NASA's EM Drive Paper finally published

[Pyropyro]

Layman version

Actual journal article

The EM drive is an "impossible" propulsion system that utilizes microwaves instead of bulky rocket fuel. If this thing actually makes it into production then space travel would be dirt cheap.

It's called impossible since it seems not to follow the "Every action there's an equal and opposite reaction" rule. I think with some esoteric physics they finally discovered how the drive works. Unfortunately, I'm no physicist so I can't confidently laymanize the article for you.


Hey Cog, I think you posted something about this drive a few years ago.

 

[Sinny91]

They (Never A Straight Answer) were trying to downplay this last year...

But there are only so many years they can keep downplaying alternative propulsion systems.

I've seen numerous craft defy conventional physics, a large portion of these were spherical, others were oval, others were triangle, and others you wouldn't even wrap your brains around.

 

[Reluctantly]

But electromagnetic radiation doesn't negate Newton's Third Law. As electrons move, their kinetic energy causes other things to move and react and push and pull. We typically call this a magnetic field and it is the inherent energy that causes an electric current to even occur.

So where's the problem exactly?

 

[Dorian Tullus]

oh thank god for layman

 

[Dorian Tullus]

oh thank god for layman

i take back what i said

 

[Grayman]

But electromagnetic radiation doesn't negate Newton's Third Law. As electrons move, their kinetic energy causes other things to move and react and push and pull. We typically call this a magnetic field and it is the inherent energy that causes an electric current to even occur.

So where's the problem exactly?

What things? A train that propels toward with magnetic force pushes against the rails. What does a spaceship push against in a vacuum?

Now you might say really small particles is what you push against but if you push a pea with your massive body which will move, the pea or your body?

 

[Reluctantly]

What things? A train that propels toward with magnetic force pushes against the rails. What does a spaceship push against in a vacuum?

Well space isn't a true vacuum. And EM fields can radiate and propagate quite far in and out of our solar system before attenuating into nothing.

Now you might say really small particles is what you push against but if you push a pea with your massive body which will move, the pea or your body?

You might be right, but the concept of propelling through space by electromagnetic radiation is theoretically sound. But in application, you might have a very good point. I'm only commenting that the theory doesn't contradict Newton's Third Law as the article points out.

 

[Cognisant]

Hey Cog, I think you posted something about this drive a few years ago.

I did, has it really been that long?

 

[billybbob18]

Damn it NASA! You stole my "cumulative frequency drive" CFD idea. My plan was to build or design a machine that was able to focus everything in the spectrum into a single small focal point using a series of mirrors of adjustable shape and varying material according to whatever wave characteristics were needed to produce the highest possible peak. Fusion would be produced at the focal point. I tried to come up with the model, but the math would have been out-there insane. I hope someone can figure it out. I really think it's possible. It could power everything on earth. There's vast amounts of energy EVERYWHERE as Richard Feynman pointed out. We just need to guide it to a single point.

 

[Pyropyro]

I did, has it really been that long?

Well dem Adeptus Mechanicus were being too lazy lately...

 

[Ex-User (9086)]

Basically, EM drive would be a very unique method to generate thrust as it doesn't require reaction mass, a feature that can only be found in photonic laser thruster / solar sail solutions, except EM drive wouldn't need any external support devices to move it along, which is the case with huge laser arrays/mirrors/sails needed to propel with PLT.

The paper you linked is being currently disputed and has been subject to many criticisms from peer reviewers before it was finally published. There are several dubious things about the experiment itself, since it hasn't been replicated anywhere else and all teams that did similar research retracted their findings or went silent. Even considering the quality of their experimental device, there's much left to be improved.

As things stand, it appears to be that while there's a potential for the claims about the reactionless drive generating thrust to be true, the theoretical limits of the amount of thrust it is capable of delivering over time make it impractical in competition with more efficient solutions that are in demand due to the nature of contemporary space exploration.

For comparison, assuming the 1.2 * 10^-3 N/KW figure is verified, that makes the EM engine some 33 times less efficient than the most generic of fully electric Ion Engines (with reaction mass). Since it takes 834 KW to produce a N of thrust and it's 25KW/N for Ion. That puts any potential applications far beyond the scope of interplanetary transfers and one has to consider how huge of a reactor / solar array (power source) it would require to meet any practical requirements.

Here's a nice breakdown of the issue in the spoiler below:

Spoiler

https://www.youtube.com/watch?v=JGcvxg7jJTs

 

[Kuu]

I thought the paper was due in December... did the leak make them release it earlier? Hopefully others replicate so that the matter can be settled. And some space tests would be interesting too. I read somewhere that the chinese might have tested one in space already (in secret); there's a Chinese group that was experimenting on an EmDrive.

I recall reading about pilot-wave theory not too long ago, interesting that they might go that way with the explanation. QM is still quite crazy and there's a ton of stuff still unknown; we still don't have a unified theory.

What's next, cold fusion?

 

[Reluctantly]

wait wait wait, I think I'm confused. I thought this was along the lines of a directed photonic drive, but supposedly it's not propelled by photons, yet uses electricity to generate a photonic EM field inside the device that creates thrust?

But...nobody really knows why it works? It just does?

Okay, this is really interesting then.

 

[Reluctantly]

You know, is it possible the device is using photons to force a particle that we haven't observed out of the device? If it works, that would seem a likely explanation I guess. Maybe dark matter? Whatever that's supposed to be exactly.

 

[Ex-User (9086)]

wait wait wait, I think I'm confused. I thought this was along the lines of a directed photonic drive, but supposedly it's not propelled by photons, yet uses electricity to generate a photonic EM field inside the device that creates thrust?

It is using photons inside a resonant cavity chamber. Microwaves are essentially low energy photons. Engines/Plates propelled by photons are what's called PLT and they already exist and there's no controversy that they work, however they are very ineffective depending on specific applications.

They can't really explain why the whole EM drive thing is being propelled though and the tiny amount of thrust they get is on par with a long list of noise/distortion errors that could falsify the experiment. Seems like they want to chalk it up to radiation pressure or something else, doesn't matter what it is, they need to test it in space and build bigger models regardless.

What's next, cold fusion?

As far as brave pseudoscience goes, that would be the next thing to see fall apart after publication I suppose. People claiming cold fusion have been ripped to shreds so many times that it's probably a boring topic at this point for people in the field.

 

[Intolerable]

Radiowaves as Blarraun noted could be anything though the journal did cite they checked for mundane influence.

You know, is it possible the device is using photons to force a particle that we haven't observed out of the device? If it works, that would seem a likely explanation I guess. Maybe dark matter? Whatever that's supposed to be exactly.

Well the issue would be to know if dark matter is even a thing. I personally am not convinced. But without a verifiable, testable thing we could never know what it is let alone if it conducts some materials easier than others.

Odds are very good that it is neither conductive nor a thing. For if the planet we're on possessed any such material in vast quantities it would have influenced our trajectory through space in some way. Well maybe it does but the way all planets move seems entirely related to space being a vacuum and celestial bodies relying on enormous mass properties to influence each other over those vast, empty distances.

 

[Rixus]

I can't see how moving photons could be providing thrust, since they have no mass. I was guessing the drive must influence some other subatomic particles. Maybe WIMPS? I don't know.

Sent from my Nexus 6P using Tapatalk

 

[Architect]

My day job work was used in the experiment which is kind of cool. We do scientific instrumentation and it's neat to see see the places it ends up, I think it was also used on the ISS and the latest lunar flybys.

There are several possible explanations I've reviewed, my favored version is that is Bohm's interpretation of Quantum Mechanics. There are three main QM interpretations, Copenhagen (most popular), many worlds and Bohmian. Copenhagen (particles don't have position/momentum until measured) is obviously illogical (may still be true, even if crazy). Many worlds is just plain crazy. Bohm says particles always have position/momentum (even if you don't happen to know what it is), but in exchange you have to accept 'spooky action at a distance' due to a mysterious 'pilot wave'. Simple, clean, just as good as any other and has opportunities for new physics, such as the em-drive. The idea is that u-wave EM fields interact with the pilot wave to provide the thrust.

Admittedly this is hand waved in the paper, but to my intuition is it is the best approach. And to be truthful my real money is that it's a bust.