An article at NasaSpaceFlight.com is claiming that the superficially reactionless EmDrive has again been tested at NASA Eagleworks, this time in hard vacuum, and the anomalous thrust is still being detected:
A group at NASA's Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics' expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.
With the popular explanations of thermal convection or atmospheric ionization being ruled out by operation in vacuum, and thrust thousands of times greater than expected from a photon rocket, is it time to start taking the EM Drive seriously as a fundamentally new form of propulsion, and possibly a door to new physics?
Roger Shawyer, the inventor of the EmDrive, claims that the device's efficiency will scale even further with greater levels of power, potentially enabling fast interstellar travel powered by a radioisotope thermoelectric generator or nuclear fission.
Previously: NASA Validates "Impossible" Space Drive's Thrust
results that were consistent with an Alcubierre drive fluctuation
Wish I could find the original source for that and verify that it's from the experiments and not just something that has got added by the internet.
If true, then I guess it neatly provides a theoretical way for this to work without propellant, and um, wow. Alcubierre has always been interesting mathematically but impossible practically due to requiring things like negative mass. If it turns out all we've got to do is bounce some microwaves around in a tin can to get a warp field then, f**k. Off to sell all my shares in dilithium crystal prospectors...