MG12 - Talk detail
 

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Talk

Abstract

On the Problem of Local Hubble Expansion

The question if the planetary orbits experience Hubble expansion has a long history, starting from the works by McVittie in 1933. Since that time, a number of researchers revisited this subject, and the most frequent conclusion was that the Hubble effect at the interplanetary scales should be negligible or absent at all. However, the particular quantitative estimates disagree with each other. Fortunately, the situation becomes much more simplified for the dark-energy-dominated cosmological models due to existence of the exact Kottler solution for a point-like mass against the cosmological background formed by the Lambda-term. Thereby, the problem is mostly reduced to the correct choice of coordinates, adequate to the physical meaning of the problem. It is the aim of the present report to confront the analysis of a test particle motion in Kottler metric written in the cosmological Robertson-Walker coordinates [Yu.V. Dumin. Phys. Rev. Lett. v.98, p.059001 (2007)] with the post-Newtonian approximation developed in the work by S.A. Klioner and M.H. Soffel [In "The Three-Dimensional Universe with Gaia", Obs. Paris-Meudon (2004), p.305; astro-ph/0411363].

Local Hubble Expansion in the Dark-Energy-Dominated Cosmology

The problem of local Hubble expansion (e.g. for the planetary orbits or for the stellar orbits in a galaxy) is discussed for over 65 years; and a number of arguments both in favor and against this effect were put forward. In the present talk, after a brief review of the previous approaches, I am going to discuss the local Hubble effect in the framework of the dark-energy-dominated cosmological models, where its existence seems to be most plausible. The starting point of our consideration will be Kottler solution of the General Relativity equations written in Robertson-Walker coordinates [Yu.V. Dumin. Phys. Rev. Lett. v.98, p.059001 (2007)]. Next, I shall discuss the problem of correct choosing the observable quantities and possible applications to the interpretation of the available data on the dynamics of the Earth-Moon system.

Simulation of Cosmological Horizons by Ultracold Atoms in Optical Lattices and Multi-Josephson-Junction Loops

Excessive formation of topological defects (monopoles, vortices, and domain walls) is a long-standing problem in the consideration of cosmological phase transitions. An important hint to its resolution was given by the multi-Josephson-junction loop (MJJL) experiment [R. Carmi et al. Phys. Rev. Lett., v.84, p.4966 (2000)], which revealed the specific thermal correlations between the phases of order parameter in the spatial subregions which were disconnected during the phase transition. Inclusion of such correlations into the simplest 1D FRW cosmological model [Yu.V. Dumin, hep-ph/0308184 (2003)] have really shown a much reduced number of the defects (kinks) of the scalar field. A further support for this idea comes from the recent experiments with clouds of ultracold atoms formed independently in the wells of an optical potential [Z. Hadzibabic et al. Nature, v.441, p.1118 (2006) and subsequent publications]. The measured efficiency of the defect formation after the interference of the clouds supports the earlier MJJL results and agrees very well with our theoretical predictions.

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