# Centre de Physique Théorique

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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

 AMADEI Lautaro PhD candidate Email Gozzini Francesco PhD candidate Email Krajewski Thomas University faculty +33.4.91.26.95.61 Email Liu Hongguang PhD candidate Email Martin-Dussaud Pierre PhD candidate Email Martinez Daniel PhD candidate Email Perez Alejandro University faculty Chef de l’équipe « Gravité quantique » +33.4.91.26.97.98 Email Rovelli Carlo University faculty +33.4.91.26.96.44 Email Sarno Giorgio PhD candidate Email Saul Andres Guest Email Speziale Simone Researcher +33.4.91.26.95.46 Email Vidotto Francesca Guest Email

### List of Publications

91 results
Book
Carlo Rovelli
General Relativity. The Most beautiful of Theories.
De Gruyter, pp.208, 2015, 978-3-11-038364-5, 978-3-11-038364-5
Journal article
Carlo Rovelli
Aristotle’s Physics: A Physicist’s look
Journal of the American Philosophical Association, Cambridge Journals, 2015, 1 (1), pp.23-40. ⟨10.1017/apa.2014.11⟩
Journal article
Seramika Ariwahjoedi, Jusak Sali Kosasih, Carlo Rovelli, Freddy P. Zen
Curvatures and discrete Gauss-Codazzi equation in (2+1)-dimensional loop quantum gravity
International Journal of Geometric Methods in Modern Physics, World Scientific Publishing, 2015, 12, pp.1550112
Journal article
Sylvain Carrozza
Discrete Renormalization Group for SU(2) Tensorial Group Field Theory
Annales de l’Institut Henri Poincaré (D) Combinatorics, Physics and their Interactions, European Mathematical Society, 2015, 2 (1), pp.49-112. ⟨10.4171/AIHPD/15⟩
Journal article
Joseph Ben Geloun, Reiko Toriumi
Parametric Representation of Rank d Tensorial Group Field Theory: Abelian Models with Kinetic Term $\sum_{s}|p_s| + \mu$
Journal of Mathematical Physics, American Institute of Physics (AIP), 2015, 56 (9), pp.093503. ⟨10.1063/1.4929771⟩
Journal article
Hal M. Haggard, Austin Hedeman, Eugene Kur, Robert G. Littlejohn
Symplectic and Semiclassical Aspects of the Schläfli Identity
Journal of Physics A: Mathematical and Theoretical, IOP Publishing, 2015, 48 (10), pp.105203. ⟨10.1088/1751-8113/48/10/105203⟩
Journal article
Massimo Cerdonio, Carlo Rovelli
A Casimir cannot cavity fly
International Journal of Modern Physics D, World Scientific Publishing, 2015, 24, pp.1544020
Journal article
Marios Christodoulou, Carlo Rovelli
How big is a black hole?
Physical Review D, American Physical Society, 2015, 91 (6), pp.064046 ⟨10.1103/PhysRevD.91.064046⟩
Journal article
Olivier Asin, Jibril Ben Achour, Marc Geiller, Karim Noui, Alejandro Perez
Black holes as gases of punctures with a chemical potential: Bose-Einstein condensation and logarithmic corrections to the entropy
Physical Review D, American Physical Society, 2015, 91 (8), pp.084005. ⟨10.1103/PhysRevD.91.084005⟩
Journal article
Hal M. Haggard, Carlo Rovelli
Black hole fireworks: quantum-gravity effects outside the horizon spark black to white hole tunneling
Physical Review D, American Physical Society, 2015, 92 (10), pp.104020. ⟨10.1103/PhysRevD.92.104020⟩
91 results

June 2019 :