Cannae/EmDrive

[Sean Mirrsen]

As has been stated oh so many times, you test the device by putting a couple of panels on it and place it into an orbit, if it can gain altitude then it works.

MY suspicion is that it will work, but it will not produce as much force as it does in the laboratory.

I agree. However, if I had been given any power to pursue my own goals, I would have been a mad scientist - or rather, as the case usually is, a mad engineer. I don't care much for theory and the "how", except as a followup to "whether". Putting the EMDrive in orbit and turning it on would make a definitive test for its usefulness as a low-Earth-orbit maneuvering engine, however it would say nothing of its usefulness as an interplanetary transfer engine, much less interstellar, so even more tests would have to follow - and setting the device up to perform those tests is much more involved and complicated. Plus, with the variable and uncertain nature of the EMDrive, various changes in configuration would have to be performed to make sure that it works or doesn't work, which is extra effort and extra things that would have to be planned for. The basic test would have been simple, but any actual testing would need a lot of time and effort. And, accordingly, money. Nobody wants to waste money on a single experiment that isn't going to prove anything but "this particular configuration works/doesn't work in this particular circumstance".

As long as it's simpler and cheaper to keep running tests on the ground, tests will be run on the ground. Sure, it's slower, it lacks the immediate answer capacity, and all it really is is a lot of filler between the drive and a proper test in orbit, but it provides more accurate data, is easier to manage, and doesn't cost much money. Once/if it's been determined that total lack of intervening gases is not an obstacle to the EMDrive, and the produced effect is (reasonably) beyond doubt not an instrument error or a product of some other odd interaction, the whole thing will be sent into orbit.

There's no point rushing it along with insufficient data and risk running a definitive test in suboptimal circumstances. If it works, a definitive test must be a definitive success, otherwise it's better to keep it low-key.

[Nibb31]

I don't care much for theory and the "how", except as a followup to "whether".

Without knowing the "how", you can't predict whether it will work or not, or how to improve it or control it. You are reduced to years of empirical testing of every combination of parameters.

[Sean Mirrsen]

Without knowing the "how", you can't predict whether it will work or not, or how to improve it or control it. You are reduced to years of empirical testing of every combination of parameters.

When you already have a thing that seems to work, why wonder how it works before wondering whether it will work as the thing you want it to work as? If someone back in history accidentally mixed together the components for black powder and ignited it, them taking years to deliberate on the exact processes that allow the reaction to happen instead of going straight to fireworks and mining charges would be the exact same thing that's being done with the EMDrive today.

I appreciate being thorough. But ultimately we, the public and the engineers, are much more interested in whether the thing works up in space where we'd be using it, than in how exactly it works. The how will be useful later, so we know how to build it bigger and better. But for now the whether, the first step, is more important. Put it to the real test, then use the result of that as a data point and go from there.

The problem is that the world doesn't have mad scientists or mad engineers anymore. It's all mad economists and mad politicians.

Edited May 10, 2015 by Sean Mirrsen

[vger]

When you already have a thing that seems to work, why wonder how it works before wondering whether it will work as the thing you want it to work as?

If this thing is actually operating under some previously unknown physics that we don't understand, putting it into orbit could actually be a bad, even dangerous idea.

We don't know why it's doing what it's doing on Earth, which means it could potentially do ANYTHING in space. It's best to keep playing with it under controlled conditions for now, and just do process of elimination. We're not Kerbals. Let's not start flying through space with weird tech that we can't even figure out.

Edited May 10, 2015 by vger

[magnemoe]

When you already have a thing that seems to work, why wonder how it works before wondering whether it will work as the thing you want it to work as? If someone back in history accidentally mixed together the components for black powder and ignited it, them taking years to deliberate on the exact processes that allow the reaction to happen instead of going straight to fireworks and mining charges would be the exact same thing that's being done with the EMDrive today.

I appreciate being thorough. But ultimately we, the public and the engineers, are much more interested in whether the thing works up in space where we'd be using it, than in how exactly it works. The how will be useful later, so we know how to build it bigger and better. But for now the whether, the first step, is more important. Put it to the real test, then use the result of that as a data point and go from there.

The problem is that the world doesn't have mad scientists or mad engineers anymore. It's all mad economists and mad politicians.

Yes, lots of stuff was discovered by accident, knowing how stuff work has the benefit that its easier to improve.

- - - Updated - - -

If this thing is actually operating under some previously unknown physics that we don't understand, putting it into orbit could actually be a bad, even dangerous idea.

We don't know why it's doing what it's doing on Earth, which means it could potentially do ANYTHING in space. It's best to keep playing with it under controlled conditions for now, and just do process of elimination. We're not Kerbals. Let's not start flying through space with weird tech that we can't even figure out.

No danger, just cost and that they are trying to adjust the drive and you can not do this in space.

[Aanker]

Even though Space.com tends to be rather speculative and sensationalist, they did have a pretty good interview* with an engineer who was familiar with (but not involved in) the EM drive research. Apparently, to his understanindg, thrust had not been consistently produced through all the tests (approaching near random success apparently?) and the levels of thrust were so small that they were on the margin of detectability (as another poster stated).

I think this invention is being overplayed. People are looking for the next big breakthrough in space tech, but this just doesn't seem to be it. I'm sure we will see amazing engines and maybe even the fabled (sub-light) warp drives in the future through multiple major discoveries and new ideas - but usually it takes more than just random chance to produce revolutionizing change.

http://m.space.com/29363-impossible-em-drive-space-engine-nasa.html

Edited May 12, 2015 by Aanker

[N_las]

Humorous take on this topic:

http://www.smbc-comics.com/index.php?id=3732

[vger]

I'm sure we will see amazing engines and maybe even the fabled (sub-light) warp drives in the future through multiple major discoveries and new ideas - but usually it takes more than just random chance to produce revolutionizing change.

Actually I've been thinking the opposite in recent years, as have a lot of people, and I think this is why there has been so much hype. It seems like with physics we're beyond the point of finding anything that 'seems like magic until we later understand it.' And I've had this horrible gut feeling that we've done nearly all we can with how far we can push technology - at least where space travel is concerned.

This isn't to say that FTL, wormholes, etc are impossible. Only that the amount of energy/fuel required to achieve it is proportional to what we need right now just to push a rocket into space. In other words, any new epic thing that gets proven to be possible won't matter, because it won't be remotely practical anyhow.

Edited May 14, 2015 by vger

[itstimaifool]

We don't know why it's doing what it's doing on Earth, which means it could potentially do ANYTHING in space.

I'm imagining a small craft being launched with an EMDrive into orbit, and when it's fired up, it instantly accelerates to a fraction of the speed of light sufficient to destroy the Moon on impact.

Later, scientists discover that they misplaced a negative sign in an equation.

But more on-topic, I have a question (I'm sorry if this has been answered previously in the thread). A main concern with the EmDrive is that it violates the conservation of momentum. But in order to do this, the drive must use energy. And as far as I understand, matter and energy are interchangeable in some respect. So, can't the drive's loss of energy be compared to a conventional engine's loss of reaction mass? And therefore, using some sort of math and science I don't understand, could it be shown that conservation of momentum is not violated?

I don't know anything about theoretical physics, so I'm sure that above paragraph is painful to read for those who do. Please help me be less wrong in the future.

Edited May 14, 2015 by itstimaifool
Added the question about conservation of momentum

[Rakaydos]

It's a symmatry thing. you can turn energy into momentum, but it has to balance out- a photon out the back to push the vessel foreward. EM drive is way more energy efficent than that, implying it's pushing off SOMETHING.

It transferring momentum to the nearby not quite vaccume, hwever, is almost as good. you lose efficency the farther you get from an atmosphere/star/galaxy, but it would still be entirly electrically powered space drive, without breaking physics.

[Sean Mirrsen]

If this thing is actually operating under some previously unknown physics that we don't understand, putting it into orbit could actually be a bad, even dangerous idea.

We don't know why it's doing what it's doing on Earth, which means it could potentially do ANYTHING in space.

I'm having trouble understanding that line of thought.

What experiments can be performed on the ground that, if they do not outright disprove the drive as a working device, will either not have the same consequences, or have consequences that could be prevented or accounted for, as the experiment performed in orbit would have?

Sure, you can test it in hard vacuum. Is it going to be tested while bombarded by the specific mix of radiation and trace particles present in LEO? Is it going to be tested under the reduced force of gravity? Or in freefall?

The problem is, no tests that outright fail the drive as a concept on the ground, are going to prevent its being sent into space while largely untested under the specific circumstances present there. And the tests that fail the drive as a concept on the ground, could very much fail it for entirely unrelated reasons that will not apply once it's in space. So one way or another, it needs to be sent into space to see if it works as a space thruster - the only thing the lab experiments are doing is trying to find out why or how the drive works. It has no applications on the ground, as a drive, so those experiments are pointless to answer the "whether" question.

[Technical Ben]

If it is microwaving the surroundings. Or if it is outgassing/expanding. Don't want this thing exploding in space. Much better to test on the ground first to rule it out.

[vger]

There's also the simple risk of it breaking. If that happens, it would be nice to know how to fix it so we don't leave astronauts stranded for no reason.

"Houston, how do we fix this?"

"Good question. We don't know why it was working in the first place."

[Sean Mirrsen]

What astronauts though? It'd never get put as a main thruster for anything manned until the whether question is answered, and bringing it to the ISS would be about the worst idea you could have, safety-wise. So most likely it'll be hocked up into space on its own, as its own mini-satellite. And it can be done as soon as the drive is shown to generate thrust in a vacuum, because all any other tests will try to answer is the how.

[HereComesTheBoom]

A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

the EM Drive’s thrust is due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant.

That was all from here : http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/

My basic understanding is that the engine uses microwaves generated from solar electric power to tap into the "quantum vaccum" (In quantum field theory, the vacuum state (also called the vacuum) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. Zero-point field is sometimes used as a synonym for the vacuum state of an individual quantized field. - Wikipedia) The microwaves use the quantum virtual particles in the quantum vaccum as propellant. The engine uses magnetic fileds to propel the particles out the back as thrust. The reason that this is said to defy the laws of physics is because of whats said in the definition "it contains no physical particles." But as you read at the top, NASA has obviously defied this theory and has proven that it is possible to do. NASA speculates that this engine could send a craft to Mars during a transfer window in just 70 days. A bit of other info, A company in Texas has a new engine called the VASMIR that has been estimated to have a 39 day transfer time to mars. Pretty cool stuff.

[sojourner]

There's a more current thread here.

[Findthepin1]

it is a kraken drive

etc.

anyway i don't really know if it works but the physics behind it seems sound. i'm not technically a physicist though so yeah i might be incorrect on that.

[ZetaX]

Can people that don't know physics please stop calling this "sound"¿ Because it has again and again been demonstrated in this thread that it totally violates known physics. I is (at a very very low chance) possible hat it works anyway, but not because physics but despite physics.

[Rakaydos]

Can people that don't know physics please stop calling this "sound"¿ Because it has again and again been demonstrated in this thread that it totally violates known physics. I is (at a very very low chance) possible hat it works anyway, but not because physics but despite physics.

It only violates physics if it works in a true vacuum. If it works in a merely high vaccume enviroment like space (even at a lower efficency) it retains many of it's advantages without breaking physics.

[ZetaX]

It only violates physics if it works in a true vacuum. If it works in a merely high vaccume enviroment like space (even at a lower efficency) it retains many of it's advantages without breaking physics.

Do you really think all those science fanboys that say "it works" are talking about that¿ No, they are talking about the idealised true vacuum wonder machine.

And the usually given explanations do violate physics because they would work in vacuum, and I am very sure that's what he talked about.

[KerbMav]

but not because physics but despite physics.

You mean, despite the laws of physics as we know and understand them.

Not saying the thing works or not, but the phrasing nagged me.

[Rakaydos]

Do you really think all those science fanboys that say "it works" are talking about that¿ No, they are talking about the idealised true vacuum wonder machine.

And the usually given explanations do violate physics because they would work in vacuum, and I am very sure that's what he talked about.

But as k2 has pointed out, the explanations for how they work in vaccume breaks conservation of momentum... unless the "quantum vacuum" being pushed off of can interact with something else before evaporating. so the expplanantios actually point to at leas a low vacuum functionality, and hopefully a limited high vacuum function as well.

[ZetaX]

You mean, despite the laws of physics as we know and understand them.

Not saying the thing works or not, but the phrasing nagged me.

Physics, as in the science. Not to be confused with reality.

But as k2 has pointed out, the explanations for how they work in vaccume breaks conservation of momentum... unless the "quantum vacuum" being pushed off of can interact with something else before evaporating. so the expplanantios actually point to at leas a low vacuum functionality, and hopefully a limited high vacuum function as well.

That they break cons. of mom. is exactly what I talked about above. And that's why all those that claim that the usual explanations (be it pushing of quantum stuff, magnetic resonance whatevers, ...) are just believing technobabble. I don't understand to what of the things I said you are actually objecting to... Please read my post again/try to get what I am actually talking about.

[Rakaydos]

That they break cons. of mom. is exactly what I talked about above. And that's why all those that claim that the usual explanations (be it pushing of quantum stuff, magnetic resonance whatevers, ...) are just believing technobabble. I don't understand to what of the things I said you are actually objecting to... Please read my post again/try to get what I am actually talking about.

Only that the people who believe in physics breaking are missing a footnote about virtual particle interaction in near vacuume, but not actually wrong per se. It's an electric propulsion that doesnt need to bring propellant, that works by pushing off the quantum vacuum. it's the second order effects I mention above (VP interaction in near vacuum) that they gloss over, but are important for energy conservation reasons.

[John FX]

It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.

Richard P. Feynman

Conversely, if an experiment shows an effect unexplained by your understanding of physics, it is not the experiment that is wrong but instead it is your understanding of physics.