User blog comment:PitaKang/Funday Monday 3: What would an interstellar civilization look like?/@comment-4758513-20130430022547/@comment-3218619-20130501234703

The article itself states: The proposed mechanism implies a negative energy density, and thus requires exotic matter. Although there has never been any evidence that such matter exists, some theoretical models (that depart from the Standard Model) require it to exist.

While exotic matter (like dark matter) has been proven, the exotic matter required in this type of drive has never been found.