From Osher Doctorow
Martin G. Richarte and Claudio Simeone, U. de Buenos Aires, arXiv:
0710.2041 v2 [gr-qc] 11 Oct 2007, 7 pages, in "Thin shell wormholes
supported for ordinary matter in Einstein-Gauss-Bonnet gravity,"
appear to have developed a theory of Wormholes not requiring Exotic
Matter, others not requiring Matter at all, and others with Exotic
Matter.
They extend the results of E. Gravanis and S. WIllison, Phys. Rev. D.
75, 084025 (2007), who showed that in pure Gauss-Bonnet gravitation,
exotic matter is not needed for wormholes to exist and even matter
itself is not needed.
A key aspect is that for certain values of parameters, energy is
localized on shell, so Wormholes can be supported by matter without
violating the Weak and Null Energy conditions.
Unlike some papers in arXiv that involve much wordy argumentation and
few equations or inequalities, Richarte and Simeone give both detailed
physics and detailed equations including explicit forms of the second
order Lovelock tensor. For dimension D = 5, the most general theory
leading to second order equations for the metric is Einstein-Gauss-
Bonnet or Lovelock theory up to second order, which is popular because
it is obtained as low energy limit of string theory, because it leads
to ghost-free self-interaction of non-trivial type for D > 4, because
for spacetime dimensions D < 5 the Gauss-Bonnet terms in the action
represent topological invariants, etc. In this type of theory
researchers get a short-distance correction to GR, etc.
Osher Doctorow
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