There is potentially exciting news for space geeks everywhere – the propellantless engine known as EmDrive seems to actually work. A few months ago, it was announced that a peer-reviewed paper on the EmDrive was accepted for publication, and that paper has now been curiously leaked.
The paper was authored by Harold White and six other engineers and scientists from NASA's Eagleworks Laboratory. It's not clear yet if this was the version approved for publication. It claims that the EmDrive produces 1.2 millinewtons per kilowatt of power supplied.
"Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 ± 0.1 millinewtons per kilowatt," the team wrote in the paper's abstract.
This might seem small at first, since NASA uses ion thrusters in probes like Dawn with a thrust-to-power ratio of about 60 millinewtons per kilowatt. However, the EmDrive has an advantage: It doesn’t require propellant.
And that’s the controversial property of the EmDrive. It appears to be producing a reaction without the need for an action, violating Newton’s third law of dynamics. The engine is a conical copper container that generates thrust when filled with microwaves.
In the paper, which will be published by the American Institute of Aeronautics and Astronautics (AIAA) Journal of Propulsion and Power next month, the researchers believe that the force is the measurable reaction to the oscillating microwave photons in a quantum vacuum field.
Their explanation requires an uncommon and hardly accepted interpretation of quantum mechanics, known as the realist interpretation. This view states that the probabilistic measurements we obtain from quantum mechanics is due to the combination of a real particle that has a perfectly determined path and velocity and a “pilot wave” that generates the probabilities we observe.
These ideas have been discussed since the inception of quantum mechanics, and even Einstein claimed that there must be some "hidden variables" inside quantum mechanics. The hidden variable theory was shown to be less likely than one chance in 170 million.
Another paper, published in June, suggests that the cause for the thrust has to do with the shape of the cavity and the energy of the photons. The researchers, who are unaffiliated with the EmDrive team, suggest that photons interact with themselves in a destructive way and that the conical structure creates an imbalance of photons on one side, thus producing thrust.
Potential explanations will be flocking in as soon as the paper is officially published. In the paper, the team detail how they carefully tried to account for many potential sources of error, and it seems they might have shown that the EmDrive does indeed work. Of course, more experiments will be necessary to confirm the findings.