Now it looks like, well, it does
was too good to be true. Researchers at Dresden University of Technology (TU Dresden) seem to have conclusively proven that EmDrive does not actually produce any momentum. They provide some compelling evidence that small indications of momentum in previous research were simply false positives produced by external forces.
How EmDrive should work
Credit: AndSus / Adobe Stock
In EmDrive, the company that owns the rights to the invention says, “Thrust is produced by amplifying the radiation pressure in an electromagnetic wave that propagates through a resonant waveguide assembly.” In simpler words, trapped microwaves bounce around a specially shaped closed container, producing shocks that push it all forward.
They also claim that while EmDrive does not exactly speak to Newton’s third law, the company says it’s completely in line with the other:
“This is dependent on Newton’s second law, where force is defined as the speed of changing momentum. An electromagnetic (EM) wave moving at the speed of light thus has a certain momentum, which it will transmit to a reflector, resulting in a small force. ”
The interest in EmDrive has been understandable given what it was supposed to do. Talking to
Popular mechanics last year, Mike McCulloch, head of DARPA’s EmDrive study, describes how the engine could “transform spaceflight and watch craftsmen lift silently from launch pads and reach beyond the solar system.” He mentioned his enthusiasm for being able to get from here to Proxima Centauri – 4.2465 light years away – in just 90 human years.
It does not work. Yes it does. No it does not.
NASA Eagleworks’ EmDriveCredit: NASA / Wikimedia Commons
DARPA, which is part of the U.S. Department of Defense, is just one of the organizations investigating the allegations about EmDrive. In 2018, the agency invested $ 1.3 million to investigate the device in research that will be wrapped up in May, ruling out significant last-minute breakthroughs.
Teams from around the world have been testing Shawyer’s idea since it was introduced, and have released often conflicting test results. This may have to do with the fact that teams detecting any EmDrive feature at all have reported vanishingly small amounts of it measured in milliNewtons (mN). An mN is equal to approx. 0.00022 pound force.
As Paul Sutter wrote in an op-ed to Space.com:
“Ever since the introduction of the EmDrive concept in 2001, a group claims to have measured a net force coming from its unit every few years. But these researchers measure an incredibly small effect: a force so small that it could not even jump a piece of paper. This leads to significant statistical uncertainty and measurement errors. ”
To get a sense of how poor these results are, consider that the possible thrust reported by NASA in 2014 at 30-50 micro-Newtons is roughly equivalent to the weight of a large ant. Chinese researchers have demanded detection of 720 mN in their tests. That would be 72 grams of stack. An iPhone 11 with case weighs 219 grams.
Too small to stand out against background noise
These small amounts of EmDrive propulsion lie at the heart of what TU Dresden researchers say: The effects are simply too small to rule out effects that do not come from EmDrive at all. The researchers have just published three articles. The title of a “High-Accuracy Thrust Measurements of the EmDrive and Elimination of False-Positive Effects” tells the story. The other two studies are here and here.
When the UT Dresden team turned on their EmDrive based on NASA’s EmDrive, they also witnessed small amounts of apparent propulsion.
However, Martin Tajmar from UT Dresden tells the German media outlet GreWi that they quickly realized what was going on: “When the current flows into the EmDrive, the engine gets hot. This also causes the fasteners on the scale to chain, causing the scale to move. to a new zero. We could prevent it in an improved structure. ”
Putting kibosh on other researchers’ findings, the authors of the studies write:
Using a geometry and operating conditions close to the model of White et al., Who reported positive results published in peer-reviewed literature, we found no pressure values within a wide frequency band including multiple resonant frequencies. Our data limits any abnormal pressure to below the power equivalent of classical radiation for a given amount of power. This sets strong limits for all proposed theories and excludes previous test results by more than three orders of magnitude. ”
This seems to be the final end to EmDrive history.
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