You'd need negative mass either way. Bending spacetime is the most plausible implementation of FTL travel a la Star Trek; doesn't matter a whole lot if you're u

You'd need negative mass either way. Bending spacetime is the most plausible implementation of FTL travel a la Star Trek; doesn't matter a whole lot if you're using the negative matter to keep the wormhole open or create an Alcubierre drive-style spacetime wave on which to surf