منابع مشابه
Sudden Future Singularities
We show that a singularity can occur at a finite future time in an expanding Friedmann universe even when ρ > 0 and ρ+ 3p > 0. Explicit examples are constructed and a simple condition is given which can be used to eliminate behaviour of this sort if it is judged to be unphysical. There have been many recent investigations into the theoretical possibility that expanding universes can come to a v...
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We link observational parameters such as the deceleration parameter, the jerk, the kerk (snap) and higher-order derivatives of the scale factor, called statefinders, to the conditions which allow to develop sudden future singularities of pressure with finite energy density. In this context, and within the framework of Friedmann cosmology, we also propose higher-order energy conditions which rel...
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Sudden singularities occur in FRW spacetimes when the scale factor remains finite and different from zero while some of its derivatives diverge. After proper rescaling, the scale factor close to such a singularity at t = 0 takes the form a(t) = 1 + c|t| (where c and η are parameters and η ≥ 0). We investigate analytically and numerically the geodesics of free and gravitationally bound particles...
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We present a general form for the solution of an expanding generalrelativistic Friedmann universe that encounters a singularity at finite future time. The singularity occurs in the material pressure and acceleration whilst the scale factor, expansion rate and material density remain finite and the strong energy condition holds. We also show that the same phenomenon occurs, but under different c...
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We show that globally and regularly hyperbolic future geodesically incomplete isotropic universes, except for the standard all-encompassing ‘big crunch’, can accommodate singularities of only one kind, namely, those having a non-integrable Hubble parameter, H. We analyze several examples from recent literature which illustrate this result and show that such behaviour may arise in a number of di...
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ژورنال
عنوان ژورنال: Classical and Quantum Gravity
سال: 2004
ISSN: 0264-9381,1361-6382
DOI: 10.1088/0264-9381/21/11/l03