The Emthruster: Thrust without reaction?

[iancampbell]

Of course photon drives aren't reactionless drives. They are, however, functionally equivalent in that nothing material has to be chucked overboard to get the thrust. And since propellant mass is the major problem for reaction drives...

Incidentally, I don't think antimatter would be quite such a magic fuel as some people think. The reason is that a significant proportion of the energy is generated in forms that are completely useless, such as neutrinos.