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New Test Supports NASA's Controversial EM Drive
An anonymous reader writes: Last year, NASA's advanced propulsion research wing made headlines by announcing the successful test of a physics-defying electromagnetic drive, or EM drive. Now, this futuristic engine, which could in theory propel objects to near-relativistic speeds, has been shown to work inside a space-like vacuum. NASA Eagleworks made the announcement quite unassumingly via NASASpaceFlight.com. The EM drive is controversial in that it appears to violate conventional physics and the law of conservation of momentum; the engine, invented by British scientist Roger Sawyer, converts electric power to thrust without the need for any propellant by bouncing microwaves within a closed container. So, with no expulsion of propellant, there’s nothing to balance the change in the spacecraft’s momentum during acceleration.
A lovely summary from the Physics StackExchange which sums up my thoughts:
"The initial tests were at atmospheric pressure. To test the fan hypothesis, an easy way is to vary the pressure, another easy way is to put dust in the air to see the air-currents. The experimenters didn't do any of this (or at least didn't publish it if they did), instead, they ran the device inside a vacuum chamber but at ambient pressure after putting it through a vacuum cycle to simulate space. This is not a vacuum test, but it can mislead one on a first read.
In response to criticism of this faux-vacuum test, they did a second test in a real vacuum. This time, they used a torsion pendulum to find a teeny-tiny thrust of no relation to the first purported thrust. The second run in vacuum has completely different effects, possibly due to interactions between charge building up on the device and metallic components of the torsion pendulum, possibly due to deliberate misreporting by these folks, who didn't bother to explain what was going on in the first experiments they hyped up. Since they didn't bother to do a any systematic analysis of the effect on the first run, to vary air-pressure, look at air flows with dust, whatever, or if they did this they didn't bother to admit their initial error, this is not particularly honest experimental work, and there's not much point in talking about it any more. These folks are simply wasting people's time."
http://physics.stackexchange.com/questions/23725/is-the-emdrive-or-relativity-drive-possible
In conclusion, they did a really really bad experiment and got a bad result. Wow!
If I were to peer-review a paper on this, I would insist on a plausible physical explanation for the claimed measurement. The burden of proof is on them: they are making a truly extraordinary claim, one that, if true, would entail revising all of physics from its very foundation.
When somebody sounds like a total fucking crackpot, they almost always are.
You might have missed high temp super conductivity entirely then. The phenomenon was measured and replicated in many labs - but it was at least a few years before any plausible theory came out - and 20 years on we do not have firm agreement on the cause.
Wrong.
Conservation of linear momentum is most certainly NOT derived from Thermodynamics.
Conservation of linear momentum is a mathematical consequence of translational symmetry - in other words, momentum is conserved if the laws of physics are invariant in space. Similarly, angular momentum is conserved if the laws of physics are invariant by rotation.
100KW is the theoretical energy that you might be able to make a deep-space craft out of with this drive. The power it's been tested with so far is three orders of magnitude lower.
BS. That most certainly does not "stand to reason". Higher-energy photons have more momentum, not less, yet this thing uses microwaves (much lower energy than visible light) and gets orders of magnitude more thrust than could be explained by the quite-well-understood thrust from EM radiation. Besides, why would there be a net thrust in one direction? The microwaves should escape the cavity in all directions, not just out the back, if they're escaping at all. A light drive has to be open at the back, or the photons would bounce off the rear wall and counter the thrust they imparted to the ship by bouncing off the reflector around the emitter.
There's no place I could be, since I've found Serenity...