65 research outputs found
Cosmological implications of an evolutionary quantum gravity
The cosmological implications of an evolutionary quantum gravity are analyzed
in the context of a generic inhomogeneous model. The Schr\"{o}dinger problem is
formulated and solved in the presence of a scalar field, an ultrarelativistic
matter and a perfect gas regarded as the dust-clock. Considering the actual
phenomenology, it is shown how the evolutionary approach overlaps the
Wheeler-DeWitt one.Comment: 4 pages; to appear in the proceedings of the II Stueckelberg
Workshop, Int.J.Mod.Phys.A, references adde
Quantum cosmology with a minimal length
Quantum cosmology in the presence of a fundamental minimal length is analyzed
in the context of the flat isotropic and the Taub cosmological models. Such
minimal scale comes out from a generalized uncertainty principle and the
quantization is performed in the minisuperspace representation. Both the
quantum Universes are singularity-free and (i) in the isotropic model no
evidences for a Big-Bounce appear; (ii) in the Taub one a quasi-isotropic
configuration for the Universe is predicted by the model.Comment: 8 pages, 3 figures; to appear in the proceedings of the II
Stueckelberg Workshop, Int.J.Mod.Phys.A, references adde
Bianchi IX in the GUP approach
The Bianchi IX cosmological model (through Bianchi I and II) is analyzed in
the framework of a generalized uncertainty principle. In particular, the
anisotropies of the Universe are described by a deformed Heisenberg algebra.
Three main results are in order. (i) The Universe can not isotropize because of
the deformed Kasner dynamics. (ii) The triangular allowed domain is
asymptotically stationary with respect to the particle (Universe) and its
bounces against the walls are not interrupted by the deformed effects. (iii) No
reflection law can be in obtained since the Bianchi II model is no longer
analytically integrable.Comment: 5 pages, to appear in the Proceedings of the 3rd Stueckelberg
Workshop, July 2008, Pescara - Ital
Quantum Dynamics of the Taub Universe in a Generalized Uncertainty Principle framework
The implications of a Generalized Uncertainty Principle on the Taub
cosmological model are investigated. The model is studied in the ADM reduction
of the dynamics and therefore a time variable is ruled out. Such a variable is
quantized in a canonical way and the only physical degree of freedom of the
system (related to the Universe anisotropy) is quantized by means of a modified
Heisenberg algebra. The analysis is performed at both classical and quantum
level. In particular, at quantum level, the motion of wave packets is
investigated. The two main results obtained are as follows. i) The classical
singularity is probabilistically suppressed. The Universe exhibits a stationary
behavior and the probability amplitude is peaked in a determinate region. ii)
The GUP wave packets provide the right behavior in the establishment of a
quasi-isotropic configuration for the Universe.Comment: 10 pages, 4 figures; v2: section added, to appear on PR
Modification of Heisenberg uncertainty relations in non-commutative Snyder space-time geometry
We show that the Euclidean Snyder non-commutative space implies infinitely
many different physical predictions. The distinct frameworks are specified by
generalized uncertainty relations underlying deformed Heisenberg algebras.
Considering the one-dimensional case in the minisuperspace arena, the bouncing
Universe dynamics of loop quantum cosmology can be recovered.Comment: 5 pages; title changed, to appear in PR
Minisuperspace dynamics in a generalized uncertainty principle framework
The minisuperspace dynamics of the Friedmann-Robertson-Walker (FRW) and of
the Taub Universes in the context of a Generalized Uncertainty Principle is
analyzed in detail. In particular, the motion of the wave packets is
investigated and, in both the models, the classical singularity appear to be
probabilistic suppressed. Moreover, the FRW wave packets approach the Planckian
region in a stationary way and no evidences for a Big-Bounce, as predicted in
Loop Quantum Cosmology, appear. On the other hand, the Taub wave packets
provide the right behavior in predicting an isotropic Universe.Comment: 8 pages, 4 figures; to appear in the proceedings of the 4th
Italian-Sino Workshop on Relativistic Astrophysics, AIP Conference Serie
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