Talk:EmDrive/Archive 4

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Archive 1

Archive 2

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Marketing claim in lede

We have:

if they are found to work as claimed, providing thrust without consuming a propellant would have important applications to all areas of propulsion.

While this may be strictly true, it is equally true that if pigs could fly it would have important implications for aerospace. Since the consensus is that have not been found to work as claimed, and are extremely unlikely to be found to work as claimed, this speculative marketing claim does, IMO, not belong in the lede. Guy (Help!) 09:51, 24 March 2016 (UTC)

It is a comment supported by the Wired source, not only that, it is a necessary comment for the lede, as it provides a necessary context to the reader as to why there is any interest in the device. Nowhere else in the lede does it impress upon the reader why the device would be useful if proved to work as claimed. Don't you think that it is important for the reader to have this information? Whether it is plausible or not is rather irrelevant, and in this case I agree that the device almost certainly does not work as claimed. However it seems necessary to explain to the reader why there is an interest in a drive that seems to break the laws of physics. Insert CleverPhrase Here 11:12, 24 March 2016 (UTC)

As I said, while it is strictly true, it doesn't belong in the lede. It is of the same class as "if this free energy device turns out to work, it could ave important implications for energy generation". True, blindingly obvious, and the dependent clause makes it clear that the implications are entirely irrelevant because (as we make very clear) the chances of the necessary condition being met for that impact to actually happen, are as close to zero as makes no difference. Further down, as part of the explanation of why this nonsense is still being promoted? Fine. Not in the lede, because it's a marketing claim that is hypothecated on something that is exceptionally unlikely to be true. Guy (Help!) 14:22, 24 March 2016 (UTC)

It is only blindingly obvious to you because you already know all about it. To a reader discovering the topic for the first time, that sentence is necessary for their understanding, why do you think the Wired article was titled and structured the way it was? To impress upon the reader why there is so much hype. It is not as if the comment is particularly promotional, it only says that if it works it would have far reaching impacts, the rest of the lede makes it clear that it probably won't turn out to work, so what is the issue? Insert CleverPhrase Here 14:26, 24 March 2016 (UTC)

The same could be said for antigravity devices. Why would we encourage the reader to speculate on the wonders of resonant cavity thrust, when it won't actually happen? Guy (Help!) 14:38, 24 March 2016 (UTC)

While I agree that it probably won't happen, see WP:CRYSTALBALL. Insert CleverPhrase Here 22:39, 24 March 2016 (UTC)

Equally, in the absence of any tangible information about how it might hypothetically be validated or at what scale, speculating as to its potential impact is also WP:CRYSTAL. In fact any concept that would break known physics, would obviously have some unknowable impact. There really is no need to lead the reader by the nose here, certainly not in the lede, anyway. Guy (Help!) 23:31, 24 March 2016 (UTC)

This has already gone on rather long, the statement is backed up by a reliable source and therefore is not original research, and helps the reader establish context for why people care about the device. There isn't more for me to say really. Insert CleverPhrase Here 02:01, 25 March 2016 (UTC)

I edited the sentence again to increase clarity and better reflect the sources and to address any potential WP:CRYSTAL issue. Insert CleverPhrase Here 02:13, 25 March 2016 (UTC)

I agree with Insert CleverPhrase Here the lede should explain what the basic motivation is for the device; maybe it's "blindingly obvious" to Guy that a reactionless "electromagnetic thruster" == sci-fi style space travel, but to many laymen, a reactionless "electromagnetic thruster" == a meaningless word salad. That said, the "would have important applications to many propulsion applications, particularly spaceflight" clause is vague and comes across as promotional. It would be better to just say something like "would revolutionize space travel"; that should be sufficient to explain to the reader "why there is any interest in the device". Rolf H Nelson (talk) 06:25, 25 March 2016 (UTC)

I changed it to "would revolutionise many propulsion applications, particularly spaceflight." Because the wired article lists several other non-spaceflight propulsion applications, I felt that just mentioning spaceflight was not representing the source correctly, moreover 'spaceflight' doesn't adequately cover other commonly stated uses (such as the most common one; satellite orbital maintenence, which isn't really 'spaceflight') Insert CleverPhrase Here 06:58, 25 March 2016 (UTC)

end sentence in the lede is a bit vague

This sentence:

The claims of proponents, especially in respect of independent validation, are disputed.

This is the final part of the lede and is rather vague. I'm not sure exactly what point it is trying to impress upon the reader, but I feel it could do it with more precision. What claims, how are they disputed, and what independent validation is claimed/disputed? Any suggestions? Insert CleverPhrase Here 05:36, 24 March 2016 (UTC)

Some new sources

A few new sources that mention or are about the em drive that I found having a quick scan of recent news articles. Some of these might be useful in editing the article, particularly the Forbes article and the Next Big Future article.

http://www.forbes.com/sites/billtucker/2015/12/06/the-power-of-the-force-the-curious-case-of-the-emdrive/#10878a8f59c1

http://nextbigfuture.com/2015/11/nasa-eagleworks-has-tested-upgraded.html

http://www.outerplaces.com/science/item/10570-the-year-in-science-the-defining-scientific-achievements-of-2015

http://www.gizmodo.com.au/2015/12/the-most-overhyped-scientific-discoveries-of-2015/

http://finance.yahoo.com/news/explaining-emdrive-physics-defying-thruster-162741826.html

http://www.biztekmojo.com/001575/science-nasa-em-drive-thruster-technology-can-it-really-work

http://www.biztekmojo.com/001550/nasas-new-tests-confirm-impossible-em-drive-thruster-can-really-work

http://mic.com/articles/128043/what-is-nasas-emdrive#.IjPUjWSVV

InsertCleverPhraseHere ^{InsertTalkHere} 04:37, 15 February 2016 (UTC)

Added NPOV tag; could use rewrite

I have to admit this edit summary [1] justifying why we should say it's been published in "journals" (plural), even though it's only been published in one journal, made me smile. Any volunteers to rewrite this article? Note that, if time is an issue, "Deleting every single statement that doesn't have an inline cite with solid WP:WEIGHT" is a perfectly valid way to conduct a rewrite for an article such as this. Rolf H Nelson (talk) 07:11, 8 February 2016 (UTC)

If you'd like to improve the wording of the sentence instead of complaining about it... that would be helpful, it certainly isn't a case of 'citation needed' as your edit indicated, also, the second part of your edit was very POV-pushy as it is clear that no consensus has been reached on the RFRCT.

"Deleting every single statement that doesn't have an inline cite with solid WP:WEIGHT" is a perfectly valid way to conduct a rewrite for an article such as this. is actually completely inappropriate. Add citation needed tags in this case, remove information only if it is unnecessary for the reader's understanding or if it is believed that the information may be false and a quick search doesn't back it up. Adding citations to unsourced material is actually a far better way to edit an article. InsertCleverPhraseHere ^{InsertTalkHere} 08:46, 8 February 2016 (UTC)

Have you read the Wikipedia policies you're citing? Rolf H Nelson (talk) 01:43, 9 February 2016 (UTC)

are you saying that a the majority of reliable sources on the subject are saying that it is definitely experimental error? Because from what I've seen that is not the case. they are still looking for an explanation for the anomalous results, error or otherwise. InsertCleverPhraseHere ^{InsertTalkHere} 22:02, 9 February 2016 (UTC)

No, but I would say that almost all physicists, if asked "are you confident that this will turn out to be experimental error?" would review the publications and say "Yes." In addition, there are WP:RS saying the theory is nonsense (Egan, Baez, and Popular Mechanics) but no WP:RS saying "the theory probably is not nonsense." Rolf H Nelson (talk) 04:54, 12 February 2016 (UTC)

True, there are a few vocal detractors such as Baez ... It might be what you say is true, but I can't seem to find a source that says so. It seems that most of the coverage is basically saying to be sceptical and not to believe reports of 'confirmation' because nasa didn't 'confirm' anything. But does this represent consensus that the results "are very likely to be due to experimental error"? The Popular mechanics articles basically say to wait and see, both of them. Even after the initial wave of "be sceptical, this has not been confirmed", there were other reports that nasa still hasn't found the causes of the anomolous readings [2]. Personally this seems to me to represent a consensus that 'more research is needed' to understand what is going on and that scepticism is advised, which is how the article is structured at the moment. However, I'm happy to support your change if you can find a source that agrees that the majority of the community believes that error is the cause. InsertCleverPhraseHere ^{InsertTalkHere} 07:13, 12 February 2016 (UTC)

If that's your position, I don't understand why you're not in agreement to remove "peer-reviewed journals" then from the lede, unless you have a source that agrees that "it has been published in peer-reviewed journals" (plural)? Because, you know, it hasn't. Rolf H Nelson (talk) 20:32, 13 February 2016 (UTC)

how about something along the lines of "...and has been published in 'xxxx', a Chinese peer reviewed journal." Still awkward, but more accurate I suppose. InsertCleverPhraseHere ^{InsertTalkHere} 00:51, 14 February 2016 (UTC)

That's an improvement. I want to come back to the lede after the rest of the article is fixed, since the lede should reflect the article. Rolf H Nelson (talk) 01:43, 14 February 2016 (UTC)

I agree that the article is currently badly formatted. It reads in a very disjoined manner with, for example, multiple sections on the emdrive and cannae drive, I've done a bit of moving stuff around, and expect I'll have a bit more time to do so than previously, (I just submitted my masters thesis last week, so I've been kind of busy). InsertCleverPhraseHere ^{InsertTalkHere} 04:05, 15 February 2016 (UTC)

Additionally, could you please explain the reason you think the article is NPOV? Without a reason specified I find it difficult to support the NPOV tag. InsertCleverPhraseHere ^{InsertTalkHere} 08:50, 8 February 2016 (UTC)

One initial reason for believing the article is NPOV is that this I disagree with the reversion [3]. I believe the scientific consensus is that the anomalous results are extremely likely to be experimental error. In addition, I believe that all weakly-cited information should be removed; an initial removal of things that are obviously weakly cited and controversial would be a helpful first step. Rolf H Nelson (talk) 01:43, 9 February 2016 (UTC)

We have been through this before you know... have a read through previous discussions. If the consensus was that the results were experimental error there would be 1: an explanation of how the errors came about (there so far is not), and 2: there would not be a significant number of high profile researchers currently investigating the phenomenon to understand how the results came about. Now I'm not saying that the thing works, far from it, but no one is sure what is causing the thrust readings (error or otherwise), until someone confirms what has been causing the errors/trust there is no 'consensus' whatsoever. Scientists don't just guess, neither do we. InsertCleverPhraseHere ^{InsertTalkHere} 10:15, 9 February 2016 (UTC)

"Significant number"... the not significant excess seen by two LHC experiments recently triggered ~200 theory preprints (and I'm sure many of them will become peer-reviewed papers in the future) from even more authors in less than two months. It got far more attention in the scientific community than this topic, although the experimental claims are much weaker and the implication of an actual result would be much weaker as well (a new elementary particle vs. a complete breakdown of a fundamental principle of all modern theories in physics). So (2) is not the case. (1) is not necessary. If I claim that I measured the rotation of Earth and the result was zero, everyone would agree that I made a mistake - up to the point that most scientists wouldn't even bother to try to spot the errors. That is the situation we have here. It is a bit better than a claim from a single person, but the overwhelming expectation is a measurement error - probably even by those investigating the experiments done by others. --mfb (talk) 16:02, 9 February 2016 (UTC)

comparing the LHC to fringe science is more than a little disingenuous. While what you said might be true, the sources on the subject are still saying "we t aren't sure how these results came about". They aren't saying "this is obviously bullshit and we are just sitting around wasting grant money". InsertCleverPhraseHere ^{InsertTalkHere} 21:57, 9 February 2016 (UTC)

So you agree that this is fringe science? Fine, then what is the point of this discussion. If the majority of physicists wouldn't be convinced of measurement errors there it would not be fringe. "We are not sure how" does not exclude "but it is probably a measurement error somewhere" - they just don't know where exactly. --mfb (talk) 10:54, 10 February 2016 (UTC)

Source it and cite it then. InsertCleverPhraseHere ^{InsertTalkHere} 12:00, 10 February 2016 (UTC)

You are the one who wants to keep unsourced claims in the article. You don't need sources for things that are not in the article. --mfb (talk) 14:30, 10 February 2016 (UTC)

Wait... when did I say that??? I simply said that the best way to deal with unsourced material is to look for a source before deleting, rather than deleting without bothering to look, as Rolf H Nelson recommended. If material can't be backed up then it should obviously be deleted. Also, by saying "source it and cite it" I meant if you want to say that "the consensus is that the results are very likely the result of experimental error" you can do that just fine it you can find a citation for it. InsertCleverPhraseHere ^{InsertTalkHere} 01:56, 11 February 2016 (UTC)

I will note in passing that Insertcleverphrasehere was banned last year from the topic of "cold fusion, broadly construed" under the ArbCom's discretionary sanctions relating to pseudoscience: ban discussion. He was banned for a pattern of tendentious timewasting on talk pages, devoted to credulous over-weighting of fringe sources and opinions. He shouldl take care not to repeat the same type of conduct. TenOfAllTrades(talk) 01:21, 10 February 2016 (UTC)

And the topic ban expires in a week... --mfb (talk) 10:54, 10 February 2016 (UTC)

Yeah, I don't look forward to the attitude above returning to the cold fusion area. TenOfAllTrades(talk) 15:56, 10 February 2016 (UTC)

InsertCleverPhraseHere: [4] "section does not belong in the 'history' section as it is simply a collection of claims by the inventor in his patent, belongs in the 'emdirve' section instead". I was totally with you until the comma. If you're going to illogically block its removal, I think the thing to do is to pause my edits and see if someone steps forward within the next month to rewrite. If they don't maybe I'll go ahead and rewrite it myself, using appropriate dispute resolution methods if it's tendetiously blocked. Rolf H Nelson (talk) 03:46, 16 February 2016 (UTC)

Well I'm not sure exactly what I'm supposedly 'blocking' or are you just parroting Tenofalltrades? I think it is clear that the section in question is much better suited for the emdrive section than the history section, as it is basically a collection of claims about how it works by the emdrive inventor. I'm having a little difficulty with the fact that nobody here seems to be able to assume good faith. Honestly do whatever the hell you want, I'm done editing this article if this is the kind of thanks I get. InsertCleverPhraseHere ^{InsertTalkHere} 04:31, 16 February 2016 (UTC)

I've removed the tag since I'm satisfied with the current version. Rolf H Nelson (talk) 04:24, 19 February 2016 (UTC)

Removed 'too technical' warning

I removed the 'too technical' warning from the top of the page, as the page is almost unrecognisable from the July 10th version when the warning was last updated. See the following diffs that show the changes between that version and the current one [5]. If anyone thinks the article is still too technical for most readers, please specify here which sections require cleanup prior to reinstating the warning box. Thanks. InsertCleverPhraseHere ^{InsertTalkHere} 03:29, 23 January 2016 (UTC)

Requested move 8 November 2015

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: not moved. There is a consensus against renaming this article "Asymmetric cavity drive". However, some participants were happy with the nominator's alternate title, "Radio frequency resonant cavity thruster", and I would recommend starting a new RM to see if there is a consensus to move to that title. Sorry if that feels overly bureaucratic, but in my experience starting a new discussion for the variant is often the best way to get a clear outcome that isn't muddied by the previous proposed title. Jenks24 (talk) 06:35, 16 November 2015 (UTC)

RF resonant cavity thruster → ? – My proposal is to rename the article Asymmetric cavity drive or Radio frequency resonant cavity thruster. Rationale for Asymmetric cavity drive can be found in section above by Tokamac. Rationale for Radio frequency rather than RF is that it makes more sense to the reader. Brian Everlasting (talk) 02:59, 8 November 2015 (UTC)

While Asymmetric cavity drive might be more correct, thats not what it is referred to in the references, where it is commonly referred to as either one of the 'brand names' or 'Radio frequency resonant cavity thruster', or 'RF resonant cavity thruster' (see WP:UCRN).

The issue of using an acronym should be considered with regard to WP:ACRONYMTITLE. the argument here is somewhat ambiguous due to the fact that this article is already too complicated for laymen to understand (which would suggest support). While the term RF is used overwhelmingly as an acronym for radio frequency (no support), non-experts may not make that connection, and there are several other common disambiguations (support). Yet none of these would fit the subject of the article very well (i.e. Russian Federation). It is however, known by both names (referred to both in the article's sources). This means we should have two pages that both link to the same page, at the very least there needs to be the creation of a page Radio frequency resonant cavity thruster that redirects to this one.

I've already updated the first line of the lede to spell out the acronym, and link to it, which helps solve any disambiguation immediately, however, I don't really have much of an opinion on whether RF resonant cavity thruster or Radio frequency resonant cavity thruster is more appropriate for the title, except that as per policy both pages should exist and one should link to the other. As this is rather clear policy from WP:ACRONYMTITLE, I'll just create that article and link it to this one now for the meantime. InsertCleverPhraseHere ^{InsertTalkHere} 04:00, 8 November 2015 (UTC)

Oppose "Asymmetric Cavity Drive" --- No Opinion "Radio frequency resonant cavity thruster". InsertCleverPhraseHere ^{InsertTalkHere} 11:12, 8 November 2015 (UTC)
STRONG OPPOSE "Asymmetric Cavity Drive" That has absolutely no value, since many things uses asymmetric cavities. -- 70.51.44.60 (talk) 05:30, 8 November 2015 (UTC)
Oppose "Asymmetric Cavity Drive" But I will reconsider if someone can provide an example of a symmetric propulsion system. Spiel496 (talk) 05:06, 10 November 2015 (UTC)

even if these existed it would be inappropriate as per (WP:COMMONNAME). InsertCleverPhraseHere ^{InsertTalkHere} 07:34, 10 November 2015 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Pseudophysics link, and proposed major rewrite by KRAPENHOEFFER

I see that KRAPENHOEFFER has linked this article to Pseudophysics, and proposes a major rewrite.

I agree with the assessment of this article as Pseudophysics, of the 4 reasons for considering an article as pseudophysics on that page, the second reason stated on the article in question seems appropriate. I'm disappointed that you didn't bring up the need for a distinction between PS and QS in your recent post on the Fringe noticeboard, as it was, all people said was that it was fringe, which is obvious, it was already listed as a fringe article. I don't agree that this subject is unambiguously pseudoscience, as it seems somewhere between that and questionable science.

Be careful of pushing the 'it's impossible' viewpoint too strongly, as you seem to have a very strong viewpoint on this subject. Please maintain NPOV and realise that as a fringe article, while we should make it clear that while wikipedia supports the mainstream viewpoint, there must be room to discuss and present fringe viewpoints fully. I also maintain that at least one of the fringe theories discussed in the article claims not to break conservation of momentum. This theory isn't universally accepted of course, but it does leave you with a little less room to stand on in terms of claiming that it definitely breaks the law of conservation. Please propose and discuss any major Edit Proposals on the talk page before going ahead with them. InsertCleverPhraseHere ^{InsertTalkHere} 20:14, 19 October 2015 (UTC)

@Krapenhoeffer and Insertcleverphrasehere: Should this article be removed from Category:Pseudophysics, then? Jarble (talk) 21:34, 6 November 2015 (UTC)

@Jarble and Insertcleverphrasehere: There are no reliable sources which indicate that the hypothesis "RF resonant cavity thrusters actually produce thrust" is plausible. Anyone claiming a violation of one of the fundamental laws of physics barring overwhelming evidence should be treated as pseudoscience. As for the one claim that "quantum vacuum virtual plasma", it appears that all the actual physicists asked about such a thing say there is no such thing as "quantum vacuum virtual plasma." Hence, I believe the label of pseudoscience easily fits. --KRAPENHOEFFER! TALK 23:25, 6 November 2015 (UTC)

Category:Pseudophysics is fine, for this reason (from the pseudophysics page):

They have been argued to be pseudophysics by some members of the mainstream physics community or other notable people (but others may disagree).

InsertCleverPhraseHere ^{InsertTalkHere} 02:37, 7 November 2015 (UTC)

EmDrive -> RF resonant cavity thruster -> Asymmetric cavity drive?

1. It is worrisome for now that the main features of the EmDrive: its asymmetry and the fact the asymmetric cavity is specifically shaped as a frustum for most test articles, are not explicated in the main section of the article but appear later in the text as almost side notes. This should be addressed. The asymmetry is so important that the title of the article should perhaps be asymmetric cavity thruster.

2. As already explained elsewhere, 'cavities are resonant in principle, rendering the name "resonant cavity" tautologous'.

3. RF should also be dropped, as RF is generally said to be comprised between 1 and 3 GHz, but the EmDrive could theoretically scale to work below and above those frequencies.

4. Also already explained elsewhere: "drive" is a little better than "thruster" since we're still not sure it's pushing rather than pulling.

5. For the above reasons the name of the article should perhaps be asymmetric cavity drive — Tokamac (talk) 20:18, 22 July 2015 (UTC)

I think we're probably OK with the current title for now. All of the existing proposals for these are RF, and not all cavities are as resonant as others -- these are explcitly engineered to be resonant. Hopefully within the next few years, we will discover whether these devices are either pseudoscience, or scientific discoveries of the first rank: they must either be one or the other, since if they work in the manner attributed to them (as opposed, for example, to phenomena such as asymmetric heating or outgassing), their action must necessarily involve new physics: either a new momentum-carrying mechanism, or the collapse of the principle of conservation of momentum. -- The Anome (talk) 14:02, 26 July 2015 (UTC)

The title is fine the way it is.

1. All propulsion devices are asymmetric.

2. Cavity is an extremely ambiguous term by itself. It can even refer to tooth decay.

3. RF commonly refers to frequencies outside the 1 to 3 GHz range.

4. Pushing and pulling are functionally the same, and -- spoiler alert -- this thing does neither.

Spiel496 (talk) 23:29, 27 July 2015 (UTC)

I agree the article should be renamed Asymmetric cavity drive. I will start a formal move proposal. All propulsion devices are NOT necessarily asymmetric. Brian Everlasting (talk) 02:47, 8 November 2015 (UTC)

It's customary, when making a "not necessarily" argument, to follow up with a counterexample. The counterexample would really drive your point home. As it is, we're just left trying to imagine what symmetric propulsion system you have in mind. Spiel496 (talk) 04:58, 10 November 2015 (UTC)

Lede is confusing

A while back, I decided to be bold, and re-wrote the lede to use stronger language to reflect the scientific consensus that this thing doesn't work. I see that it has been changed back to the weaker language. My proposal is to reword "Their design principles seem to be not scientific, because they violate the fundamental law of momentum conservation." in the lede to the more accurate "Their design principles are rejected by mainstream science, because they violate the fundamental law of momentum conservation."

Without reliable sources indicating otherwise, failing to include the stronger language gives WP:UNDUE weight to a fringe position. If there aren't any objections, I will make the edit myself in 24 hours. --KRAPENHOEFFER! TALK 20:56, 15 October 2015 (UTC)

The issue that I have is that 'rejected by mainstream science' is too strong a term, as ongoing experiments at NASA indicate that it hasn't been wholly rejected. I agree that the sentence you singled out is badly worded however and would support a rewrite, but not to a definitive 'rejected by mainstream science'. Perhaps changed to 'Rejected by the majority of mainstream scientists' InsertCleverPhraseHere ^{InsertTalkHere} 00:16, 16 October 2015 (UTC)

It flat out violates the conservation of momentum, and there is not a single reliable source which indicates that this is physically possible. Not a single finding of "thrust" has even been submitted to peer review. Unless that changes, the view that the device produces thrust is a fringe view, and by not making that clear via strong/harsh language serves a disservice to the readers and our policies. --KRAPENHOEFFER! TALK 15:10, 16 October 2015 (UTC)

Flat out lying and saying that all of the mainstream scientific community has rejected the device in order to promote harsh language is a little dishonest in my opinion, given that some very distinguished scientists at NASA are ongoing in their research into anomalous thrust. Like i said, use harsh language but don't use absolutes that aren't true. EDIT: you also say that it hasn't been published in peer review but the lede of this article contradicts you. InsertCleverPhraseHere ^{InsertTalkHere} 07:07, 17 October 2015 (UTC)

Eagleworks is a hobby pet project that NASA allows to use their facilities when nobody else is. The elephant in the room remains that the devices is purported to operate via a mechanism which is in violation of the laws of nature. The RS are clear: it is impossible for the device to actually produce thrust. The studies published in China do not qualify as RS in this scenario, simply because of the impossibility of the device functioning as described. To claim that the EM Drive produces thrust is to claim that one of the fundamental bedrocks of science is false: there must be overwhelming evidence before the encyclopedia should even entertain such a claim. --KRAPENHOEFFER! TALK 01:06, 18 October 2015 (UTC)

I don't know where you get the idea that I'm claiming it produces thrust... have you read what I proposed? It seems you just want to argue the point that it is impossible, and I'm not interested in having such an argument. That being said, your argument essentially boils down to "it's impossible so its impossible", which is not how science works. What you should have said is: "There is no possible way that anyone can explain how it works within the standard model, therefore unless the standard model is wrong or incomplete (evidence to prove such a thing would have to be extraordinary), it cannot produce thrust". I'll note that you didn't raise any objections to my suggested wording below, so I'll change the sentence in the lede to that. InsertCleverPhraseHere ^{InsertTalkHere} 06:31, 18 October 2015 (UTC)

It is overwhelmingly stated in the literature that momentum is conserved always and everywhere. The proposed mechanism of action for this device violates the conservation of momentum. As a result, any appearance of entertaining the notion that the device actually produces thrust using the encyclopedia's voice gives undue weight to a WP:FRINGE idea. And given the fundamental importance of the law of conservation of momentum in physics, the voice of the encyclopedia should be clear that the device does not produce thrust. Frankly, were it not for the discussion of the topic in many pop-science and non-specialist news outlets, this article would not be notable and would have been deleted long ago. --KRAPENHOEFFER! TALK 07:41, 18 October 2015 (UTC)

I agree that "Their design principles seem to be not scientific" is very weasely. I would support a change to: "Their design principles are not supported by prevailing scientific theories, and they apparently violate the law of conservation of momentum" InsertCleverPhraseHere ^{InsertTalkHere} 07:21, 17 October 2015 (UTC)

It's not just a "prevailing scientific theory"; the scientific consensus is clear: violating the law of conservation of momentum is impossible. Given the guidance at WP:FRINGE/PS, we should not make any attempt at denying this basic fact of nature. --KRAPENHOEFFER! TALK 07:50, 18 October 2015 (UTC)

Prevailing theories represent the scientific consensus. Saying prevailing theories is to separate the fringe theories of operation described in the article (by proponents) from those of the scientific mainstream. There are several theories presented in the article for how the device 'might' work within the framework of the standard model, none of these are prevailing, none of them are accepted by even a significant percentage of scientists knowledgeable on the subject of drive technology. The distinction should therefore be made. InsertCleverPhraseHere ^{InsertTalkHere} 08:51, 18 October 2015 (UTC)

If you want to argue whether this subject is Pseudoscience or Questionable Science as per WP:FRINGE/PS you'll have to bring that up and get the article declared as pseudoscience, as of now, given the contents of this talk page and the way the current article is written, it seems to be considered Questionable Science, and therefore the current structure of the lede seems appropriate. InsertCleverPhraseHere ^{InsertTalkHere} 08:56, 18 October 2015 (UTC)

I have brought this article up at the Fringe Science noticeboard. --KRAPENHOEFFER! TALK 09:12, 18 October 2015 (UTC)

Sounds like a good idea. A distinction between PS and QS would be useful for further editing, and to establish tone in the article. It is probably somewhere in the middle, but those guys on the noticeboard can probably figure out what to do. InsertCleverPhraseHere ^{InsertTalkHere} 09:46, 18 October 2015 (UTC)

Consensus there is stating that this appears to be fringe idea. My other complaint, is that the sentence in the lede we've been having a disagreement about does cite a source, an article in Ars Technica, which uses very strong language in its assessment of the device. I suppose my greater problem with this isn't really the lede, but the article in general, which lacks reliable engineering/scientific sources. It may be time for a re-write. --KRAPENHOEFFER! TALK 17:34, 19 October 2015 (UTC)

not designed to produce thrust

This line in the lede:

A small thrust has also been observed in devices deliberately built to not produce thrust.

is disingenuous at worst, misleading to readers at best. The test in question was a control, and was used to determine if the Cannae drive creators' theory of radial slots being necessary was correct. it wants 'designed not to produce thrust' it was 'designed to test if radial slots are necessary for thrust production'. In science you might design something so that under a certain persons theory (if correct) it would not produce thrust, but you aren't making a device to specifically not produce thrust, you are doing it to test that theory. This test was a SUCCESS in testing the canna drive radial slot theory, (disproving it in favour of the competing theory that radial slots were not necessary). When this is taken into context, the line that has been inserted into the lede is very misleading, and instead suggests that there was some error in measurement, or that thrust measurements were badly made. Im reverting the edit again. InsertCleverPhraseHere ^{InsertTalkHere} 00:27, 14 October 2015 (UTC)

changed to:

A small thrust was also observed in a null test with a device lacking radial slots, indicating that the slots are not necessary for anomalous thrust production.

This both indicates that it was a null test, and makes clear what was accomplished by said null test. InsertCleverPhraseHere ^{InsertTalkHere}

I modified the description to make clear what the purpose of the slots was. It's not just a random useless feature. --mfb (talk) 11:16, 14 October 2015 (UTC)

yep I like yours better... its also shorter which is good. InsertCleverPhraseHere ^{InsertTalkHere} 00:04, 15 October 2015 (UTC)

Notes On Edit Of The History Section

I added quiet a lot to the history section which seemed to be missing a context for general public readers. Isaac Newton as reinterpreted after General Relativity was presented as a way to show that the RF resonant cavity thrusters are attempting to alter a perception that has survived several hundred years of scrutiny.

The intervening history was discussed to show that there are long standing theories and proofs about how thrust can be generated without violating conservation of momentum.

Some other writer has removed one sentence about gravity waves about which much is researched and published, but does not have a consensus and is not essential for the purpose of history.

I deleted one other sentence about interference patterns canceling Poynting vectors found objectional to one of the editors as too technical to convey a meaning.

All of the other editors are welcome to improve on the history section, hopefully to show there is a robust science of mechanics since Galileo and dynamics since Newton that Einstein didn't overturn, and many theories about thrust force have been created and tested since then without violating a long standing principle.

I'm not a fan of RF resonant cavity thrusters, but feel every topic gets a fair chance, and there are new things waiting to be discovered and published that haven't found a place yet in Wikipedia guiding principles. In that regard I have left out some of the recent history that is most contentious and is best contained in private correspondence.

As always thanks to the people who helped so far. Astrojed (talk) 17:39, 15 September 2015 (UTC)

Adapt the EM drive to drive a electrical generator

This page is not a forum for general discussion about EmDrive/Archive 4. Any such comments may be removed or refactored. Please limit discussion to improvement of this page. You may wish to ask factual questions about EmDrive/Archive 4 at the Reference desk.

Using numbers representing the thrust of the EM generator shown here in Wikipedia and using the aid of superconductivity, the drive could be used on the perimeter of a wheel which drives an electrical generator which will then give vast amounts of power above what is needed to maintain the thrust. This will use one moving part plus electronics and cooling.

Development for domestic power generation will give the world a new standard of living with clean air and little need for energy from coal and petroleum.

Richard Smith — Preceding unsigned comment added by Power102 (talk • contribs) 20:52, 4 September 2014 (UTC)

Okay, this may be original research, but I think Power102 (Richard Smith) makes an interesting point: According to the article, the proposed superconducting version would produce 30 kN/kWatt. If you supply 1 watt and use the resulting 30N of force to push something at 1 m/s, the EmDrive will be doing 30 N * 1 m/s = 30 watts of mechanical work. Use some of that to generate 1 watt of electricity, and the rest is free, right?

Where are pulling the 1 m/s velocity out of? That is not mentioned in the article. So far as I can see, these test drives travel at zero meters per second. That velocity gives us a rather different number of watts. Rwflammang (talk) 15:42, 17 May 2015 (UTC)

Well, the whole point of a thruster is that some day it will travel at a non-zero speed. My point was, if it does continue to generate thrust at 1 m/s, then -- as described in the article -- it will be generating free energy. I picked 1 m/s arbitrarily. When something is bogus, it will be bogus at many speeds. The article does not say "the thrust decreases as the speed increases". That restriction would solve the energy-conservation problem, while introducing another. Spiel496 (talk) 02:17, 19 May 2015 (UTC)

The power input for the Emdrive is electricity. It cannot be made into a perpetual motion machine because the output force could not produce enough electrical energy for self perpetuation. It's best use presently appears to be as a better propulsion system than ion drive since it does not require fuel; it can generate electricity for itself through solar cells. It also seems to be more efficient than a solar sail for acceleration. Of course all experiments so far have been small-scaled and tentative. Its biggest potential for the next century might be as a much more efficient lift-to-orbit system/ engine, and for solar system touring crafts, heavy freighters, and landing craft. This would involve large Rocket sized devices but with very small acceleration, noise, and G forces. Maybe a perfect low-cost passenger craft to the moon, mars, Jupiter's moons, and the asteroid belt, mining etc.. Much larger prototypes need to be built involving superconductive, and supercooled electrical and internal components, to show the proof-of-concept for multi-flight heavy-lift devices -- possibly at production costs as low as large aircraft. It has also been mentioned that time efficiency to get started would require rocket fuel once orbital heights have been reached. Forrestnoble (talk) 04:51, 10 September 2014 (UTC)

Forrestnoble, don't hijack the thread. If you want to talk about Jupiter's moons or freighters, start a new section. This section is addressing the question of whether an EmDrive can drive an electrical generator. Spiel496 (talk) 18:14, 10 September 2014 (UTC)

If people want to OR speculate about unsourced possibilities there are other forums for that kind of thing. This: ...addressing the question of whether an EmDrive can drive an electrical generator is off-topic for this talk page. It has nothing to do with the Wikipedia article. This whole thread has been purely speculative, so nothing can have been "hijacked".__ E L A Q U E A T E 18:57, 10 September 2014 (UTC)

Good point. However, this can be about the article. My "30 N * 1 m/s = 30 watts" is only a very tiny bit of OR. With it, the article text leads directly to a perpetual motion machine. So there's probably something wrong or missing in the article. Or I and Power102 missed something, and here is the perfect place to set us straight. Spiel496 (talk) 21:24, 10 September 2014 (UTC)

The article doesn't state how much electricity could be produced from that force (with or without the aid of superconductivity). Guess what, it's going to be less than what can be produced from what comes out of the engine. If we can't find where anyone's actually proposing a perpetual motion machine, it's pointless to concoct one here ourselves. This isn't about the article at this point and you're assuming things not directly found in the sources. __ E L A Q U E A T E 22:08, 10 September 2014 (UTC)

Here's your error, the theoretical projection actually made in that source said that 1 watt might produce 16 millinewtons of thrust. In your comment you have it producing a spectacular 30 newtons. I'm sure you see the problem. This is a pointless thread. __ E L A Q U E A T E 22:23, 10 September 2014 (UTC)

I didn't make up the number 30 N/W. The article says "30 kN/kW". The source says "30,000 newtons per kilowatt". Anyway there's no threshold here. Name a thrust and an electrical power, and I will name a velocity at which the mechanical work exceeds that power. Spiel496 (talk) 02:16, 11 September 2014 (UTC)

There is a threshold. It's 1/299792458 N/W, the efficiency of a photon drive. — DanielLC 08:01, 1 May 2015 (UTC)

And adding speculative and currently unavailable superconducting engines into the mix still means you will never be producing more power than what you put in. Superconduction has a natural limit of how efficient it can make the conduction of energy. __ E L A Q U E A T E 22:47, 10 September 2014 (UTC)

I'm not saying it will actually produce more power than is put in. I'm saying, the way EmDrive is described in the article implies that result. Spiel496 (talk) 02:16, 11 September 2014 (UTC)

I think you're making a funny jump from a quoted x Newtons of thrust to an assumption of how much work is being talked about here. A Newton isn't the same thing as a Newton meter per second. Airplanes create massive amounts of thrust, but you can't stick an electric generator on their nose to produce more energy than they need to move in the first place. __ E L A Q U E A T E 12:04, 11 September 2014 (UTC)

I assumed a velocity of 1 m/s and used the formula: Power = Force x velocity = 30N * 1m/s = 30 watts. The "funny jump" you talk about is high school physics. Spiel496 (talk) 17:11, 11 September 2014 (UTC)

Umm, good for you? That's a good way to determine the rate of work that happens when you move, say, a 30kg satellite, and you assume that particular velocity of one m/s. (That assumption is wholly your own and what makes your jump from plain n to n*m/s an arbitrary one, the original source does not mention the time or distance only an abstracted thrust under completely unlikely conditions). But back to your satellite; it would then have about 15 watts of kinetic energy in best conditions. If the electric generator is within the frame of reference of the EM generator, then it might as well be nothing. If it's not in the frame of reference, how are you suggesting we'd transfer a magical watt back to the original system? If you have to add additional perpetual motion concepts to back up your first one, then this is just a talk page fantasy, not a claim by anyone else. I think ultimately this is all silly OR speculation, trying to force an impossible scenario that goes beyond any of the actual claims made in source. This is not the way to make a better Wikipedia article.__ E L A Q U E A T E 22:24, 11 September 2014 (UTC)

I see no evidence that you read what I wrote. Spiel496 (talk) 22:33, 11 September 2014 (UTC)

If you want a source, I suggest the Atomic Rockets page for Reactionless Drives subsection Power Requirements. — DanielLC 08:01, 1 May 2015 (UTC)

Thanks. That page does a good job of describing my concern about power-->thrust. It doesn't conserve energy. I notice the author also picks an arbitrary speed to make his point. See? When you're proving something bogus, you get to choose an arbitrary set of realistic conditions that lead to a contradiction. Spiel496 (talk) 02:08, 19 May 2015 (UTC)

In the FAQ reference [6] I found a mention of the conservation of energy in regards to the specific thrust figure (N/W): "because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper)." So quoting a number like 30kN/kW is somewhat misleading, because the thrust "rapidly decreases" if the drive is used for its intended purpose. So, while this clears up the confusion about energy conservation (in my mind, anyway) I still don't know how the article should read. Spiel496 (talk) 16:31, 9 July 2015 (UTC)

In that case, it violates relativity. It's thrust depends on how fast its going, which requires having a preferred reference frame. — DanielLC 17:48, 17 October 2015 (UTC)

Intro, and claims

We really should avoid presenting the working of these devices as implicit fact in the intro. Whether they work as claimed or not, their operation is still being investigated, and the jury is still out. No-one (except perhaps their inventors) would be more excited if they work than me (new physics! flying cars! etc.!) but we need to be very cautious in our reporting. The null hypothesis must still be that they don't work, until iron-clad experimental evidence is available to answer the question one way or another. -- The Anome (talk) 10:05, 30 July 2015 (UTC)

Too right. Fixed! The result changed a lot of the format and layout of the first dozen paragraphs; please help clean up and make the result more readable. I tried to be accurate without prejudicing the reader for or against any particular study or result. To me the remarkable points are that a) inventors themselves have never built effective versions of their designs; b) five years later, noone has even attempted to replicate the (reportedly enormously successful) Xi'an experiment; and c) a few scientists known for other work have attempted the experiment; though many many fewer than say with cold fusion [something theoretically possible under existing physics but without known realization path].

A comparison to the history of cold fusion might be appropriate if someone can work it in. – SJ + 18:57, 30 July 2015 (UTC)

What is meant by the phrase in the Intro "...building on existing designs for spacecraft propulsion"? It comes off sounding like it's a modification of an ion drive or other thruster, which I doubt was the intended meaning. Spiel496 (talk) 01:39, 31 July 2015 (UTC)

I've now changed the intro paragraph to read like this:

RF resonant cavity thrusters are a proposed new type of electromagnetic thruster. Unlike conventional electric thrusters, they not designed to use any form of reaction mass, nor to emit any directional radiation. They have not as yet been proven to work as claimed, nor are their design principles accepted by mainstream science, which predicts that they should be unable to produce thrust. However, small thrust effects have been measured in some experiments using prototype devices, and research is in progress to see if these effects are caused by some as yet unknown phenomenon, or artifacts due to experimental error.

I hope this combines necessary skepticism with fairness to those involved. The experiments do show measurable effects, theory predicts that they must be experimental error, and experience shows that in cases like this theory is almost certainly right -- but the preliminary results are intriguing enough that it's worth keeping on researching, just in case.

And, yes, cold fusion does come to mind as a very similar situation: impossible in theory, tantalizing experimental results suggesting theory might be wrong (but with a small effect size that is hard to measure reproduceably), massively exciting consequences if real. Even though I expect the story is likely to have a similar ending to the cold fusion work a decade or so ago, I think this is currently a valid example of fringe physics, and I've added this article to Category:Fringe physics to reflect that. -- The Anome (talk) 10:59, 31 July 2015 (UTC)

Also: I believe most of Quantum vacuum thruster should really be split off and merged into this article, as it overlaps this topic almost completely. -- The Anome (talk) 11:19, 31 July 2015 (UTC)

On Quantum vacuum thruster, I think it belongs as a separate article. It goes into several theoretical ideas, many with no suggestion of how they can be proved experimentally. One of the many suggestions for the RF thruster is that it is a quantum vacuum thruster. That's not enough reason to merge the theoretical idea into this article. Even if it was proved it worked that way, then it would just confirm one example of a quantum vacuum thruster. It wouldn't show that the other types of quantum vacuum thruste proposed are impossible.

But it could as easily, more likely many would say, be shown to be experimental error, or have another explanation such as accelerating WIMPs or warping of space time - and in that case disproving that this is a real device would still leave the theoretical idea of a quantum vacuum thruster intact, because it is pure theory not grounded in any experiments.

The two articles overlap which is permitted, but each has a substantial amount of its own material. See also Talk:Quantum_vacuum_thruster#Revisiting_the_merge_proposal Robert Walker (talk) 14:47, 4 August 2015 (UTC)

Listed as violating conservation of momentum

The table at the top says "violates conservation of momentum" as if that was an established fact. It should say something like "Claimed by some critics to violate conservation of momentum", or "apparently violates conservation of momentum". Until we know how it works, if it does work, you can't say it violates COM.

For now all we have is the experimental data, which suggests a thrust of micronewtons, in a stationary apparatus (we don't have any kind of a spaceship drive yet).

This does appear to violate COM - but then - new physics can do that - as happened historically with beta decay before the discovery of the neutrino.

The inventors of the drive and the experimenters - neither of them say that it is a reactionless drive. And the io9 article you link to refers to an opinion of a single scientist. That is not the same as a consensus, and there seems to be a diversity of views here amongst scientists.

The theory section also should probably be filled out with more theories. For instance in the Eagleworks presentation available on video (if that is an acceptable source for the article) they gave several ideas of how it might work. Including for instance, the idea of a mild space warp (their most "out there" idea which got a lot of publicity) which would work similarly to the Alcubierre drive - and of some new kind of very weakly interacting particle to carry the momentum - and talked about ways they could test for these possibilities with experiments.

Robert Walker (talk) 14:06, 1 August 2015 (UTC)

Other articles on fringe topics suffer these same problems (see the Steorn free energy device, for example). The proponents of bogus technology tend to make unclear explanations. Frankly, if they were more clear, it would be easier to identify how they screwed up their theory. So, Wikipedia editors are left to fill in the gaps as best we can. Yes, Shawyer says the drive doesn't violate momentum conservation, but he contradicts this statement by saying it should work without matter or energy leaving the system. And his FAQ says the thrust decreases with velocity, but he doesn't say what that velocity is relative to, so we're left to guess at what he means. If the experimental results were definitive, then it would be appropriate to include some speculation about warp fields and unknown particles, but under the current circumstances it benefits no one to expand on the theory. Spiel496 (talk) 20:56, 3 August 2015 (UTC)

Yes, I noticed the thrust decreasing with velocity bit. Shaywer seems to have derived this from the conservation of energy principle. However, as far as I can see, this now makes the behaviour of the system no longer invariant under different choices of inertial frame, breaking Galilean invariance, unlike systems which eject reaction mass, for which the conservation of energy rather neatly stays valid under changes of inertial frame, exactly because of the existence of the kinetic energy of the reaction mass. -- The Anome (talk) 11:24, 4 August 2015 (UTC)

I agree also, unless it is a velocity relative to some particular inertial frame, or something that locally approximates an inertial frame (e.g. at rest relative to the three degree background radiation). Or at least relative to something. Otherwise how does the system "know" to produce reduced delta v for the same energy input? If he specified an inertial frame to measure the velocity from it would make sense. Otherwise he would have to show somehow that it is something that is independent of your choice of inertial frame, and hard to see how that would work. Robert Walker (talk) 12:43, 4 August 2015 (UTC)

Yes that would be a good point if this was an article dedicated to his theory only - if the title was "Roger Shawyer's theory of the RF resonant cavity thruster" - then you could say that most experts say he has made a mistake in his theory. Indeed would probably be more accurate to say that it fails at an earlier stage - that they think his idea just wouldn't work at all because his calculations are invalid. If his calculations were valid, it wouldn't violate the conservation laws but hard to make sense of them.

But most experimenters don't subscribe to his views at all and don't think that can be the reason why it works. For instance, as I said, the Eagleworks team are exploring negative energy and warp fields and unknown particles. And other experimenters are at the stage of just measuring the effect without testing for any particular theory at all particularly.

So that's why I think it is inappropriate to say that the thruster itself violates conservation laws. It is experimental data obtained at a pre-theory stage, where any theories are regarded by the experimenters as highly preliminary and where the data comes first. And where for most researchers, the inventor's own idea of how his drive works are ignored. Though he invented the device he doesn't "own it" in the sense that his ideas of how it works have to be taken as the only possible explanation of how it works, if it works. Robert Walker (talk) 22:58, 3 August 2015 (UTC)

I better understand what you're saying now, thanks. I guess it depends a lot on what the scope of the article is. If we're talking about a class of RF-cavity drives, then it is somewhat ambiguous to say that "it" violates COM. Spiel496 (talk) 01:23, 4 August 2015 (UTC)

Thanks, yes that's what I'm saying exactly :). Robert Walker (talk) 01:31, 4 August 2015 (UTC)

Correct. It's possible -- just -- that the drives might work, but not in the way that their inventors' theories suggest, because some exotic new physical principle, yet to be discovered, is creating the thrust. This is something which can only be either detected or ruled out by experiment. But without some new physical phenomenon to balance things out, no current physical theories appear to suggest any way to create this sort of apparently reactionless thrust without violating known conservation laws. -- The Anome (talk) 11:35, 4 August 2015 (UTC)

Yes that seems to be true - but - if it is some exotic new physical principle or particles, then it would be new physics. If writing at the time that Dirac predicted the neutrino, would you mark all articles on beta decay with this flag, because they had no explanation with current physics and the only available explanation involved new physics not yet proved?

With the main contenders for new physics at present, apart from Roger Shawyer's ideas, and the ideas of a "virtual plasma", AFAIK:

New weakly interacting particles in some way accelerated by the device, picked up from the surroundings
Negative energy density inside the chamber like the Cassini effect leading to a mild warping of space - time

Both of those involve reasonable extrapolations from known physics, like Pauli's suggestion of the neutrino to balance the equations of conservation of energy and momentum in beta decay. The idea of the new weakly interacting particles probably require least by way of changes in our ideas of physics. Which is not to say it is either of these, but we have a reasonable range of theories that don't violate the conservation laws, so it is surely inappropriate to label an article about the device, rather than individual theories, as violating conservation of energy and momentum. Robert Walker (talk) 12:51, 4 August 2015 (UTC)

One suggestion, what about dividing up the theory section, and moving this block down there and using it to flag just the section on Roger Shawyer's theories? And then in that section, also give his own explanation of why he thinks it doesn't violate COM, and say why others find his explanation not convincing. And similarly label any other theories that most people think would violate COM / COE. Robert Walker (talk) 12:57, 4 August 2015 (UTC)

I think also that this should be changed, as in accurate

" particularly because there are no compelling explanations for the apparent violation of the law of conservation of momentum,[9] and claims of such a surprising result would need especially thorough efforts to rule out possible sources of error." (end of lede)

It is sourced to a single io9 article, which in turn does voice the opinion of a scientist - but one scientist saying something doesn't make it a consensus, and it is not even a peer reviewed paper but just an interview quote. The main problem is not the apparent violation of COM, you can say that of course, but when it goes on to say "claims of such a surprising result". That suggests that the experiments if they verified the effect would also prove a failure of conservation of momentum. Which is untrue. They wouldn't prove that, any more than the experiments on beta decay proved failure of COM / COE. Just prove an apparent violation which would lead physicists to scratch their heads and try to find a new physical theory or new particles to explain it. Only a perpetual motion machine, or an infinite energy source or similar would immediately prove a failure of COM / COE with no hope of rescuing the laws with new physics. Robert Walker (talk) 13:03, 4 August 2015 (UTC)

You don't need to work in terms of criticising any particular theory. According to all current scientific knowledge, anything which pushes in one direction must push something else in the other direction, or the law of conservation of momentum is broken. This is basic science, taught in all undergraduate science courses. These devices are not designed to emit either matter or directional radiation, and therefore there's, in theory, no "something" to be pushed against. So there are really only three choices: either the effect is experimental error, or there's a missing "something" being pushed against, or our knowledge of physical laws needs revising. -- The Anome (talk) 13:12, 4 August 2015 (UTC)

Yes exactly. If the intro said that, then I'm fine with it. And that's how most of the experimenters are treating the experiments - either it is experimental error, which we have to identify, or there is something else that balances up the momentum equations - or more radically that our knowledge of physical laws need revising (e.g. to permit negative energy / Alcubierre drive type effects). Nobody AFAIK is suggesting that the experiments will end up with scientists concluding that conservation of momentum is actually violated (rather than just apparently violated). Robert Walker (talk) 14:19, 4 August 2015 (UTC)

The point about a perpetual motion machine is that if you constructed one of those, it is an immediate and actual violation of COM and COE, not just an apparent one, which can't be explained by new physics so long as the end state is the same as the start state in all respects. If you haven't got a perpetual motion machine, if the end state differs from the start state, that leaves scope for new physics to explain it. In the case of the EM drive we have a net input of energy so with the experiments so far at least, the end state is not the same as the start state before the thrust so permitting new physics as an explanation. Robert Walker (talk) 14:25, 4 August 2015 (UTC)

BTW I'm author of an article on the EM drive which may be a useful source of citations. I'm not sure how many of my citations would pass muster as citations on wikipedia, e.g. can you cite the Eagleworks video?? Or forum posts by members of the Eagleworks team and other scientists? And some of it would surely count as original research also, and it is not peer reviewed, is just a news story, but it does have a few links that may be useful. Suggestion: The EM Drive Is Getting The Appropriate Level Of Attention From The Science Community Robert Walker (talk) 13:07, 4 August 2015 (UTC)

I've added one word, "otherwise", to the sentence in question, which changes its meaning subtly but significantly. I hope this addresses your main concern. -- The Anome (talk) 13:26, 4 August 2015 (UTC)

That's much better. Thanks! Though the citation backing up that sentence is also a low quality one, would be better to have something more than an io9 article reporting an interview with a single scientist to back it up. I'd add a "more citations needed" tag to that sentence as well. Probably you can find much better citations with a search, just saying that they do seem to be needed.

Is it possible to move the "violates conservation of momentum" block into the theories section? If you feel there aren't enough citations to mention the other theories in the article yet, at least putting it there would make it clear that it applies to his theory rather than to the device itself. Robert Walker (talk) 14:29, 4 August 2015 (UTC)

Why? The conservation of momentum issue is the crucial issue in the whole business, as it would be with any apparently resactionless drive, and really doesn't need a cite for anyone with basic physics knowledge. If you're looking for cites, the popular press is full of them, typically with the words "appears to violate the conservation of momentum". You are unlikely to find any in the academic literature, because journals tend not to publish papers that merely restate basic principles. -- The Anome (talk) 19:14, 4 August 2015 (UTC)

Well I suppose it is still the "claims of such a surprising result" which needs citation most of all or rephrasing, because there is nobody claiming a violation of conservation of momentum AFAIK. Apparently reactionless needn't mean it really is reactionless. And suggests that they are doing the research only because it seems to violate conservation of momentum, when they would do it anyway because it is not understood. If you found a citation, you could say whatever is said in that citation, and then attribute it to someone as well, that the "National academy of sciences says that ..." or whatever is the source of the statement. As it is, it is a summary that I think verges a little on OR in the way it is presented. Just the way it comes over to me. If all it is saying is that when you get an apparent violation of the conservation of momentum, then you need to investigate to find an explanation for it, then it could perhaps be phrased a little differently? And if it is intended to refer instead to the issues with Roger Shawyer's theory, it should mention his theory and make it clear it is his theory that is at issue raather than the experiment, and not the only idea being considered I think.

As for suitable cites, I've no idea, I've often come up with this issue on Wikipedia that the cites that seem best to me are often said to be not appropriate and ones that seem of least value are favoured. E.g. newspaper reports favoured over reporting directly what they say in the Eagleworks video because that's seen as a primary source and we are supposed apparently to use those only if we find someone else reporting on it elsewhere rather than just summarize what they say in their own words. Or some such. I have often tangled with wikipedia editors on this point and except in a few specialist topic areas or very obvious changes, I have pretty much given up on attempting to fully understand how you decide what are and are not suitable cites on wikipedia. In controversial areas that is. In mainstream science it is often clear enough how to apply it. I've suggested the Eagleworks video as a citation source, but they don't say that it violates COM and I don't know of anything I'd regard as a reliable source that says this, the newspaper reports generally just give a few statements by scientists in other topic areas who have neither investigated the experiments nor acted as reviewers for them nor given them extensive study as is often clear from the things they say. Though you could probably find good cites that criticise Roger Shawyer's theory. Robert Walker (talk) 19:35, 4 August 2015 (UTC)

Indeed. All it is saying is that when you get an apparent violation of the conservation of momentum, then you need to investigate to find an explanation for it. And, on the face of it, that is what these devices seem to present. But you really need to do that investigation thoroughly -- the burden of proof is entirely on the investigator to prove either a cause for the effect that preserves the conservation principle, or to provide ironclad, reproducible, proof of apparent conservation violation, and for others to independently reproduce that result, at which point that result would then hit the global #1 slot in interest among physicists. Until then, skepticism is entirely warranted, based simply on the appearance of conservation violation. -- The Anome (talk) 20:24, 4 August 2015 (UTC)

Yes agree with that 100%. Is only a question about whether the intro and the "Controversial Invention" box would convey that to the casual reader of the article. Especially because of the large number of news stories etc that dismiss it out of hand. Many seem almost to go as far as to say that although we don't know what is going on, that we shouldn't investigate it to find out what is happening in case it turns up an apparent violation of COM, but should just say it has to be experimental error. In my view, for what it's worth, it is improved a lot already with your addition of the word "otherwise". 21:05, 4 August 2015 (UTC)

The apparent violation of momentum conservation is exactly why it's interesting, snd it's not at all unreasonable to continue to investigate. Indeed, at the moment, this looks like worthwhile research: it's amazingly cheap compared to big science, and the prize is great if these devices turn out to work as advertised, and the effort at least educational if the results turn out to be due to experimental error, or some other more mundane phenomeon. The groups currently investigating these anomalous results are serious researchers, and they will want to get to the bottom of it, one way or another, and we will learn something, whichever way it goes. I wonder if bookmakers have begun offering odds on the results? -- The Anome (talk) 23:21, 4 August 2015 (UTC)

Yes my feeling exactly. Yes indeed they are serious researchers. Totally agree with everything you say, about great prize and educational if it turns out to be experimental error. Had a search for bookmaker odds out of interest, found nothing. I'd expect them to be quite low. But even a 1 in a 1000 chance (or less) of new physics, and even if it is has no practical value (like the Higgs boson) but tells us something we didn't know before about physics, is a punt well worth taking in my book, good that there are a few researchers researching it, just in case it comes up gold. And we learn from it anyway, and just should follow up things like this, as scientists - it's going against the spirit of science if you ignore experiments you don't yet understand. Robert Walker (talk) 01:30, 5 August 2015 (UTC)

Queries

Anyway to explain this without violating the laws of physics. 176.252.136.138 (talk) 17:50, 31 August 2015 (UTC)

The teams studying this are still working on answering that. – SJ +

Also it is worth mentioning that all the intermediate steps ie superconducting cavities, RF feedback at resonance are well established engineering principles. The problem is that because teams are reluctant to report null results the scientific community do not take them seriously.

I've actually run into a variant of this with my HTSC research, noticed significant resistance drops in heavy metal doped pyrolytic graphite but no journal will even look at my draft because it is not from an established research institution. — Preceding unsigned comment added by 185.3.100.53 (talk) 10:37, 8 September 2015 (UTC)

This page is not a forum for general discussion about EmDrive/Archive 4. Any such comments may be removed or refactored. Please limit discussion to improvement of this page. You may wish to ask factual questions about EmDrive/Archive 4 at the Reference desk.

Peer review?

Removed from the article:

One of the experiments showing positive thrust has been published in a peer reviewed journal. [citation needed] [further explanation needed]

The only peer-reviewed article about these drives that I know of is Shawyer's recent article in Acta. Which doesn't show any positive thrust; it is a hypothetical and theoretical paper (with extraordinarily optimistic predictions). – SJ + 01:51, 8 September 2015 (UTC)

The following statement in the article:

"This experimental work has been published in university journals and conference proceedings, but as of 2015 none has been published in independent, peer-reviewed journals"

is simply wrong. It is true Pr Juan Yang published her results in the journal of the NWPU at first. But Acta Physica Sinica then Chinese Physics B are independent, peer-reviewed scientific journals, edited by the Chinese Physical Society. The sentence above should be modified to add those three papers:

Yang, Juan; Wang, Yu-Quan; Li, Peng-Fei; Wang, Yang; Wang, Yun-Min; Ma, Yan-Jie (2012). "Net thrust measurement of propellantless microwave thrusters" (PDF). Acta Physica Sinica (in Chinese). 61 (11). Chinese Physical Society. doi:10.7498/aps.61.110301.
Yang, Juan; Wang, Yu-Quan; Ma, Yan-Jie; Li, Peng-Fei; Yang, Le; Wang, Yang; He, Guo-Qiang (May 2013). "Prediction and experimental measurement of the electromagnetic thrust generated by a microwave thruster system" (PDF). Chinese Physics B. 22 (5). IOP Publishing: 050301. doi:10.1088/1674-1056/22/5/050301.
Shi, Feng; Yang, Juan; Tang, Ming-Jie; Luo, Li-Tao; Wang, Yu-Quan (September 2014). "Resonance experiment on a microwave resonator system" (PDF). Acta Physica Sinica (in Chinese). 63 (15). Chinese Physical Society: 154103. doi:10.7498/aps.63.154103.

Thus I modified the text to reflect the truth. I didn't add the first 2008 Yang paper which appears to be published in a peer-reviewed journal too, because I can't find if the Journal of Astronautics is high level or not.Tokamac (talk) 17:25, 10 September 2015 (UTC)

To put this in perspective, Acta Physica Sinica/Chinese Physics B has an impact factor of about 1.6; whereas Science has an impact factor of 33, and Nature has an impact factor of 44. Higher is better. This is not considered a high number or a prestigious journal. Research published in that journal does not seem to lead to much further research.GliderMaven (talk) 02:27, 11 September 2015 (UTC)

Pseudoscience

The overwhelming academic consensus is that the subject of the article is pseudoscientific. In this regards, the article clearly lends the subject undue credence, although there has certainly been a lot of hype and speculation in the media. I appreciate any help editing this to be move NPOV and I have requested the help of an expert in physics on their page. 139.222.202.221 (talk) 11:10, 31 August 2016 (UTC)

Please point to reliable sources for your claim that "overwhelming academic consensus is that the subject of the article is pseudoscientific".- Mr X 11:45, 31 August 2016 (UTC)

There are a lot of academics against the concept already described in the article, but if you want more [7] is a recent article that has more criticism from a few scientists. Curious Sargon (talk) 13:03, 31 August 2016 (UTC)

I know there were some edits today, but as of right now, I think the article does a pretty good job of saying what is and isn't accepted by mainstream physicists and why. Can you point to particular passages that are problematic? --Steve (talk) 12:14, 31 August 2016 (UTC)

I think in particular the History and the Controversy sections should be either removed or rewritten/combined. They make it sound like this thruster is the pinnacle of propulsion research and not a largely discredited concept created by a man with a spurious academic reputation. There is also a lot of good criticism scattered throughout the article, so maybe this could benefit from a separate Criticism section that would sum up all of those sources that criticism is based on. Some passages I particularly dislike: "Roger Shawyer has reported seven independent positive reviews from experts..." from subsection 'Static thrust tests'; source actually says he has claimed he has those reviews. "Shawyer has self-published theory papers about the EmDrive. These include the fundamental assertion underlying the theory..." from the section 'Hypothesis'. Not sure we should be referring to Shawyer's self published content. I am sure I will spot more later on. The introduction looks good after the recent edits. Curious Sargon (talk) 13:00, 31 August 2016 (UTC)

I edited the history section a bit. I don't think it was unbalanced, it just came across that way because the writing was unclear. Is it better now? --Steve (talk) 13:40, 31 August 2016 (UTC)

That does look a lot better, thank you. Curious Sargon (talk) 13:52, 31 August 2016 (UTC)

I undid the revisions to the lede by IP above. Contrary of his claim to remove POV, their changes essentially changed the lede to be from only one POV. Furthermore, many of the changes recreated many of the older problems with the lede that were corrected via extensive talk page discussions and compromises. Insert CleverPhrase Here 21:31, 31 August 2016 (UTC)

I don't think that's very constructive and I cannot see the talk page discussion about the Introduction you are referring to. The Introduction as it stands in your revert does lend undue credence to this fringe theory by presenting the scientific consensus as skepticism. Curious Sargon (talk) 22:31, 31 August 2016 (UTC)

I'll ask it again, where is this so called scientific consensus that declares the subject of the article to be pseudoscience? A link to a few sources will do nicely.- Mr X 23:03, 31 August 2016 (UTC)

Please see the article I have linked in response to your original question for a few examples. Are you suggesting that conservation of momentum is not scientific consensus? Curious Sargon (talk) 23:28, 31 August 2016 (UTC)

The article says "While in the past Shawyer has been criticized by other scientists for incorrect and inconsistent science, if the paper does indeed get published, it may begin to legitimize the EmDrive and spur more testing and research.", which is not even close to supporting "The overwhelming academic consensus is that the subject of the article is pseudoscientific". I have no idea why you mentioned "conservation of momentum" or what bearing that has on the OP's assertion.- Mr X 00:09, 1 September 2016 (UTC)

I like both the previous version and the current lede. I don't think the current lede is excessively pro-EMdrive. Well, maybe it is a bit in two places. (1) I would suggest deleting the phrase "as a result they are controversial". The rest of the sentence is better without it. (2) I also dislike the sentence "Although generally considered implausible, if they are found to work as claimed, providing thrust without consuming a propellant, they would revolutionise many propulsion applications, particularly spaceflight." In particular I think that "implausible" is too weak. I would reword and shorten the sentence to: "Although generally considered impossible, a device with these properties would have a revolutionary impact on spaceflight." --Steve (talk) 02:18, 1 September 2016 (UTC)

The other thing about this sentence is that if you read the source for it, the source does not just talk about spaceflight, it is about other applications as well (which is why it says "many propulsion applications, particularly spaceflight."). Again, this is part of a previous collaboration and discussion on this talk page (see the archives if necessary) Insert CleverPhrase Here 12:11, 2 September 2016 (UTC)

I collaborated in writing that sentence. You're welcome to rewrite it for readability and style, but I still think that it needs to briefly explain that the revolution on spaceflight would be due to it being reactionless and not requiring to expel mass to gain thrust, thus not needing to recharge fuel; a general audience wouldn't understand that if not explicitly written down. Diego (talk) 09:56, 1 September 2016 (UTC)

Eh it's fine as is (see my comment below).

This might be nitpicky, but shining a laser out the window of your spacecraft produces thrust without "expelling mass". But it does use up energy. Then again, so does EmDrive. So if you don't add that the EmDrive's electrical power requirements per unit of thrust are supposed to be orders of magnitude better than directional radiation, then you haven't really explained why it would be useful. You do, after all, need to lift batteries to run the EmDrive just as a normal rocket needs to lift propellant. But I couldn't think of how to add that to the sentence without it getting excessively wordy and complicated. :-) --Steve (talk) 12:44, 1 September 2016 (UTC)

I have mentioned conservation of momentum essentially because of this quote from the article: "The issue is, the entire concept of a reactionless drive is inconsistent with Newton’s conservation of momentum, which states that within a closed system, linear and angular momentum remain constant regardless of any changes that take place within said system. More plainly: Unless an outside force is applied, an object will not move." Even the Introduction and several other places in the current revision of the article point out that conservation of momentum is broken if this engine does work, and the fact that conservation of momentum is never broken is the overwhelming scientific consensus right now. The quote you have provided simply says that if Shawyers research is legitimate this time, only then will the concept be legitimised as scientific and thus warranting further study. Anyway, I agree with Steve that we can work with the reverted introduction if need be, but I think that the infobox in particular is unnecessary and the "Skeptics" sentence at the end is very misleading of the source its referring to. Personally I would be in favour of bringing back the IP introduction but I will listen to your feedback and decide based on it. Curious Sargon (talk) 08:57, 1 September 2016 (UTC)

Update: I'm OK with "generally considered implausible" in the context of the current version, because it is shored up by the clear strong phrase in the first paragraph "reactionless drives appear to violate the currently known laws of physics...". So it reads like the claims are generally considered implausible and the concept is generally considered impossible, which is right and good. (I only didn't like the previous implication that the concept was generally considered merely implausible.) My new (more minor) complaint is that "unworkable" is too weak, I would prefer "impossible". As I understand the term "unworkable"—and I am not a dictionary—a concept can be fundamentally sound but "unworkable" in practice, because it's too complex or whatever. But that's not what we should be implying that "scientists generally believe". --Steve (talk) 12:37, 1 September 2016 (UTC)