Mankind has come a long way in understanding the universe. We have a physical framework mostly fits our observations, and with new technologies we analyzed the big bang and took photos of black holes. But the hypothetical EmDrive rocket engine threatens to sharpen the knowledge we know about physics … if it works. After the last round of testing, we can say with a high degree of certainty that this is not the case.
If you have memories from the 90s, you probably remember the interest in cold fusion, a putative chemical process that can melt energy from fusion at room temperature instead of millions of degrees (choose your favorite scale, the numbers are huge). The EmDrive is basically cold fusion for the 21st century. The EmDrive, first introduced in 2001, uses an asymmetric resonator cavity in which electromagnetic energy can bounce around. There are no exhaust fumes, but proponents claim that the EmDrive has a thrust.
The idea behind the EmDrive is that the tapered shape of the cavity would reflect radiation in such a way that on the one hand a greater net force was exerted on the resonator. Thus, an object can use this ‘engine’ for hyper-efficient propulsion. This would be a direct violation of conserving momentum. Interest in the EmDrive was spreading until 2016 when NASA’s Eagelworks laboratory built and tested a prototype. According to the team, they detected a small but measurable net force, and that got people interested.
There was a lot of skepticism about the Eagelworks results, and other teams could not duplicate the results. A team from Dresden University of Technology has completed a comprehensive new test and is trying to replicate the results of Eagelworks. And they found nothing – the Dresden EmDrive generated no surge when electromagnetic radiation bounced around inside the resonator.
The Dresden EmDrive is an exact copy of the NASA Eagelworks setup.
The team also tried to explain the Eagelworks results, which they did by varying the experimental design. The Dresden researchers used better measurement techniques to show that the EmDrive does not deliver thrust, but by adjusting the scale and changing resonator suspensions, they got the same small apparent range as NASA. This confirms that the thrust of Eagelworks was actually just a thermal effect. The researchers also speculate that the data was selected by Eagelworks by reporting random fluctuations in a way that does not represent the complete data set.
It really feels like the end of the road for the EmDrive. Unless someone can identify a major element of the physics we missed, this engine can in no way function as described. EmDrive proponents will have to pack it in, unless they want to end up like cold mergers from the ’90s. It’s just science in action, but it’s a little awkward too, because the EmDrive would have changed the world if it were not a fantasy.
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