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NASA's Impossible Propulsion EmDrive Is Heading to Space (popularmechanics.com)
An anonymous reader writes:The EmDrive, a hypothetical miracle propulsion system for outer space, has been sparking heated arguments for years. Now, Guido Fetta plans to settle the argument about reactionless space drives for once and for all by sending one into space to prove that it really generates thrust without exhaust. Even if mainstream scientists say this is impossible. Fetta is CEO of Cannae Inc, and inventor of the Cannae Drive. His creation is related to the EmDrive first demonstrated by British engineer Roger Shawyer in 2003. Both are closed systems filled with microwaves with no exhaust, yet which the inventors claim do produce thrust. There is no accepted theory of how this might work. Shawyer claims that relativistic effects produce different radiation pressures at the two ends of the drive, leading to a net force. Fetta pursues a similar idea involving Lorentz (electromagnetic) forces. NASA researchers have suggested that the drive is actually pushing against "quantum vacuum virtual plasma" of particles that shift in and out of existence. Most physicists believe these far-out systems cannot work and that their potential benefits, such as getting to Mars in ten weeks, are illusory. After all, the law of conservation of momentum says that a rocket cannot accelerate forward without some form of exhaust ejected backwards. Yet the drumbeat goes on. Just last month, Jose Rodal claimed on the NASA Spaceflight forum that a NASA paper, "Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum" has finally been peer-reviewed and accepted for publication by the American Institute of Aeronautics and Astronautics, but this cannot be confirmed yet.
Even if he sends this to space, the argument that it is leaking evaporated bits from the interior of the cavity will persist.
I expect others to follow.
Until he sends the damned thing on a tour of the solar system with no other forms of propulsion, where any such arguments would require the evaporation of significant portions of the cavity internals, and where both speedup and slowdowns happen, this will never be settled.
... or can ye?
At this point, it seems that what is happening is a combination of two factors: 1) Experimental error. 2) Small amounts of material are being heated up and outgassed. This is consistent with an open cavity and is consistent with some of the reports having the drive's thrust take a small amount of time to start off, which looks a lot like it is taking time for the cavity to heat up.
The laws of physics have changed so much in the last few thousand years, why do we suddenly think we are at the pinnacle of dictating the laws that govern the universe just because we haven't found anything contrary in the last few hundred years? Our laws of physics are based around our extremely limited observation of a tiny portion of the universe; surely when more is observed then some of the laws are going to change.
Science relies on an open mind and proof of a theory by repeatable experimentation so all the naysayers who instantly dismiss anything with even the remotest possibility of redefining one of these laws of physics cannot be truly called scientists and are no better than those that would dismiss the notion of there being no god just as easily.
The press hype goes on despite results of two experimental results that clearly indicated the mythical drive to not thrust: A group of physicists at the university of Dresden measured miniscule thrust, but strangely enough the thrust went into the same direction when the "EMdrive" was rotated by 90. So they figured that what they measured was probably resulting from an interaction of the electric powering from the outside with the magnetic field of earth. They couldn't easily remove this probable source of error in their setup, but a chinese group of physicists managed to do so: They powered the "EM-drive" from a battery that was within the same enclosure - and voila - no more thrust to be measured.
It seems to me this is indeed the infinite improbability drive. If it actually propels something doe we care why?
Some drink at the fountain of knowledge. Others just gargle.
Good thing it's not a rocket then.
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NASA's Impossible Propulsion EmDrive Is Heading to Space
It's not NASA's.
systemd is Roko's Basilisk.
Not all observable, repeatable phenomena can be explained yet. The random formation of DNA seemingly defies statistical probability, yet, it happened. Just sayin' here...
When the king heard the words of the Book of the Law he tore his robes.2Kings22:11
First off, if the engineers designing this thing are remotely competent there won't be any out-gassing.
Uncontrolled out-gassing is, and has since the beginning of the space age, been a really obvious problem. So it'll be designed from the get-go to avoid uncontrolled out-gassing.
It also doesn't have to be brought back to Earth to be weighed. Acceleration, if any occurs, can be measured pretty precisely. The degree of acceleration is a product of the mass and velocity of out-gassing.
If there is any observed acceleration you just have to wait until the amount of reaction mass necessary to account for that acceleration exceeds some reasonable amount and we're done - it works. No tour of the solar system necessary.
Minutus cantorum, minutus balorum, minutus carborata descendum pantorum.
I've been following emdrive for a while now. Prof McCulloch's book and emdrive paper provide the best description I have yet seen of an emdrive. As mentioned above there are no 'laws' of physics, just a collection of theories which seem to describe observed facts well. The theories change or are expanded to suit fresh observations. The best theories can be used to make predictions and provide explanations in disparate other problematic observations and this is the case with Prof McCulloch's work.
If NASA are prepared to use resources to send one of these things to orbit then the case for emdrive is at least still open. Speaking personally, I would like to use a 3d printer to build a 10x10x10 Cu block of these cavities, that should give a definitive answer. How about it Mr Musk?
Problems always arise on the edge of physics from the difficulties of making measurements. That's the fun of the thing...
Any energy released comes from the chemical reactions which are the bonds between electrons being broken and created.
The reaction products have a mass that is ever so slightly lower than the mass was before the reaction.
A lot of online explanations get this wrong. Like this one: from the BBC, explaining conservation of mass in chemical reactions. It would probably unnecessarily confuse the students who focus on all the mass that a fire "loses" as CO2 and water vapour and such, which is not lost at all.
The mass loss is extremely small of course. For an energy release of 1J, you lose 11 femtogram (1J/c^2). Good luck measuring that on your high school scales, or indeed any scales at all.
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