Example of a stable wormhole in general relativity
  We study a static, spherically symmetric wormhole model whose metric
coincides with that of the so-called Ellis wormhole but the material source of
gravity consists of a perfect fluid with negative density and a source-free
radial electric or magnetic field. For a certain class of fluid equations of
state, it has been shown that this wormhole model is linearly stable under both
spherically symmetric perturbations and axial perturbations of arbitrary
multipolarity. A similar behavior is predicted for polar nonspherical
perturbations. It thus seems to be the first example of a stable wormhole model
in the framework of general relativity (at least without invoking phantom thin
shells as wormhole sources).
