantum Cosmology · Physics 2015-01-30 Madhavan Varadarajan

General Relativity is an extremely successful theory, at least for weak gravitational fields, however, it breaks down at very high energies, such as in correspondence of the initial singularity. Quantum Gravity is expected to provide more…

General Relativity and Quantum Cosmology · Physics 2023-04-20 Ana Rita Ribeiro , Daniele Vernieri , Francisco S. N. Lobo

We show that the quantization ambiguities of loop quantum cosmology, when considered in wider generality, can be used to produce discretionary dynamical behavior. There is an infinite dimensional space of ambiguities which parallels the…

General Relativity and Quantum Cosmology · Physics 2023-05-03 Lautaro Amadei , Alejandro Perez , Salvatore Ribisi

The usual Einstein's equations is modified as a one parameter family of equations in the framework of rainbow gravity. In this paper we derive the modified Friedmann-Robertson-Walker (FRW) equations when the cosmological evolution of…

General Relativity and Quantum Cosmology · Physics 2010-04-15 Yi Ling , Qingzhang Wu

The near-zero value of the cosmological constant \Lambda in an equilibrium context may be due to the existence of a self-tuning relativistic vacuum variable q. Here, a cosmological nonequilibrium context is considered with a corresponding…

General Relativity and Quantum Cosmology · Physics 2008-11-26 F. R. Klinkhamer

In the present work, we study the noncommutative version of a quantum cosmology model. The model has a Friedmann-Robertson-Walker geometry, the matter content is a radiative perfect fluid and the spatial sections have zero constant…

General Relativity and Quantum Cosmology · Physics 2016-05-05 G. Oliveira-Neto , M. Silva de Oliveira , G. A. Monerat , E. V. Corrêa Silva

Quantum effects play an essential role in modern cosmology. Perhaps the most striking example comes from large-scale structures, generally assumed to originate from vacuum quantum fluctuations and stretched by an expansion phase. Inflation…

General Relativity and Quantum Cosmology · Physics 2020-10-08 Emmanuel Frion

We implement Polymer Quantum Mechanics on the Hamiltonian formulation of the isotropic Universe in both the representations of the standard Ashtekar-Barbero-Immirzi connection and of a new generalized coordinate conjugate to the Universe…

General Relativity and Quantum Cosmology · Physics 2023-02-01 Gabriele Barca , Eleonora Giovannetti , Federico Mandini , Giovanni Montani

We analyze the semiclassical and quantum polymer dynamics of the isotropic Universe in terms of both the standard Ashtekar-Barbero-Immirzi connection and its conjugate momentum and also of the new generalized coordinate conjugate to the…

General Relativity and Quantum Cosmology · Physics 2022-06-01 Eleonora Giovannetti , Gabriele Barca , Federico Mandini , Giovanni Montani

We review an approach to non-commutative geometry, where models are constructed by quantisation of the coordinates. In particular we focus on the full DFR model and its irreducible components; the (arbitrary) restriction to a particular…

Mathematical Physics · Physics 2010-09-24 Gherardo Piacitelli

Some long standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big bang singularity in loop…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Abhay Ashtekar , Tomasz Pawlowski , Parampreet Singh

In Vilenkin's tunneling wavefunction proposal our expanding universe is born via a tunneling through a barrier from nothing at the zero scale factor. We explore the viability of this proposal for the spatially closed FLRW model with a…

General Relativity and Quantum Cosmology · Physics 2023-04-17 Meysam Motaharfar , Parampreet Singh

The hypothesis of a discrete fabric of the universe--the "Planck scale"--is always on stage, since it solves mathematical and conceptual problems in the infinitely small. However, it clashes with special relativity, which is designed for…

Quantum Physics · Physics 2016-10-26 Alessandro Bisio , Giacomo Mauro D'Ariano , Paolo Perinotti

The goal of spin foam models is to provide a viable path integral formulation of quantum gravity. Because of background independence, their underlying framework has certain novel features that are not shared by path integral formulations of…

General Relativity and Quantum Cosmology · Physics 2011-01-25 Abhay Ashtekar , Miguel Campiglia , Adam Henderson

The evolutions of the flat FLRW universe and its linear perturbations are studied systematically in the dressed metric approach of LQC. When it is dominated by the kinetic energy of the inflaton at the quantum bounce, the evolution of the…

General Relativity and Quantum Cosmology · Physics 2017-10-25 Tao Zhu , Anzhong Wang , Gerald Cleaver , Klaus Kirsten , Qin Sheng

The primary aim of this work is to explore feasible bouncing cosmological solutions in the framework of $f(\mathcal{Q}, \mathcal{C})$ gravity, where $\mathcal{Q}$ denotes non-metricity and $\mathcal{C}$ indicates the boundary term. To…

General Relativity and Quantum Cosmology · Physics 2025-08-12 M. Sharif , M. Zeeshan Gul , Ahmad Nawaz

The quantum bouncer (QB) concept is a known QM textbook example of confined particle, namely, a solution to the 1D Schroedinger equation for a linear potential (the so-called Airy equation). It would be a great methodological challenge to…

Quantum Physics · Physics 2009-06-30 Anatoli Andrei Vankov

We conduct a (pre-)inflationary dynamics study within the framework of a simple noncommutative extension of effective loop quantum cosmology -- put forward recently by the authors -- which preserves its key features (in particular, the…

General Relativity and Quantum Cosmology · Physics 2023-08-04 Luis Rey Díaz-Barrón , Abraham Espinoza-García , S. Pérez-Payán , J. Socorro