In Finland we have a traditional vehicle called a kicksledge . The sledge is propelled forward by kicking backwards against the ground, thus demonstrating the conservation of momentum.
British aerospace engineer Roger J. Shawyer have invented a kind of a space kicksledge, which is a drive that supposedly operates without propellant, but still generating thrust in some magic way.
Last month, the Wired magazine  wrote that Nasa had tested an other similar device, a Cannae drive designed by one Guido Fetta. Amazingly, they reported that the drive produced thrust. Very weak but still measurable thrust.
Ok, I have a problem with this. The device is supposed to work by bouncing microwaves in a cavity and somehow generating the thrust. I have no idea what to make out of this, but the conclusions of Nasa test engineers are even more nonsensical. They say in the report:
“Test campaign 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.”
So, the space kicksledge is kicking against “quantum vacuum virtual plasma”. Now, putting it mildly, this sounds like wild speculation to me. John Baez called it “graduate-level baloney” .
Reactionless drive is problematic, because it is also easily an over unity device . When accelerating with constant thrust without loosing propellant, the spaceships kinetic energy grows proportional to the square of the velocity. At some point the kinetic energy can be shown to exceed the work done by the reactionless thruster and thus the spaceship becomes a perpetuum mobile.
“I cannae change the laws of physics! I’ve got to have thirty minutes!”
Shawyer says, this does not happen, because the devices thrust decreases as the velocity increases. But I don’t know how this could be, because the principle of relativity says the laws of physics are the same in all inertial frames of reference .
Well, the accelerating spaceship is not an inertial frame, but if EmDrive efficiency somehow decreases when speed increases, this would anyways seem give us a method of measuring some kind of absolute speed for the spacecraft. According to relativity, such thing as absolute speed does not exist.
I may be wrong in this, but it all sounds to me like Shawyer’s space kicksledge is trying to bring back the aether theories .
Picture: Wikimedia Commons