INSTYTUT FIZYKI TEORETYCZNEJ
WYDZIAŁ FIZYKI UNIWERSYTETU WARSZAWSKIEGO

Conferences

Contact

Chair of Theory of
Relativity and Gravitation,
Institute of Theoretical Physics,
University of Warsaw
ul. Pasteura 5,
02-093 Warsaw, Poland

Phone: (+48 22) 5532245
Fax: (+48 22) 6219475

List of talks given by members of the Department of the Theory of Relativity and Gravitation in a reverse chronological order.




Fifth Tux workshop on Quantum Gravity, February 13-17, 2017, Tux, Austria


Jerzy Lewandowski
Lorentz and deformed Poincare symmetry in curved spacetime
             Mehdi Assanioussi
Approximation methods for the dynamics in deparametrized LQG




Quantum Spacetime '17, January 30-February 3, 2017, Porto, Portugal


Jerzy Lewandowski
Canonical Loop Quantum Gravity: available framework




Nonlinearity & Geometry, January 20-23, 2017, Warszawa


Jacek Tafel (invited speaker)
Covariant description of isothermic surfaces




37th Winter School Geometry and Physics, January 14-21, 2017, Srni, Czech Republic


Jerzy Lewandowski
Non-expanding horizons including near horizon geometries as related subject




Gravitational waves. Mathematical, computational, astrophysical and quantum approaches, December 9-11, 2016, Warszawa


Andrzej Trautman
Gravitational waves: what little I remember of my early work on the subject
Jacek Tafel
Optical geometries and algebraically special spacetimes




The 3rd Conference of the Polish Society on Relativity, September 25-29, 2016, Kraków, Poland


Ilkka Makinen
Time evolution in deparametrized models of loop quantum gravity




The 3rd BNU International Summer School on Quantum Gravity, August 15-20, 2016, Beijing Normal University (BNU), Beijing, China


Jerzy Lewandowski
Canonical Loop Quantum Gravity (lecture course)




21st International Conference on General Relativity and Gravitation (GR21), July 10-15, 2016, New York City, USA


Jerzy Lewandowski
When near horizon geometries meet non-expanding horizons
Canonical Loop Quantum Gravity





Noncommutative geometry, quantum symmetries and quantum gravity II - XXXVII Max Born Symposium hosting 2016 WG3 Meeting of COST Action MP 1405, July 4-7, 2016, Wrocław, Poland


Jerzy Lewandowski
Canonical Loop Quantum Gravity - Status Report (plenary talk)




The Helsinki Workshop on Quantum Gravity, June 1-3, 2016, Helsinki, Finland


Ilkka Makinen
Scalar field as a physical time variable in loop quantum gravity


 

Carlo Fest, May 23-27, 2016, Luminy and Jardin du Pharo, Marseille, France


Jerzy Lewandowski and Chun-Yen Lin
From The Quantum Scalar Constraint To The Minkowski Theorem




Fourth Tux workshop on Quantum Gravity, February 15-19, 2016, Tux, Austria


Ilkka Makinen
The Hamiltonian operator in deparametrized loop quantum gravity




International Loop Quantum Gravity Seminar


Jerzy Lewandowski
New applications for LQG
October 28, 2014

Antonia Zipfel
Linking canonical and covariant LQG
April 15, 2014

Norbert Bodendorfer
Black hole entropy from loop quantum gravity: Generalized theories and higher dimensions
October 1, 2013

Emanuele Alseci
Quantum reduced loop gravity
March 12, 2013




Workshop on Noncommutative Field Theory and Gravity, September 22-26


Jerzy Lewandowski
Non-commutative structure of spacetime from classical general relativity




XXXV Max Born Symposium, September 7-12, 2015, Wrocław, Poland


Norbert Bodendorfer
Symmetry reductions in loop quantum gravity based on classical gauge fixings
Ilkka Makinen
A new Hamiltonian operator for loop quantum gravity




Quantum Gravity Meeting, July 20 - 23, 2015, University of Rome La Sapienza, Rome, Italy


Emanuele Alesci
 

Jerzy Lewandowski





Fourteenth Marcel Grossmann Meeting - MG14, July 12-18, 2015, University of Rome La Sapienza, Rome, Italy


Emanuele Alesci
Quantum Reduced Loop Gravity

Mehdi Assanioussi
Recent developments in quantum dynamics of LQG

Jerzy Lewandowski
Canonical LQG

Jędrzej Świeżewski
Quantum Reduction To Spherical Symmetry

Andrea Dapor
Coherent State Operators in Loop Quantum Gravity

Andrea Dapor
Coherent State Operators in Loop Quantum Gravity

Ilkka Mäkinen
Loop Quantum Gravity with a Scalar Field: A Physical Hamiltonian Operator




LOOPS 15, July 6-10, 2015, Erlangen, Germany


Emanuele Alesci
Quantum Reduced Loop Gravity

Norbert Bodendorfer
Higher dimensional connection dynamics and applications

Mehdi Assanioussi
New perspectives for canonical LQG dynamics

Jerzy Lewandowski
New applications for canonical LQG

Jędrzej Świeżewski
Using radial gauge to define quantum spherical symmetry

Wojciech Kamiński
Gravity in the radial gauge

Antonia Zipfel
A stability criterion for coherent states




GENERAL RELATIVITY AND GRAVITATION: A CENTENNIAL PERSPECTIVE, June 7-12, 2015, Pennsylvania, USA


Jerzy Lewandowski
New Results in the Canonical Loop Quantum Gravity




Third EFI winter conference of quantum gravity, February 16-20, 2015, Tux, Austria


Mehdi Assanioussi
Deparametrized gravity with a scalar field & Beyond: A new quantum Hamiltonian operator for LQG

Norbert Bodendorfer
A quantum reduction to Bianchi I models in LQG

Andrea Dapor
Rainbows from Quantum Gravity

Marcin Kisielowski
First-order Dipole Cosmology

Ilkka Mäkinen
Coherent state operators in loop quantum gravity

Tomasz Pawłowski
Interfacing loop quantum gravity with cosmology

Jedrzej Świeżewski
Radial Gauge - reduced phase space of General Relativity

 



Conceptual and Technical Challenges for Quantum Gravity, Rome, Italy, September 8-12, 2014


Jerzy Lewandowski
Conceptual and technical chalanges of LQG
Friday

Emanuele Alesci
Quantum Reduced Loop Gravity
Tuesday
Abstract
Quantum Reduced Loop Gravity is a recently proposed model to address the quantum dynamics of the early Universe. We will review it’s semiclassical limit, a link with LQC and how the QRLG could simplify the analysis of the dynamics in the full theory.

 



Frontiers of fundamental physics 14, Marseille, France, July 15-18, 2014


Jerzy Lewandowski
Background independence of GR and in LQG
July 17
Abstract
The physical meaning of the diffeomorphisms in the general relativistic theories will be discussed, the issues of time evolution in terms of the Dirac observables and physical Hamiltonian will be addressed. New proposals for geometric deparametrization will be presented. The quantum part of the lecture will concern the canonical LQG. New, improved formulations of the quantum Hamiltonian will be proposed. New applications for LQG will be offered. Original results that will be presented in this lecture were obtained in collaboration with: Dapor, Duch, Kaminski, Swiezewski, Alesci, Assanioussi, Dziendzikowski and Sahlmann.

Jerzy Lewandowski
Exact formulation of the quantum scalar constraint in LQG
July 18
Abstract
Several new applications for LQG will be presented. The first one is a new quantum representation of the gravitational scalar constraint. In this representation, for the first time in the literature, the quantum C(N) itself preserves the Hilbert space for every laps function N. Owing to that property, solutions to the quantum constraints of vacuum GR can be well defined by the spectral decomposition and set a physical Hilbert space. Our representation admits also a new proposal of the quantum physical Hamiltonian of the Rovelli-Smolin model of gravity coupled to the mass-less Klein-Gordon time field. The third application we propose, is a new operator for the quantum Hamiltonian of the Klein-Gordon Scalar field coupled to LQG. Our new framework captures the degrees of freedom of the scalar field lost in the framework in which time is deparametrized by the scalar field.

Jędrzej Świeżewski
Observers diffeomorphism-invariant description of a general relativistic system
July 18
Abstract
I will present a construction of observables following naturally from an introduction of an observer into a relativistic theory. The observables are invariant under a large class of spatial diffeomorphisms. I will discuss the description of the theory in terms of spatial-diffeomorphism-invariant degrees of freedom. The talk will be based on P. Duch, W. Kaminski, J. Lewandowski and J. Swieżewski, Observables for General Relativity related to geometry, arXiv:1403.8062 [gr-qc].

Mehdi Assanioussi
Application of the Curvature operator: Matrix Elements and properties of the new Hamiltonian Constraint operator in LQG
July 18
Abstract
This talk is a presentation of an ongoing work based on [1] of the same authors. In this work we study properties of the Lorentzian Hamiltonian constraint operator expressed using the curvature operator introduced in [1] and we evaluate its action.
[1] E. Alesci, M. Assanioussi and J. Lewandowski, A curvature operator for LQG, Submitted for publication in Phys. Rev. D [arxiv: 1403.3190v2].

Andrea Dapor
Coherent State Operators in Cosmology and Gravity
July 18
Abstract
Coherent States (CS) are widely used in physics, and quantum gravity is not an exception. However, the application of CS in the construction of operators is rather unexplored in the areas of quantum gravity and quantum cosmology. In my talk, I will present how CS can be used to define “coherent state operators” via a procedure known as “coherent state quantization” [1]. This procedure produces operators with inbuilt good semiclassical properties, while at the same time preserving typical quantum attributes (e.g., discreteness of spectra). Examples of such coherent state quantization will cover: (1) operators on homogeneous isotropic quantum cosmology [2] (based on the affine group); (2) possible extensions to Bianchi I case; (3) simple operators on L2(SU(2),dμH).
[1] S. Twareque Ali, J.-P. Antoine and J.-P. Gazeau, Coherent States, Wavelets, and Their Generalizations, Springer-Verlag (2013)
[2]H. Bergeron, A. Dapor, J.-P. Gazeau and P. Malkiewicz, Smooth big bounce from affine quantization/, Phys. Rev. D 89, 083522 (2014)

Antonia Zipfel
Plebanski sectors of the Lorentzian 4-simplex amplitude
July 15
Abstract
The spin foam model is based on a BF-type action restricted by the simplicity constraint. However, the solutions to the simplicity constraint fall into five different sectors. In [1,2] it was argued that a certain mixing of these sectors and the freedom of choosing a tetrad orientation generates undesired terms in the asymptotic of the Euclidean EPRL-model and can be cured by an additional constraint. We here show that this is also the case for the Lorentzian model. This is joint work with J. Engle.
[1] J. Engle, A spin-foam vertex amplitude with the correct semiclassical limit, Phys.Lett. B724 (2013) 333-337.
[2] J. Engle, A proposed proper EPRL vertex amplitude, Phys.Rev D87 (2012) 084048.

Emanuele Alesci
Quantum Reduced Loop Gravity
July 18
Abstract
We will review the current developments of Quantum Reduced Loop Gravity, a recently proposed model to address the quantum dynamics of the early Universe. In particular we will discuss its semiclassical limit, a link with LQC and will review how the QRLG technique naturally selects states based on coherent intertwiners that could simplify the analysis of the dynamics in the full theory.




XXXIII Max Born Symposium, Wrocław, Poland, July 6-10, 2014


Norbert Bodendorfer
The Verlinde formula and higher-dimensional black hole entropy
July 8

Jerzy Lewandowski
The issues and advances in LQG
July 9




DPG-Frühjahrstagung 2014, Berlin, Germany


Norbert Bodendorfer
Loop quantum gravity in higher dimensions and black hole entropy
March 17, 2014, Berlin




4th Central European Relativity Seminar, Vienna, Austria, February 27 - March 1, 2014


Norbert Bodendorfer
Loop quantum gravity in higher dimensions and black hole entropy
March 1, 2014, Tux

Jędrzej Świeżewski
Geometrical observables for General Relativity related to distances and angles
February 27, 2014, Tux
Abstract
In my talk, I will present the progress obtained in a certain approach to constructing diffeomorphism invariant observables for General Relativity possessing a direct geometrical interpretation. After introducing the observables I will discuss their Poisson algebra. A possibility of reducing the phase space of General Relativity to diffeomorphism invariant degrees of freedom will be highlighted.




New trends in Teichmuller theory and mapping class groups, Oberwolfach (MFO), Germany, February 9-17, 2014


Piotr Sułkowski
Chord diagrams, random matrices, and topological recursion




Second EFI winter conference on canonical and covariant LQG, Tux, Austria, February 10-14, 2014


Jerzy Lewandowski
Deparametrising GR with distances and angles and interpreting it geometrically
February 14, 2014, Tux

Jędrzej Świeżewski
Deparametrising GR with distances and angles
February 14, 2014, Tux

Antonia Zipfel
Plebanski sectors of the Lorentzian 4-simplex amplitude
February 14, 2014, Tux

Norbert Bodendorfer
Some comments and open questions on black hole entropy from LQG
February 13, 2014, Tux

Wojciech Kaminski
Surprises in the asymptotic analysis of the spin-foam vertex
February 10, 2014, Tux




Symposium of the Institute for Theoretical Physics, Warsaw, Poland, December 13-14, 2013


Piotr Sułkowski
On dualities in string theory




II Konwencja Badań i Innowacji, Warsaw, Poland, November 29, 2013


Piotr Sułkowski
Quantum Fields and Knot Homologies
Nobember 29, 2013, Warsaw




Sympozjum KRAB, Warsaw, Poland, November 28, 2013


Piotr Sułkowski
Quantum Fields and Knot Homologies
Nobember 28, 2013, Warsaw




Loops 13, Perimeter Institute, Waterloo, Canada, July 22-26, 2013


Marcin Kisielowski
On first­order contributions to the Dipole Cosmology transition amplitude
July 26, 2013, Waterloo
Abstract
We discuss some first-order contributions to the (Euclidean) Dipole Cosmology transition amplitude. These amplitudes correspond to spin foams having the boundary graph of Dipole Cosmology, one internal vertex and no edges connecting this vertex with itself. We expect that the amplidutes are dominated by the Bianchi-Rovelli-Vidotto transition amplitude in a limit of large volume of the universe, and the transition amplitude including contributions from all these spin foams gives the correct Friedmann dynamics in the classical limit.

Antonia Zipfel
On the relation between canonical and covariant Quantum Gravity
July 26, 2013, Waterloo
Abstract
Heuristically, spin foams can be understood as the Feynman graphs of Quantum Gravity. Yet, summing over all histories would lead to a projector on the physical Hilbert space of the canonical theory rather than to a true propagator due to the constraint nature of GR. Following this idea we construct a spin-foam operator acting on the kinematical Hilbert space and analyze its properties.

Jerzy Lewandowski
Exact solutions of canonical LQG
July 23, 2013, Waterloo
Abstract
In the case of LQG coupled to the massless scalar field (the Rovelli-Smolin model) the form of the quantum scalar constraint drastically simplifies in comparison to other cases. The properties of the physical Hamitonian will be discussed.

Jędrzej Świeżewski
Geometrical observables for General Relativity coupled to dust
July 23, 2013, Waterloo
Abstract
In my talk I will present a proposal for the construction of Dirac observables for General Relativity. The construction relies on the use of geometrically defined coordinates with a clear physical interpretation. I will discuss some problems of the construction and turn to a similar construction of observables for a simplified theory of General Relativity coupled to a dust field.

Mehdi Assanioussi
A Quantum Curvature Operator for LQG
July 23, 2013, Waterloo
Abstract
We introduce a new operator in Loop Quantum Gravity - the 3D curvature operator - related to the 3-dimensional Ricci scalar. The construction is based on the concepts of Regge. We define this operator starting from the classical expression of Regge curvature then we derive some of its properties and discuss some explicit checks of the semi-classical limit.

Norbert Bodendorfer
Black hole entropy in LQG and the Wald formula
July 23, 2013, Waterloo

Emanuele Alesci
Quantum Reduced Loop Gravity
July 22, 2013, Waterloo
Abstract
We present a new framework to study symmetric sectors of loop quantum gravity. The reduction is performed at a quantum level using projected spin networks coherent states and spinfoam techniques that allow us to project the Hilbert space of the full canonical theory. As a first application we present an inhomogeneous extension of the Bianchi I model and discuss the semi-classical limit of the theory.

Andrea Dapor
QFT in Quantum Spacetime
July 22, 2013, Waterloo
Abstract
We develop a systematic classical framework to accommodate canonical quantization of both geometric and matter perturbations on a quantum homogeneous isotropic flat spacetime. It is shown that the existing approach of standard cosmological perturbations is good only (i) up to first order in the inhomogeneities and (ii) if the background is treated classically. A new set of classical phase space variables is proposed which in a natural gauge define a complete and canonical algebra of relational Dirac observables. We compute the physical Hamiltonian that generates the dynamics of such observables (with respect to the homogeneous mode of a Klein-Gordon clock field) and offer a proposal for quantization: what we obtain is a theory of quantum perturbations on a quantum (cosmological) spacetime.

Wojciech Kaminski
Curvature constraints in the spin foam models
July 22, 2013, Waterloo
Abstract
I will present surprising constraints for internal holonomies in the asymptotic (semi-classical) limit in the EPRL model.




GR20 & Amaldi 10, Warsaw, Poland, July 7-13, 2013


Marcin Kisielowski
The Dipole Cosmology transition amplitude: first­order contributions
July 12, 2013, Warsaw
Abstract
Bianchi, Rovelli and Vidotto introduced Dipole Cosmology, a quantum cosmological model that opens a new theory which can be called Spin Foam Cosmology. In the original formulation they use a specific 2-complex. Its introduction was judged a posteriori by a correct semiclassical limit of the transition amplitude. The 2-complex chosen has one internal vertex, and the calculation of a transition amplitude may be thought to be first-order calculations. We found other possible first-order contributions. We expect, that those contributions are dominated by the BRV transition amplitude in a limit of large volume of the universe, and a Spin Foam Cosmology model taking into acount those contributions has a proper semiclassical limit.

Andrea Dapor
QFT in Quantum Spacetime
July 11, 2013, Warsaw

Piotr Sułkowski
Super-A-polynomials and 3-dimensional theories
July 11, 2013, Warsaw

Jacek Tafel
Generalization of initial data for the Kerr metric
July 10, 2013, Warsaw
Abstract
We find new classes of exact solutions of the initial momentum constraint for vacuum Einsteins equations. They are either axially symmetric or the exterior curvature tensor has a simple algebraic structure. In general the mean curvature $H$ is non-constant and initial metric is not conformally flat. Solutions depend on several free functions. The conformal method of Lichnerowicz, Choquet-Bruhat and York is used to prove solvability of the Hamiltonian constraint if $H$ vanishes. The existence of marginally outer trapped surfaces in initial manifold is discussed.

Jędrzej Świeżewski
Construction of Dirac observables for General Relativity with the use of geometry
July 9, 2013, Warsaw
Abstract
In my talk I will present results obtained jointly with Paweł Duch, Wojciech Kamiński and Jerzy Lewandowski. They consist of a proposal for the construction of Dirac observables for General Relativity. The construction relies on the use of geometrically defined coordinates with a clear physical interpretation. I will discuss some problems of the construction and turn to a similar construction of observables for a simplified theory of General Relativity coupled to a dust field.

Jacek Tafel
Static spherical black holes with scalar field
July 9, 2013, Warsaw
Abstract
Static spherically symmetric black holes and particle like solutions with self interacting minimally coupled scalar field $varphi$ are analyzed. They are asymptotically flat or anti-de Sitter (AdS). We express them in terms of a single function $ ho$ which undergoes simple conditions. If $varphi$ is nontrivial the ADM mass $M$ has to be positive. No-hair theorems are generalized to the AdS asymptotic. For both asymptotics the Killing horizon is nondegenerate and its radius cannot be bigger than $2M$. Derivatives of $ ho$ at singularity determine properties of admissible potentials $V(varphi)$ as regularity, boundedness and behaviour for maximal values of $varphi$. Several classes of solutions with singular or nonsingular potentials are obtained. Their examples are presented in a form of plots.




XXXII Workshop on Geometric Methods in Physics, Białowieża, Poland, June 30 - July 5, 2013


Piotr Sułkowski
On knots, super-A-polynomial, and BPS states




Mathematics and physics of knot homologies, Montreal, Canada, June 24 - July 5, 2013


Piotr Sułkowski
Super-A-polynomials
June 26, 2013, Montreal




String Math 2013 conference, Simons Center, Stony Brook University, USA, June 17-21, 2013


Piotr Sułkowski
Matrix model for moduli spaces and chord diagrams
June 19, 2013, Stony Brook




Moduli spaces and macromolecules, IHES, Bures-sur-Yvette, France, May 14-18, 2013


Piotr Sułkowski
Random matrices, topological recursion, and RNA enumeration
May 15, 2013, Bures-sur-Yvette




Stringtheory.pl/2013, Kraków, Poland, April 5-7, 2013



Piotr Sułkowski
Whats new in mathematical aspects of string theory?
April 6, 2013, Kraków




EFI winter conference on canonical and covariant LQG, Tux, Austria, February 25 - March 01, 2013


Andrea Dapor
QFT in Quantum Spacetime: a compatible classical framework
February 28, 2013, Tux

Marcin Kisielowski
On first­order contributions to the Dipole Cosmology transition amplitude
February 27, 2013, Tux
Abstract
We present some results of an investigation of the amplitudes contributing to the (Euclidean) Dipole Cosmology transition amplitude at the first order. These amplitudes correspond to spin foams having the boundary graph of Dipole Cosmology, one internal vertex and no edges connecting this vertex with itself. We expect the transition amplitude including contributions from all these spin foams gives the correct Friedmann dynamics in the classical limit.

Jędrzej Świeżewski
Constructing geometrical Dirac observables for GR
February 26, 2013, Tux




Third Latin Congress on Symmetries in Geometry and Physics, Sao Luis, Brasil, February 1-10, 2013


Piotr Sułkowski
Series of lectures on Knots, quantization and super-A-polynomials
February 6-8, 2013, Sao Luis




Topological recursion and quantum algebraic geometry, Aarhus, Denmark, January 28 - February 1, 2013



Piotr Sułkowski
Quantization and super-A-polynomials
January 29, 2013, Aarhus




The XXIX International Colloquium on Group­ Theoretical Methods in Physics, August 20-26, 2012, Tianjin, China


Marcin Kisielowski
Spin Foams contributing in first order of vertex expansion to the Dipole Cosmology transition amplitude
August, 22, 2012, Tianjin
Abstract
In this talk we will present a general method for finding all foams with given boundary and given number of internal vertices. We will apply the method to the Dipole Cosmology model and find all spin foams contributing to the transition amplitude in first order of vertex expansion.




Thirteenth Marcel Grossmann Meeting, Stockholm, July 1-7, 2012


Andrea Dapor
Quantum Field Theory on LQC Bianchi Spacetimes
6th July 2012, Shtockholm
Abstract
We develop the quantum theory of a scalar field on LQC Bianchi I geometry. In particular, we focus on single modes of the field: the evolution equation is derived from the quantum scalar constraint, and it is shown that the same equation can be obtained from QFT on an "classical" effective geometry. We investigate the dependence of this effective spacetime on the wave-vector of the mode (which could in principle generate a deformation in local Lorentz-symmetry), focusing our attention on the dispersion relation. We prove that at first order no Lorentz-violation is present - despite the effective metric being different than the classical Bianchi I one. A preliminary analysis of the correction due to inclusion of backreaction is briefly discussed in the context of Born-Oppenheimer approximation.

Andrea Dapor
Loop Quantum Cosmology for nonminimally coupled Scalar Field
6th July 2012, Shtockholm
Abstract
We conduct a LQC-quantization of the FRW cosmological model with nonminimally coupled scalar field. (This model is interesting from the classical point of view because it allows heavy fields (such as the Higgs) to produce inflation.) Making use of a canonical transformation (between Jordan variables and Einstein variables), we recast the theory in a minimally coupled one, for which standard LQC techniques can be applied to find the physical Hilbert space and the dynamics. Though the analysis of the genuine quantum system can be performed, we focus on the semiclassical sector - obtaining a "classical" effective Hamiltonian. At this level, we can transform back to the Jordan frame, and study the dynamics. It turns out that the initial singularity is replaced by a "mexican hat"-shaped bounce, joining the contracting and expanding branches.

Andrea Dapor
Nonminimally coupled Scalar Field in Loop Quantum Cosmology
6th July 2012, Shtockholm
Abstract
FRW model with nonminimally coupled scalar field is considered. It is classically known that for a specific form of the coupling the scalar field produces inflation: of particular interest these days is the observation that this model allows for Higgs-driven inflation, avoiding introduction of new particle physics. We consider the LQC corrections to the equations of motion in the framework of "effective dynamics", finding the dynamics of the model at early times. It is found that the initial singularity is replaced by a peculiar "mexican hat" bounce: the universe collapses, at Planck scales it undergoes two consecutive bounces between which it rapidly expands and recollaplses, and finally it reaches inflation. For physical values of the coupling constant the count of e-foldings and the computation of cosmological parameters show that the model is in agreement with observations - providing a nonsingular cosmology where inflation can be generated by standard model fields (such as the Higgs).

Jędrzej Świeżewski
Between General Relativity and Electrodynamics - hamiltonian description of a field theory
6th July 2012, Shtockholm
Abstract
In the talk I will present a hamiltonian analysis of a simplified teleparallel theory. The analysis consists of a derivation of the hamiltonian and calculation of the Poisson brackets of the constraints that will apear in the process. The theory I will consider has the same kinematics as the full teleparallel theory in its cotetrad formulation, however, the dynamics is considerably simplified. The simplification consists of choosing a lagrangian which resembles the electrodynamics lagrangian, hence the theory no longer describes gravitational phenomena. Inspite of that, a close resemblance to the teleparallel theory is kept. Firstly, the hamiltonian consists of scalar and vector constraints which form the usual Dirac algebra under Poisson bracket. Secondly, the form of the constraints is very similar to the form of constraints of the full teleparallel theory, which have been derived by the co-author.

Marek Demiański
High redshift cosmography: new results and implications for dark energy
6th July 2012, Shtockholm
Abstract
We use all the available date on high redshift objects (Union2 Type Ia supernovae, GRBs and BAO) to derive constrains on the parameters of FRWL cosmological model without imposing any a priori assumptions about on the dynamical equations for gravity. These data sets allow us to put constrains on the cosmographic expansion up to the fifth order. To perform our analysis we use the Markov Chain Monte Carlo Method. To investigate the dark energy component we use different parametrizations of its equation of state. We show that the deceleration parameter clearly confirms the present acceleration phase of the Universe, there are hints that the dark energy equation of state is evolving and there are possible deviations from the LCDM model.

Tomasz Pawłowski
Geometric time in quantum cosmology
6th July 2012, Shtockholm
Abstract
In quantum cosmology a physically meaningful description of a models dynamical evolution requires selection of a suitable function of its degrees of freedom as an internal clock. Requirement of independence of this choice on the matter content restricts it to the geometry degrees of freedom. In Loop Quantum Cosmology (LQC) the phenomenon of the bounce further excludes scale factor/volume variables leaving out only their momenta. We test the latter possibility on the model of FRW universe with massive scalar field quantized within framework of geometrodynamics. The results are compared against known description using the scale factor time. We discuss the consequences of both treatments for formalisms featuring infinite number of massive fields. Further application within LQC to describe scalar inflaton is also discussed.

Tomasz Pawlowski
Computable framework of Loop Quantum Gravity
3rd July 2012, Shtockholm
Abstract
We present a framework of a non-perturbative quantization of general relativity coupled to dust and other matter fields. The irrotational dust provides a natural time variable, leading to a physical Hamiltonian with spatial diffeomorphism symmetry. The surprising feature is that the Hamiltonian is not a square root. This property, together with the kinematical structure of loop quantum gravity, provides a complete theory of quantum gravity with strict control over the physical Hilbert space, action of the Hamiltonian on it and the construction of physical observables. This puts in technical reach applications to cosmology, quantum gravitational collapse and Hawking radiation.

Jacek Puchta
Operator Spin-network Diagrams in calculations of higher order amplitudes in dipole cosmology
3rd July 2012, Shtockholm
Abstract
The Operator Spin-network Diagrams is a new framework that enables to express Spin-foam amplitudes in a clear graphical way. Within this framework it is easy to find and characterise all the spin-foams with a given fixed boundary graph. We used this technique to characterise transition amplitudes in Dipole Cosmology in higher order in the vertex expansion.

Andrzej Okołów
ADM-like Hamiltonian formulation of gravity in the teleparallel geometry
3rd July 2012, Shtockholm
Abstract
The Teleparallel Equivalent of General Relativity is considered as a theory of cotetrad fields on a four-dimensional manifold. The 3+1 decomposition of the cotetrad is described by means of the lapse and the shift appearing in the ADM Hamiltonian formulation of General Relativity. The Legendre transformation is carried out and both a Hamiltonian and a constraint algebra is derived. There are six primary constraints which define local Lorentz transformations on the phase space and four secondary ones - three of them form a vector constraint and the fourth one is a scalar constraint. All the constraints are of the first class.

Jerzy Lewandowski
Quantizable canonical LQG
3rd July 2012, Shtockholm
Abstract
The canonical quantization scheme can be complited with the framework of Loop Quantum Gravity for several examples of the gravitational field coupled to matter fields. Explicitly, that has been accomplished for the generic dust, non-rotating dust, and massless scalar field. Those results will be presented and recent progress will be discussed. reported.



Relativity and Gravitation - 100 Years after Einstein in Prague


Jerzy Lewandowski
Loop Quantum Gravity - where are we?
28th June 2012, Prague
Abstract
For several models of gravity coupled to other fields, the algorithm of the canonical quantization has been completed and performed to an end. It gave rise to well defined, exact quantum theories. The Dirac observables are provided by the relational and the deparametrization frameworks. The quantum states, Hilbert spaces and concrete quantum operators are furnished by the canonical Loop Quantum Gravity framework. The models are not confirmed experimentally and admit ambiguities, but they are there, available for further study and applications.

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