Talk detail

Participant	Pawlowski, Tomasz
Institution	KMMF, University of Warsaw - Hoza 74 - Warsaw - Mazowieckie - Poland

Session	QG1	Accepted	Yes	Order	8	Time	17:30 - 17:50
Talk	Oral abstract	Title	Computable framework of Loop Quantum Gravity
Co-authors	Viqar Husain
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.

Session	QG4	Accepted	Yes	Order	6	Time	16:30 - 17:00
Talk	Oral abstract	Title	Geometric time in quantum cosmology
Co-authors
Abstract	In quantum cosmology a physically meaningful description of a model's 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.

Session	CM4	Accepted	Yes	Order	5	Time
Talk	Oral abstract	Title	Dust reference frame in quantum cosmology
Co-authors	Viqar Husain
Abstract	We present a formulation of quantum cosmology with a pressureless dust and arbitrary additional matter fields. The system has the property that its Hamiltonian constraint is linear in the dust momentum. This feature provides a natural time gauge, leading to a physical hamiltonian that is not a square root. Quantization leads to Schroedinger equation for which unitary evolution is directly linked to geodesic completeness. Our approach simplifies the analysis of both Wheeler-deWitt and loop quantum cosmology (LQC) models, and significantly broadens the applicability of the latter, allowing in particular to derive the modified Friedman equation without semiclassical approximations. The strength of the framework is demonstrated for arbitrary scalar field potential and cosmological constant in LQC.

Session	AT4	Accepted	Yes	Order	995	Time
Talk	Poster abstract	Title	Time and a physical Hamiltonian for Quantum Gravity
Co-authors	Viqar Husain
Abstract	We present a framework of a non-perturbative quantization of general relativity modified by coupling it to irrotational dust. Such matter field 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, putting within technical reach applications to cosmology, quantum gravitational collapse and Hawking radiation.