91. Zdzislaw A. Golda, Andrzej Woszczyna
Acoustics of early universe. I. Flat versus open universe models
Class. Quant. Grav., vol. 18, pp. 543-554 (2001).
[abstract] [preprint] [journal] |
Abstract:
A simple perturbation description unique for all signs of curvature, and based on the gauge-invariant formalisms is proposed to demonstrate that:
(1) The density perturbations propagate in the flat radiation-dominated universe in exactly the same way as electromagnetic or gravitational waves propagate in the epoch of the matter domination.
(2) In the open universe, sounds are dispersed by curvature. The space curvature defines the minimal frequency $\omega_{\rm c}$ below which the propagation of perturbations is forbidden.
Gaussian acoustic fields are considered and the curvature imprint in the perturbations spectrum is discussed |
92. Zdzislaw A. Golda, Andrzej Woszczyna
Acoustics of early universe. II. Lifshitz vs. gauge-invariant theories
J. Math. Phys., vol. 42, pp. 856-862 (2001).
[abstract] [preprint] [journal] |
Abstract:
Appealing to classical methods of order reduction, we reduce the Lifshitz system to a second order differential equation. We demonstrate its equivalence to well known gauge-invariant results. For a radiation dominated universe we express the metric and density corrections in their exact forms and discuss their acoustic character.
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93. M. Heller, W. Sasin, Z. Odrzygó¼d¼
State Vector Reduction as a Shadow of Noncommutative Dynamics
Journal of Mathematical Physics, vol. 41, pp. 5168-5179 (2000).
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Abstract:
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94. Grazyna Siemieniec-Ozieblo, Andrzej Woszczyna
Order reduction in semiclassical cosmology
Phys. Rev. D, vol. 59, p. 083504 (1999).
[abstract] [preprint] [journal] |
Abstract:
We investigate the Robertson-Walker cosmology with Lagrangian $R+\alpha_1\hbar R^2+\alpha_2\hbar R^{\mu\nu}R_{\mu\nu} +L_{rad}$ where $L_{rad}$ means classical source with traceless energy-momentum tensor. We weaken the self-consistence condition (L. Parker, J. Z. Simon, Phys. Rev. {D47}(1993),{1339}). Quantum corrections are expressed as contributions to the effective equation of state. We show that the empty space-time is stable within the class of radiation-filled expanding universes with no order reduction of the field equations.
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95. M. Heller, W. Sasin
Noncommutative Unification of General Relativity and Quantum Mechanics
International Journal of Theoretical Physics, vol. 38, pp. 1619-1642 (1999).
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Abstract:
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96. M. Heller, W. Sasin
Origin of Classical Singularities
General Relativity and Gravitation, vol. 31, pp. 555-570 (1999).
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Abstract:
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