China building impossible space drive

[dragon]

Would be cool if it worked but only a small percentage of scientists belive its possible. And hell even if it doesn't work the information obtained should still be usefull in some way.

Chinese researchers claim they've confirmed the theory behind an "impossible" space drive, and are proceeding to build a demonstration version. If they're right, this might transform the economics of satellites, open up new possibilities for space exploration –- and give the Chinese a decisive military advantage in space.

To say that the "Emdrive" (short for "electromagnetic drive") concept is controversial would be an understatement. According to Roger Shawyer, the British scientist who developed the concept, the drive converts electrical energy into thrust via microwaves, without violating any laws of physics. Many researchers believe otherwise. An article about the Emdrive in New Scientist magazine drew a massive volley of criticism. Scientists not only argued that Shawyer's work was blatantly impossible, and that his reasoning was flawed. They also said the article should never have been published.

"It is well known that Roger Shawyer's 'electromagnetic relativity drive' violates the law of conservation of momentum, making it simply the latest in a long line of 'perpetuum mobiles' that have been proposed and disproved for centuries," wrote John Costella, an Australian physicist. "His analysis is rubbish and his 'drive' impossible."

Shawyer stands by his theoretical work. His company, Satellite Propulsion Research (SPR), has constructed demonstration engines, which he says produce thrust using a tapering resonant cavity filled with microwaves. He is adamant that this is not a perpetual motion machine, and does not violate the law of conservation of momentum because different reference frames apply to the drive and the waves within it. Shawyer's big challenge, he says, has been getting people who will actually look into his claims rather than simply dismissing them.

Such extravagant claims are usually associated with self-taught, backyard inventors claiming Einstein got it all wrong. But Shawyer is a scientist who has worked with radar and communication systems and was a program manager at European space company EADS Astrium; his work rests entirely on Einstein being right. The thrust is the result of a relativistic effect and would not occur under simple Newtonian physics. Many have dismissed his work out of hand, and British government funding has ceased. He has had some interest from both the United States and China. Now the Chinese connection with the Northwestern Polytechnical University (NPU) in Xi'an seems to have paid off.

"NPU started their research program in June 2007, under the supervision of Professor Yang Juan. They have independently developed a mathematical simulation which shows unequivocally that a net force can be produced from a simple resonant tapered cavity," Shawyer tells Danger Room. "The thrust levels predicted by this simulation are similar to those resulting from the SPR design software, and the SPR test results."

What's more, Shawyer says, NPU is "currently manufacturing" a "thruster" based on this theoretical work.

The NPU have confirmed that they have reproduced the theoretical work, and are building a demosntration version of the Emdrive.

Needless to say, independent confirmation is a big deal -- though many will want to see it published in a peer-reviewed journal. Even when it is, I doubt the controversy will subside. Prof. Yang has plenty of experience in this type of area, having previously done work on microwave plasma thrusters, which use a resonant cavity to accelerate a plasma jet for propulsion. While the theory behind the Emdrive is very different, the engineering principles of building the hardware are similar. The Chinese should be capable of determining whether the thruster really works or whether the apparent forces are caused by experimental errors.

The thrust produced is small, but significant. Shawyer compares a C-Band Emdrive with the existing NSTAR ion thruster used by NASA. The Emdrive produces 85 mN of thrust compared to 92 for the NSTAR (that's about one-third of an ounce), but the Emdrive only consumes a quarter of the amount of power and weighs less than 7 kilos, compared to over 30 kilos. The biggest difference is in propellant: NSTAR uses 10 grams per hour; the Emdrive uses none. As long as it has an electricity supply, the Emdrive will keep going.

The possibilities are phenomenal: Instead of going out of service when they run out of fuel, satellites would have greatly extended endurance and be able to move around at will. (We wouldn't have to shoot them down because of the risk from toxic fuel either.) Deep space probes could go further, faster –- and stop when they arrive. Shawyer calculates that a solar-powered Emdrive could take a manned mission to Mars in 41 days. Provided it works, of course.

What will China do with the technology? It may be relevant that professor Yang is not unknown in military circles, having published a paper called "Plasma Attack Against Low-Orbit Spy Satellites."

Meanwhile, what about the American interest? Shawyer told me that "the flight thruster program is on hold for the present. [O]nce the U.K. government had provided an export license for a U.S. military application, the major U.S. aerospace company we had been dealing with stopped talking to us. "

The company may have decided that the Emdrive could not work. If they're wrong, China has at least a year's head start in a technology that will dominate space and make previous satellites as obsolete as sailing ships in the age of steam.

link

[Surlethe]

Hmm. Exciting if it works, but this pdf is apparently a letter by a PhD in QED who says the idea is bullshit.

[dragon]

Hmm. Exciting if it works, but this pdf is apparently a letter by a PhD in QED who says the idea is bullshit.

Yup read that as well, but appearently there's a few experts out there that say it might work. But then this happens all the time one expert says yes, another says no and some say maybe.

Hell even when most of the expert agree on something doesn't mean they're right. Its happened several times in history where everyone was against 1 or 2 ideas that turned out to be right.

But still nothing wrong with looking into the idea.

[Surlethe]

Hmm. Exciting if it works, but this pdf is apparently a letter by a PhD in QED who says the idea is bullshit.

Yup read that as well, but appearently there's a few experts out there that say it might work. But then this happens all the time one expert says yes, another says no and some say maybe.

It's not just one expert saying yes and another saying no, it's one man saying yes, and the entire field saying no. There's a substantial difference between the two. I'm therefore not inclined to take this "Emdrive" seriously, although it might be fun to look into the science this weekend.

[Zac Naloen]

The quotes in the article make it seem that he's quite adament it's not a perpetual motion machine.

Here's hoping it works I guess.

[mr friendly guy]

Would be cool if it worked but only a small percentage of scientists belive its possible. And hell even if it doesn't work the information obtained should still be usefull in some way.

As someone who only has a high school level of science knowledge, if it doesn't work, what sort of added useful information do you think the experiment will produce.

[Wyrm]

Hmm. Exciting if it works, but this pdf is apparently a letter by a PhD in QED who says the idea is bullshit.

That letter is essentially my argument. The walls are the key to why this 'drive' cannot possibly work, and it's clear that Sawyer thinks that the walls don't matter — if you look carefully, Sawyer omits the derivation of the backthrust from the walls from his thrust derivation.

[kc8tbe]

While they're at it, why not test polywell fusion as well? They'll need a way to generate the electricity for all those microwaves!

[FOG3]

So is his idea is to have:

Power Source->Useful Electricity->Microwave Emitter->Partial Microwave containment designed to encourage photons to go out the back side?

or is it:

Power Source->Useful Electricity->Microwave Emitter->Partial Microwave containment designed to heat air and try to encourage it to go out the back side in a useful manner?

While not impossible I would seriously question what assumptions he's using in regards to the first case if he's projecting comparable thrust to a system using ionized matter instead of photons. Nevermind a LASER should be more efficient if that trick worked as LASERs have already been designed and refined to keep the photons all going in one direction and strike me as having far fewer sources of potential inefficiencies.

I'm not really seeing from the article how this would be superior to a solar sail, which I'm quite sure can be made lighter then all that microwave and containment hardware.

[Zixinus]

While they're at it, why not test polywell fusion as well? They'll need a way to generate the electricity for all those microwaves!

Last I heard, the Navy is looking into that one and they are keeping a low profile until they have more experimental data on their hand.

[FOG3]

Okay... he wants to make a steady state constant operation cat-in-a-box drive. Cat-in-a-box drive however involves something having a significant portion of the net objects mass moving against a wall creating a pronounced force basically based around shifting the center of mass. Cat-in-a box is only able to really get anywhere because friction is usually enough the cat can slowly reset without exerting a meaningful force in the process.

The thing is that doesn't really work with what this guys talking about. If it did all he'd need to do is shove Ye Standard Gas Cylinder onto a heat source upside down and measure the force of gravity on it decreasing in the process.

[RedImperator]

So is his idea is to have:

Power Source->Useful Electricity->Microwave Emitter->Partial Microwave containment designed to encourage photons to go out the back side?

That would be a straightforward photon drive, which is an idea which has been around for a while. There's no doubt that one would work, that I'm aware of, but the efficiency is nightmarish (300mw per newton); without some kind of physics-busting power plant, you'd never get to Mars in 40 days with one. Anyway, if this was just a photon drive employing microwaves, I doubt physicists would say it's impossible, just that it would never work well enough to be practical. It certainly wouldn't outperform an ion drive, as you noted (and it's not like ion drives are all that miraculous anyway; their specific impulse is astronomical, but their thrust is miniscule).

or is it:

Power Source->Useful Electricity->Microwave Emitter->Partial Microwave containment designed to heat air and try to encourage it to go out the back side in a useful manner?

And that would just be a regular rocket that uses microwaves to heat the propellant instead of a chemical reaction. Since he's promising it would work in space, that rules out using air as a propellant, and since it would need propellant, that negates all the supposed advantages of the system. And if microwave-heated propellant provided more thrust or higher specific impulse than chemical rocket fuel, we'd have microwave rockets up there already.

[Wyrm]

Power Source->Useful Electricity->Microwave Emitter->Partial Microwave containment designed to encourage photons to go out the back side?

or is it:

Power Source->Useful Electricity->Microwave Emitter->Partial Microwave containment designed to heat air and try to encourage it to go out the back side in a useful manner?

Neither. It's Power Source → Useful Electricity → Microwave Emitter → Microwave Power to Waste Heat converter — that is, a microwave dead end that has a complex shape, but is in reality no more useful than nuking a blueberry muffin. Well, not quite. After nuking a muffin, you can eat the muffin.

[Sriad]

While they're at it, why not test polywell fusion as well? They'll need a way to generate the electricity for all those microwaves!

Last I heard, the Navy is looking into that one and they are keeping a low profile until they have more experimental data on their hand.

Hey, if the guy who thought up Bussard Ramjets says it'll work, who am I to disagree?

[The Duchess of Zeon]

Considering that Heim Theory is based around a relationship between electromagnetism and gravity, is this supposed to actually have some kind of connection to that proposed gravito-magnetic drive those Austrian scientists came up with based on Heim Theory, I wonder? That would certainly also explain the general but not universal dismissal of the scientific community.

To elaborate, Heim Theory includes a prediction that photons can be converted into gravito-photons, resulting in measurable force, which sounds something like what he seems to be aiming at.

[Beowulf]

Hmm. Exciting if it works, but this pdf is apparently a letter by a PhD in QED who says the idea is bullshit.

Yeah, but I distrust that he is a PhD in QED. Your typical physicist isn't a computer programmer working on image compression. He's also a JFK conspiracy theorist.

That said, I don't believe the thing will work either. However, the inventor claims that it can provide horizontal thrust on a air cushion, which means either something wacky is going on, or the effect is real, and something wacky is going on.

[CaptainChewbacca]

Considering that Heim Theory is based around a relationship between electromagnetism and gravity, is this supposed to actually have some kind of connection to that proposed gravito-magnetic drive those Austrian scientists came up with based on Heim Theory, I wonder? That would certainly also explain the general but not universal dismissal of the scientific community.

To elaborate, Heim Theory includes a prediction that photons can be converted into gravito-photons, resulting in measurable force, which sounds something like what he seems to be aiming at.

That's generally it. We're pretty sure this drive won't work, but because we havn't proven or disproven Heim Theory we can't know for sure. If it works the way its supposed to, it'll teach us a lot about gravity.