https://arxiv.org/abs/gr-qc/0409007
https://arxiv.org/abs/gr-qc/0409007
ARXIV.ORG
Counter example to a quantum inequality
A `quantum inequality' (a conjectured relation between the energy density of a free quantum field and the time during which this density is observed) has recently been used to rule out some of the macroscopic wormholes and warp drives. I discuss the possibility of generalizing that result to other similar spacetimes and first show that the problem amounts to verification of a slightly different inequality. This new inequality emph{can} replace the original one, if an additional assumption (concerning homogeneity of the `exotic matter' distribution) is made, and emph{must} replace it if the assumption is relaxed. Then by an explicit example I show that the `new' inequality breaks down even in a simplest case (a free field in a simply connected two dimensional space). Which suggests that there is no grounds today to consider such spacetimes `unphysical'.
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