When NASA scientists think they have built something that breaks the laws of physics, do you take them at their word?

Science has long buzzed about an "impossible" rocket thruster, one that looks like an air blaster you'd buy at Disney Land and somehow generates thrust without propellant to push it forward. The so-called electromagnetic or EM drive makes headlines annually, but this year is different: An American team working on the drive released a peer-reviewed paper demonstrating that their prototype works, and a Chinese team claims that they have tested their own functional model.