DOCSLIB.ORG

AIX-MARSEILLE UNIVERSITÉ ECOLE DOCTORALE ED352 Centre De Physique Théorique/UMR 7332 Équipe De Gravité Quantique

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
AIX-MARSEILLE UNIVERSITÉ ECOLE DOCTORALE ED352 Centre De Physique Théorique/UMR 7332 Équipe De Gravité Quantique AIX-MARSEILLE UNIVERSITÉ ECOLE DOCTORALE ED352 Centre de Physique Théorique/UMR 7332 Équipe de Gravité Quantique Thèse présentée pour obtenir le grade universitaire de docteur Discipline : PHYSIQUE ET SCIENCES DE LA MATIERE Spécialité : Physique Théorique et Mathématique Hongguang Liu Aspects of Quantum Gravity Aspects de Gravitation Quantique Soutenue le 04/07/2019 devant le jury composé de : Francesca Vidotto University of the Basque Country, Spain Rapporteur Yidun Wan Fudan University, China Rapporteur Marc Geiller ENS Lyon Examinateur Federico Piazza Aix-Marseille University Examinateur Daniele Steer APC, Paris 7 Examinateur Madhavan Varadarajan Raman Research Institute, India Examinateur Karim Noui LMPT, Tours Co-Directeur de thèse Alejandro Perez Aix-Marseille University Directeur de thèse Numéro national de thèse/suffixe local : Cette oeuvre est mise à disposition selon les termes de la Licence Creative Commons Attribution - Pas d’Utilisation Commerciale - Pas de Modification 4.0 International. Résumé La nature de la gravite quantique est une question ouverte importante en phy- sique fondamentale dont la résolution nous permettrait de comprendre la struc- ture la plus profonde de l’espace-temps et de la matière. Cependant, jusqu’a’ présent, il n’y a pas de solution complète a’ la question de la gravité quantique, malgré de nombreux efforts et tentatives. La gravitation quantique en boucle est une approche particulière de la gravitation quantique indépendante du fond, inspirée par une formulation de la relativité générale en tant que théorie dynamique des connexions. La théorie contient deux branches, l’approche canonique et l’approche de mousses de spin. La manière canonique est basée sur la formulation hamiltonienne de l’action de premier ordre de la relativité générale suivant une quantification à la Dirac sur des algèbres de flux, tandis que les modelés de mousses de spin se présentent comme une formulation covariante de la gravite quantique, définie comme un modelé de somme d’état sur graphiques. Cette thèse concerne principalement, sans toutefois s’y limiter, le problème de la gravite quantique dans le contexte de la gravite quantique en boucle. Les deux aspects fondamentaux et les conséquences physiques de la gravite à boucles sont étudies dans ce travail. La description de la gravite en termes de groupe de jauge non compacte su(1, 1) est étudiée a’ la fois de manière canonique et sous forme de mousse de spin. Nous étudions l’invariance de Lorentz de la gravite quantique de la boucle, a’ la fois dans l’approche canonique et dans le modelé de mousse de spin. Nous présentons une description de jauge su(1, 1) de la théorie de la gravite en quatre dimensions, au lieu de la description habituelle su(2). Nous étudions la quantification de boucle au niveau cinématique, ou’ nous avons constate que les aires de type espace ont des spectres discrets, tandis que les aires de type temps ont des spectres continus. Pour les aires de type espace, il n’y a pas d’anomalie entre la description su(1, 1) et la description su(2). Dans le même temps, nous effectuons l’analyse semi-classique (asymptotique pour grand j ) du modelé de mousse de spin de Conrady-Hnybida dans une situation très générale dans laquelle des tétraèdres de type temps avec des triangles de type temps sont pris en compte. Nous identifions la contribution dominante avec des géométries simplicales discrètes et nous retrouvons l’action de gravite de Regge. Dans une seconde partie de cette thèse, je me suis penche sur le problème de la dynamique effective de la gravitation à boucle a’ haute énergie en cosmologie et dans le contexte de la physique de trous noirs. Nous étudions le lien entre la gravite mimétique étendue, une classe de théories scalaires-tenseurs, et la dy- 3 namique effective de la cosmologie quantique à boucles ainsi que les modèles de trous noirs polymères sphériques inspirés de la gravite quantique à boucles. La comparaison entre les formulations mimétiques et hamiltoniennes de poly- mère nous fournit un guide pour comprendre l’absence de covariance dans les modèles de polymères non homogènes. En attendant, nous résolvons explicite- ment les équations d’Einstein modifiées dans le cadre de modèles de polymères effectifs a’ symétrie sphérique. La métrique effective pour une géométrie de trou noir intérieure statique décrivant la région piégée est donnée. Les résultats obte- nus dans cette partie ont des implications intéressantes pour la cosmologie sans singularité et les trous noirs qui méritent d’être approfondies. Mots-clés : gravité quantique, gravité quantique en boucle, modèles de mousse de spin, limite semi-classique, dynamique effective, trous noirs, cosmologie quan- tique en boucle, gravité mimétique, théories scalaires-tenseurs 4 Abstract The nature of quantum gravity is an important open question in fundamental physics whose resolution would allow us to understand the deepest structure of space-time and matter. However, up to now there is no complete solution to the question of quantum gravity, despite many efforts and attempts. Loop quan- tum gravity is a tentative background independent approach to quantum gravity inspired by a formulation of general relativity as a dynamical theory of connec- tions. The theory contains two approaches, the canonical approach and the spin foam approach. The canonical way is based on the Hamiltonian formulation of the first order action of pure gravity following a dirac quantization of holonomy- flux algebras, whereas the spin foam model arises as a covariant formulation of quantum gravity, which is defined as a state sum model over certain graphs. This thesis mostly involves, but not restricts to, the problem of quantum grav- ity in the context of loop quantum gravity. Both fundamental aspects and the physical consequences of loop gravity are investigated in this work. The descrip- tion of gravity in terms of a non-compact gauge group su(1, 1) is studied in both the canonically as well as in the spin foam approach. We study the Lorentzian invariance of loop quantum gravity, in both the canonical approach and the spin foam model approach. We introduce an su(1, 1) gauge description of gravity the- ory in four dimensions, instead of the usual su(2) description. We investigate the loop quantization at the kinematical level, where we find that space-like areas have discrete spectra, whereas time-like areas have continuous spectra. And we show that there is no anomaly between the su(1, 1) description and the su(2) description of space-like areas. Meanwhile, we perform the semi-classical (large- j asymptotic) analysis of the spin foam model (Conrady-Hnybida extension) in the most general situation, in which timelike tetrahedra with timelike triangles are taken into account. We identify the dominant contribution to the discrete simplicial geometries and recover the Regge action of gravity. On a second part of this thesis we focus on the problem of the high energy effective dynamics of loop gravity in cosmology and black holes through simpli- fied models. We investigate the link between the family of extended Mimetic gravity, a class of scalar-tensor theories, and the effective dynamics of loop quan- tum cosmology as well as the spherical polymer black hole models inspired from loop quantum gravity. This comparison provides us with a guide to understand the absence of covariance in inhomogeneous polymer models. Futhermore, we solve the modified Einstein’s equations explicitly in the framework of effective spherically symmetric polymer models. The effective metric for a static interior 5 Black Hole geometry describing the trapped region is given. The results obtained in this part lead to some interesting implications for singularity free cosmology and black holes which are worth pursuing further. Keywords: quantum gravity, loop quantum gravity, spin foam models, semi- classical limit, effective dynamics, black holes, loop quantum cosmology, mimetic gravity, scalar-tensor theories 6 List of Publications The thesis is based on the following papers, which are the result of my own work and of collaborations during my doctoral studies at Aix-Marseille University since Oct. 2016. a 1. ‘‘Asymptotic analysis of spin foam amplitude with timelike triangles” H. Liu and M. Han. Phys. Rev. D 99, no. 8, 084040 (2019), arXiv:1810.09042 [gr-qc] 2. ‘‘Polymer Schwarzschild black hole: An effective metric” J. Ben Achour, F. Lamy, H. Liu and K. Noui. EPL 123, no. 2, 20006 (2018), arXiv:1803.01152 [gr-qc] 3. ‘‘Non-singular black holes and the Limiting Curvature Mechanism: A Hamil- tonian perspective” J. Ben Achour, F. Lamy, H. Liu and K. Noui. JCAP 1805, no. 05, 072 (2018), arXiv:1712.03876 [gr-qc] 4. ‘‘Effective loop quantum cosmology as a higher-derivative scalar-tensor the- ory” D. Langlois, H. Liu, K. Noui and E. Wilson-Ewing. Class. Quant. Grav. 34, no. 22, 225004 (2017), arXiv:1703.10812 [gr-qc] 5. ‘‘Gravity as an su(1, 1) gauge theory in four dimensions” H. Liu and K. Noui. Class. Quant. Grav. 34, no. 13, 135008 (2017) ,arXiv:1702.06793 [gr-qc] The following recent work and early investigations will not be directly ad- dressed in this thesis: 1. ‘‘Stealth Schwarzschild-(A)dS black hole in DHOST theories after GW170817: Linear time-dependent scalar dressing” J. B. Achour and H. Liu. Phys. Rev. D 99, no. 6, 064042 (2019), arXiv:1811.05369 [gr-qc] 2. ‘‘Semiclassical analysis of black holes in loop quantum gravity: Modeling Hawking radiation with volume fluctuations” P. Heidmann, H. Liu and K. Noui. Phys. Rev. D 95, no. 4, 044015 (2017), arXiv:1612.05364 [gr-qc] a. The complete list of publications can be found on inspire hep: http://inspirehep.net/author/profile/Hong.Guang.Liu.1. All publications listed here are peer-reviewed papers. 7 3. ‘‘Distinguishing f(R) theories from general relativity by gravitational lens- ing effect” H.
Load more

Recommended publications
  • Iniziativa Specifica Ts11
    TS11 (PAVIA) INIZIATIVA SPECIFICA TS11 Gravità, Campi e Stringhe (Bo, Pv, Pi, RM1, Ts) Componenti sede Pavia: M. Carfora, A. Marzuoli, C. Dappiaggi Dottorandi: Francesca Vidotto (XXIV ciclo) (completed) Giandomenico Palumbo (XXV ciclo) Dimitri Marinelli (XXVI ciclo) TS11 provides a common area where problems at the intersection of gravity, field theory and string theory are investigated. The leit motiv of our IS is the exchange of ideas and the cross-fertilization among nearby areas of research, notably String theory, Condensed matter physics, geometric analysis, and Relativistic physics. Research highlights for 2011/12 : (i) Topological Quantum Field Theory and Quantum computation: This approach develops a scheme for quantum computation based on modular functors of Chern— Simons theory realized by the recoupling theory of N SU(2) angular momenta. Modelli di gravità quantistica discretizzata e applicazioni. -Nella monografia LN Physics sono riportati risultati sulle applicazioni di metodi originariamente utilizzati in modelli 3d di gravità discretizzata -triangolazioni decorate, SU(2) state sums di Turaev- Viro e associate osservabili quantistiche- finalizzate a stabilire una descrizione microscopica unificata delle fasi topogiche di sistemi 2d di interesse per la condensed matter e la computazione quantistica. -In collaborazione con D Marinelli e Università di Perugia: analisi semiclassica di ‘spin networks’ con metodi geometrici-combinatorici e applicazioni allo schema di Askey-Wilson dei polinomi ipergeometrici. Computazione quantistica topologica In collaborazione con G Palumbo: -Teorie di campo di tipo BF come azioni azioni effettive per il grafene ((2+1)d) e gli isolanti topologici ((3+1)d), versioni miscroscopiche, teorie di bordo discretizzate e loro applicazioni alla ‘anyonic’ quantum computation.
    [Show full text]
  • White-Hole Dark Matter and the Origin of Past Low-Entropy Francesca Vidotto, Carlo Rovelli
    White-hole dark matter and the origin of past low-entropy Francesca Vidotto, Carlo Rovelli To cite this version: Francesca Vidotto, Carlo Rovelli. White-hole dark matter and the origin of past low-entropy. 2018. hal-01771746 HAL Id: hal-01771746 https://hal.archives-ouvertes.fr/hal-01771746 Preprint submitted on 20 Apr 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 White-hole dark matter and the origin of past low-entropy Francesca Vidotto University of the Basque Country UPV/EHU, Departamento de F´ısicaTe´orica,Barrio Sarriena, 48940 Leioa, Spain [email protected] Carlo Rovelli CPT, Aix-Marseille Universit´e,Universit´ede Toulon, CNRS, case 907, Campus de Luminy, 13288 Marseille, France [email protected] Submission date April 1, 2018 Abstract Recent results on the end of black hole evaporation give new weight to the hypothesis that a component of dark matter could be formed by remnants of evaporated black holes: stable Planck-size white holes with a large interior. The expected lifetime of these objects is consistent with their production at reheating. But remnants could also be pre-big bang relics in a bounce cosmology, and this possibility has strong implications on the issue of the source of past low entropy: it could realise a perspectival interpretation of past low entropy.
    [Show full text]
  • Pos(EDSU2018)046
    Quantum insights on Primordial Black Holes as Dark Matter PoS(EDSU2018)046 Francesca Vidotto∗y University of the Basque Country UPV/EHU, Departamento de Física Teórica, Barrio Sarriena s/n, 48940 Leioa, Biscay, Spain E-mail: [email protected] A recent understanding on how quantum effects may affect black-hole evolution opens new sce- narios for dark matter, in connection with the presence of black holes in the very early universe. Quantum fluctuations of the geometry allow for black holes to decay into white holes via a tun- nelling. This process yields to an explosion and possibly to a long remnant phase, that cures the information paradox. Primordial black holes undergoing this evolution constitute a peculiar kind of decaying dark matter, whose lifetime depends on their mass M and can be as short as M2. As smaller black holes explode earlier, the resulting signal have a peculiar fluence-distance relation. I discuss the different emission channels that can be expected from the explosion (sub-millimetre, radio, TeV) and their detection challenges. In particular, one of these channels produces an ob- served wavelength that scales with the redshift following a unique flattened wavelength-distance function, leaving a signature also in the resulting diffuse emission. I conclude presenting the first insights on the cosmological constraints, concerning both the explosive phase and the subsequent remnant phase. 2nd World Summit: Exploring the Dark Side of the Universe 25-29 June, 2018 - EDSU2018 University of Antilles, Pointe-à-Pitre, Guadeloupe, France ∗Speaker. yThe work presented is the fruit of collaborations, in particular with Aurelien Barrau, Alvise Raccanelli, and Carlo Rovelli.
    [Show full text]
  • Primordial Fluctuations from Quantum Gravity
    Primordial fluctuations from quantum gravity Francesco Gozzini a;b and Francesca Vidotto c;d a CPT, Aix-Marseille Universit´e,Universit´ede Toulon, CNRS, 13288 Marseille, France b Dipartimento di Fisica, Universit´adi Trento, and TIFPA-INFN, 38123 Povo TN, Italy c Department of Applied Mathematics, University of Western Ontario, London, ON N6A 5B7, Canada d University of the Basque Country UPV/EHU, Departamento de F´ısica Te´orica, 48940 Leioa, Spain We study fluctuations and correlations between spacial regions, generated by the primordial quantum gravitational phase of the universe. We do so by a numerical evaluation of Lorentzian amplitudes in Loop Quantum Gravity, in a non-semiclassical regime. We find that the expectation value of the quantum state of the geometry emerging from the early quantum phase of the universe is a homogeneous space but fluctuations are very large and correlations are strong, although not maximal. In particular, this suggests that early quantum gravitational effects could be sufficient to solve the cosmological horizon problem. I. INTRODUCTION The second result is that (contrary to our initial ex- pectation), the variance of these variables is very large. This variance cannot be too small, because the variables The universe emerged from its early quantum gravi- do not commute, but one might have expected a coher- tational phase in a state that included fluctuations with ent state minimizing the spread. Instead, the spread is correlations between distinct regions of space. These pri- almost maximal. This means that (in spite of what the mordial fluctuations play a key role in cosmology | with first result mentioned above might misleadingly suggest), or without inflation | in particular as seeds for struc- the quantum state that emerges from the big bang in this ture formation.
    [Show full text]
  • Carlo Rovelli
    Carlo Rovelli Centre de Physique Theorique Ph +33 614 59 3885, fax +33 491 26 9553 Luminy, Case 907, [email protected] F-13288 Marseille, France http://www.cpt.univ-mrs.fr/∼rovelli Present position { Professeur de classe exceptionnelle, Universit´ede la M´editerran´ee,Marseille, France. Honorary positions { Universidad de San Martin, Buenos Aires, Argentina, Laurea Honoris Causa. { Beijing Normal University, Beijing, China, Honorary Professor. { Institut Universitaire de France, Senior Member. { Perimeter Institute, Canada, Distinguished Visiting Research Chair. { Acad´emieInternationale de Philosophie des Sciences, Membre Titulaire. { Accademia di Agricultura Scienze e Lettere di Verona, Honorary Member. { Accademia Galileana, Member. { Department of History and Philosophy of Science, Pittsburgh University, Affiliated Professor. { Citt`adi Condofuri, Honorary citizen.- { Fondazione, Orchestra Federico II di Svevia, membro del Comitato d'Onore. Education 1970-1975 Liceo Maffei, Verona Classical studies 1975-1981 Universit`adi Bologna Laurea in Fisica (with honors) 1983-1986 Universit`adi Padova Dottorato di Ricerca (Ph.D.) in Physics Professional Employment 2006-pres Universit´ede la M´editerran´ee Professeur de classe exceptionnelle 2000-2006 Universit´ede la M´editerran´ee Professeur (1ere classe) 1999-2000 Pittsburgh University Full Professor 1998-1999 CPT Luminy Directeur de Recherche 1994-1999 Pittsburgh University Associate Professor 1990-1994 Pittsburgh University Assistant Professor 1989 Sissa, Trieste Post-Doctoral position 1989 Syracuse University Visiting Fellow 1987 Yale University Post-doctoral Fellowship 1987-1988 Universit`adi Roma INFN Post-doctoral position 1986 Imperial College London Visiting position Recognitions, Awards, Honors { Watkin's 2021 Prize. { Included in the 2019 list of the 100 most influential \Global Thinkers" by Foreign Policy magazine.
    [Show full text]
  • Covariant Loop Quantum Gravity
    Covariant Loop Quantum Gravity An elementary introduction to Quantum Gravity and Spinfoam Theory CARLO ROVELLI AND FRANCESCA VIDOTTO iii . Cover: Martin Klimas, ”Jimi Hendrix, House Burning Down”. Contents Preface page ix Part I Foundations 1 1 Spacetime as a quantum object 3 1.1 The problem 3 1.2 The end of space and time 6 1.3 Geometry quantized 9 1.4 Physical consequences of the existence of the Planck scale 18 1.4.1 Discreteness: scaling is finite 18 1.4.2 Fuzziness: disappearance of classical space and time 19 1.5 Graphs, loops and quantum Faraday lines 20 1.6 The landscape 22 1.7 Complements 24 1.7.1 SU(2) representations and spinors 24 1.7.2 Pauli matrices 27 1.7.3 Eigenvalues of the volume 29 2 Physics without time 31 2.1 Hamilton function 31 2.1.1 Boundary terms 35 2.2 Transition amplitude 36 2.2.1 Transition amplitude as an integral over paths 37 2.2.2 General properties of the transition amplitude 40 2.3 General covariant form of mechanics 42 2.3.1 Hamilton function of a general covariant system 45 2.3.2 Partial observables 46 2.3.3 Classical physics without time 47 2.4 Quantum physics without time 48 2.4.1 Observability in quantum gravity 51 2.4.2 Boundary formalism 52 2.4.3 Relational quanta, relational space 54 2.5 Complements 55 2.5.1 Example of timeless system 55 2.5.2 Symplectic structure and Hamilton function 57 iv v Contents 3 Gravity 59 3.1 Einstein’s formulation 59 3.2 Tetrads and fermions 60 3.2.1 An important sign 63 3.2.2 First-order formulation 64 3.3 Holst action and Barbero-Immirzi coupling constant 65 3.3.1
    [Show full text]
  • Grailquest: Hunting for Atoms of Space and Time Hidden In
    Voyage 2050 - long term plan in the ESA science programme GrailQuest: hunting for Atoms of Space and Time hidden in the wrinkle of Space{Time A swarm of nano/micro/small{satellites to probe the ultimate structure of Space-Time and to provide an all-sky monitor to study high energy astrophysics phenomena Contact Scientist: Luciano Burderi Dipartimento di Fisica, Universit`adegli Studi di Cagliari SP Monserrato-Sestu km 0.7, 09042 Monserrato, Italy Tel.: +39-070-6754854 Fax: +39-070-510171 E-mail: [email protected] 2 Contact Scientist: Luciano Burderi Core Proposing Team: Luciano Burderi Dipartimento di Fisica, Universit`adegli Studi di Cagliari, SP Monserrato-Sestu km 0.7, 09042 Monserrato, Italy Andrea Sanna Dipartimento di Fisica, Universit`adegli Studi di Cagliari, SP Monserrato-Sestu km 0.7, 09042 Monserrato, Italy Tiziana Di Salvo Universit`adegli Studi di Palermo, Dipartimento di Fisica e Chimica, via Archirafi 36, 90123 Palermo, Italy Lorenzo Amati INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, I-40129 Bologna, Italy Giovanni Amelino-Camelia Dipartimento di Fisica Ettore Pancini, Universit`adi Napoli \Federico II", and INFN, Sezione di Napoli, Complesso Univ. Monte S. Angelo, I-80126 Napoli, Italy Marica Branchesi Gran Sasso Science Institute, I-67100 L`Aquila, Italy Salvatore Capozziello Dipartimento di Fisica, Universit`adi Napoli \Federico II", Complesso Universitario di Monte SantAngelo, Via Cinthia, 21, I-80126 Napoli, Italy Eugenio Coccia Gran Sasso Science Institute, I-67100 L`Aquila, Italy Monica Colpi Dipartimento di Fisica \G. Occhialini", Universit`adegli Studi Milano - Bicocca, Piazza della Scienza 3, Milano, Italy Enrico Costa INAF-IAPS,Via del Fosso del Cavaliere 100, I-00133 Rome, Italy Paolo De Bernardis Physics Department, Universit`adi Roma La Sapienza, Ple.
    [Show full text]
  • Pos(FFP14)222 † ∗ [email protected] Speaker
    Atomism and Relationalism as guiding principles for Quantum Gravity PoS(FFP14)222 Francesca Vidotto∗† Radboud University Nijmegen, Institute for Mathematics, Astrophysics and Particle Physics, Mailbox 79, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands E-mail: [email protected] Research in quantum gravity has grown jauntily in the recent years, intersecting with conceptual and philosophical issues that have a long history. In this paper I analyze the conceptual basis on which Loop Quantum Gravity has grown, the way it deals with some classical problems of philosophy of science and the main methodological and philosophical assumptions on which it is based. In particular, I emphasize the importance that atomism (in the broadest sense) and relationalism have had in the construction of the theory. Frontiers of Fundamental Physics 14 - FFP14, 15-18 July 2014 Aix Marseille University (AMU) Saint-Charles Campus, Marseille ∗Speaker. †FV is supported by the Netherlands Organisation for Scientific Research (NWO) with a Veni Fellowship. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ Atomism and Relationalism as guiding principles for Quantum Gravity Francesca Vidotto Scientists are guided in their investigation of Nature by ideas brought to them by philosophers. Not always scientists are aware of this, but still their way of working and the kind of questions that they address, have emerged in a humus of philosophical debates of long history. Being aware of these debates, that shaped our present investigations, can help us to recognize paths and new directions for our science.
    [Show full text]
  • Fast Radio Bursts and White Hole Signals Aurélien Barrau, CR, Francesca Vidotto
    Planck Stars: Black-to-white hole tunnelling and Fast Radio Bursts Carlo Rovelli Collaborators Main idea: Francesca Vidotto Classical solution: Hal Haggard Phenomenology: Aurélien Barrau, Francesca Vidotto, Boris Bolliet, Celine Weimer A clear theme emerges from these spacetime diagrams: ⌥ build a time symmetric model (cfr intro talk Akim Kempf) Two deep puzzles we have all wondered about: → → A brief (very incomplete) history of ideas What is the final fate What does actually happen of a black hole? at the classical singularity? What do we miss? Quantum gravity Quantum gravity is not quantum field theory on a geometry! Quantum gravity is the quantum theory of the geometry Difficulties remain until we keep thinking about a classical spacetime and qft over it 3WCPVWOTGIKQP What happens here? General relativity does not teach us that there is a singularity General relativity does teaches us that there is new physics there What happens to the matter falling into black holes? - It disappears (?) - It creates“another universe” (Smolin) - It stays there forever (nothing is forever) - It comes out. At MG2 and in a paper ’79-’81 Valeri Frolov Grigori A. Vilkovisky (left) 1992: remnants Steve Giddings In ’93 Cristopher R. Stephens Gerard ’t Hooft Bernard F. Whiting In ’05 Abhay Ashtekar Martin Bojowald Sean A. Hayward in ’06 cfr Sven Koppel Also: P. Nicolini B. Carr L. Modesto I. Premont-Schwarz S. Hossenfelder J. M. Bardeen G. Ellis … (cfr G Ellis) (cfr Bernard Carr: [see M. Smerlak’s talk] Loop Black Holes) Quantum mechanics is still missing Singularity avoidance by collapsing The Hajicek-Kiefer bounce shells in quantum gravity Petr Hájíček, Clauss Kiefer.
    [Show full text]
  • Covariant Loop Quantum Gravity Carlo Rovelli , Francesca Vidotto Frontmatter More Information
    Cambridge University Press 978-1-107-06962-6 — Covariant Loop Quantum Gravity Carlo Rovelli , Francesca Vidotto Frontmatter More Information Covariant Loop Quantum Gravity Quantum gravity is among the most fascinating problems in physics. It modifies our understanding of time, space, and matter. The recent development of the loop approach has allowed us to explore domains ranging from black hole thermodynamics to the early universe. This book provides readers with a simple introduction to loop quantum gravity, centred on its covariant approach. It focuses on the physical and conceptual aspects of the prob- lem and includes the background material needed to enter this lively domain of research, making it ideal for researchers and graduate students. Topics covered include quanta of space, classical and quantum physics without time, tetrad formalism, Holst action, lattice gauge theory, Regge calculus, ADM and Ashtekar variables, Ponzano–Regge and Turaev–Viro amplitudes, kinematics and dynamics of 4d Lorentzian quantum gravity, spectrum of area and volume, coherent states, classi- cal limit, matter couplings, graviton propagator, spinfoam cosmology and black hole thermodynamics. Carlo Rovelli is Professor of Physics at Aix-Marseille Universite,´ where he directs the gravity research group. He is one of the founders of loop quantum gravity. Francesca Vidotto is NWO Veni Fellow at the Radboud Universiteit Nijmegen and initiated the spinfoam approach to cosmology. © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-06962-6 — Covariant Loop Quantum Gravity Carlo Rovelli , Francesca Vidotto Frontmatter More Information “The approach to quantum gravity known as loop quantum gravity has progressed enor- mously in the last decade and this book by Carlo Rovelli and Francesca Vidotto admirably fills the need for an up-to-date textbook in this area.
    [Show full text]
  • Francesca Vidotto, Planck Stars
    Planck Stars the final fate of quantum no-singula black hoes and its phenoenoogical cosequences Francesca Vidotto UPV/EHU - Bilbao SINGULARITIES OF GENERAL RELATIVITY AND THEIR QUANTUM FATE Warsaw - May 23rd, 2018 Planck Stars the final fate of quantum no-singula black hoes and its phenoenoogical cosequences Francesca Vidotto UPV/EHU - Bilbao SINGULARITIES OF GENERAL RELATIVITY AND THEIR QUANTUM FATE Warsaw - May 23rd, 2018 QUANTAQUANTA OF OFSPACE SPACETIME It is a theory about quanta of spacetime Each quantum is Lorentz invariant The states are boundary states at fixed time SL(2, C) SU(2) ! i The physical phase space is spanned by SU(2) group variables L⌅ = L ,i=1, 2, 3 l { l} gravitational field operator (tetrad) SU(2) generators i i Geometry is quantized: AΣ = LlLl. l Σ ⇥ ∈ 2 2 i j k VR = Vn,Vn = ijkLlL Ll” . 9 | l | n R ∈ Discrete spectra: minimal non-zero eigenvalue Spinfoam & Singularities Francesca Vidotto QUANTIZATION OF THE CLASSICAL ACTION 1 GR action S[e, !]= e e F ⇤[!]+ e e F [!] (Holst term) ^ ^ γ ^ ^ Z Z BF theory S[e, ω]= B[e] F [ω] ^ Z 1 Canonical variables ⇥,B=(e e)⇤ + (e e) ^ γ ^ a i On the boundary n = e n nie =0 SL(2, C) SU(2) i i a ! ni =(1, 0, 0, 0) B (K = nB, L = nB⇤) ! Simplicity constraint K<latexit sha1_base64="0y/FFa7mathXZtw2BIirz4YmJ9k=">AAAB8XicdZDLSgMxFIYz9VbrrerSTbAIrkqmldYulIIbQRcV7AXboWTSTBuaZIYkI5Shb+HGhSJufRt3vo2ZtoKK/hD4+M855JzfjzjTBqEPJ7O0vLK6ll3PbWxube/kd/daOowVoU0S8lB1fKwpZ5I2DTOcdiJFsfA5bfvji7TevqdKs1DemklEPYGHkgWMYGOtu6uz3hALgeF1P19ARVQulVEFWkCVEqrNoFyq1qBrIVUBLNTo5997g5DEgkpDONa666LIeAlWhhFOp7lerGmEyRgPadeixIJqL5ltPIVH1hnAIFT2SQNn7veJBAutJ8K3nQKbkf5dS82/at3YBKdewmQUGyrJ/KMg5tCEMD0fDpiixPCJBUwUs7tCMsIKE2NDytkQvi6F/0OrVHRR0b05KdTPF3FkwQE4BMfABVVQB5egAZqAAAkewBN4drTz6Lw4r/PWjLOY2Qc/5Lx9At+VkGE=</latexit>
    [Show full text]
  • Vidotto-Guadalupe-18.Pdf
    Quantum Insights o Primordial Black Holes as Dak Mate Francesca Vidotto UPV/EHU - Bilbao 2ND WORLD SUMMIT ON EXPLORING THE DARK SIDE OF THE UNIVERSE Guadalupe Island - June 29th, 2018 THE DARK SIDE OF GRAVITY Caution: not a complete list! DARK ENERGY Cosmological Constant (or more complicated GR modification) Gravitational Backreaction see Buchert’s talk Quantum Gravity: Spacetime Discreteness Perez, Sudarsky, Bjorken 1804.07162 … DARK MATTER Mond, Mimetic Gravity and other classical modification of GR Bimetric Gravity see Henry-Couannier’s talk N-body Equivalence Principle Alexander, Smolin 1804.09573 Quantum Gravity: Minimal Acceleration Smolin 1704.00780 Emergent Gravity Verlinde 1611.02269 … Primordial Black Holes see also Garcia-Bellido’s talk Quantum Gravity Phenomenology Francesca Vidotto PRIMORDIAL BLACK HOLES PBHs are the least exotic beast in the dark universe zoo of theories PBHs are a viable DARK MATTER candidate * careful with old constraints in the literature! PBHs are interesting even if they are not all DARK MATTER * PBHs can be used to test QUANTUM GRAVITY Quantum Gravity Phenomenology Francesca Vidotto IN THIS TALK: QUANTUM GRAVITY 1. QG makes PBH remnants stable * Quantum Gravity: minimal aerea 2. QG cures GR singularities * NO central BH singularity, NO cosmological singularity: instead a bounce 3. QG allows for Black-to-White tunnelling * Decay happens faster than the Hawking evaporation: new phenomenology 3 different scenarios discussed in this talk Quantum Gravity Phenomenology Francesca Vidotto T. BANKS AND M. O'LOUGHLIN 47 AND M. O'LOUGHLIN 47 u (r, n }=e T. BANKS(2.4) tion, but here the dilaton dynamics gives rise to an infinite set of spherically symmetric solutions of the In terms of these fields the Lagrangian is source free field equations in a finite region.
    [Show full text]