Carlo Rovelli
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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. -
BEYOND SPACE and TIME the Secret Network of the Universe: How Quantum Geometry Might Complete Einstein’S Dream
BEYOND SPACE AND TIME The secret network of the universe: How quantum geometry might complete Einstein’s dream By Rüdiger Vaas With the help of a few innocuous - albeit subtle and potent - equations, Abhay Ashtekar can escape the realm of ordinary space and time. The mathematics developed specifically for this purpose makes it possible to look behind the scenes of the apparent stage of all events - or better yet: to shed light on the very foundation of reality. What sounds like black magic, is actually incredibly hard physics. Were Albert Einstein alive today, it would have given him great pleasure. For the goal is to fulfil the big dream of a unified theory of gravity and the quantum world. With the new branch of science of quantum geometry, also called loop quantum gravity, Ashtekar has come close to fulfilling this dream - and tries thereby, in addition, to answer the ultimate questions of physics: the mysteries of the big bang and black holes. "On the Planck scale there is a precise, rich, and discrete structure,” says Ashtekar, professor of physics and Director of the Center for Gravitational Physics and Geometry at Pennsylvania State University. The Planck scale is the smallest possible length scale with units of the order of 10-33 centimeters. That is 20 orders of magnitude smaller than what the world’s best particle accelerators can detect. At this scale, Einstein’s theory of general relativity fails. Its subject is the connection between space, time, matter and energy. But on the Planck scale it gives unreasonable values - absurd infinities and singularities. -
Physics Needs Philosophy. Philosophy Needs Physics. Carlo Rovelli
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PhilSci Archive Physics needs philosophy. Philosophy needs physics. Carlo Rovelli Extended version of a keynote talk at the XVIII UK-European Conference on the Foundation of Physics, given at the London School of Economics the 16 July 2016 Published on Foundations of Physics, 48, 481-491, 2018 Abstract Contrary to claims about the irrelevance of philosophy for science, I argue that philosophy has had, and still has, far more influence on physics than is commonly assumed. I maintain that the current anti-philosophical ideology has had damaging effects on the fertility of science. I also suggest that recent important empirical results, such as the detection of the Higgs particle and gravitational waves, and the failure to detect supersymmetry where many expected to find it, question the validity of certain philosophical assumptions common among theoretical physicists, inviting us to engage in a clearer philosophical reflection on scientific method. 1. Against Philosophy is the title of a chapter of a book by one of the great physicists of the last generation: Steven Weinberg, Nobel Prize winner and one of the architects of the Standard Model of elementary particle physicsi. Weinberg argues eloquently that philosophy is more damaging than helpful for physics—although it might provide some good ideas at times, it is often a straightjacket that physicists have to free themselves from. More radically, Stephen Hawking famously wrote that “philosophy is dead” because the big questions that used to be discussed by philosophers are now in the hands of physicistsii. -
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. -
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. -
Loop Quantum Gravity: the First 25 Years Carlo Rovelli
Loop quantum gravity: the first 25 years Carlo Rovelli To cite this version: Carlo Rovelli. Loop quantum gravity: the first 25 years. Classical and Quantum Gravity, IOP Publishing, 2011, 28 (15), pp.153002. 10.1088/0264-9381/28/15/153002. hal-00723006 HAL Id: hal-00723006 https://hal.archives-ouvertes.fr/hal-00723006 Submitted on 7 Aug 2012 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. Loop quantum gravity: the first twenty five years Carlo Rovelli Centre de Physique Th´eorique de Luminy∗, Case 907, F-13288 Marseille, EU (Dated: January 27, 2011) I give a synthetic presentation of loop quantum gravity. I spell-out the aims of the theory and compare the results obtained with the initial hopes that motivated the early interest in this research direction. I give my own perspective on the status of the program and attempt of a critical evaluation of its successes and limits. I. INTRODUCTION The history of quantum gravity is full of great hopes later disappointed. I remember as a young student sitting in a major conference where a world-renowned physicists Loop gravity is not quite twenty-five years old, but announced that the final theory of quantum gravity and is getting close to such a venerable age: several basic everything had finally been found. -
Loop Quantum Gravity
QUANTUM GRAVITY Loop gravity combines general relativity and quantum theory but it leaves no room for space as we know it – only networks of loops that turn space–time into spinfoam Loop quantum gravity Carlo Rovelli GENERAL relativity and quantum the- ture – as a sort of “stage” on which mat- ory have profoundly changed our view ter moves independently. This way of of the world. Furthermore, both theo- understanding space is not, however, as ries have been verified to extraordinary old as you might think; it was introduced accuracy in the last several decades. by Isaac Newton in the 17th century. Loop quantum gravity takes this novel Indeed, the dominant view of space that view of the world seriously,by incorpo- was held from the time of Aristotle to rating the notions of space and time that of Descartes was that there is no from general relativity directly into space without matter. Space was an quantum field theory. The theory that abstraction of the fact that some parts of results is radically different from con- matter can be in touch with others. ventional quantum field theory. Not Newton introduced the idea of physi- only does it provide a precise mathemat- cal space as an independent entity ical picture of quantum space and time, because he needed it for his dynamical but it also offers a solution to long-stand- theory. In order for his second law of ing problems such as the thermodynam- motion to make any sense, acceleration ics of black holes and the physics of the must make sense. -
Quantum Gravity Past, Present and Future
Quantum Gravity past, present and future carlo rovelli vancouver 2017 loop quantum gravity, Many directions of investigation string theory, Hořava–Lifshitz theory, supergravity, Vastly different numbers of researchers involved asymptotic safety, AdS-CFT-like dualities A few offer rather complete twistor theory, tentative theories of quantum gravity causal set theory, entropic gravity, Most are highly incomplete emergent gravity, non-commutative geometry, Several are related, boundaries are fluid group field theory, Penrose nonlinear quantum dynamics causal dynamical triangulations, Several are only vaguely connected to the actual problem of quantum gravity shape dynamics, ’t Hooft theory non-quantization of geometry Many offer useful insights … loop quantum causal dynamical gravity triangulations string theory asymptotic Hořava–Lifshitz safety group field AdS-CFT theory dualities twistor theory shape dynamics causal set supergravity theory Penrose nonlinear quantum dynamics non-commutative geometry Violation of QM non-quantized geometry entropic ’t Hooft emergent gravity theory gravity Several are related Herman Verlinde at LOOP17 in Warsaw No major physical assumptions over GR&QM No infinity in the small loop quantum causal dynamical Infinity gravity triangulations in the small Supersymmetry string High dimensions theory Strings Lorentz Violation asymptotic Hořava–Lifshitz safety group field AdS-CFT theory dualities twistor theory Mostly still shape dynamics causal set classical supergravity theory Penrose nonlinear quantum dynamics non-commutative geometry Violation of QM non-quantized geometry entropic ’t Hooft emergent gravity theory gravity Discriminatory questions: Is Lorentz symmetry violated at the Planck scale or not? Are there supersymmetric particles or not? Is Quantum Mechanics violated in the presence of gravity or not? Are there physical degrees of freedom at any arbitrary small scale or not? Is geometry discrete i the small? Lorentz violations Infinite d.o.f. -
Can We Make Sense of Relational Quantum Mechanics?
Noname manuscript No. (will be inserted by the editor) Can we make sense of Relational Quantum Mechanics? Quentin Ruyant November 2017 Abstract The relational interpretation of quantum mechanics proposes to solve the measurement problem and reconcile completeness and locality of quantum mechanics by postulating relativity to the observer for events and facts, instead of an absolute \view from nowhere". The aim of this paper is to clarify this interpretation, and in particular, one of its central claims concern- ing the possibility for an observer to have knowledge about other observer's events. I consider three possible readings of this claim (deflationist, relation- ist and relativist), and develop the most promising one, relativism, to show how it fares when confronted with the traditional interpretative problems of quantum mechanics. Although it provides answers to some problems, I claim that there is currently no adapted locality criterion to evaluate whether the resulting interpretation is local or not. Keywords Relational Quantum Mechanics · Bell's theorem · Locality · Relativism Universit´eCatholique de Louvain 2 Quentin Ruyant Carlo Rovelli has proposed an interpretation of quantum mechanics, which he has dubbed relational quantum mechanics (RQM) (Rovelli, 1996; Smerlak Rovelli, 2007). Rovelli claims that this interpretation solves the measurement problem while preserving both the locality and completeness of quantum me- chanics, all this without additional structure nor many-worlds. This is a bold claim: how is this possible? By positing that the states quantum mechanics describes are relative to the observer rather than absolute. We should abandon the idea that there is a \view from nowhere", and all our worries will be put at ease. -
String Theory, Einstein, and the Identity of Physics: Theory Assessment in Absence of the Empirical
String theory, Einstein, and the identity of physics: Theory assessment in absence of the empirical Jeroen van Dongen Institute for Theoretical Physics Vossius Center for History of the Humanities and Sciences University of Amsterdam, Amsterdam, The Netherlands Abstract String theorists are certain that they are practicing physicists. Yet, some of their recent critics deny this. This paper argues that this conflict is really about who holds authority in making rational judgment in theoretical physics. At bottom, the conflict centers on the question: who is a proper physicist? To illustrate and understand the differing opinions about proper practice and identity, we discuss different appreciations of epistemic virtues and explanation among string theorists and their critics, and how these have been sourced in accounts of Einstein’s biography. Just as Einstein is claimed by both sides, historiography offers examples of both successful and unsuccessful non-empirical science. History of science also teaches that times of conflict are often times of innovation, in which novel scholarly identities may come into being. At the same time, since the contributions of Thomas Kuhn historians have developed a critical attitude towards formal attempts and methodological recipes for epistemic demarcation and justification of scientific practice. These are now, however, being considered in the debate on non-empirical physics. Introduction Theoretical high energy physics is in crisis. Many physicists may wish to deny this, but it is richly illustrated by the heated exchanges, charged manifestos and exclamations of despair in highly visible publications. For example, three prominent cosmologists, Anna Ijjas, Paul Steinhardt and Abraham Loeb, argued in the February 2017 issue of Scientific American that the long favoured model for the early universe, inflationary cosmology, has no data to support it and has gone through so many patch-ups that it is now beyond testability. -
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. -
Physics Needs Philosophy. Philosophy Needs Physics. Carlo Rovelli
Physics needs philosophy. Philosophy needs physics. Carlo Rovelli To cite this version: Carlo Rovelli. Physics needs philosophy. Philosophy needs physics.. Foundations of Physics, Springer Verlag, 2018, 48 (5), pp.481-491. 10.1007/s10701-018-0167-y. hal-01771743 HAL Id: hal-01771743 https://hal.archives-ouvertes.fr/hal-01771743 Submitted on 19 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. Physics needs philosophy. Philosophy needs physics. Carlo Rovelli Abstract Contrary to claims about the irrelevance of philosophy for science, I argue that philosophy has had, and still has, far more influence on physics than is commonly assumed. I maintain that the current anti-philosophical ideology has had damaging effects on the fertility of science. I also suggest that recent important empirical results, such as the detection of the Higgs particle and gravitational waves, and the failure to detect supersymmetry where many expected to find it, question the validity of certain philosophical assumptions common among theoretical physicists, inviting us to engage in a clearer philosophical reflection on scientific method. 1. Against Philosophy is the title of a chapter of a book by one of the great physicists of the last generation: Steven Weinberg, Nobel Prize winner and one of the architects of the Standard Model of elementary particle physics1.