64,766 research outputs found
Some notes on the Big Trip
The big trip is a cosmological process thought to occur in the future by
which the entire universe would be engulfed inside a gigantic wormhole and
might travel through it along space and time. In this paper we discuss
different arguments that have been raised against the viability of that
process, reaching the conclusions that the process can actually occur by
accretion of phantom energy onto the wormholes and that it is stable and might
occur in the global context of a multiverse model. We finally argue that the
big trip does not contradict any holographic bounds on entropy and information.Comment: 8 pages, no figures, LaTe
Perdurance of multiply connected de Sitter space
This paper deals with a study of the effects that spherically symmetric
first-order metric perturbations and vacuum quantum fluctuations have on the
stability of the multiply connected de Sitter spacetime recently proposed by
Gott and Li. It is the main conclusion of this study that although such a
spacetime is stable to the classical metric perturbations for any size of the
nonchronal region, it is only stable against the quantum fluctuations of vacuum
if the size of the multiply connected region is of the order the Planck scale.
Therefore, boundary conditions for the state of the universe based on the
notion that the universe created itself in a regime where closed timelike
curves were operative and stable, still appear to be physically and
philosophically so well supported as are those boundary conditions relying on
the notion that the universe was created out of nothing.Comment: 13 pages, RevTe
Dark energy without dark energy
It is proposed that the current acceleration of the universe is not
originated by the existence of a mysterious dark energy fluid nor by the action
of extra terms in the gravity Lagrangian, but just from the sub-quantum
potential associated with the CMB particles. The resulting cosmic scenario
corresponds to a benigner phantom model which is free from the main problems of
the current phantom approaches.Comment: 4 pages, 1 figure, to appear in AIP proceedings of "Dark side of the
Universe
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