[Cosmologie quantique (à boucle) et paradigme inflationnaire]
La gravité quantique, en tant que théorie fondamentale de l'espace-temps, est supposée fournir des scénarios décrivant le début de l'univers, peut-être pendant ou avant une ère inflationnaire. Elle a alors pu laisser des signatures potentiellement observables (mais probablement minuscules) dans les grandes structures, qui semblent être en bon accord avec les prédictions des modèles d'inflation. Une recherche systématique visant à dériver ces petits effets dans le cadre d'une théorie quantique de la gravitation, la gravitation quantique à boucle, s'est heurtée à des obstacles inattendus. Ces modèles sont incomplets, et il n'est pas évident que la théorie quantique à boucle soit cohérente en tant que théorie complète. Mais des effets surprenants, qui modifieraient radicalement notre conception de l'espace-temps à grande densité, semblent être génériques. Ces nouveaux effets à grande courbure sont la conséquence d'un décalage grandissant entre la gravité quantique et la théorie quantique des champs ordinaires en espace-temps courbe.
Quantum gravity, as a fundamental theory of space-time, is expected to reveal how the universe may have started, perhaps during or before an inflationary epoch. It may then leave a potentially observable (but probably miniscule) trace in cosmic large-scale structures that seem to match well with predictions of inflation models. A systematic quest to derive such tiny effects using one approach, loop quantum gravity, has, however, led to unexpected obstacles. Such models remain incomplete, and it is not clear whether loop quantum gravity can be consistent as a full theory. But some surprising effects appear to be generic and would drastically alter our understanding of space-time at large density. These new high-curvature phenomena are a consequence of a widening gap between quantum gravity and ordinary quantum-field theory on a background.
Mot clés : Cosmologie quantique, Espace-temps, Théorie efficace, Anomalies
@article{CRPHYS_2015__16_10_1012_0,
author = {Martin Bojowald},
title = {(Loop) quantum gravity and the inflationary scenario},
journal = {Comptes Rendus. Physique},
pages = {1012--1017},
publisher = {Elsevier},
volume = {16},
number = {10},
year = {2015},
doi = {10.1016/j.crhy.2015.08.007},
language = {en},
}
Martin Bojowald. (Loop) quantum gravity and the inflationary scenario. Comptes Rendus. Physique, Volume 16 (2015) no. 10, pp. 1012-1017. doi : 10.1016/j.crhy.2015.08.007. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2015.08.007/
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