I just read about this in New Scientist. Even if the article had gone into detail regarding the physics, I couldn't have followed it. A brief synopsis: A method of propulsion has apparently been devised based on resonating microwaves in a waveguide. Microwaves are created within a chamber by a magnetron. No photons need to escape from the device. Rather, the resonating radiation imparts unequal forces on the different walls of the chamber as the photons bounce back and forth, causing a net force in one direction. It seems that the engine will be at least as effective as an ion drive, with the added bonus that it needs no propellant. It may even generate enough force to accelerate itself (and a good bit more) at 1G, allowing it to hover (with some well-chosen high-temperature superconductors). Seems to good to be true to me, but what do I know? Here's somewhere to start. Please give me your opinions.