When taking General Relativity I did that calculation as part of the take-home exam. It's mostly a matter of calculating the curvature tensor of a wormhole and

When taking General Relativity I did that calculation as part of the take-home exam. It's mostly a matter of calculating the curvature tensor of a wormhole and finding that it is freaky, so the energy-momentum tensor that would satisfy the Einstein equation would need to include negative energy and/or momentum (the Einstein equation basically says curvature tensor = energy tensor(1)). Then exactly how the thing would unravel is a matter of computation, but unravel it would. Or one could presumably find a form of matter that has negative energy density and start building wormholes. 1) The energy tensor has energy as the time diagonal value, and momentum as the space diagonal values.