Lee Smolin—Curriculum Vita July 2017
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Emergence and Phenomenology in Quantum Gravity
Emergence and Phenomenology in Quantum Gravity by Isabeau Premont-Schwarz´ A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Physics Waterloo, Ontario, Canada, 2010 © Isabeau Premont-Schwarz´ 2010 AUTHOR’S DECLARATION I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii AUTHORSHIP STATEMENT This thesis is based on the following five articles: • A. Hamma, F. Markopoulou, I. Pr´emont-Schwarz and S. Severini, “Lieb-Robinson bounds and the speed of light from topological order,” Phys. Rev. Lett. 102 (2009) 017204 [arXiv:0808.2495 [quant-ph]]. • I. Pr´emont-Schwarz ,A. Hamma, I. Klich and F. Markopoulou, “Lieb-Robinson bounds for commutator-bounded operators ,” Phys. Rev. A 81, 040102(R) (2010) .[arXiv:0912.4544 [quant-ph]]. • I. Pr´emont-Schwarz and J. Hnybida, “Lieb-Robinson bounds with dependence on interaction strengths, ” [arXiv:1002.4190 [math-ph]]. • L. Modesto and I. Pr´emont-Schwarz, “Self-dual Black Holes in LQG: Theory and Phenomenology,” Phys. Rev. D 80, 064041 (2009) [arXiv:0905.3170 [hep-th]]. • S. Hossenfelder, L. Modesto and I. Pr´emont-Schwarz, “A model for non-singular black hole collapse and evaporation ,” Phys. Rev. D 81, 044036 (2010) [arXiv:0912.1823 [gr-qc]]. I did the majority of the work in the first article, but the project was initiated by Fotini Markopoulou-Kalamara and Alioscia Hamma and the manuscript was mostly written by Alioscia Hamma. -
Effective Field Theory from Spin Foam Models :3D Example
Effective field theory from spin Foam models :3d example Laurent Freidel Pennstate 2007 Background independent Loop Quantum Gravity in a nutshell Background independence: what the quantum geometry is at Planck scale cannot be postulated its needs to be determined dynamically •Hamiltonian quantisation: gravity is a gauge theory 2 SU(2) Yang-mills phase space (A,E) + constraints i1 (Γ, j , i ) (15) •Kinematical Hilbert space is spannede v by j1 j5 j2 spin network: graph colored by su(2) rep j6 j4 i4 Wave function i3 Ψ(Γ,je,iv)(A) i2 j3 (16) •Eigenstates of Geometrical operators, Area, Vol = trj(h (A)) (17) discrete spectra quantized space◦ geometry s’ 2 •Dynamics:Area !encodedΨΓ,je,i vin= spin8πγ foamlP modelsje(j eallowing+ 1) ΨΓ ,jthee,iv (18) e R Γ + ... computation of transition amplitudes∈!∪ "between Spin networks states: quantum spacetime geometry s 2 Area!Ψ(Γ,je,iv) = 8πγlP je(je + 1) Ψ(Γ,je,iv) (19) # e R Γ ( ∈!∪ " $ %& ' 3 2 VolΨΓ,je,iv = 8πγlP vje,iv ΨΓ,je,iv (20) # v R Γ ( * ∈!∪ ) F (A) E (21) ∝ Area(! H) = A (22) H = tr([E, E]F (A)) (23) Hj(i) (24) i ! i S(g) Dg e lP (25) + K (j) k (l d ) (26) F ∝ F P j ! k [Xi , Xj] = ilP #ijkX (27) m sin(κm)/κ (28) → S3 SU(2) (29) ∼ X ∂ (30) ∼ P 2 (Γ, je, iv) (15) Ψ(Γ,je,iv)(A) (16) v v Ue Pe + [Ωe, Pe] = 0 (0.32) = trj(h (A)) (17) ◦ ∂!e=v 2 S = tr(XeGe) (0.33) Area!ΨΓ,je,iv = 8πγlP je(je +T1ra)nsΨitioΓn,jaem,ipvlitudes between spin network state(1s a8)re defined by e e R Γ s, s! = A[ ], (11) ∈ ∪ ! "phys F ! " ! F:s→s! v v ! δXe = Ue Φwhvere the[nΩotaeti,onΦanvtic]ip=ates t0he interpretation of such amplitudes as defining the physical (0.34) scala−r product. -
What Can We Learn from Shape Dynamics? International Loop Quantum Gravity Seminar
What can we learn from shape dynamics? International Loop Quantum Gravity Seminar Tim A. Koslowski University of New Brunswick, Fredericton, NB, Canada November 12, 2013 Tim A. Koslowski (UNB) What can we learn from shape dynamics? November 12, 2013 1 / 19 Outline 1 Motivation from 2+1 diemsnional qunatum gravity to consider conformal evolution as fundamental 2 Conformal evolution is different from spacetime (i.e. abandon spacetime) 3 Generic dynamical emergence of spacetime in the presence of matter (i.e. regain spacetime) Tim A. Koslowski (UNB) What can we learn from shape dynamics? November 12, 2013 2 / 19 Introduction and Motivation Tim A. Koslowski (UNB) What can we learn from shape dynamics? November 12, 2013 3 / 19 Motivation Canonical metric path integral in 2+1 (only known metric path integral) ab p necessary: 2+1 split and CMC gauge condition gabπ − t g = 0 R 2 ab R ab a pπ c i dtd x(_gabπ −S(N)−H(ξ)) Z = [dgab][dπ ][dN][dξ ]δ[ g − t]δ[F ] det[FP ]e R 2 A R A i dtd x(_τAp −Vo(τ;p;t)) = [dτA][dp ]e [Carlip: CQG 12 (1995) 2201, Seriu PRD 55 (1997) 781] where: τA are Teichm¨ullerparameters, Vo(τ; p; t) denotes on-shell volume, which depends explicitly on time t ) QM on Teichm¨ullerspace, phys. Hamilt. Vo(τ; p; t) [Moncrief: JMP 30 (1989) 2907] Fradkin-Vilkovisky theorem: [cf. Henneaux/Teitelboim: \Quantization of Gauge Systems"] \Partition function depends on gauge fixing cond. only through the gauge equivalence class of gauge fixing conditions." for a discussion and some examples of non-equivalence [see Govaerts, Scholtz: J.Phys. -
The Metaphysical Baggage of Physics Lee Smolin Argues That Life Is More
The Metaphysical Baggage of Physics Lee Smolin argues that life is more fundamental than physical laws. BY MICHAEL SEGAL ILLUSTRATION BY LOUISA BERTMAN JANUARY 30, 2014 An issue on tme would not be complete without a conversaton with Lee Smolin. High school dropout, theoretcal physicist, and founding member of the Perimeter Insttute for Theoretcal Physics in Waterloo, Canada, Smolin’s life and work refect many of the values of this magazine. Constantly probing the edges of physics, he has also pushed beyond them, into economics and the philosophy of science, and into popular writng. Not one to shy away from a confrontaton, his 2008 bookThe Trouble with Physicstook aim at string theory, calling one of the hotest developments in theoretcal physics of the past 50 years a dead end. In his thinking on tme too, he has taken a diferent tack from the mainstream, arguing that the fow of tme is not just real, but more fundamental than physical law. He spoke to me on the phone from his home in Toronto. How long have you been thinking about tme? The whole story starts back in the ’80s when I was puzzling over the failure of string theory to uniquely tell us the principles that determine what the laws of physics are. I challenged myself to invent a way that nature might select what the laws of physics turned out to be. I invented a hypothesis called Cosmological Natural Selecton, which was testable, which made explicit predictons. This wasn’t my main day job; my main day job was working on quantum gravity where it’s assumed that tme is unreal, that tme is an illusion, and I was working, like anybody else, on the assumpton that tme is an illusion for most of my career. -
A Singing, Dancing Universe Jon Butterworth Enjoys a Celebration of Mathematics-Led Theoretical Physics
SPRING BOOKS COMMENT under physicist and Nobel laureate William to the intensely scrutinized narrative on the discovery “may turn out to be the greatest Henry Bragg, studying small mol ecules such double helix itself, he clarifies key issues. He development in the field of molecular genet- as tartaric acid. Moving to the University points out that the infamous conflict between ics in recent years”. And, on occasion, the of Leeds, UK, in 1928, Astbury probed the Wilkins and chemist Rosalind Franklin arose scope is too broad. The tragic figure of Nikolai structure of biological fibres such as hair. His from actions of John Randall, head of the Vavilov, the great Soviet plant geneticist of the colleague Florence Bell took the first X-ray biophysics unit at King’s College London. He early twentieth century who perished in the diffraction photographs of DNA, leading to implied to Franklin that she would take over Gulag, features prominently, but I am not sure the “pile of pennies” model (W. T. Astbury Wilkins’ work on DNA, yet gave Wilkins the how relevant his research is here. Yet pulling and F. O. Bell Nature 141, 747–748; 1938). impression she would be his assistant. Wilkins such figures into the limelight is partly what Her photos, plagued by technical limitations, conceded the DNA work to Franklin, and distinguishes Williams’s book from others. were fuzzy. But in 1951, Astbury’s lab pro- PhD student Raymond Gosling became her What of those others? Franklin Portugal duced a gem, by the rarely mentioned Elwyn assistant. It was Gosling who, under Franklin’s and Jack Cohen covered much the same Beighton. -
Shape Dynamics
Shape Dynamics Tim A. Koslowski Abstract Barbour’s formulation of Mach’s principle requires a theory of gravity to implement local relativity of clocks, local relativity of rods and spatial covariance. It turns out that relativity of clocks and rods are mutually exclusive. General Relativity implements local relativity of clocks and spatial covariance, but not local relativity of rods. It is the purpose of this contribution to show how Shape Dynamics, a theory that is locally equivalent to General Relativity, implements local relativity of rods and spatial covariance and how a BRST formulation, which I call Doubly General Relativity, implements all of Barbour’s principles. 1 Introduction A reflection on Mach’s principle lead Barbour to postulate that rods and spatial frames of reference should be locally determined by a procedure that he calls “best matching,” while clocks should be locally determined by what he calls “objective change.” (For more, see [1].) More concretely, Barbour’s principles postulate lo- cal time reparametrization invariance, local spatial conformal invariance and spatial covariance. The best matching algorithm for spatial covariance and local spatial conformal invariance turns out to be equivalent to the imposition of linear diffeo- morphism and conformal constraints Z Z 3 ab 3 H(x) = d xp (Lx g)ab; C(r) = d xr p; (1) S S Tim A. Koslowski Perimeter Institute for Theoretical Physics, 31 Caroline St. N, Waterloo, Ontario, Canada New address: Department of Mathematics and Statistics, University of New Brunswick Fredericton, New Brunswick E3B 5A3, Canada e-mail: [email protected] 1 2 Tim A. -
Covariant Phase Space for Gravity with Boundaries: Metric Vs Tetrad Formulations
Covariant phase space for gravity with boundaries: metric vs tetrad formulations J. Fernando Barbero G.c,d Juan Margalef-Bentabola,c Valle Varob,c Eduardo J.S. Villaseñorb,c aInstitute for Gravitation and the Cosmos and Physics Department. Penn State University. PA 16802, USA. bDepartamento de Matemáticas, Universidad Carlos III de Madrid. Avda. de la Universidad 30, 28911 Leganés, Spain. cGrupo de Teorías de Campos y Física Estadística. Instituto Gregorio Millán (UC3M). Unidad Asociada al Instituto de Estructura de la Materia, CSIC, Madrid, Spain. dInstituto de Estructura de la Materia, CSIC, Serrano 123, 28006, Madrid, Spain E-mail: [email protected], [email protected], [email protected], [email protected] Abstract: We use covariant phase space methods to study the metric and tetrad formula- tions of General Relativity in a manifold with boundary and compare the results obtained in both approaches. Proving their equivalence has been a long-lasting problem that we solve here by using the cohomological approach provided by the relative bicomplex framework. This setting provides a clean and ambiguity-free way to describe the solution spaces and associated symplectic structures. We also compute several relevant charges in both schemes and show that they are equivalent, as expected. arXiv:2103.06362v2 [gr-qc] 14 Jun 2021 Contents I Introduction1 II The geometric arena2 II.1 M as a space-time2 II.2 From M-vector fields to F-vector fields3 II.3 CPS-Algorithm4 IIIGeneral Relativity in terms of metrics5 IV General relativity in terms of tetrads8 V Metric vs Tetrad formulation 13 V.1 Space of solutions 13 V.2 Presymplectic structures 14 VI Conclusions 15 A Ancillary material 16 A.1 Mathematical background 16 A.2 Some computations in the metric case 19 A.3 Some tetrad computations 21 Bibliography 22 I Introduction Space-time boundaries play a prominent role in classical and quantum General Relativity (GR). -
Sabine Hossenfelder on “The Case Against Beauty in Physics” Julia
Rationally Speaking #211: Sabine Hossenfelder on “The case against beauty in physics” Julia: Welcome to Rationally Speaking, the podcast where we explore the borderlands between reason and nonsense. I'm your host, Julia Galef, and I'm here with today's guest, Sabine Hossenfelder. Sabine is a theoretical physicist, focusing on quantum gravity. She's a research fellow at the Frankfurt Institute for Advanced Studies, and blogs at Back Reaction. She just published the book, "Lost in Math: How Beauty Leads Physics Astray." "Lost in Math” argues that physicists, in at least certain sub-fields, evaluate theories based heavily on aesthetics, like is this theory beautiful? Instead of simply, what does the evidence suggest is true? The book is full of interviews Sabine did with top physicists, where she tries to ask them: what's the justification for this? Why should we expect beauty to be a good guide to truth? And, spoiler alert, ultimately, she comes away rather unsatisfied with the answers. So, we're going to talk about "Lost in Math" and the case for and against beauty in physics. Sabine, welcome to the show. Sabine: Hello. Julia: So, probably best to start with: what do you mean by beauty, in this context? And is it closer to a kind of “beauty is in the eye of the beholder” thing, like, every physicist has their own sort of aesthetic sense? Or is more like there's a consensus among physicists about what constitutes a beautiful theory? Sabine: Interestingly enough, there's mostly consensus about it. Let me put ahead that I will not try to tell anyone what beauty means, I am just trying to summarize what physicists seem to mean when they speak of beauty, when they say “that theory is beautiful.” There are several ingredients to this sense of beauty. -
Arxiv:Gr-Qc/0303027 V1 6 Mar 2003
MATTERS OF GRAVITY The newsletter of the Topical Group on Gravitation of the American Physical Society Number 21 Spring 2003 Contents GGR News: GGR Activities, by Richard Price ....................... 3 We hear that... by Jorge Pullin ........................ 4 Institute of Physics Gravitational Physics Group, by Elizabeth Winstanley . 5 Center for Gravitational Wave Astronomy, by Mario D´ıaz .......... 6 Research Briefs: LIGO’s first preliminary science run, by Gary Sanders ........... 8 Quantization of area: the plot thickens, by John Baez ............ 12 Convergence of G Measurements – Mysteries Remain, by Riley Newman . 16 Conference reports: Brane world gravity, by Elizabeth Winstanley ................. 18 Massive black holes focus session, by Steinn Sigurdsson ........... 19 GWDAW 2002, by Peter Saulson ....................... 21 Source simulation focus session, by Pablo Laguna .............. 23 RRI workshop on loop quantum gravity, by Fernando Barbero ........ 25 Lazarus/Kudu Meeting, by Warren G. Anderson ............... 27 arXiv:gr-qc/0303027 v1 6 Mar 2003 Editor Jorge Pullin Department of Physics and Astronomy Louisiana State University 202 Nicholson Hall Baton Rouge, LA 70803-4001 Phone/Fax: (225)578-0464 Internet: [email protected] WWW: http://www.phys.lsu.edu/faculty/pullin ISSN: 1527-3431 1 Editorial Not much to report here. This newsletter is a bit late, since I wanted to wait till LIGO could report on its first science run. I want to encourage the readership to suggest topics for articles in MOG. In the last few issues articles were solicited by myself. This is not good for keeping the newsletter balanced. Either contact the relevant correspondent or me directly. The next newsletter is due September 1st. -
Pos(Rio De Janeiro 2012)002 † ∗ [email protected] Speaker
Loop Quantum Gravity and the Very Early Universe PoS(Rio de Janeiro 2012)002 Abhay Ashtekar∗† Institute for Gravitational Physics and Geometry, Physics Department, Penn State, University Park, PA 16802, U.S.A. E-mail: [email protected] This brief overview is addressed to beginning researchers. It begins with a discussion of the distinguishing features of loop quantum gravity, then illustrates the type of issues that must be faced by any quantum gravity theory, and concludes with a brief summary of the status of these issues in loop quantum gravity. For concreteness the emphasis is on cosmology. Since several introductory as well as detailed reviews of loop quantum gravity are already available in the literature, the focus is on explaining the overall viewpoint and providing a short bibliography to introduce the interested reader to literature. 7th Conference Mathematical Methods in Physics - Londrina 2012, 16 to 20 April 2012 Rio de Janeiro, Brazil ∗Speaker. †A footnote may follow. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ Loop Quantum Gravity Abhay Ashtekar Loop quantum gravity (LQG) is a non-perturbative approach aimed at unifying general rela- tivity and quantum physics. Its distinguishing features are: i) Background independence, and, ii) Underlying unity of the mathematical framework used to describe gravity and the other three basic forces of nature. It is background independent in the sense that there are no background fields, not even a space-time metric. All fields —whether they represent matter constituents, or gauge fields that mediate fundamental forces between them, or space- time geometry itself— are treated on the same footing. -
Vacuum GR in Chang--Soo Variables: Hilbert Space Structure In
Vacuum GR in Chang–Soo variables: Hilbert space structure in anisotropic minisuperspace Eyo Eyo Ita III January 20, 2009 Department of Applied Mathematics and Theoretical Physics Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road Cambridge CB3 0WA, United Kingdom [email protected] Abstract In this paper we address the major criticism of the pure Kodama state, namely its normalizability and its existence within a genuine Hilbert space of states, by recasting Ashtekar’s general relativity into set of new variables attributed to Chang–Soo/CDJ. While our results have been shown for anisotropic minisuperspace, we reserve a treat- ment of the full theory for a following paper which it is hoped should finally bring this issue to a close. We have performed a canonical treat- ment of these new variables from the level of the classical/quantum algebra of constraints, all the way to the construction of the Hilbert space of states, and have demonstrated their relevance to the principle arXiv:0901.3041v1 [gr-qc] 20 Jan 2009 of the semiclassical-quantum correspondence. It is hoped that these new variables and their physical interpretation should provide a new starting point for investigations in classical and quantum GR and in the construction of a consistent quantum theory. 1 1 Introduction The main focus of the present paper to establish a new Hilbert space struc- ture for quantum gravity by recasting general relativity in terms of a set of new variables. The traditional approach in loop variables utilizes the spin network states, which have been rigorously shown to meet the requirements of a Hilbert space [1]. -
The Black Hole Information Paradox and Relative Locality Arxiv
The black hole information paradox and relative locality Lee Smolin∗ Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2J 2Y5, Canada October 24, 2018 Abstract We argue that the recently proposed principle of relative locality offers a new way to resolve the black hole information puzzle. Contents 1 Introduction 2 2 A possible resolution of the BH information paradox 5 2.1 The usual statement of the black hole information paradox . 5 2.2 The point of view of an observer at the formation of the black hole . 6 2.3 The point of view of the observer at the final evaporation . 7 arXiv:1108.0910v1 [gr-qc] 3 Aug 2011 3 Conclusion 8 ∗[email protected] 1 1 Introduction The black hole information paradox1 has challenged theorists of quantum gravity since first proposed by Hawking[1]. One much discussed view has been that some kind of non- locality is required to resolve the puzzle[4]. A recently proposed framework for quantum gravity phenomenology, called relative locality[5, 6, 7, 8] does feature a very controlled form of non-locality. We argue here that the kind and scale of non-locality implied by relative locality is sufficient to resolve the black hole information paradox. Whatever the quantum theory of gravity that describes nature is, we have good reason to suspect that it involves a dissolving of the usual notion of locality in spacetime. It is therefore of interest to characterize exactly how non-locality first appears in physical phenomena in experimental regimes where one of the Planck scales becomes evident.