Talk detail

Participant	Lecian, Orchidea Maria
Institution	Sapienza Unviersity of Rome - Piazzale Aldo Moro, 5 - Rome - RM - Italy

Session	ES2	Accepted	Yes	Order	2	Time	14:50	20'
Talk	Oral abstract	Title	The Hamiltonian constraint and its possible deformations
Coauthors	Giovanni Amelino Camelia, Lorenzo Cesarini
Abstract	The role of the Hamiltonian constraint is discussed within GR, its possible modifications within the Dirac hypersurface-deformation algebra and its consequences for the corresponding Poincar\'e algebra are investigated for quantum-gravity models. Possible corresponding non-commutative spaces are analyzed with their Heisenberg algebra. The semiclassical transition is found relevant for the definition of asymptotically-flat classical spaces originated from quantum spaces whose symmetry group is more general than that exhibited by the (quantized) Schwarzschild solution.
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Session	ES3	Accepted	Yes	Order	13	Time	18:00	15'
Talk	Oral abstract	Title	An analysis of the symmetries of cosmological billiards
Coauthors
Abstract	The symmetries of cosmological billiards are analyzed. Particular attention is devoted to the classification of the initial conditions, with respcet to their continued-fraction decomposition, as far as their characterization allows one to discriminate between singular universes (i.e. the billiard ball reaches the corners of the billiard and therefore the cosmological singularity) and non-singular ones (i.e. the corners of the billiard are never reached by the billiard ball); among the initial conditions giving rise to non-singular universes, in particular, periodic configurations are investigated according to their role in the description of the stochastization of the original BKL dynamics.
Pdf file