Talk:EmDrive/Archive 7

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Chen's statement was confused and exaggerated by IBT; now clarified in the article. It seems he said only that they had developed/refined a device that was ready to be tested in orbit, not that the test was underway or even scheduled. This thread highlights some of the reasons to triple-check any claims about the Chinese tests, given telephone-effect and the limited independence of state media: Verifiable details about the chinese emdrive

Chen also filed a patent for a design using a semicylindrical cavity, so the discussion of shapes can be made more general. An electromagnetic propulsion system and method – SJ + 10:37, 2 March 2017 (UTC)

Can you read Chinese?--Sparkyscience (talk) 15:01, 2 March 2017 (UTC)

會. Takes a while, though. Chen never specifies what "in orbit" means; the LEO detail, and the idea that he is director of anything, is inserted by the IBT: not the most reliable source. – SJ + 06:05, 3 March 2017 (UTC)

The Chinese source clearly claims that Emdrive tests are currently taking place in orbit. There is no ambiguity in this claim. The caveat is that while CAST have claimed to perform successful tests it leaves it ambiguous as to whether there has yet been a successful test in orbit, only that they are currently taking place. Multiple reliable secondary sources (excluding the IBT for the sake of debate here) have also reiterated that this is what the CAST statement says. i.e. [10] --Sparkyscience (talk) 10:35, 3 March 2017 (UTC)

They claimed that in-orbit verification was underway. Lots of wiggle room there. (Compare Cannae's announcement last year that space-based tests of his drive were happening.) Chen's claims should be taken with plenty of salt until confirmed. It's hard to overstate how empty of detail or data these announcements are compared to normal drive-test announcements. – SJ + 18:11, 5 March 2017 (UTC)

Removed: free-thought association about anisotropic EM fields. – SJ + 11:39, 2 March 2017 (UTC)

There are other situations where the electromagnetic field is believed to be anisotropic for example, doped active centers in anisotropic glasses,[1][2][3] emission of active atoms in a waveguide,[4] spontaneous emission from atoms adsorbed on metallic or dielectric surfaces,[5] emission in a spatially dispersive medium[6] which allows the possibility of longitudinal electromagnetic fields (classically not found in free space but in substances like plasmas) and emission between two conducting plates,[7][8][9] which is a problem of great interest due to the Casimir effect.[10][11][12]

Sparkyscience reverted to he free-thought-association version. This leaves the "Device" section pretty useless to readers: dominated by and closed out with irrelevant facts, as though those irrelevancies had informed any of the drive designs. (There is no indication that this has happened.) The edit summary said something about the Casimir effect: again, irrelevant to device structure. – SJ + 06:05, 3 March 2017 (UTC)

Sj I am perplexed. You seem like a intelligent guy, but you frequently dismiss scientific concepts as "irrelevant" or "wrong" without so much of a word of explanation as to your perspective of the underlying physics. Without passing judgement as to the quality of the proposed explanations, the dynamical Casmir effect is referenced by NASA Eagleworks and McCulloch's theory is called MiHsC "Modified inertia by a Hubble-scale Casimir effect". Might leave you with the impression that, if the Emdrive works, the Casmir effect has something to do with it... As I'm sure you know, any apparent broken symmetry in nature can be accounted for as a transfer to the vacuum state, the Casimir effect is an example of such a vacuum instability. How much do you know about the Casimir effect? I would appreciate a detailed technical explanation of where you are struggling to make sense of things, and i'll see if I can help.--Sparkyscience (talk) 11:17, 3 March 2017 (UTC)

Scientific concepts aren't right or wrong, they're concepts, relevant in some context. It's your interpretation of them that is wrong, and your use out of context. You don't seem to understand basic physics, and are seeking out unusual terms and concepts and trying to link them together; this is common enough that the term 'physics crank' was coined to describe it. My experience with others in your position suggests that nothing I can say will either help you or divert you from what for many becomes a lifelong pursuit. So for the most part, to save time, I am not responding to you directly; just communicating with other visitors to this page interested in the topic.

One thing I will say to you: don't plagiarize. I wondered why the above sentence seemed so random and out of place; now I see that you copied it verbatim from one of the cited papers. If you're using an entire long sentence of someone else's work, it should be marked as an explicit quote. – SJ + 06:31, 18 April 2017 (UTC)

The names "EmDrive" and "Cannae Drive" are trademarks used by their inventors. Many, including the press, mistakenly use "EmDrive" to describe any resonant cavity thruster, but that's confusing. (It's not even a clear name for the physics of such thrusters: there are better-known electromagnetic drives – ion thrusters, &c.) Scientific papers and reports tend not to use that term. I think it should only be used when referring to Shawyer's own experiments and models. – SJ + 08:04, 28 November 2016 (UTC)

It, overwhelmingly, is the most common name; probably most-searched one for this entry, so I opted to add it as also known as. El_C 02:16, 15 February 2017 (UTC)

Ok. I was concerned that Shawyer had trademarked the name, but don't see any indication that this is the case. 11:39, 2 March 2017 (UTC)

The International Business Times really likes writing off-the-cuff pieces about these thrusters for some reason. They're not the most reliable source, so I would be wary of any information from them that isn't confirmed elsewhere. For instance:

In November 2016 the International Business Times claimed the U.S. government was testing a version of the EmDrive on the Boeing X-37B and that the Chinese government has made plans to incorporate the EmDrive on its orbital space laboratory Tiangong-2.[1][2] However, prior to flight, the propulsion experiment aboard the X-37B was officially announced as a test of a Hall-effect thruster built by Aerojet Rocketdyne.[3]

This whole paragraph could really be dropped. The Boeing claim was wrong, and there is no confirmation that any testing is happening on Tiangong rather than on a[nother] satellite. IBT also modified and added to Chen's public statements about CAST's tests when they published a quick analysis of the article on him in STD, either because they misread the translation or because they have unsourced private communication with the scientist that noone else does. I'm betting on the former. – SJ + 06:25, 3 March 2017 (UTC)

We don't know the Boeing claim to be wrong, it has not been directly addressed. We can only present claim and counterclaim with proper attribution. Corporate communications can be just as distortive of the facts as elements of the press. Nothing is said without an underlying agenda or strategy. The problem with stating that IBT is unreliable, regardless of what you think of their journalistic standards, is we know for a fact that IBT has direct access to Roger Shawyer, as he has done a number of interviews for them. [11] Shawyer makes reference to the X-37B being capable of containing an Emdrive prototype in a paper he wrote in 2014 [12]. Seems odd that he would mention that out of the blue. The IBT X-37B report that also claims the Chinese are testing on the Tiangong-2 [13] was published on the 7th December 2016 and came before the CAST announcement on the 11th December [14]. This is either a very lucky coincidence that IBT published this days before the CAST announcement, or it partially corroborates the validity of the anonymous source which gave information about the X-37B. This coincidence has been noted by other reliable media outlets [15]. I don't think its hard to guess who that anonymous source might be if there is one, and that person might be being fed (dis?)information by the Chinese...

Chinese propaganda is clearly stoking the rumour mill on the X-37B, see for example [16] [17]. This is quite intentional and there are a few possibilities: if the US really is secretly testing an Emdrive on the X-37B this would be China's way of saying "we know what you are doing" much to the annoyance of those in the US. On the other hand lets say the US is not conducting secret test. It could be disinformation/fake news from a Chinese sources, i.e. give the IBT a lead for a story, partly back it up in the next few days, and leave everyone believing the other half of the story. i.e. a psyop. My only problem with that is if the Emdrive really doesn't work what do the Chinese achieve by making themselves look like fools? Fake news on the Emdrive is hardly going to cause civil unrest in the West, most of the population will never care about this subject. Nothing really adds up in a way that makes sense on the information we have and I do not believe we are in a position to make a judgement about any of the claims.

The above cited text gives clear attribution and states it is only a claim. I think the average person is intelligent enough to decipher fact from claim and has a right to hear about these claims from a source which is known to be in contact with Roger Shawyer. I don't think we need to act as the thought police.--Sparkyscience (talk) 13:11, 3 March 2017 (UTC)

@

WP:CLAIM we are not actually allowed to use the word 'claim' in the manner you have described above. DOing so would be using loaded language to lead our readers to a conclusion of our choice. I have changed the wording to 'reported' but left it attributed.  InsertCleverPhraseHere

  10:41, 5 March 2017 (UTC)

@

WP:SYNTH says: "Do not combine material from multiple sources to reach or imply a conclusion not explicitly stated by any of the sources.", which is exactly what is being done here. It seems clear that the SpaceflightNow article should be removed unless we have another source which directly claims that the IBTimes was confusing the two thrusters (which is not stated in any of the sources above but nevertheless implied by the paragraph).  InsertCleverPhraseHere

  22:04, 3 March 2017 (UTC)

One approach that might be useful here is to ask—how frequently are IBT stories on this topic later confirmed by better-quality outlets?

That is, if IBT has been publishing stories on this topic for a while now, we ought to be able to look at their coverage and actually assess their track record. If we find that stories in IBT frequently are not substantiated by later independent reports – or worse, that they are contradicted or refuted – that will strongly suggest that IBT isn't a robust source on this topic, and likely shouldn't be used as the sole source to support claims in this article. TenOfAllTrades(talk) 14:33, 5 March 2017 (UTC)

This was all gone over in the post above at RSN. Per your point however, in this very instance, IBTimes was the first to break that the chinese govt was testing the drive, which was later picked up by numerous others, notably Popular Science [18], who seem to consider IBTimes to be a reliable source.  InsertCleverPhraseHere  18:25, 5 March 2017 (UTC)

Actually, no, the previous RSN discussion very much did not address that question. (And the unreliable, clickbaity nature of that one particular Pop Sci blogger's interests was also touched on in that discussion.) TenOfAllTrades(talk) 22:25, 5 March 2017 (UTC)

Alright then. I guess I don't know what you are trying to say then.  InsertCleverPhraseHere  22:40, 5 March 2017 (UTC)

Thanks to both of you for the context! Re: a country stoking rumors, didn't we see this w/ cold fusion as well? Many countries insisted for years their programs were successful (hoping to catch up with others), before finally admitting this was not true. I can imagine lots of reasons for both US and Chinese sources to encourage rumors, and Shawyer is a natural channel to pass them on. Whatever the cause, I expect this sort of fuzzing will continue, with no clear results, for another few years.

I hadn't seen the IBT issue on RS. It makes sense; I think they have a single person (who is not otherwise a science writer?) writing all of their articles on it & doing interviews with Shawyer, and they are willing to take Shawyer's claims at face value. This September article for instance makes many statements of fact that get the physics wrong, or repeat Shawyer's claims as though they were confirmed, or are credulous of unlikely statements (this last happens in most science writing, however).

It's ok to say in the article "[Space-related source] reports X"; it would be undue weight to say "[local business journal] reports X" as there is no reason to expect reliability from them on this topic; and IBT is somewhere in-between. I trust IBT about their direct correspondence with Shawyer, but assume any other details may be repeating what he tells them verbatim, without fact-checking. – SJ + 17:38, 5 March 2017 (UTC)

Re: Shawyer mentioning tests on the X-37B in his 2014 paper: a) It's in his interest to constantly promote any interest from governments as a way to garner investment. Hence he claimed for years his engagement with Boeing was a "license" of his tech even though they never licensed, until they publicly confirmed they had abandoned the project that had been working wih him. And he has for years said "there is active US DOD and UK DOE interest", which is just puff and hard to disprove. b) All of his requests for funding for the last decade have been to do space-based testing. I'm sure people mentioned X-37B as a possible test platform, if the prototype worked out; it was designed to support such tests w/out having to send drives up on a rocket/sat. – SJ + 17:51, 5 March 2017 (UTC)

Do you have sources we can use for any of the above? While what you say may be true,

WP:TRUTH applies, we need to follow what has been reported in reliable sources.  InsertCleverPhraseHere

  18:07, 5 March 2017 (UTC)

I don't, haven't seen any RS that cared enough about this to evaluate Shawyer's or Fetta's bias in self-reporting. You're right that IBT being early to report on Chinese interest in this drive gives them some currency, let's wait and see how their other claims and predictions turn out. – SJ + 04:06, 22 April 2017 (UTC)

The X-37B returned to Earth today [19], and that SpaceFlightNow article (which is one of most reputable specialized spaceflight news sources) states that the vehicle carried "an experimental electric propulsion thruster", adding "Made by Aerojet Rocketdyne, the enhanced five-kW Hall Thruster, called the XR-5A, was tested aboard the spaceplane for the Air Force Research Laboratory and Space and Missile Systems Center." Clearly the X-37B did not carry an EM Drive test article. I searched a bit to see if this was known beforehand, and indeed this has been reported by multiple news sources, including specialized spaceflight sites, even as far back as the time of launch of the mission in 2015: see [20] [21] [22] [23] [24] [25] [26].

So, can we follow what every other news site has been saying since 2015 about the payload of the X-37B instead of that one IBT article, and remove the suggestion that the spaceplane tested the EM Drive? Meithan (talk) 15:09, 7 May 2017 (UTC)

I support removing it. Ideally together with all other claims only backed by IBT. They have an EM-Drive fan in their staff and report about everything that remotely looks like it could be related to the topic. Technically the test of a Hall thruster doesn't exclude the test of other propulsion methods, but the IBT claim gets very questionable as they probably misunderstood reports about the Hall thruster test. --mfb (talk) 18:29, 7 May 2017 (UTC)

I support removing it as it does indeed seem reasonable to assume that IBT got this wrong. Is there even anything else that is only supported by the IBT? — InsertCleverPhraseHere 19:17, 7 May 2017 (UTC)

I don't know if it is still in the article (I don't find it right now), some nonsense attempt to explain the observed thrust was published in an obscure paper, picked up by IBT, and then added to this article. --mfb (talk) 19:34, 7 May 2017 (UTC)

Well that's a different situation then. Republication is very different from speculation. — InsertCleverPhraseHere 20:31, 7 May 2017 (UTC)

The publication was nonsense, not even proper speculation. Anyway, not the topic here. --mfb (talk) 20:33, 7 May 2017 (UTC)

I'd say it's safe to eliminate the mention of a test article being flown on the X-37B, as it's very clear this was false news. This much is dead clear to me.

Now, I'm not sure specifically what other mentions Insertcleverphrasehere was referring to, but the other supposed test in space, supposedly on Tiangong-2, is also questionable. The first two cited sources, [27] and [28], are IBT articles from December 2016 that support the claim of tests on Tiangong-2 by self-referencing the November article, [29]. The third reference to the Chinese in-orbit tests is from Science and Technology Daily, [30], an official government source. I can't read Chinese, but I used Google translate to get an approximate English version and cannot find any mention of tests being conducted in space by the Chinese government. The fifth reference, [31], also cites the November IBT article as source. The only apparently independent source is the fourth, [32], a Chinese state-owned news site that doesn't mention any sources for the supposed in-space tests.

Can we find a separate, reputable source for that claim that does not lead back to IBT? Or, alternatively, evidence that the Chinese are not testing the Drive on Tiangong-2? If we can't find any additional sources either way I'd suggest we declare the November IBT article bogus (since half its content has been shown to be false, despite being ample information online on the X-37B's payload since even before launch) and stop considering it and any other article that references it as source as valid sources (thus removing them, and any text that can only be supported through them, from the article). Meithan (talk) 02:21, 8 May 2017 (UTC)

Well we don't know that the X-37B claim was definitely bogus (not 'shown to be false) as the two test thrusters might have both been on board (not mutually exclusive). It is just that nothing else about this has surfaced, so we are assuming that IBT confused the two thrusters (which is plausible). I'll support removing the claim specifically about the X-37B claim based on this uncertainty. However, we had a massive discussion over at RSN about IBT, and I am wary of simply declaring the IBT as 'unreliable' on this topic, given that we are not actually certain that anything that they published is 'false'. The Tiangong-2 claim was widely cited elsewhere and presumably these other high profile news sources did some checking before they published. Or are you suggesting that we ignore all of that and throw it out simply because the IBT reported on it first and that we suspect that another of their stories might not be true? — InsertCleverPhraseHere 02:36, 8 May 2017 (UTC)

ICPH's point about the Hall-effect thruster and EmDrive onboard the X-37B not being mutually exclusive is very important. Nothing in the IBT article has yet been shown to be false, or directly addressed by another reliable source. We are merely speculating the IBT got it wrong but have no source to address the issue. I think it is important the report remains attributed and that we add info about the Hall-effect thruster for balance. It was there at one point, but seems to have been removed.

As a speculative side point, the Hall-effect is also called the topological Hall-effect and is a type of Berry phase. Its worth looking into how they increase the "performance" and "efficiency" of a Hall effect thruster.--Sparkyscience (talk) 08:56, 9 May 2017 (UTC)

If anyone cares to dare to add it after familiarizing themselves with it: https://en.wikipedia.org/wiki/Yarkovsky_effect Could be? Yes? — Preceding unsigned comment added by 97.90.91.57 (talk) 10:36, 1 April 2017 (UTC)

No. The reported force values are too large to be explained by radiation pressure. --mfb (talk) 16:06, 1 April 2017 (UTC)

Well the more important issue... is there any source that says anything of the sort that the IP has proposed above (I have not seen any). InsertCleverPhraseHere 04:40, 2 April 2017 (UTC)

I removed a para of trivia from his section:

For instance, the electromagnetic waves associated with the geometry of a truncated cone create an anisotropic electromagnetic field where there are no analytical solutions for the resonant modes. This geometry intrinsically does not suffer from mode degeneration. A sharp distinction between the propagating and evanescent electromagnetic waves cannot be achieved and as a result a non-zero power flow runs through truncated cone focusing a portion of energy near the apex. There is no well-defined cutoff wavelength but rather a cutoff radius. Due to the absence of sharp cut off wavelengths this allows the interior of a truncated cone to support an inhomogeneous electromagnetic field. There are many situations where the electromagnetic field becomes anisotropic, for example emission between two conducting plates which relates to the Casimir effect. The dynamical Casimir effect has been given as means of explaining the apparent thrust by NASA Eagleworks.

This is a combination of false/misunderstood things (there are no waves 'associated' with a geometry, just resonant modes; almost all fields are 'anisotropic' – that just means they vary in some direction; &c.), random trivia about conical waveguides which don't seem to have informed device structure (for one thing, devices reported to have worked had a wide range of shapes), and a recurring inaccurate claim about White's reference to the Casimir effect. (White said that the dynamic Casimir effect may be a theoretical avenue to pursue: he never said this informed the design of current resonant cavity thrusters.) The sources were similarly confused: they were not related to these drives, just papers where someone mentioned the stray cited fact... other than two sources for the Eagleworks claim, which were two versions of a single source. – SJ + 06:52, 18 April 2017 (UTC)

I understand and agree with the removal, but is there anything we can say except "its complicated"? I feel like we can do better than this, even with the sources that we have. — InsertCleverPhraseHere 19:50, 18 April 2017 (UTC)

ICPH: We can say a bit more. (Though I seem to have been reverted, and don't plan to fight over this para.) For one thing, the very lack of motivation for the geometries used is unusual, even among 'exotic' engine designs, and makes claims about these devices harder to falsify. At the moment, the vagueness in describing what could possibly make such a thruster work means any cavity you pump lots of RF into could be called one of these thrusters.

For the popular truncated-cone structure, experimenters (now) agree thrust is expected to "come out" of the larger end. That should be mentioned here, perhaps without synthesizing an explanation. There are few and inconsistent explanations as to why, mostly back-constructions to justify observations. [The removed stream of consciousness above is synth, largely from non-EMdrive research. If we're making up our own synth, contrary explanations could include: 'if the engine observations are some placebo effect, it would be natural to see thrust in the same direction it would be for a classical engine of that shape' or: 'displacement due to heating & expansion, a major source of error in many setups, will bias away from the larger end.'] Regards, – SJ + 08:48, 21 April 2017 (UTC)

"Anisotropic" refers to the symmetry of the mathematical equations themselves not the value of those equations i.e. it is nothing to do with how the magnitude of how the field varies from place to place but everything to do with how the equations themselves vary (pp 147-150 [33] ). For example take a pencil and lie it flat on the ground at the north pole of a globe, slide it along the surface in the direction it is pointing to the equator, keeping it perpendicular to the equator, slide it to another line of longitude and move the pencil back to the north pole: the pencil no longer points in the same direction. This is an example of the failure of a certain variable (i.e a vector) describing the system to return the original value - we need to include notions about topology to understand the system fully [34]. Vectors describing electromagnetic fields for the most part are described by homogenous equations (i.e Maxwells equations) with no notion of topology - special relativity contains no notion of topologically varying fields whatsoever (unlike general relativity which is a nonlinear theory [35] ). The Casimir effect is a topological effect (i.e the parallel plates mentioned on p. 147 [36]) and is explanation of how the EMdrive might work given by White and by MMcCulloch's who's theory is called MiHsC "Modified inertia by a Hubble-scale Casimir effect" The current article doesn't even mention the Casimir effect or how it might relate to the Emdrive.

All Emdrive formulas (Shawyers, MucCullochs, Whites) predict greater thrust with a large difference between the diameters of the big and small bases of a truncated cone - saying there is no evidence the EM-field associated with this geometry has informed the device structure flies in the face of the obvious. Wrong or right, how did they derive those equations in the first place?!

All too often SJ adopts a false voice of authority decrying things as wrong/false/misunderstood/misguided rarely addressing the underlying substance of the science and never with a citation. When he does attempt an explanation on the talk pages, like when he says "almost all fields are anisotropic'" or "Non-equilibrium" effects do exist in the world, but they have nothing to do with non-linearity" its clear he has no idea what he is talking about. All the more amusing because you can tell he is the type of person who prides himself on thinking he understands everything!--Sparkyscience (talk) 09:30, 19 April 2017 (UTC)

Came here to say this paragraph reads to me like somewhere on the spectrum between pseudoscience and nonsense, and it is not helped by grammar errors ("power flow runs through truncated cone") and inconsistent use ("cutoff" vs. "cut off" for example). Found this paragraph is already under discussion. I would support its removal until someone can significantly improve it. 72.208.150.248 (talk) 19:56, 9 May 2017 (UTC)

Yeah. The basic physics problems are all still there. The second paragraph of this section is nonsense after the first sentence. It includes trivia properly sourced about frustrum/conical waveguides, but no source tries to connect those stray facts with EM drive designs. Unfortuntately some science forums now point to this WP article as a primary source proving 'specialness' of the geometry. Can someone else review the section -- mfb? – SJ + 02:50, 8 June 2017 (UTC)

Some remarks by Shawyer:

• "The equations used to calculate the guide wavelengths in the static thrust equation are very non-linear. This is exploited in the design of the resonator to maximise the ratio of end plate forces, while minimising the axial component of the side wall force. This results in a net force that produces motion in accordance with Newton’s laws."-Roger Shawyer [37]

• "The mathematical derivation of the theory behind the EmDrive propulsion system has been reviewed and verified by Dr Richard B Paris, a senior mathematics lecturer at University of Abertay Dundee."- Roger Shawyer[38]
  • Richard Paris is an expert in MHD (magnetohydordynamics) [39]. It appears work at Dundee was done as part of BAE systems "Project Greenglow" [40] [41]

The above statements make clear that Shawyer claims to exploit the geometry of the cavity due due to the nonlinear nature of the fields involved. Do external sources back up the Shawyer's claim the field equations are nonlinear for the geometry he talks about? Yes they do:

• "There are no analytical solutions for the resonant modes of a truncated cone." - White et al. [42]

• "Hollow conical waveguides (horns) have got successful applications in many fields such as...laser-wakefield accelerators. A theoretical treatment of a tapered optical waveguide presents formidable mathematical difficulties. One can not but , therefore, have recourse to approximate methods." [43]

• "Chebyshev-Galerkin solution of the electric field integral equation for the surface current induced on a conducting frustum by an incident plane wave is presented." [44]
  • Chebyshev-Galerkin formulation is used as an linear approximation to nonlinear electromagnetic problems. [45]

• "One way to make a resonator sensitive to this type of measurement is to excite [wave guide] travelling wave modes in an asymmetric resonator; some possible configurations are shown in figure 8....The only way to accurately calculate the sensitivity of such experiments is through numerical simulation, and we will pursue this path in the future." [46]

• "Fig. 18.24 Tilted-plate plasma reactor with polarized plasma wedge in unstable equilibrium...If the geometry is changed by tilting the two electrodes, an electric field gradient will exist horizontally...This can be understood as an imbalance in electrostatic pressure that provides a net paraelectric body force."[47]

• Also interesting are tests using resonant cavities for "light shining through walls" and axions, which are "very sensitive to the geometry used"[48]. There appears to be a whole "Low-Energy Frontier of Particle Physics" [49] that resonant cavities can explore.

I'm all for completely rewriting a section to clarify and explain things, but I can't see the "nonsense" or "basic physics errors" to which you refer. Perhaps you'd like to use your extensive understanding of nonlinear field theory to point a specific issues out?--Sparkyscience (talk) 12:30, 8 June 2017 (UTC)

I'll start with details:

"Mathematically speaking the variables describing the waves cannot be isolated from the description of the overall system" - what does that mean?

"a sharp distinction between the propagating and evanescent electromagnetic waves cannot be achieved" - the text is discussing resonant modes, there is nothing propagating.

"and as a result a non-zero power flow runs through a truncated cone focusing a portion of energy near the apex." - how does that follow, and what does "focusing the energy somewhere" mean? Just a region with higher energy density? And why should that be near the apex? And what is the relevance of that?

"There is no well-defined cutoff wavelength but rather a cutoff radius." - radius of what?

"Due to the absence of sharp cutoff wavelengths this allows the interior of a truncated cone to support an inhomogeneous electromagnetic field." - you can get inhomogeneous electromagnetic fields in every cavity, what does this have to do with cutoff wavelengths? 4 remarks, that all don't seem to explain that.

Remark a: "The new cavity is superior" - on which scale? Which new cavity, which old cavity?

"There are many situations where the electromagnetic field becomes anisotropic" - the electromagnetic field is a vector field. It has to be anisotropic (if non-zero).

Overall: What is this part telling us? "Resonant modes in complex structures are complicated and do not have nice symmetries." Okay, sure. Is that all? Because that could be summarized much shorter. In addition, the section seems to be written according to Maxwell's laws. But Maxwell's laws conserve momentum exactly. You can't explain thrust with laws that predict exactly zero thrust.

--mfb (talk) 17:56, 8 June 2017 (UTC)

These are excellent constructive comments that I think really get to some areas that need clearing up. I'll do my best and hopefully significant changes and clarifications can be made. Apologies in advance for the wall of text (particularly for answer to 1.)! I'll try to answer to the best of my understanding and to talk as simply as possible.

• "Mathematically speaking the variables describing the waves cannot be isolated from the description of the overall system" - what does that mean?
  • Taking a step back, mathematics is all about expressions that describe objects together with the rules for manipulating them. Usually (certainly all the mathematics you learn at school, and unless you do MS in mathematics) the object (or variable) and the rules of the system that govern that variable can be separated, that is, generally speaking you can separate the variable to one side of an equality, for example ${\displaystyle y=ax^{2}+bx+c}$ You isolate the variable ${\displaystyle y}$ from the description of the system. There are a whole class of systems, nonlinear expression or equations, where a variable cannot be separated to one side of the expression even in principle. The description of the variable or object and its environment are coupled. Certainly, in the expression we have just talked about ${\displaystyle x}$ is a nonlinear variable with respect to ${\displaystyle y}$ but that does not mean you cannot write a equation in terms of ${\displaystyle x}$, you can. It is easy to conflate nonlinear variables with nonlinear equations.

The separation of variables is intimately tied to the existence of symmetries in equations.[50] Seperation of variables, in general, can only be done for sets of linear equations. Examples of nonlinear equations are a

Mandlebrot set and the field equations of general relativity (except in special situations). Unlike linear equations where I can write an equality that equals something, in nonlinear expressions there is no expression, that is, there is no equality to equate a variable with the system. Nonlinear systems, can be thought of as not equations to be solved but processes to be followed, for example the Mandlebrot set is a shape not defined by the solution to an equation but defined by a process. In general relativity the same principle applies, only in very special situations we can solve for a centre of mass - in general a center of mass may never settle into equilibrium and it may dynamically change at any given time for non-stationary fields. See Mass in general relativity for details on nonlinear issues - indeed most of the mass in the universe arrises not from summing particles that have intrinsic mass (gluons have no mass) but as a result of a dynamical nonlinear process (see Quantum chromodynamics binding energy

). The whole is as fundamental as the part. All nonlinear systems are open systems because the object and the environment cannot be separated. This is what makes nonlinear systems so difficult mathematically - we are used to assuming that I can derive some equation where I can plug in any value of ${\displaystyle x}$ and tell you what the state will be ahead of time - the seperation of a variable, which leads to a symmetry of an equation, leads to the power of prediction - in a nonlinear system I have to plug in ${\displaystyle x}$, see what the equation describing the environment or state is, plug in ${\displaystyle x}$ again, and iterate repeatedly to know the end state of the system is because the environment and object are coupled. A lot of physicists don't like nonlinear systems and assume them to be "ugly" because of this difficulty, they assume that there is some deep principle which we will one day discover that will allow us to find a solution exactly, but It is an inherent feature of the system not a fault in our understanding of the system that we need to resort to numerical methods or approximations. The assumption I can always derive an exact expression for a variable or part is the ideology of reductionism.

The standard set of Maxwell equations in the vacuum, or free space, are linear expressions. [51] you can plug in a value for the E field or B field and know what the state is - this cannot be done for nonlinear systems. In QED you can have self-interactions of fields - but not all self-interactions are nonlinear - for example in QED there is something called perturbation theory or renormalisation, which is effectively deals with expressions that are like a

Yang-Mills theory that Maxwell's equations were generalized for situations the potentials are not homogenous (i.e they exhibit nontrivial topology), in these instances potentials, not just differences in potentials, take on real physical meaning. If the potentials have nontrivial topology, as is the case for a host of topological effects such as Hall effect, quantum Hall effect, fractional quantum Hall effect, spin Hall effect, quantum spin Hall effect, Aharonov–Bohm effect, Sagnac effect

etc. then the requirements for the EM vacuum to become a nonlinear may be radically different from that assumed in homogenous space.

• "a sharp distinction between the propagating and evanescent electromagnetic waves cannot be achieved" - the text is discussing resonant modes, there is nothing propagating.
  • "The eigenfunctions/modes of a uniform transmission line, such as the circular tube, have sharp cut-off frequencies below which the field is evanescent and above which unattenuated propagation occurs... In contrast, the modes of a nonuniform transmission line, such as the conical waveguide...experience a gradual transition from propagation to evanescence, as a function of electrical distance ${\displaystyle kr}$."[53]

"As ${\displaystyle kr}$ decreases all modes run continuously from a propagating through a transition to an evanescent region. We note that a strict distinction between pure propagating and pure evanescent modes can not be achieved."[54]

Usually a wave will only propagate down the waveguide if the excitation frequency is larger than the cut-off frequency, if the frequency is less than the cut-off frequency, the wave is evanescent and will not propagate. In these instances the propagation constant becomes an imaginary number. A solution to the wave equation having an imaginary wave number does not propagate as a wave but falls off exponentially, so the field excited at that lower frequency is considered evanescent. In a cylinder we are able to define sharp cutoff frequencies where propagation will begin to occur but in a truncated cone we cannot do this. The presence of evanescent modes seems to be important in terms of the interaction of virtual particles and quantum tunneling [55] [56] (this something I've only just come across).

• "and as a result a non-zero power flow runs through a truncated cone focusing a portion of energy near the apex." - how does that follow, and what does "focusing the energy somewhere" mean? Just a region with higher energy density? And why should that be near the apex? And what is the relevance of that?
  • "Therefore, real nonzero time-average power flow does occur in a conical waveguide that is smaller in cross section than any cut-on circular waveguide at the same frequency of operation. This observation can also be qualitatively explained by considering the oppositely directed evanescent waves that are excited at the cascaded junctions of successively larger but still individually cut off circular waveguides that form a stepped approximation to the cone. Effectively, then, the conical scatterer tends to focus a portion of the energy of the incident radio wave, at least in comparison to the uniform tubular scatterer.[57]

"In most respects, the scattering by the frustum is a distortion of that by the circular tube. One important difference is the internal focusing effect that is predominantly experienced when the exciting plane wave is incident from the wide end of the frustum."[58]

I'm happy to stand corrected on this but it looks like there is a slight mistake in the current version of text. There is a non-zero power flow but it is smaller then that of the circular wave guide, thus unlike a cylinder waveguide energy builds up within an area of the field. The relevance of that is....does it gravitate? (see below)

• "There is no well-defined cutoff wavelength but rather a cutoff radius." - radius of what?
  • "There is no well-defined cutoff wavelength but rather a cutoff radius ${\displaystyle (R_{c})}$[59] I could be wrong, but I I think this basically saying is that evanescent waves do not decay exponentially.

• "Due to the absence of sharp cutoff wavelengths this allows the interior of a truncated cone to support an inhomogeneous electromagnetic field." - you can get inhomogeneous electromagnetic fields in every cavity, what does this have to do with cutoff wavelengths? 4 remarks, that all don't seem to explain that.
  • No - Maxwells equations we are familiar with in a vacuum, or free space, are homogeneous. We are conflating values, magnitudes and variables with the equations themselves. The values certainly vary, but the expression that governs the values keep the same form and do not change regardless of the point in space we are talking about. "Due to the absence of sharp cut-off frequencies for the nonuniform conical waveguide, the interior of the frustum can support nontrivial field amplitudes" [60] An amplitude would be trivial if i can translate its value, via a symmetry of an equation, to another position. But I cant do that here. For example take a pencil and lie it flat on the ground at the north pole of a globe, slide it along the surface in the direction it is pointing to the equator, keeping it perpendicular to the equator, slide it to another line of longitude and move the pencil back to the north pole: the pencil no longer points in the same direction. [61] This is an example of the failure of a certain variable (i.e a vector) describing the system to return the original value - we need to include notions about topology to understand the system fully. In particular the vector field contains incomplete information about the system - Maxwell's equations tell you that vectors fields alone describe the whole system!

It is interesting to note that if there is more energy contained in an area of space then another area, then gravitational effects should apply. This is certainly true of the Casimir effect, which again can be viewed as an effect of the topology of the fields.

• Remark a: "The new cavity is superior" - on which scale? Which new cavity, which old cavity?
  • "The new cavity is superior to the often used cylindrical cavity, because it intrinsically does not suffer from mode degeneration." [62] Cylinders can be solved analytically - they can be described by linear equations and they have resonant modes. Because they have resonant modes it suffers from degeneracy. Conical cavities don't have analytical expressions for resonant modes, and so no two modes can have the same resonant frequency, this is how it intrinsically does not suffer from mode degeneration.

• "There are many situations where the electromagnetic field becomes anisotropic" - the electromagnetic field is a vector field. It has to be anisotropic (if non-zero).
  • Absolutely not. Anisotropic refers to the symmetry of the equations, not the value of the equations. Maxwells equations in free space are isotropic regardless of the values, magnitudes of the vector field. Thus anisotropic refers to the fact that Maxwells equations are modified to be directionally dependant. Simplistically this means that the speed of light is different in one direction when compared to another. This is common in laser physics and brings in the idea of group velocity discussed below.

• Overall: What is this part telling us? "Resonant modes in complex structures are complicated and do not have nice symmetries." Okay, sure. Is that all? Because that could be summarized much shorter. In addition, the section seems to be written according to Maxwell's laws. But Maxwell's laws conserve momentum exactly. You can't explain thrust with laws that predict exactly zero thrust.
  • If the system could be described by a set of linear equations I'd completely agree. But it is nonlinear, so it cannot be described completely by a set of linear equations like Maxwell's equations. I think it important to separate that which we can be definitely sure of about the electromagnetics of the conical cavity and any effects this may lead to. Shawyers theory relies on the idea of group velocity [63] [64] Something which the current article completely misses and it is this idea which Richard Paris seems to have endorsed. This allows the phase velocity vector and group velocity vector to be different. Wheres that in Maxwell's equations? This book [65] seems to talk about the group velocity idea with respect to the Emdrive in more detail so I'll see if I get a copy from a local library.--Sparkyscience (talk) 16:06, 9 June 2017 (UTC)

Is a reader expected to fill in all these explanations while reading? And some of them are wrong:

"But it is nonlinear, so it cannot be described completely by a set of linear equations like Maxwell's equations." - is this an experimental result? If yes, who measured it? That would be worth a Nobel Prize, because QED does not predict relevant nonlinear effects at that scale (light-by-light scattering has been measured, but with much stronger fields). It is clearly not a theoretical result - Maxwell's laws are linear and self-consistent. You can apply them to any shape you want. I don't see any reason to expect a difference for the particular shape discussed here.

I've given a long list of topological effects, plenty of which have won Nobel prizes (last year for example), that cannot be explained in the standard formulation of Maxwells equations or QED. Both contain no notion of topology - in both the spacetime is flat because the potentials are trivial. There are no solitons in U(1) Maxwell equations.Sparkyscience (talk) 22:40, 9 June 2017 (UTC)

Topological effects in matter. Not in cavities.

Casimir effect.--Sparkyscience (talk) 09:30, 10 June 2017 (UTC)

"Wheres that in Maxwell's equations?" - It is a typical consequence of propagation of electromagnetic signals if not in vacuum. Where is the problem?

We're talking about a vacuum. Sparkyscience (talk) 22:40, 9 June 2017 (UTC)

We have a vacuum with conducting walls. That is not the same as a vacuum.

You can rewrite every equation to isolate any variable by defining suitable operators. That is not always useful, but always possible. I don't see how you relate this to words chosen in the article. You seem to use "system" in an unusual way, and I think you confuse "nonlinear" with "chaotic" in some cases.

Where did you get that from?! If there is a proof that states i can always separate a variable by changing operators I want to know about it! Whats the theorem called? I can't find it in either of these books [66] [67] but maybe I'm looking in the wrong place.Sparkyscience (talk) 22:40, 9 June 2017 (UTC)

For every equation 0=f(x,y) (or any other shape, doesn't really matter), you can define a function F such that x=F(y) satisfies the first equation by definition of F. That does not always help you solve a problem, but mathematically it is possible. There is nothing to prove, it is a definition.

"in a nonlinear system I have to plug in ${\displaystyle x}$, see what the equation describing the environment or state is, plug in ${\displaystyle x}$ again, and iterate repeatedly to know the end state of the system is because the environment and object are coupled." - You gave a counterexample to that claim already! Here is an even easier one: y=x² (x,y>0) is not linear, but it is trivial to solve for x: x=sqrt(y).

I'm pretty sure the above satisfies the conditions of homogeneity and superposition. Nonlinear_system#DefinitionSparkyscience (talk) 22:40, 9 June 2017 (UTC)

So what? It is a counterexample to your earlier claim.

I could go on, but I don't think this would be helpful. --mfb (talk) 19:40, 9 June 2017 (UTC)

Apart from you as author, four users commented here (me included), and all are supporting a removal - I removed the section. --mfb (talk) 01:17, 10 June 2017 (UTC)

With respect, you've made a lot of errors in the above. Homogeneity, isotropy, symmetry etc. Its very clear theres a huge gulf in understanding of nonlinear systems. You've made the assumption you can set every function = 0. This sounds like the definition of an equilibrium system, not a nonequilbrium one. I'm really not sure where I've contradicted myself but I do understand the onus is on me to try and explain things. Clearly some of the removed material is factually correct; other parts clearly need review in light of the above.Sparkyscience (talk) 09:26, 10 June 2017 (UTC)

Okay, one last comment: For every equation a=b, you can rewrite it as 0=b-a. That is extremely elementary mathematics. --mfb (talk) 16:02, 10 June 2017 (UTC)

Everything Mfb wrote above looks right to me – presented with unfailing graciousness. SS, you seem to be using your own private definitions of nonlinearity, homogeneity, isotropy, symmetry (What is an 'isotropic equation'?), which makes it hard to discuss details with you. Luckily, WP is not the place to discuss such details: for discussions / explanations / debates about physics, and examples of clear explanations, try StackExchange. Here we have the luxury of limiting discussion to something much simpler: what is said in reliable sources. On that front, this paragraph was synthesis. – SJ + 22:47, 10 June 2017 (UTC)

Though it should not matter, my background is in mathematics (not specifically physics per say) and I'm using the same definitions any mathemicican would use, (and i think any mathematical physicist would use?). You are both very wrong on some key issues here, which is causing mass confusion. mfb - If I was to say that angles in a triangle add up to 167° you would insist it is "extremely elementary mathematics" that angles in a triangle always add up to 180°, when actually angles on a triangle can add up to below 180° in Hyperbolic geometry or more that 180° in Elliptic geometry by definition. Similarly here, I am telling you that there are systems where it is impossible to separate variables, by definition, and that these systems are nonlinear. There is a good introductory overview here [68]. The assertion that you can always seperate variables is wrong. Nonlinear expressions are extremely hard to "solve" or form closed form expressions except in very special cases because they do not form analytic expressions. The field equations for a truncated cone are not analytic. Sj- An isotropic equation, in this context would be an isotropic field equation. Equations that describe eucleadean space, minkowski space, Maxwell's equations are all isotropic. It arrises as a consequence of the preservation of rotational symmetries. Similarly, homogeneous fields arrise from the preservation of translational symmetry. If a field is nonhomogeneous it is always anisotropic, but a field can be anisotropic while still being homogeneous. Both of you are wrong by saying this has something to do with variation in the values of the field, it has everything to do with do with field equations looking the same at each point in space regardless of direction or rotation. While wikipedia is not a forum, portions of this text have been removed because you don't understand the concepts. If the sources are not explained, the resulting text with regard to the field arising from a truncated cone will be utterly impenetrable to nearly every reader--Sparkyscience (talk) 12:05, 11 June 2017 (UTC)

To be perfectly honest, one of the key tenets of wikipedia is to make articles understandable. See

WP:TECHNICAL. This sort of highly technical explanation is not only not necessary but confusing to readers. Keep it simple, and the summary from reliable sources does that just fine. — InsertCleverPhraseHere

12:24, 11 June 2017 (UTC)

I think it best to remove the device structure section entirely for now (current version has no references) until a clear english version can be made. With respect to the above debate, thankfully the NatGeo aticle [69] links to this paper here [70] as a brief overview on conservation of momentum / homogeous fields / linear operators etc and how they might apply to the EmDrive.--Sparkyscience (talk) 14:53, 13 June 2017 (UTC)

Modern physics seems to be in a transition at the moment from the Standard-Model (SM) of particle physics to the Standard-Model Extension (SME). The main difference is that the new SME allows Lorentz violations (i.e special relativity does not always hold in some cases of spontaneous symmetry breaking). There seems to be two big tests of Lorentz violations that would put the SME on course to being fully adopted and replace the Standard Model: Vacuum birefringence from neutron stars, for which there is now very strong evidence [71] [72]... and observations from optical or microwave resonant cavities. The scientists who came up with the SME expects to find Lorentz violations present in microwave resonant cavities [73]. The Lorentz violating terms are usually very small and discarded from calculations (standard renormalizable QED throws it all away) but resonant cavities seem to be highly sensitive to any such effects. Lorentz violating terms are predicted to occur due to nonlinear self interactions between the fields and matter, under certain conditions (for instance very strong magnetic fields, or curved spacetime) these effects are amplified.

I have not had time to read anything in the literature thoroughly, but it struck me as an odd coincidence that the EmDrive, a resonant cavity, violates Lorentz invariance and that resonant cavities are indeed expected to be sensitive Lorentz violations in the SME. initial thoughts:

• The geometry of the cavity affects the sensitivity to Lorentz violations (as is standard in CQED).

• There seems to be a distinction in observing Lorentz violations between cavities that are degenerate and nondegenerate. [74] We know that the geometry of the EmDrive does not suffer from degeneration.

• Usually modes in two identical symmetric cavities are compared (as in Michelson–Morley experiment), but If the resonant cavity is asymmetric it leads to nonlinear chaotic "ray dynamics" [[75]]. two modes propagating in opposites directions in the same cavity can be compared instead (
  ring resonator
  ).

• there is something called stochastic resonance [76] where background noise, say from Lorentz violating terms of the vacuum, can be amplified by nonlinear systems. This is why White et al proposed stochastic electrodynamics as theory to explain the EmDrive - it allows for such an amplification effect.

Even if turns out there is no support EmDrive physics in the SME, should be a good area to find out more about resonant cavity physics, because it seems to be current hot topic in the field.--Sparkyscience (talk) 14:13, 1 June 2017 (UTC)

Just to add to this... the NASA team do seem to have used a Fabry–Pérot interferometer to do a Michaelson-Morely type experiment with a single asymmetric cavity to do just the experiment mentioned in point three above. the cavity was a scaled down version of the EmDrive test article. An anisotropic vacuum will result in a relative phase shift in the observed diffraction pattern. They claim to have observed this,[77] but have not mentioned it in their final paper. The light, if the effect was present, would be blueshifted.

In this video [78] Harold White states that he spent years working an Hall-effect thrusters and that the principle with the EmDrive should be exactly the same. Hall thrusters emit blueshifted Cherenkov radiation . Light will be sped up in a Casimir cavity due to the Scharnhorst effect, [79], which is exactly analogous to blueshifted Cherenkov radiation. The "speed" difference in relative phase is ultimately due to topology of the field

This paper in Physical Review [80] also mentioned in here [81], is very interesting... fig. 8 looks just like an emdrive. this stucture is suggested as a way of improving sensitivity to Lorentz violations over current methods presumably because "This device naturally separates the injected and reflected wave in the same way as a

ring cavity at optical frequencies, without degrading the frequency discrimination"...and "The only way to accurately calculate the sensitivity of such experiments is through numerical simulation, and we will pursue this path in the future." Cant find a follow up yet...--Sparkyscience (talk

) 20:23, 1 June 2017 (UTC)

Unless the literature makes specific reference to resonant cavity thrusters in relation to SME, it doesn't belong here (

WP:SYNTH). Any sourced you have found that do so? — InsertCleverPhraseHere

20:28, 1 June 2017 (UTC)

The Michaelson-Morely type experiment by White clearly connects the concepts.--Sparkyscience (talk) 20:44, 1 June 2017 (UTC)

In what way does it connect the concepts? Could you quote the relevant section? — InsertCleverPhraseHere 20:56, 1 June 2017 (UTC)

Someone appears to have made a whole article on the topic -

Quotes from the video [84]

"We're trying to change the optical path length in a very small region of the interferometer by having the appropriate conditions that general relativity requires. It says that in a local region it changes the perceived path length of the photon line intergrals. That will manifest itself in a slight change in the interference pattern."

"If your pushing off the quantum vacuum you are establishing an anisotropic state in the quantum vacuum and so it is putting a wake out of the back of the thruster."

"You never locally exceed the speed of light so you can't time travel - I like doctor who as much as the next guy."

"The low fidelity test article is trying to create a blue-shifted frame relative to the lab. So we are just using a large potential energy with our low fidelity article. The higher fidelity test article that i showed you guys a picture of, that is based on the q-thruster physics and so thats where we go to work on using the negative vacuum energy to try and satisfy all the explicit requirements of the field equations. That test article is trying to establish more accurately the requirements as required by the mathematics - working with negative vacuum energy - the Casimir force."

Explanation: When he says change the path length or relative phase - he is talking about the hypothetical spontaneously symmetry breaking of lorentz invariance that will lead to a detectable difference in relative phase.

Translation: A gauge transformation is a symmetry transformation in physics that leads leads to the conservation of some local property known as a particle or quantum number (for instance the charge, spin, baryon number, lepton number etc.). One of the key ideas that helped Albert Einstein develop his theory of general relativity was the idea that the field equations should be the same in every co-ordinate system, Lorentz symmetry is preserved as a local property just like the symmetry principles of quantum numbers. From a modern point of view, this too is an example of a gauge symmetry. Every symmetry in nature leads to an unobservable - the unobservable for a gauge symmetry is relative phase. It is known that symmetries in nature can be broken, SME allows for the spontaneous symmetry breaking of lorentz symmetry and therefore relative phases can be detected. This is precisely what the referenced resonant cavity experiments in SME are designed to try and detect and what White is describing in the above.--Sparkyscience (talk) 21:56, 1 June 2017 (UTC)

I don't see anything here in the sources that directly links Lorenz symmetry to resonant cavity thrusters. Until someone publishes something linking the two directly, we have to sit on our hands (this is an encyclopedia, not a research journal). — InsertCleverPhraseHere 22:35, 1 June 2017 (UTC)

If I do a

Michelson-Morley experiment what am I testing for?--Sparkyscience (talk

) 22:44, 1 June 2017 (UTC)

WP:SYNTH. — InsertCleverPhraseHere

22:47, 1 June 2017 (UTC)

If NASA does a Michaelson-Moreley experiment with an EmDrive EXPLAIN to me what law of physics this confirms or does not confirm? SYNTH is not explanation --Sparkyscience (talk) 22:53, 1 June 2017 (UTC)

That is the point. The reference has to explain that, not users on talk pages. --mfb (talk) 23:40, 1 June 2017 (UTC)

The source has to specifically make the connection not you. That's what

WP:SYNTH explains in detail. — InsertCleverPhraseHere

23:53, 1 June 2017 (UTC)

SYNTH is not explanation doesn't apply here: that policy applies when you are explaining in detail one or more sources that do make the connection directly. What you are doing is combining different sources where no source makes the connection directly. — InsertCleverPhraseHere 23:58, 1 June 2017 (UTC)

Well okay, I thought it was obvious common knowledge a that Michaelson-Morely type experiment tests Lorentz invariance; I'm sure if you insist on a source, one should be easy enough to come by to explain what White's Fabry–Pérot interferometer is actually trying to measure! Anyway...There is a very interesting sentence on Shawyer's webpage that I have just spotted. Never really bothered to read it before because I automatically assumed his "theory" to be "cranky" and "wrong". [85]:

"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."

Whats a

I think an EXPLAINATION of what radiation pressure is and what a laser gyroscope does should be added to Shawyer's claims. This isn't pseudoscience at all, its a very testable hypothesis that may or may not work --Sparkyscience (talk) 11:56, 2 June 2017 (UTC)

If you think there is anything mysterious or even Lorentz-violating about ring lasers in guidance systems, you misunderstand both. --mfb (talk) 14:08, 2 June 2017 (UTC)

I'll be honest looking into the debate over rotating frames of reference in general relativity has made my head hurt.--Sparkyscience (talk) 16:18, 2 June 2017 (UTC)

The large bulk of this section violates our policy on original research. I'm bringing it here we can determine if any of it is usable in the article:

Extended content

Conservation of momentum Main article: conservation of momentum The EmDrive purports to violate the vacuum field described by Maxwell's equations or by quantum electrodynamics (QED), which preserves momentum and is therefore invariant under arbitrary spacial translation is said to be homogenous. Symmetries give rise to the geometry or properties of spacetime.[6] Some symmetries in physics[3][4][5] Symmetry Transformation / Invarient Unobservable Conservation law Field properties Space translation ${\displaystyle \mathbf {r} \rightarrow \mathbf {r} +\Delta }$ absolute position in space momentum homogenous Time translation ${\displaystyle t\rightarrow t+\tau }$ absolute time energy path independent Rotation ${\displaystyle \mathbf {r} \rightarrow \mathbf {r} '}$ absolute direction in space angular momentum isotropic Lorentz symmetry ${\displaystyle t'=\gamma \left(t-{vx}/{c^{2}}\right)}$ absolute velocity with respect to ${\displaystyle c}$ generators of the Lorentz group equivalence between inertial frames of reference Einstein believed all laws of nature could be described by symmetries Casimir force[14] the magnitude of which depends on the size, geometry and topology of the cavity and field.[15] If the EmDrive were to able to induce an instability in the vacuum it may be able to produce a net force,[1][2] However, if these vacuum forces are indeed present, they are expected to be exceptionally tiny based on our current understanding.[13][16][17] In the unlikely event that the force is not an experimental error, the positive result would be indicative of novel new physics[18][19] References ^ a b Siegal, Ethan (23 November 2016). "How Physics Falls Apart If The EMdrive Works". Forbes.com. Forbes. Retrieved 23 November 2016. ^ a b Lee, C. (8 Feb 2013). "Generating Thrust Without Fuel Relies on Missing Details". arstechnica.com. WIRED Media Group. Archived from the original on 11 May 2017. ^ ISBN 978-0-521-60272-3 . ^ ISBN 978-981-238-711-0 . ^ ISBN 978-3-7186-0033-5 . OCLC 81205872 . ^ ISSN 0031-9228 . ^ Richerme, P. (18 January 2017). "Viewpoint: How to Create a Time Crystal". physics.aps.org. APS Physics. Archived from the original on 2 Feb 2017. ISBN 978-3-7186-0033-5 . ISSN 0262-4079. {{cite journal}}: Invalid |ref=harv (help ) ISSN 1539-0748. Archived from the original on 24 Feb 2013. doi:10.1038/news040126-19. Archived from the original on 1 Feb 2017. ^ arXiv:1411.5359 . ^ Maxey, K. "Propulsion on an Interstellar Scale – the Quantum Vacuum Plasma Thruster". engineering.com. engineering.com. Archived from the original on 15 Feb 2013. ISSN 0370-1573 . ^ Cite error: The named reference Freeman 2015 was invoked but never defined (see the help page). ^ Marcus, A. (12 Oct 2009). "Research in a Vacuum: DARPA Tries to Tap Elusive Casimir Effect for Breakthrough Technology". scientificamerican.com. Scientific American. Archived from the original on 2 Mar 2015. ^ Cite error: The named reference TZF 2016 was invoked but never defined (see the help page). ^ Cite error: The named reference Poitras 2016 was invoked but never defined (see the help page).

- MrX 16:37, 13 June 2017 (UTC)

What part do you think constitutes OR? The first two sources clearly state that conservation of momentum is based on a symmetry, specifically translation symmetry, and the EmDrive appears to violate this. Standard textbook sources (one of which is written by a Nobel prize winner who was awarded it due to his work on symmetry) are used to explain this in the first paragraph and table in more detailSYNTH is not explanation.

The latter paragraph is based on this document here [87] which is all about the Emdrive, talks about the Casimir effect, homogeous fields etc, and which is linked to in this article here [88] which again is all about the emdrive. So there is no original research here. Just basic physics facts, which is covered anyway under Wikipedia:Scientific citation guidelines--Sparkyscience (talk) 16:49, 13 June 2017 (UTC)

In order for this to be classed as OR there must be claim here which from a primary source or a new synthesis of statements not included in the sources. How do you think this qualifies?

OK, let's break it down: The first sentence "The EmDrive purports to violate the conservation of momentum and its associated symmetry." is not supported in either source. Specifically, please indicate the sentence in a source that says that the EmDrive purport anything. I think you mean the EmDrive researchers purport, but even that is not in those sources.16:56, 13 June 2017 (UTC)

Sure lets break it down:

"But if the EMdrive is truly reactionless, then Newton is wrong. Also, Einstein is wrong, Maxwell is wrong and all of quantum physics is wrong. There's a fundamental symmetry that causes momentum conservation: translational symmetry. It means that if my system is over here, at a certain point in space, it should obey the same laws as if it's over there, at a different point in space. But if momentum conservation isn't truly fundamental, then translational symmetry cannot be a good symmetry of the Universe. In other words, there must be a preferred location, where the laws of physics are different in one location than others. The laws of physics, all of a sudden, depend on position."[89]

"The key claim to the EmDrive is that it breaks this symmetry, allowing a net force to exist."[90]

"Because there is no preferred reference frame for the quantum vacuum (nor does it even have a rest frame), any force observed to be produced in O, must also be observed in O¯. However, relative to O¯, there is a symmetry about the parallel fields, and thus no net force is expected. The only way that such an observation can be reconciled with any apparent force observations made in O, is if the net force in O is also zero. In the next section we formally confirm this using a QFT calculation."[91]

I don't think changing the word "purport" is going to be controversial, but its not a reason to remove a whole section.--Sparkyscience (talk) 17:07, 13 June 2017 (UTC)

The issue is not with the word choice; it's with the attribution. An EmDrive can purport, claim, assert, say, state, mention... The correct thing to do here is paraphrase the source: "If the EmDrive is reactionless,..."

By the way, it seems that Forbes and Ars Technica as discussing two different types of symmetry. We should either describe both, or just use one source.- MrX 17:24, 13 June 2017 (UTC)

No they are discussing the same symmetry. "In our simple picture of two mirrors facing each other, the mirrors are subject to equal and opposite forces. Essentially, the photons reflect from each mirror, exerting a force in doing so. Because this is symmetric, the cavity cannot have a net force" No net force = conservation of momentum. equal and opposite force = newtons third law = consequence of conservation of momentum. --Sparkyscience (talk) 17:31, 13 June 2017 (UTC)

Please self-revert this and please thread your talk page replies.

I will accept that the article are discussing the same symmetry concept, as it seems more likely than not. I think we can salvage some of the second and third sentences of your proposed content, provided we write it so that it is a reasonable paraphrasing of the Forbes and Ars Technica sources.- MrX 17:59, 13 June 2017 (UTC)

I'm sorry, but the assertion that this section is breaches the Wikipeda policy of

The cited National Geographic article about the EmDrive makes clear that the central issue at play is the apparent violation of the conservation of momentum [96] "The trouble is, the EmDrive violates Newton’s third law, which states that for every action, there is an equal and opposing reaction...Weirdly, the EmDrive doesn’t expel anything at all, and that doesn’t make sense in light of Newton’s third law or another tenet of classical mechanics, the conservation of momentum." The Forbes and Ars Technica article just restate the obvious, that conservation of momentum is a consequence of a symmetry, namely translational symmetry. It is clearly an obscene and untenable position to try and contend that an article about the EmDrive cannot use physics textbooks to explain the conservation of momentum, unless those textbooks also include direct reference to the EmDrive. It is certainly not an idea based on any Wikipedia policy. If a reference about topic [A] contains a mention of concept [B]. then a separate reference [C] that explains topic [B] can be used. SYNTH is not explanation. SYNTH is when two sources are combined to create an original new thesis that is not directly addressed in either source. There is no statement in the above which is not factually correct, or not directly addressed by the cited source.

The cited National Geographic article also links to this overview paper [97] to explain remarks by Sean Carrol that the quantum vacuums is not "available for pushing against". This is an excellent paper, which directly discusses the possible science behind the EmDrive, states that no net momentum transfer can occur where the symmetry of homogenous fields are preserved but that " This relies on the use of the assumption of homogeneous electric and magnetic fields. If there is a spatial variation, then this argument cannot be used so simply, because in this case there is no single reference frame in which the fields now appear co-linear everywhere. In the context of pair production, such situations have required numerical calculations to solve the resulting equations [19]. It seems unlikely though that spatial variations alone would produce a net force. Although the extraction of a net momentum has been postulated in inhomogeneous vacuums." The paper directly references the work of Feigel, which are discussed in more detail in the provided "from nothing" references here [98] [99] both of which are from top tier reliable sources. The paper also disusses the Casimir effect, which has been used as the main mechanism of explanation by NASA team and by Mike Mcculloch [100].

In short, a section that explains the conservation of momentum is eminently reasonable on an article about a device that apparently violates it . It is the central issue. All of the concepts discussed in the draft are directly relevant to how the Emdrive does or does not work. i.e. in the likely case that the EM fields are homogenous it is impossible. It seems you have deleted this multiple times because you are unfamiliar with the basics, that somehow fundamental concepts in physics are "original research". and it does not appear you have reviewing the citations in any level of detail.--Sparkyscience (talk) 08:37, 14 June 2017 (UTC)

I have rewrote the section for clarity on Newtons laws, added more references relating to the emdrive and dialled back some of the broken symmetry stuff to avoid confusion.--Sparkyscience (talk) 10:11, 14 June 2017 (UTC)

I disagree, and last I checked, we build articles by

WP:3RR, a blockable offense). This is not a good path.- MrX

13:39, 14 June 2017 (UTC)

Lets be clear - I have always maintained that the EmDrive is most likely explained by experimental error and my edits reflect that: In the edit that clarified the conservation of momentum, the section on experimental error was significantly expanded [101] I've also edited the lede sentence to include the word "purported" in clear violation of

Most of the cited sources do now directly mention the EmDrive. But you simply cannot claim that using a standard textbook definitions of conservation of momentum is

I have added more caveats to the possibility of net force from inhomogenous fields. I really don't think a reader draw any wrong conclusions from reading this text.--Sparkyscience (talk) 17:14, 14 June 2017 (UTC)

I like the first paragraph of the new section and the table. I'm sceptical about the second paragraph. The Casimir effect is often misunderstood by pop-science articles. It is an attractive force between conducting plates. What is so special about it? We also have attractive forces between electrically charged objects, and between all objects with mass (not limited to massive particles, but that detail is irrelevant here). In all these cases you can describe the attraction with virtual particles, but you do not have to.^[1] It is simply a symmetric force between objects in space, and in the second and third case no one calls it "extracting energy from the vacuum" - so why do it for the first one? None of these phenomena violate energy or momentum conservation.

Suggestion for the article: Remove the Casimir effect confusion. Keep the statement that some authors suggest inhomogeneous laws of physics.

Personal comment: The suggestion that the laws of physics depend strongly on the position, i. e. change notably within a meter-sized apparatus, looks absurd. --mfb (talk) 17:18, 15 June 2017 (UTC)

Good suggestions. But disagree on the Casimir effect. Jaffe's commentary on the Casimir effect is well known. His final paragraph is key:

"Certainly there is no experimental evidence for the “reality” of zero point energies in quantum field theory (without gravity). Perhaps there is a consistent formulation of relativistic quantum mechanics in which zero point energies never appear. I doubt it. Schwinger intended source theory to provide such a formulation. However, to my knowledge no one has shown that source theory or another S-matrix based approach can provide a complete description of QED to all orders. In QCD confinement would seem to present an insuperable challenge to an S-matrix based approach, since quarks and gluons do not appear in the physical S-matrix. Even if one could argue away quantum zero point contributions to the vacuum energy, the problem of spontaneous symmetry breaking remains: condensates that carry energy appear at many energy scales in the Standard Model. So there is good reason to be skeptical of attempts to avoid the standard formulation of quantum field theory and the zero point energies it brings with it. Still, no known phenomenon, including the Casimir effect, demonstrates that zero point energies are “real”."[102]

This was written in 2005 before the experimental verification of the Dynamical Casimir Effect [103][104][105][106], where amplified vacuum fluctuations are observed. Direct observations of vacuum fluctuations both in the lab [107][108][109] and in space [110][111][112]. His analysis is now out of date and does not fit the data. It has also been criticised by

The cited source on the Casimir effect [114] has over 1000 citations and is based on the standard book in the subject [115]. We have to go with what the source states rather then our own opinions:

"A slightly different situation arises however for the Casimir effect in spaces with a non-eucleadean topology....this kind of Casimir effect cannot be considered as a close relative of the van der waals force"

The Dynamical Casimir effect is a type of

"In the bag model of hadrons in Quantum Chromodynamics the Casimir energy of quark and gluon fields makes essential contributions to the total nucleon energy. In Kaluza-Klein field theories Casimir effect offers one of the most effective mechanisms for spontaneous compactification of extra spatial dimensions. Moreover, measurements of the Casimir force provide opportunities to obtain more strong constraints for the parameters of long-range interactions and light elementary particles predicted by the unified gauge theories, supersymmetry, supergravity, and string theory"

i.e. Most mass in the universe arrises not from "fundamental particles' like the Higgs but as dynamical Casimir type field interaction (See Quantum chromodynamics binding energy) and this vid [116].--Sparkyscience (talk) 18:11, 15 June 2017 (UTC)

I don't know how to incorporate this in the article as this is

This article needs a complete reset. After examining not only the glaring biases of the article, but also taking time to note and consider the debate on the nature of science in terms of this Drive on the Talk section itself, it is required that the entirety of the article be vetted by those capable of making informative content containing no bias, ill will, or good will, towards this subject, without the traditional considerations of science or as scientists, without conflating the issue of properly recording and reporting the information in impersonal article format from all sides and viewpoints in the most intelligent, stable, accessible, and demure form possible. This article should contain as many new sources specifically cited, as per still the conditions of policy and plagiarism, presenting information representing and referring to those parties from whom the information or viewpoint was taken. If too many sources and points of view and alternative theories cannot be fully and harmoniously documented within this article, and enough sections cannot be sustained, then repeating the following statement may be most even handed; "There are continuous reasons beyond the currently available scope of this article to be fully integrated and shared for the fullest understanding of this debate." 2600:1700:BCE0:A230:49AD:964B:5606:567D (talk) 20:19, 26 February 2018 (UTC)

Please acquaint yourself with

WP:NOTFORUM. The current article has been produced as a result os much painstaking consensus-building. Additionally I would like to note that your objection to scientists participating in writing a page about science is entirely unreasonable. 81.164.228.206 (talk

) 00:05, 12 April 2018 (UTC)

WP:NOTFORUM doesn't apply to 2600:1700:BCE0:A230:49AD:964B:5606:567D's comment. That comment is about how to improve the articles, not a general discussion about the subject of the article. --Ahecht (TALK
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) 22:07, 13 April 2018 (UTC)