International Loop Quantum Gravity Seminar

This is a seminar on research that takes place every Tuesday at 9am (US Central Time). Audio is distributed via telephone. Slides of the talks are posted in advance here. Talks are recorded and the audio posted here. Among the groups that participate live are PennState, Perimeter Institute, Marseille, AEI-Potsdam, Utrecht, UNAM-Mexico, FUW-Poland, CSIC-Madrid, UDELAR, Uruguay, UWO-Canada, UNB-Canada, Umass Dartmouth, Hamilton College, LSU. Others may join soon. Unfortunately, the phone bridge we have has a limited number of lines so we cannot open live participation to everyone. If your group wishes to participate, please write to pullin at Locally at LSU, we listen to the talks in 241 Nicholson Hall. You are welcome to join the mailing list.

Seminar Schedule Fall 06

Seminar Schedule Spring 07

Seminar Schedule Fall 07

Seminar Schedule Spring 08

Upcoming talk:

Seminars will restart in the fall of 2008.

Past Talks

Tuesday, May 6th
Jerzy Lewandowski

Title: LQC: unfrequently asked questions
PDF [85K] of the slides
Audio [.mp3 6MB]

Tuesday, April 22nd
Carlo Rovelli, Marseille

Title: Stepping out of Homogeneity in Loop Quantum Cosmology
PDF [122k] of the slides
Audio [.mp3 10MB]

Tuesday, April 8th
Laurent Freidel, Perimeter Institute

Title: Quantum gravity perspective on AdS/CFT
PDF [10M] of the slides
Audio [.aif 1MB] Audio [.mp3 89MB, complete]

Tuesday, Mar 25th
Kristina Giesel, Albert Einstein Institute

Title: Manifestly gauge invariant relativistic pertrubation theory
PDF [1.3M] of the slides
Audio [.aif 3MB] Audio [.wav 34MB, complete]

Tuesday, Feb 19th
Victor Taveras, PennState

Title: Improved effective equations in loop quantum cosmology
PDF [380k] of the slides
Audio [.mp3 7MB] of the slides

Tuesday, Feb 5th
Kirill Krasnov, University of Nottingham

Title: Self Dual Gravity
PDF [177k] of the slides
Audio [.mp3 10MB]

Tuesday, Jan 22nd
Madhavan Varadarajan, Raman Research Institute

Title: Quantum gravity and the information loss problem
PDF [1.5M] of the slides
Audio [.aif 4MB] Audio [.mp3 10MB, complete]

Tuesday, Nov 27th
Kevin Vandersloot, Portsmouth

Title: Schwarzschild interior with loop quantum effects
PDF [150K] of the slides
Audio [.wav 35MB] Audio [.aif 3.8MB] Audio [.mp3 9MB, complete]

Tuesday, Nov 13th
Garrett Lisi, FQXi

Title: A connection with everything.
PDF [2MB] of the slides
alternate PDF [8MB] of the slides
Audio [.wav 30MB] Audio [.aif 3MB] Audio [.mp3 7MB, complete]

Tuesday, Oct 30
Dan Christensen, UWO

Title: Computations involving SN, SF, QG and LGT.
PDF [600KB] of the slides

Audio [.wav 36MB] Audio [.aif 4MB]

Tuesday, Oct 16
David Sloan, PennState

Title: Strong gravity and the BKL conjecture
PDF [260KB] of the slides
Audio [.mp3 8MB] Audio [.aif 4MB] of the slides

Tuesday, Sep 18th (at 9:15 AM US Central time)
Jonathan Engle, Marseille

Title: The loop quantum gravity vertex: a proposal
PDF [260KB] of the slides
Audio [.wav 42MB] Audio [.aif 4MB]

Tuesday, Sep 4th (at 9:15 AM US Central time)
Johannes Tambornino, Aachen

Title: Relational observables and cosmological perturbation theory
PDF [860KB] of the slides
Audio [.wav 38MB] Audio [.aif 4MB]

Tuesday, May 15th
Laurent Freidel, Perimeter Institute

Title: Matter coupling to 3d quantum gravity and effective field theory I
PDF [10MB] of the slides
Audio [.mp3 65MB] Audio [.aif 6MB]

Tuesday, April 24th
Martin Bojowald, PennState

Title: The KITP program on quantum singularities (encore)
PDF [420K] of the slides
Audio [.mp3 12MB] Audio [.aif 6MB]

Tuesday, April 10th
Jose Antonio Zapata, UNAM Morelia

Title: Effective theories, continuum limit and background independence in LQG
PDF [ 370kb] of the slides
Audio [.mp3 53MB] Audio [.aif 4MB]

Tuesday, April 3rd
Lee Smolin, Perimeter Institute

Title: Emergent chiral excitations of quantum geometries: progress report
PDF of the slides [5.5MB]
Audio [.mp3 56MB] Audio [.aif 5MB]

Tuesday, March 27th
Jorge Pullin, Louisiana State

Title: Spherically symmetric loop quantum gravity
PDF of the slides [2MB]
Audio [.wav 26MB] Audio [.aif 5MB]

Tuesday, March 20th
Kirill Krasnov, Perimeter Institute

Title: Non metric gravity
PDF of the slides [128k]
Audio [.aif 6MB] Audio [.wav 4MB]

Tuesday, March 13th
Michele Arzano, Perimeter Institute

Title: Quantum fields and Noether charges for kappa-spacetime symmetries
PDF of the slides [268k]
Audio [.aif, 8MB] Audio [.wav, 4MB]

Abstract: After a brief review of the kappa-Poincare' Hopf algebra I will discuss how it can be used to describe the symmetries of kappa-Minkowski non-commutative spacetime. In particular I will focus on how apparent ambiguities in defining the action of translations can be overcome and how conserved Noether charges can be associated with such symmetries. Moving from the classical to the quantum field framework, I will first recall some older results on perturbative calculations in a path-integral approach for phi^4 scalar field theory. I will then show how recent work on the symplectic structure of classical kappa-fields suggests a new approach to canonical quantization of free fields and I will close with some remarks on the recent efforts and results on such topic.

Tuesday, March 6th
Alejandro Corichi, UNAM Morelia

Title: Relation between Schroedinger and polymer quantum mechanics
PDF of the slides [190k]
Audio [.aif, 8MB]

The relation between the ordinary Schroedinger representation and the so-called polymer representation will be explored. We will show how the polymer representation can be obtained as an appropriate limit of the Schroedinger one, and how we can recover this one by means of a precise renormalization procedure of the polymer quantum mechanics. Some examples will be discussed.

Tuesday February 27th
Abhay Ashtekar, PennState

Title: Diffeomorphism invariance in LQG
PDF [105K] of the slides
Audio [.wav, 39MB] Audio [.aif, 4MB]

Tuesday February 20th
Martin Bojowald, PennState

Title: KITP program on singularities summary
PDF [420K] of the slides
[there were problems with the audio, talk will be repeated 4/21]

Tuesday February 13th
Radu Roiban, PennState

Title: On the UV properties of N=8 supergravity: is it finite?

PDF [190K] of the slides
Audio [.wav, 38MB] Audio [.aif, 4MB]

Tuesday November 28th
Bianca Dittrich, Perimeter Institute

PDF [196K] of the slides
Audio [.wav, 29MB] Audio [.aif, 3MB] Title: Approximate observables

Tuesday November 7th
Alex Corichi, UNAM Morelia
Title: Quantum Isolated Horizons: The Planck regime

PDF [171K] of the slides
Audio [.wav, 33MB] Audio [.aif, 3MB]

Tuesday November 7th
Winston Fairbairn, Ecole Normale Lyon
Title: Matter in quantum BF theory

PDF [171K] of the slides
Audio [.wav, 34MB] Audio [.aif, 3MB]

Tuesday October 31st.
Guillermo Mena Marugan, CSIC, Madrid, Spain
Title: Inhomogeneous quantum cosmology: the Gowdy T3 model

PDF [430K] of the slides
Audio [.wav, 38MB] Audio [.aif, 4MB]

Tuesday October 17th.
Robert Oeckl, UNAM Morelia
Title: Quantum gravity, probabilities and general boundaries

PDF [700K] of the slides
Audio [.wav, 41MB] Audio [.aif, 4MB]

Abstract: In quantum field theory, knowing all transition amplitudes or the S-matrix is usually considered sufficient to specify the physical content of a theory. We are often accustomed to adopt a similar attitude when developing quantum gravity, concentrating on technical advances. I want to start this talk with a reminder that conceptual problems with the physical interpretation of quantities in quantum gravity remain open. In particular, I will review the problem of time and what I shall call the quantum cosmology problem. I will then review the general boundary formulation of quantum theory and explain in which sense it addresses these problems. The key conceptual step in this is a generalization of the probability rule of quantum theory and of the associated notion of probability conservation. Finally, I want to discuss the recent application of the general boundary formulation in the context of graviton amplitudes from a conceptual point of view.

Tuesday October 10th.
Fernando Barbero, CSIC, Madrid
Title: Perturbative treatment of 2+1 gravity with scalars

PDF [180K] of the slides
Audio [.wav, 31MB] Audio [.aif, 3MB]

Tuesday October 3rd.
Simone Speziale, Perimeter Institute
Title: Graviton propagator from loop quantum gravity II

PDF [1MB] of the slides
Audio [.wav, 40MB] Audio [.aif, 4MB]

Tuesday September 26th.
Carlo Rovelli, CPT Marseille
Title: Graviton propagator from loop quantum gravity

PDF [2MB] of the slides
Audio [.wav, 44MB] Audio [.aif, 4.6MB]

Tuesday September 19th.
Abhay Ashtekar, PennState
Title: Loop quantum gravity frequently asked questions

PDF [46kb] of the slides
Audio [.wav, 33MB] Audio [.aif, 3MB]

This is based on the MG11 invited talk

Tuesday June 27th.
Frank Saueressig, Utrecht
Title: Renormalization group improved cosmologies

PDF [223k] of the slides
Audio [.wav, 33MB] Audio [.aif, 3MB]

Title: Renormalization group improved cosmologies Abstract: It is generally believed that in the very early universe, at times smaller than the Planck time, quantum gravity effects play a crucial role. Since the physics in the Planck era prepares the initial conditions for the subsequent classical evolution of the universe it is desirable to gain some understanding of the quantum gravitational processes which took place immediately after the Big Bang. Based on the Einstein-Hilbert approximation of asymptotically safe quantum gravity we discuss a consistent renormalization group based framework which allows for the inclusion of such quantum gravitational effects into the cosmological field equations and applies to all stages of the cosmological evolution. The very early universe is found to contain a period of "oscillatory inflation". Lateron the cosmological evolution is classical and asymtotes to a de Sitter era at cosmologically late times.

Tuesday June 20th.
Andrzej Okolow, Warszaw
Title: Quantization of diffeomorphism invariant theories of connections with a non-compact structure group --- an example

PDF [250k] of the slides
Audio [.wma, 33MB] Audio [.wav, 48MB] Audio [.aif, 3.5MB]

A simple diffeomorphism invariant theory of connections with the non-compact structure group R of real numbers is quantized. The theory is defined on a four-dimensional 'space-time' by an action resembling closely the self-dual Plebanski action for general relativity. The space of quantum states is constructed by means of projective techniques by Kijowski. Except this point the applied quantization procedure is based on Loop Quantum Gravity methods.

Tuesday June 13th.
No talk.

Tuesday June 6th.
Parampreet Singh (PennState).
Title: The Big Bang and Loop Quantum Cosmology

PDF [1 MB] of the slides
Audio [.wav, 35MB] Audio [.aif, 3.7MB] of the talk of the talk

The talk deals with the recent developments in homogeneous and isotropic loop quantum cosmology on the Planck scale physics near the Big Bang. By constructing the physical Hilbert space, Dirac observables and physical semi-classical states definite and robust predictions about quantum nature of big bang can be made. The analysis leads to a prediction that the current, classical, expanding phase of the Universe is deterministically joined to a contracting phase by a quantum gravitational bridge. Quantum geometric effects at Planck scales make gravity replusive replacing big bang singularity with a big bounce. Slides will be posted here on Monday. Audio will be posted after the talk.