Popularly known as the EM Drive, the radio frequency resonant cavity thruster can impact space travel as we know it – if brought to reality and its full potential realized. It’s neither fact or fantasy… yet.
As you can see, lots of tests and experiments are still needed to further develop the 2001 design proposal by Roger Shawyer. In 2016, Harold White’s group at NASA’s Eagleworks Laboratories reported a test of their own model had observed 40–100 μN of thrust from inputs of 40–80 W. In December 2016, Yue Chen, part of the communication satellite division of the China Academy of Space Technology (CAST), said his team had tested several prototypes using an “experimental verification platform”, observed thrust, and was carrying out in-orbit verification. What an exciting time!
Further reading: https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster