ah.clem and infodragon write:
This story from a Wired article: NASA is a major player in space science, so when a team from the agency this week presents evidence that "impossible" microwave thrusters seem to work, something strange is definitely going on. Either the results are completely wrong, or Nasa has confirmed a major breakthrough in space propulsion. British scientist Roger Shawyer has been trying to interest people in his EmDrive for some years through his company SPR Ltd. Shawyer claims the EmDrive converts electric power into thrust, without the need for any propellant by bouncing microwaves around in a closed container. He has built a number of demonstration systems, but critics reject his relativity-based theory and insist that, according to the law of conservation of momentum, it cannot work.
NASA states... "Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma"
However, it it turns out to be a small effect that is largely non-reproducible
It is a bit past that already. First designed and tested in the UK, effect reproduced in China, and now reproduced again by NASA - different experiments with different kit, all showing the effect.
What still isn't clear is how exactly it works, and how to tune it and scale it.
The NASA results, at least the little bit that one can gleam from their conference summary, are underwhelming in their magnitude and I would worry about a problem with their experimental setup. The Chinese result is rather large and is on the order of what you get out of an ion drive; if those results are good they should be relatively easy to replicate.
The NASA design is different from the device used in the China tests. The difference in measured thrust might be because NASA did a better job accounting for all the factors and the device really does only generate such a tiny amount of thrust, or NASA's device might not have been as evolved and the Chinese device really did generate the greater thrust.
Either way three different independent groups have found something and currently no one can say exactly what.
What was considered impossible just 60 years ago is no commonplace, its all about advancing technology and our understanding of how nature works. This might just be a flash in the pan or it might be the key to a new understanding of the Universe.