Implementation of faster-than-light (FTL) interstellar travel via traversable wormholes generally requires the engineering of spacetime into very specialized local geometries. The analysis of these via Einstein's general theory of relativity, plus the resultant equations of state, demonstrates that such geometries require the use of 'exotic' matter. It has been claimed that since such a matter violates the energy conditions, FTL spacetimes are not plausible.

However, it has been shown that this is a spurious issue. The identification, magnitude, and production of exotic matter are seen to be a key technical challenge. These issues are reviewed and summarized, and an assessment of the present state of their resolution is provided.