Recent observations suggest that the cosmological equation-of-state parameter w is close to -1. To say this is to imply that w could be slightly less than -1, which leads to R. Caldwell's ``Phantom cosmologies''. These often have the property that they end in a ``Big Smash'', a final singularity in which the Universe is destroyed in a finite proper time by excessive expansion. We show that, classically, this fate is not inevitable: there exist Smash-free Phantom cosmologies, obtained by a suitable perturbation of the de Sitter equation of state, in which the spacetime is in fact asymptotically de Sitter. [ Contrary to popular belief, such cosmologies, which violate the Dominant Energy Condition, do not necessarily violate causality.] We also argue, however, that the physical interpretation of these classically acceptable spacetimes is radically altered by ``holography'', as manifested in the dS/CFT correspondence. It is shown that, if the boundary CFTs have conventional properties, then recent ideas on ``time as an inverse renormalization group flow'' can be used to rule out these cosmologies. Very recently, however, it has been argued that the CFTs in dS/CFT are of a radically unconventional form, and this opens up the possibility that Smash-free Phantom spacetimes offer a simple model of a ``bouncing'' cosmology in which the quantum-mechanical entanglement of the field theories in the infinite past and future plays an essential role.
Journal of High Energy Physics
- Pub Date:
- August 2002
- High Energy Physics - Theory;
- 22 pages, clarification of triple analytic continuation, additional Comments added in the light of hep-th/0207245