em drive

[ohiovr]

this is interesting if you haven't seen it, its another propellantless thruster

http://emdrive.com/

Apparently it is passing peer review in china where they were able to make a 720 millinewtons of thrust from about 2.5 kw of microwave energy in a high q resonator. I kind of doubt there would be any academic fraud (it is possible though) because I presume it is off with your head if you are lying there. There are other fantastic things it can do if you dig around on the site.

So which is it, crazy fantasy, or peer reviewed fact?

[tokamac]

Using search with "EM Drive" shows a thread already exists: viewtopic.php?t=2949
There's nothing new about it since the last posts almost a year and a half ago.

[Tom Ligon]

A physicist friend of mine would say "I've been warning people that the Chinese were working on this."

Supposedly this is all Kosher under Maxwell's laws, but involves phase shifts and/or applications of the right hand rule to orientations not generally seen in textbooks. He pointed me to a well-respected physics textbook that has a paragraph or two on this. Essentially, the cases that produce these effects produce results which most educators are reluctant to get into because they buck conventional teaching.

[GIThruster]

Shawyer's EM Drive involves a violation of conservation. Sonny and Paul did a replication of it down at Eagle since Sonny's QVF model predicts it should generate thrust, but everyone with a clue has known this is a fraud since the time it was being funded by the British government back about 2004.

It's based upon a misunderstanding of what "group velocity" entails. No good physicists think this can work.

[ohiovr]

no good

http://www.wired.co.uk/news/archive/201 ... pace-drive

[ScottL]

Skeptical analysis of what's going on:

http://arstechnica.com/science/2014/08/ ... -just-yet/

[rcain]

thanks for that last link. i thought for a moment there had been some real scientific revalation. but same old, by the look of it. SLACKNESS. shame.

[djolds1]

A physicist friend of mine would say "I've been warning people that the Chinese were working on this."

Supposedly this is all Kosher under Maxwell's laws, but involves phase shifts and/or applications of the right hand rule to orientations not generally seen in textbooks. He pointed me to a well-respected physics textbook that has a paragraph or two on this. Essentially, the cases that produce these effects produce results which most educators are reluctant to get into because they buck conventional teaching.

IIRC, Maxwell's equations as usually used are not the complete corpus of Maxwell's equations - some scalar wave results and so forth are dropped for convenience's sake, to reformulate the math in a more eaasily accessible form. Is that what you're talking about?

[birchoff]

thanks for that last link. i thought for a moment there had been some real scientific revalation. but same old, by the look of it. SLACKNESS. shame.

what do you mean by SLACKNESS? On whose part the skeptics or the experimenters?

[rcain]

thanks for that last link. i thought for a moment there had been some real scientific revalation. but same old, by the look of it. SLACKNESS. shame.

what do you mean by SLACKNESS? On whose part the skeptics or the experimenters?

both. & also journalism. & NASA.

eg: i can't easily find anywhere (eg: in the chinsese 2012 paper, or articles), anything about discounting of other effects (eg: radiative, thermal, atmospheric, etc) - appears it was not tested in vaccum (?) - tho i could be wrong. the more relevant since their H0 (null) model, also purportedly & unexpectedly provided thrust. tho there is even dispute about 'who's' idea of a 'null machine' it actually was. seems know noone knows still what the frick, if anything, is happening.

nice idea tho. hope it does work. (pardon the pun).

[Betruger]

Is it wrong to suspect this is yet another instance of White pushing for hype way too early? Who exactly would gain from this?

[birchoff]

thanks for that last link. i thought for a moment there had been some real scientific revalation. but same old, by the look of it. SLACKNESS. shame.

what do you mean by SLACKNESS? On whose part the skeptics or the experimenters?

both. & also journalism. & NASA.

eg: i can't easily find anywhere (eg: in the chinsese 2012 paper, or articles), anything about discounting of other effects (eg: radiative, thermal, atmospheric, etc) - appears it was not tested in vaccum (?) - tho i could be wrong. the more relevant since their H0 (null) model, also purportedly & unexpectedly provided thrust. tho there is even dispute about 'who's' idea of a 'null machine' it actually was. seems know noone knows still what the frick, if anything, is happening.

nice idea tho. hope it does work. (pardon the pun).

As far as the reporting on what actually happened, I completely and wholeheartedly agree. you would think the papers that were presented could only be accessed for some large amount of money. No just $25 dollars to get an accurate picture of what the EagleWorks researchers tested and their test protocol. Throw in an extra 25 and you get to read what Cannae's theory and testing results were. Now while the Cannae paper is a little harder to digest for a lay person the NASA paper is a considerably easier read.


As for Slackness on NASA's part I can only partially agree with you here. The EagleWork's team were being slack as far as making sure that the abstract on NTRS was consistent with what they presented in the Paper. though I suspect someone assumed that people would actually read the paper, to get the details instead of reading the abstract and letting their imagination fill in the blanks. So I can kinda almost forgive them if that was the assumption.

As for "discounting of other effects (eg: radiative, thermal, atmospheric, etc)". When I originally read the paper I was under the belief that the Cannae devices were tested in a Hard Vacuum while the EmDrive replica wasn't. But after GIThrusther pointed out the statement in the abstract on NTRS I re read the description of the protocol and the Summary and I think it is fair to say that they probably didn't run any of the devices in a Hard Vacuum; they only ran them locked inside a vacuum chamber at ambient pressure. The teams stated reason for this was that the RF amplifier they were using contained an electrolytic capacitor, thus it was not capable of operating inside a hard vacuum environment. That's fine because they are planning to do some follow up testing with a RF Amplifier that is vacuum capable at a higher power level(the higher power level is nice because I would expect to see thrust getting closer to that reported by Yang Juan on the Chinese paper published in 2012 at least for the EmDrive replica). Once that's done they plan to get JPL and JHU Applied Physics Lab to do independent verification and validation. So the information you are looking for was partially covered; and the next test campaign they do, which is rumored to be kicking off later this year (2014), should cover the other cases that were missed. Followed by another replication by a separate set of labs.

Now as for the hub bub about the null test article. Everyone seems to be interpreting the statement about the null test article in the NTRS abstract as proof that EagleWorks screwed up the experiment. That interpretation is valid as long as you assume that EagleWorks built the null test article to reflect their understanding of what is going on. Now if these journalists and commentators read the paper they would quickly realize their mistake. The null test article was created by Cannae in accordance with their understanding of how these RF devices are supposed to work. All the NASA experimenters did was run it through the same tests they performed on the non-null device and record the results. In addition they did some computer modeling of the Cannae devices and seemed to postulate that the reason the null article actually produced thrust is that the thrust is being produced in a section of the device far away from where Cannae's theory claims the thrust should originate; and this section of the device existed on both of the Cannae drives.

[Betruger]

Birchoff your links to the papers in the other thread are broken.

[birchoff]

Is it wrong to suspect this is yet another instance of White pushing for hype way too early? Who exactly would gain from this?

On a seperate note it would seem the Warp Interferrometer tests could now be officially considered dead in the water

http://arxiv.org/abs/1407.7772

I doubt this has anything to do with the attempt at replicating thrust with these RF devices, as far as trying to build hype. But I do think that if the argument in that paper is solid at the very least White will need to either find some other way of triggering and detecting the warping of space time or wait till we build sensors sensitive enough to detect it with his current proposed testing protocol.

I do think that White may be changing gears over to finding and testing examples of Q-Thrusters though. In the paper that has caused all of this unrest they repeatedly refer to the devices being tested as Q-Thrusters. I hope that white does not let his theory bias guide the testing but instead let the testing guide the theory. In the end if the testing pans out the only thing the name influences is most likely who gets the nobel.

[birchoff]

Birchoff your links to the papers in the other thread are broken.

My bad I originally markedup the paper names with an underline, didnt occur to me that they looked like links. I took the links from tokomac's post below and edited the markup in my post so that no one has that happen to them again. thanks for the heads up.