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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
Carlo Rovelli
Michelangelo's Stone: an Argument against Platonism in Mathematics
European Journal for Philosophy of Science, 2017, 7 (2), pp.285-297. ⟨10.1007/s13194-016-0159-8⟩
Journal article
Laurent Freidel, Alejandro Perez, Daniele Pranzetti
Loop gravity string
Physical Review D, 2017, 95 (10), pp.106002. ⟨10.1103/PhysRevD.95.106002⟩
Book Section
J. Fernando Barbero G., Alejandro Perez
Quantum Geometry and Black Holes
A. Ashtekar; J. Pullin. Loop Quantum Gravity : The First 30 Years , 4, World Scientific, pp.241-279, 2017, 100 Years of General Relativity, 978-981-3209-92-3. ⟨10.1142/9789813220003_0008⟩
Journal article
Alberto S. Cattaneo, Alejandro Perez
A note on the Poisson bracket of 2d smeared fluxes in loop quantum gravity
Classical and Quantum Gravity, 2017, 34 (10), pp.107001. ⟨10.1088/1361-6382/aa69b4⟩
Journal article
Thibaut Josset, Alejandro Perez, Daniel Sudarsky
Dark Energy from Violation of Energy Conservation
Physical Review Letters, 2017, 118 (2), pp.021102 ⟨10.1103/PhysRevLett.118.021102⟩
Journal article
Simone Speziale
Boosting Wigner's nj-symbols
Journal of Mathematical Physics, 2017, 58 (3), pp.032501 ⟨10.1063/1.4977752⟩
Journal article
Marios Christodoulou, Tommaso de Lorenzo
Volume inside old black holes
Physical Review D, 2016, 94 (10), ⟨10.1103/PhysRevD.94.104002⟩
Journal article
Jibril Ben Achour, Karim Noui, Alejandro Perez
Analytic continuation of the rotating black hole state counting
Journal of High Energy Physics, 2016, 2016 (08), pp.149. ⟨10.1007/JHEP08(2016)149⟩
Journal article
Tommaso de Lorenzo, Alejandro Perez
Improved Black Hole Fireworks: Asymmetric Black-Hole-to-White-Hole Tunneling Scenario
Physical Review D, 2016, 93 (12), pp.124018. ⟨10.1103/PhysRevD.93.124018⟩
Preprint, Working paper
Eugenio Bianchi, Wolfgang Wieland
Horizon energy as the boost boundary term in general relativity and loop gravity
130 results