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Quantum Gravity

Group “Fundamental Interactions”

The QG equipe works on a major unsolved question in fundamental physics: understanding the quantum properties of gravity. Since gravity is the dynamics of spacetime, this amount to study the quantum behaviour of time and space.

Loop Quantum Gravity (LQG), is a main approach towards the solution of this problem, and the CPT is a leader in this field. The group works on the formal definition of the theory, its mathematical aspects, and its applications.

Among the formal developments, the group is studying the properties of the coherent semiclassical states which describe quantum geometry, and is developing a reformulation of the theory in terms of twistors which should simplify its application.

The main applications are to early cosmology and to black hole physics. The objective of the research is to find observable phenomena that could test the theory empirically.

In the context of early cosmology, LQG allows to explore the region around the initial singularity predicted by classical general relativity. The theory indicates that the present expansion phase was preceded by a contraction phase.

In the context of Black hole physics, LQG opens the possibility to study the physics of the high-curvature region (the “Planck star”), suggesting that the singularity predicted by classical general relativity is cured by quantum effects. A black hole is consequently unstable: it can explode via a quantum tunnelling process, akin to conventional radioactive nuclear decay. The equipe studies the signals produced by such black hole explosions. One hypothesis is that currently observed astrophysical phenomena such as very-high-energy gamma rays or Fast Radio Bursts could be originated by such a quantum gravitational explosion of primordial black holes.

The quantum structure of spacetime is also relevant for the thermal properties of the black holes and for the so-called black-hole “information paradox”. The group is at the forefront of the analysis of these questions.

Directory of Members

Krajewski Thomas University faculty
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ODAK Gloria PhD candidate
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Perez Alejandro University faculty
Chef de l’équipe « Gravité quantique »
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RIBISI Salvatore PhD candidate
RIGNON BRET Antoine PhD candidate
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Rovelli Carlo Emeritus
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Saul Andres Guest
Speziale Simone Researcher
Chef du Groupe « Interactions fondamentales »
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VIOLLET Sami PhD candidate
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List of Publications

130 results
Journal article
Eugenio Bianchi, You Ding
Lorentzian spinfoam propagator
Physical Review D, 2012, 86, pp.104040. ⟨10.1103/PhysRevD.86.104040⟩
Other publication
Carlo Rovelli
Quantum Gravity: third edition
2012, pp.179001. ⟨10.1088/0264-9381/29/17/179001⟩
Journal article
Carlo Rovelli
De la gravitation à boucles
Images de la Physique, 2012, pp.35
Journal article
Marcin Kisielowski, Jerzy Lewandowski, Jacek Puchta
Feynman diagrammatic approach to spin foams
Classical and Quantum Gravity, 2011, 29 (1), pp.015009. ⟨10.1088/0264-9381/29/1/015009⟩
Journal article
Daniele Pranzetti
2+1 gravity with positive cosmological constant in LQG: a proposal for the physical state
Classical and Quantum Gravity, 2011, 28 (22), pp.225025. ⟨10.1088/0264-9381/28/22/225025⟩
Conference paper
Alejandro Perez
Black hole entropy in LQG: Recent developments
Spanish Relativity Meeting 2011 (ERE2011), Aug 2011, Madrid, Spain. pp.100, ⟨10.1063/1.4734407⟩
Journal article
Eugenio Bianchi, Hal M. Haggard
Discreteness of the volume of space from Bohr-Sommerfeld quantization
Physical Review Letters, 2011, 107, pp.011301. ⟨10.1103/PhysRevLett.107.011301⟩
Journal article
Eugenio Bianchi
Black Hole Entropy, Loop Gravity, and Polymer Physics
Classical and Quantum Gravity, 2011, 28 (11), pp.114006. ⟨10.1088/0264-9381/28/11/114006⟩
Journal article
Jonathan Engle, Karim Noui, Alejandro Perez, Daniele Pranzetti
The SU(2) Black Hole entropy revisited
Journal of High Energy Physics, 2011, 2011 (5), pp.16. ⟨10.1007/JHEP05(2011)016⟩
Journal article
Eugenio Bianchi, Carlo Rovelli
Is dark energy really a mystery?
Nature, 2010, 466, pp.321
130 results