It was bound to happen eventually. A group of researchers that may actually be competent and well-funded is investigating alternative thrust concepts. This includes our favorite, the WTF-thruster EM-drive, as well as something called a Mach-Effect thruster. The results, presented at Space Propulsion 2018, are pretty much as expected: a big fat meh.
The key motivation behind all of this is that rocket technology largely sucks for getting people around the Solar System. And it sucks even worse as soon as you consider the problem of interstellar travel. The result is that good people spend a lot of time eliminating even the most far-fetched ideas. The EM-drive is a case in point. It's basically a truncated hollow copper cone that you feed electromagnetic radiation into. The radiation bounces around in the cone. And, by some physics-defying magic, unicorns materialize to push you through space.
Well, that explanation is at least as plausible as any of the others. There is no physics explaining how this could work, but some people at NASA have claimed that it does.
Up until now, the people behind these ideas have basically funded their work off scraps and haven't had a solid testing setup, so the experimental data was all over the place. There was absolutely no consistent relationship between thrust and power nor between different setups. The experiments had progressively eliminated possible sources of noise, but, as they did so, they introduced new sources of noise, or the amount of thrust kept falling off.
The key problem seemed to be that the main proponents of crazy space thrusters may actually be pretty bad at doing experiments. All in all, I would have moved on, but others are more thorough than I am.
A group of German scientists has now gotten a reasonable amount of money under the rubric of testing all the things. Basically, because the various space agencies have whispered that no idea is too silly to ignore, we need an effective way to quickly test all the stupid space stuff on the Internet. The Germans are currently building something that is designed to do all that testing. It is an awesome bit of equipment.
They shouldn't get their hopes up. To read more, click here.