Last year, NASA scientists caused a stir by talking shop with fans online and revealing that a design by Roger Shawyer, called the EmDrive, might actually have something to it — despite being impossible under the current understanding of physics. And all that talk is about to be revived, because not only did the EmDrive pass peer review, NASA might be on track to figuring out how it works.
To understand why this is a big deal, the EmDrive, aka the RF-resonant cavity thruster, shouldn’t work at all. The idea is that electromagnetic radiation is released in a microwave cavity and bounces around like mad. Since in space even a flashlight will give you thrust, this would in theory push the ship without any propellant, a big deal because until you use it, propellant is just dead weight and you need a lot of it. That manages to violate both Newton’s third law, for every action there is an equal and opposite reaction, and the conservation of momentum (i.e. when you add up all the forces in an interaction, the momentum comes out to zero), and so the drive is impossible.
The problem is that multiple people have built the thing and they keep finding that it works, though measurement errors and other issues keep cropping up. The problem is the amount of thrust is so small, it falls within the margin of error in the experiment. However, a new experiment, in vacuum, has revealed consistent results — so NASA brought in a bunch of its peers to look over the data and check if they missed anything. It looks, quite a bit, like they haven’t.
So why does it work? NASA’s paper addresses that via quantum theory. They use the theory of pilot waves to argue that there’s something going on in this thing that we haven’t figured out yet. You know how you hear that in quantum theory, measuring a system changes it? Basically that’s what NASA is saying. “This thing can’t violate the laws of physics, but we’re not really sure just how it can’t do that and still work. Whatever, it works.”
You would be surprised just how often this happens in science.
The next step is to launch this thing into space and see what happens. If it works, in theory that would mean you could get to Mars in just a few months and Pluto in a year and a half. So once the EmDrive is in space, it’s put up or shut up time. Hopefully that will happen next year.