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I'd like to see an EM Drive put into testing up there too (yes, yes, yes - I know it's defying the [known] laws of science. No reason not to test it in space since it seems to pass all tests on earth)

Hey maybe we could strap the ION Drive face-to-face with an EM Drive, throw them out the hatch and see who pushes who around!

A "working EmDrive" would be a reversible electromagnetic machine, functioning equally well as a motor or a generator:
http://www.emdrive.com/2Gupdat... (page 6, ironically titled Conservation of Energy)

If allowed to accelerate, the microwaves in the cavity would red-shift and lose energy, if accelerated in the other direction, they would blue-shift and gain energy. A "working EmDrive" placed on one end in Earth's surface gravity would thus either continuously create or destroy energy.

The reasonable conclusion is that there is no such thing as a "working EmDrive".

If it manages to violate conservation of momentum and that stands up to the inevitable scientific pig pile that follows, I'll be impressed.

One theory of how it works...
http://www.emdrive.com/theoryp...

I am not a physicist, and don't *really* understand what they are theorizing, except that they are suggesting that special relativity applies to the engine instead of newtonian mechnics. (which isn't really a surprise).

If you can follow the math and the judge the theory, have at it...

Just have a look at the older articles (circa 2010) from this site. You will not have too look for very long to find very bogus physics.

Its difficult to explain to a layman because you don't have the background.
Actually I have the background. Hence my complaint :D

Electromagnetism is the theory of photons, microwaves, electric fields, magnetic fields.
In the grand picture of things, yes.

But not in this case, or a wind turbine creating power with a generator based on electrons moved inside of a cable through a static magnetic field would be the same as a microwave creating photons.

Which is clearly not the same thing :D

Reducing everything down to Maxwell does not help if you don't grasp those differences.

So far you made no single argument that made any sense to a Physicist.

My understanding is that the EM drive claims to produce thrust with no exhaust, and / or claims to produce more thrust / power than can be produce by photons. Neither of those is possible because both violate conservation of energy / momentum.
Here it is again.

WHY PLEASE PLEASE PLEASE: Neither of those is possible because both violate conservation of energy / momentum. Why do you jump to this sentence? There is no logical relation between those statements, and none based on laws of physics. You just say that.

First of all, the inventors of the EM drive don't claim that there is no "exhaust". There are plenty of things that happen in the universe that have "no exhaust", conserve the momentum and accelerate something. E.g. a stone dropping to earth in a gravity field.

Instead of throwing random "it violates the law of conservation of momentum" into the room you should e.g. read this: http://emdrive.com/principle.h... and point out the flaw.

The principles "the inventors" think, make the thing working are based on the law of conservation of momentum!

Perhaps they made a mistake? Point it out and you will be famed. But your arguments sound like: at night it is darker than outside. A grammatically completely correct sentence. However I would likely not start my PhD thesis with it.

The claim is that due to particles/waves moving at the speed of light you can not use classical "mechanics" but have to use relativist calculations. Coming from those calculations the "inventors" built the first prototypes. And a few international research labs did the same. All claim to have found "unexplainable" thrust (That includes NASA, btw).

Others think that "very low amounts" of acceleration have some strange side effects (on the other hand, that would be new physics and I don't believe that): https://www.technologyreview.c...

Interesting are e.g. those passages:

"Crucially, McCullochâ(TM)s theory makes two testable predictions. The first is that placing a dielectric inside the cavity should enhance the effectiveness of the thruster.
The second is that changing the dimensions of the cavity can reverse the direction of the thrust. That would happen when the Unruh radiation better matches the size of the narrow end than the large end. Changing the frequency of the photons inside the cavity could achieve a similar effect."

So, bottom line I have no idea if the drive works or not. I simply find the self proclaimed debunkers extremely unscientific because none of them was able to write a bunch of sentences that follow a line of logic, math and laws of physics.

For starters: there is no law of physic that can be simply pulled out of a book that states: "this is impossible". But that exactly is what they do (and you did).

The only ways to debunk this device is to explain why we see thrust (NASA is reporting thrust in a hard vacuum) in those experiments and why e.g. that finish paper is wrong, in other words, where it is wrong..

As a wishful thinker I hope we put one in space and watch what happens :D Probably we can use a 100g nano satellite ...

Can you point to an actual theoretical explanation/prediction of the effect?

Here's the latest one, though he's been saying for years that the key to making it more powerful is the Q value of the cavity because the thrust will scale exponentially with Q. On the same note: the claims of Shawyer and the Chinese team aren't absurd if you factor in the point that it would only take making the walls smoother and coating them with silver to improve upon copper cavities. There has also been substantial talk on the nasaspaceflight forums that you could improve things slightly (a few orders of magnitude) by tuning the size of the cavity to the frequency of the input due to destructive and constructive interference produced. While that potential optimization does nothing to explain the underlying effect, it is entirely possible the two groups either guessed the right size or hit it by chance.

Confirming propellantless thrust from a 2nd Generation superconducting EM Drive would outweigh local effects. (http://emdrive.com/secondgenengines.html) 2G (2nd Gen.) testing started in 2006, according to Roger Shawyer's paper: http://www.emdrive.com/2Gupdat...

Scientists Confirm 'Impossible' EM Drive Propulsion

Science News, Space / July 27, 2015 / by Giulio Prisco/

Later today, July 27, German scientists will present new experimental results on the controversial, "impossible" EM Drive, at the American Institute for Aeronautics and Astronautics' Propulsion and Energy Forum in Orlando. The presentation is titled "Direct Thrust Measurements of an EmDrive and Evaluation of Possible Side-Effects."

Presenter Martin Tajmar is a professor and chair for Space Systems at the Dresden University of Technology, interested in space propulsion systems and breakthrough propulsion physics.

A Revolutionary Development for Space Travel

The EM Drive (Electro Magnetic Drive) uses electromagnetic microwave cavities to directly convert electrical energy to thrust without the need to expel any propellant. First proposed by Satellite Propulsion Research, a research company based in the UK founded by aerospace engineer Roger Shawyer, the EM Drive concept was predictably scorned by much of the mainstream research community for allegedly violating the laws of physics, including the conservation of momentum.

However, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold G. “Sonny” White at the Johnson Space Center (JSC) – investigated the EM Drive and presented encouraging test results in 2014 at the 50th Joint Propulsion Conference.

White proposes that the EM Drive’s thrust is due to virtual particles in the quantum vacuum that behave like propellant ions in magneto-hydrodynamical propulsion systems, extracting "fuel" from the very fabric of space-time and eliminating the need to carry propellant. While a number of scientists criticize White's theoretical model, others feel that he is at least pointing to the right direction. The NASASpaceFlight website and forums have emerged as unofficial news source and discussion space for all things related to the EM Drive and related breakthrough space propulsion proposals such as the Cannae Drive.

Shawyer has often been dismissed by the research establishment for not having peer-reviewed scientific publications, but White and Tajmar have impeccable credentials that put them beyond cheap dismissal and scorn. Physics is an experimental science, and the fact that the EM Drive works is confirmed in the lab. "This is the first time that someone with a well-equipped lab and a strong background in tracking experimental error has been involved, rather than engineers who may be unconsciously influenced by a desire to see it work," notes Wired referring to Tajmar's work.

Hacked has obtained a copy of Tajmar's Propulsion and Energy Forum paper, co-authored by G. Fiedler.

"Our measurements reveal thrusts as expected from previous claims after carefully studying thermal and electromagnetic interferences," note the researchers. "If true, this could certainly revolutionize space travel."

“The nature of the thrusts observed is still unclear.”

"Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts," conclude the researchers. "Nevertheless, we do observe thrusts close to the magnitude of the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation."

Contrary to sensationalist reports published by the sensationalist press, the EM Drive is not a "warp drive" for faster than

The inventor knows.
He formulated the theory of the device. And actually it is pretty easy to grasp for a layman. http://en.wikipedia.org/wiki/E...

Have you actually read the paper? Hint: there's a very, very good reason why it is not in a peer-reviewed journal.

It's also worth noting that his claim reeks to high heaven - if the momentum is somehow extracted from the microwave photons then it should be balanced by the momentum imparted to those photons when first generated. The drive+power source is operating as a closed system, and thus according to classical physics the net momentum cannot change, and the microwave photons remain completely contained until they are eventually absorbed by the resonance chamber.

It's possible that this thing actually works, but if it does it will almost certainly prove not to be governed by his theory of extracting net momentum from bouncing photons. Maybe it's pushing against the quantum vacuum, maybe it's pushing against the fabric of space-time itself, but if it does in fact accelerate it's almost certainly pushing against *something* that is not confined within the resonance chamber. But hey, that's fine. Science is full of people who have discovered fascinating new phenomena only to have their theories about the cause smashed when others in the community offer a better explanation.

I'll admit I'm not well-versed in relativistic effects, but a quick skim of his principle of operation page appears to throw up a huge red flag at the beginning of the third paragraph:

If the same EM wave is travelling at a fraction of the speed of light...

Which sounds like nonsense to me - EM waves (aka photons) travel at the speed of light in vacuum - no more, no less. Ever. You can alter their energy and thus momentum by choosing a different frame of reference, but their velocity is constant from any frame - that's the crazy impossibility that Einstein uncovered.

It's worth noting that Roger Shawyer (the original inventor) maintains that this effect does not violate Conservation of Momentum.

In my opinion, you can't just say "this is obviously wrong."

Yes you can: it's obviously wrong. Read the paper from the inventors on how the engine is supposed to work. It's a series of novice-level mistakes about physical principles and mechanisms. The entire idea is completely fucking batshit from the very beginning. The very fact that somebody actually got funding to build one of these absurd snake-oil devices indicates very little except that something is very, very wrong with the funding process. NASA is infamous for this kind of loony bullshit, and they really need to stop. It makes them look like morons.

I agree that the theory (or, at least, that theory) is obviously wrong. Cool, but from experimentalist standpoint, irrelevant. This paper, and the chinese paper, do not appear to the written by charlatans, they claim positive results, and so this will have to confirmed or denied by experiment. I have seen some very bad experimental NASA studies of new physics (*cough*warp drive*cough*), but this one doesn't appear to be so. If you see an obvious flaw in the full paper, please post it and I will publicize it.

I would advise in general that you don't hyperventilate so much. This process will work out just as it should; I have no doubt that in a year there will be a dozen tests of this and we will likely know for sure one way or the other; in the meantime, I would take a $ 200 bet that the standard model will still prevail when this is over.

In my opinion, you can't just say "this is obviously wrong."

Yes you can: it's obviously wrong. Read the paper from the inventors on how the engine is supposed to work. It's a series of novice-level mistakes about physical principles and mechanisms. The entire idea is completely fucking batshit from the very beginning. The very fact that somebody actually got funding to build one of these absurd snake-oil devices indicates very little except that something is very, very wrong with the funding process. NASA is infamous for this kind of loony bullshit, and they really need to stop. It makes them look like morons.

Reaction-less thrust would appear to be not only possible, but something that's in active development!

Here's the site for the group that's working on it: http://www.emdrive.com/
And here's the relevant research paper: http://www.newscientist.com/data/images/ns/av/shawyertheory.pdf

http://www.emdrive.com/ Why not develop this technology so everyone can use their microwaves and a copper cone to have a spaceport in their driveway?

Governments could even rake in tons of revenue and taxes on emdrive certification and licensing fees. This would be great for the economy.

BZZZT wrong.

Take a look at http://www.emdrive.com/theorypaper9-4.pdf

This is the original from which the Chinese work is derived. Paragraph 5 refers to end plates at both ends. This theory is entirely reliant on standing waves, not emitted photons. This is clear from the mathematics.

There are no emitted photons - this is a closed system. The linked article omits to state this -- but if you do your research you'll see that the claim is regarding a closed system.

I believe the law of conservation of energy should be regarded as the 'root' of the 'conservation of ...' laws. While I don't really think this device can possibly work, it doesn't claim to violate conservation of energy, only conservation of momentum. It's entirely possible that new physics have been discovered.

'interact' has no basis in science, so unless you want to be a lot more clear in your wording, then just be quiet.

"The thrust is reported to be from the large end towards the small end. "

No, TFA says:

"... experiences a net thrust towards the wide end."

"Thrust towards" is ambiguous. Dig through the website on the proposed theory. The implication is the force is exerted on the large end, so the contraption moves large end first.

Which - again - is the same behavior you'd get from heating air along the length of the taper.

http://emdrive.com/principle.html

The inevitable objection raised, is that the apparently closed system produced by this arrangement cannot result in an output force, but will merely produce strain within the waveguide walls. However, this ignores Einstein's Special Law of Relativity in which separate frames of reference have to be applied at velocities approaching the speed of light. Thus the system of EM wave and waveguide can be regarded as an open system, with the EM wave and the waveguide having separate frames of reference.

A similar approach is necessary to explain the principle of the laser gyroscope, where open system attitude information is obtained from an apparently closed system device.

That last paragraph intrigues me. Could someone who understands ring laser physics comment on this?

Sure. This is BS designed to confuse and bamboozle people who don't understand special relativity or ring laser gyros.

The FAQ deals with conservation of momentum, allowance for bouyancy, electromagnetic effects, convection and other issues here: http://emdrive.com/faq.html. A fantastic picture of the device on this page: http://emdrive.com/.

Here are some of the FAQ answers:
Q. Why does the EmDrive not contravene the conservation of momentum when it operates in free space?
A. The EmDrive cannot violate the conservation of momentum. The electromagnetic wave momentum is built up in the resonating cavity, and is transferred to the end walls upon reflection. The momentum gained by the EmDrive plus the momentum lost by the electromagnetic wave equals zero. The direction and acceleration that is measured, when the EmDrive is tested on a dynamic test rig, comply with Newtons laws and confirm that the law of conservation of momentum is satisfied.

Q. Are there any convection currents which might affect the results?
A. Convection currents did not affect the results, as measurements were taken with the thrust vector up, down and horizontal. Test runs were also carried out using a thermal simulation heater to quantify the effects of change of coolant temperature.

Q. Have electromagnetic effects been taken into account? These include interactions between current-carrying conductors and between such conductors carrying RF currents and nearby metallic structures in which currents might be induced.
A. Stray electromagnetic effects were eliminated by using different test rigs, by testing two thrusters with very different mounting structures, and by changing the orientation by 90 degrees to eliminate the Earth’s magnetic field.

The FAQ deals with conservation of momentum, allowance for bouyancy, electromagnetic effects, convection and other issues here: http://emdrive.com/faq.html. A fantastic picture of the device on this page: http://emdrive.com/.

Here are some of the FAQ answers:
Q. Why does the EmDrive not contravene the conservation of momentum when it operates in free space?
A. The EmDrive cannot violate the conservation of momentum. The electromagnetic wave momentum is built up in the resonating cavity, and is transferred to the end walls upon reflection. The momentum gained by the EmDrive plus the momentum lost by the electromagnetic wave equals zero. The direction and acceleration that is measured, when the EmDrive is tested on a dynamic test rig, comply with Newtons laws and confirm that the law of conservation of momentum is satisfied.

Q. Are there any convection currents which might affect the results?
A. Convection currents did not affect the results, as measurements were taken with the thrust vector up, down and horizontal. Test runs were also carried out using a thermal simulation heater to quantify the effects of change of coolant temperature.

Q. Have electromagnetic effects been taken into account? These include interactions between current-carrying conductors and between such conductors carrying RF currents and nearby metallic structures in which currents might be induced.
A. Stray electromagnetic effects were eliminated by using different test rigs, by testing two thrusters with very different mounting structures, and by changing the orientation by 90 degrees to eliminate the Earth’s magnetic field.

http://emdrive.com/principle.html

The inevitable objection raised, is that the apparently closed system produced by this arrangement cannot result in an output force, but will merely produce strain within the waveguide walls. However, this ignores Einstein's Special Law of Relativity in which separate frames of reference have to be applied at velocities approaching the speed of light. Thus the system of EM wave and waveguide can be regarded as an open system, with the EM wave and the waveguide having separate frames of reference.

A similar approach is necessary to explain the principle of the laser gyroscope, where open system attitude information is obtained from an apparently closed system device.

That last paragraph intrigues me. Could someone who understands ring laser physics comment on this?

I want this EmDrive to be true, but I'll wait and see. On YouTube I saw a video of a prototype EmDrive rotating itself, but even if it's not fake I wonder if they have accounted for magnetic effects.

I want this to be true because space exploration would be tremendously faster if the spacecraft could accelerate the whole way without ever running out of reaction mass. Even if the acceleration was low, continuous acceleration would build to really fast velocities.

Fit out the sats with an electric drive instead, like this: http://emdrive.com/

I really wish something like this finally got off the ground: http://emdrive.com/ Microwaves in one end, thrust out the other.

It's too bad it's self-delusion by the inventor at best, and an outright scam to get government grants from credulous but scientifically-challenged bureaucrats at worst.

The only published explanation for the mechanism of operation contains an obviously incorrect mathematical assumption which neglects important but extremely straightforward physical effects to generate a fictitious force. (Briefly, the the EmDrive relies on microwaves bouncing off the end plates of a truncated conical cavity. The inventor assumes that since the area of one end plate is smaller than the area of the other, there will be a smaller total momentum transfer from the microwaves reflecting from that surface, resulting in a net force. In all of his calculations, he neglects to account for the axial component of force applied to the tapered walls of the cavity, which would nullify his drive's imaginary effect. The inventor attempts to handwave away this irretrievable flaw with blather about relativistic effects; the entire thing was pretty thoroughly debunked by competent and qualified physicists shortly after it started to get wide press coverage.) There has been no peer-reviewed publication in any reputable venue, and one is very unlikely to be seen.

.

Q. How can the EmDrive produce enough thrust for terrestrial applications?
A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.

Old hat. emDrive already works, demonstrated here: http://www.youtube.com/watch?v=57q3_aRiUXs&fmt=18 Uses microwaves in an enclosed cavity to transform lots of electricity into a bit of reactionless drive. emDrive Home: http://www.emdrive.com/