scholarly journals Spacetime quanta?: the discrete spectrum of a quantum spacetime four-volume operator in unimodular loop quantum cosmology

2016 ◽  
Vol 34 (3) ◽  
pp. 035003
Author(s):  
J Bunao
2016 ◽  
Vol 25 (08) ◽  
pp. 1642008 ◽  
Author(s):  
Aurélien Barrau ◽  
Boris Bolliet

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. The present paper reviews several approaches to the problem of building a consistent formalism that describes the dynamics of perturbations on a quantum spacetime and tries to address their respective strengths and weaknesses. We also review the main open issues in loop quantum cosmology.


2008 ◽  
Vol 78 (6) ◽  
Author(s):  
Abhay Ashtekar ◽  
Edward Wilson-Ewing

2017 ◽  
Vol 26 (12) ◽  
pp. 1743023 ◽  
Author(s):  
Spyros Basilakos ◽  
Vahid Kamali ◽  
Ahmad Mehrabi

In this paper we investigate the observational signatures of Loop Quantum Cosmology (LQC) in the CMB data. First, we concentrate on the dynamics of LQC and we provide the basic cosmological functions. We then obtain the power spectrum of scalar and tensor perturbations in order to study the performance of LQC against the latest CMB data. We find that LQC provides a robust prediction for the main slow-roll parameters, like the scalar spectral index and the tensor-to-scalar fluctuation ratio, which are in excellent agreement within [Formula: see text] with the values recently measured by the Planck collaboration. This result indicates that LQC can be seen as an alternative scenario with respect to that of standard inflation.


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