Description
We analyze the dynamics of extended bodies in an expanding universe, in the context of General Relativity. The objects of study are one-dimensional string loops and two-dimensional spherical membranes, both elastic and rigid, with a Schwarzschild - de Sitter metric. We first consider them as test bodies via parametrization and secondly as hypersurfaces that backreact on the metric. We characterize their motion and determine under which conditions this motion is bounded. We conclude that in both approaches there are five different regimes of motion, and that for small initial radius and mass the motion of the elastic body is bounded. Expansion occurs only if the radius is on the order of a third to half the cosmological radius.
| Field of Research/Work | Cosmology, Astrophysics, and Gravitation |
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