Last year, a groundbreaking peer-reviewed paper announced that the mysterious and controversial EmDrive did indeed produce a small thrust and since then new announcements have been re-igniting people’s interest in the unorthodox technology.

Now researchers from the University of Lisbon claim to have an explanation for how the propellant-less engine works. Using an archaic interpretation of quantum mechanics, they suggest that inside the EmDrive it is possible to have an impulse that doesn’t have to obey the third law of dynamics, thus creating thrust without having to eject anything.

The starting point of the research was a suggestion made in the original EmDrive paper itself about using the so-called eurhythmic interpretation of quantum mechanics. The study can be read online and is published in the Journal of Applied Physical Science International, although the publisher doesn’t appear to have a stellar reputation.

Eurhythmic physics has nothing to do with the famous British music duo, instead it has a lot to do with an old interpretation of quantum mechanics. It was used to create a deterministic interpretation of quantum mechanics and has recently found a resurgence based on some interesting application in the study of liquids. I’m sure there are several physicists who have sweet dreams of making this a widely accepted theory but there are similar argumentative drawbacks.

Followers of this interpretation complain about several aspects of the common interpretation of quantum mechanics like its probabilistic nature, its particle-wave duality, and its disagreement with general relativity. And yet, eurhythmic physics disagrees with special relativity, requires the existence of hidden variables (that we cannot know), and violates several accepted principles of physics, like action and reaction.

The EmDrive is a big copper cavity shaped like a truncated cone. According to the tests, when microwaves are introduced into the cavity, there’s a small thrust at the smaller end of the cavity. Since nothing comes out of the cavity, this appears to violate the laws of dynamics. It produces a reaction without the need for an action.

Maybe this is the first proof that this is the correct interpretation of quantum mechanics, but we need more evidence to be sure. The controversial technology has been tested at NASA’s Eagleworks laboratory for years and the team is confident to have nullified every potential source of thrust. More testing is currently taking place. Earlier this year, the Chinese media reported that China has a working EmDrive that it is planning to test in space.