# Talk:Metamaterial

## Better caption to the refraction video

The video showing refraction at at an air-metamaterial interface is highly enlightening. Is it an experimentally-acquired sequence of photographs, is it a plot of the numerical solution of Maxwell's equations, is it a plot of some approximate solution, or is it simply a cartoon painted up by a human artist? Whichever it is should be noted in the caption. 129.63.129.196 (talk) 18:38, 18 October 2012 (UTC)

This article is a complete hotch-potch, and I think it would be completely useless for anyone who wanted to become familiar with this topic. By the look of things editors have been using this page to trumpet their own contributions to the field (which may or may not be relevant) rather than to provide a useful overview of the area. The problem is not helped by a lack of a good definition of a metamaterial - should it include the artificial dielectrics from the 1940's, left-handed tranmsission line media, and photonic crystals? (No Worries 05:40, 25 September 2007 (UTC))

Is the diagram correct? It appears to contradict the later statement in the article "but rays are refracted away from the normal on entering the material" whereas the diagram has the rays being refracted closer to the normal, and more surprisingly, on the other side of the normal. If the diagram is wrong can someone delete it please.

The diagram is correct; I've corrected the text. See, if N1 sin theta1 = N2 sin theta2 and N1 and N2 have opposite signs, then theta1 and theta2 must have opposite signs as well; following the usual sign convention, this means that they are on the same side of the normal. User:Ben Standeven as 70.129.35.107 06:17, 13 July 2006 (UTC)

Can/should we talk about superlenses here? Can someone at least answer some of the basic questions? Like do the concave/convex lenses work opposite from a regular lens?

Why is it that the only meta-material that is talked about is negative refractive index? Shouldn't that get its own page then?

As long as there's enough information on "metamaterial" to justify a page with that heading, negative index lenses should probably be under here. Way too easy to get a horde of small pages for many topics otherwise. As for non-NI materials, the only other case that comes to mind at present is the use of comb-shaped structures to polarize microwaves (reflects waves polarized in one direction, transmits waves polarized perpendicularly to that). Probably other examples for microwave-frequency use that I'm overlooking, but NI materials are popular because they're potentially so useful (lenses that are allegedly not diffraction-limited). --Christopher Thomas 04:36, 25 May 2005 (UTC)
Question for optics people out there - do photonic crystals (photonic band-gap structures) count as metamaterials? They seem to satisfy the definition written in metamaterial, but I might be missing some subtle distinction. --Christopher Thomas 04:37, 25 May 2005 (UTC)
No, one basic properties of metamaterials is that they are homogeneous on a wavelength scale. The interaction of the material with light must come from sub-wavelength scaled features. Photonic crystals, on the other hand, are structure with features of about one wavelength long; diffraction around these features is the main effect here. The definition of metamaterials in the article should maybe be modified to refelect this.

## 2nd and 3rd intro paragraphs

Hi, I couldn't follow the connection between the 2nd and 3rd paragraphs. Could some one in the know edit this article and make these two paragraphs flow better ? Thanks -kg

I took a stab at this. How does it look now? --Christopher Thomas 05:43, 26 May 2005 (UTC)
Much better! thanks! --Kaushik

## Superlens

The superlens created at Berkley did not have a negative index of refraction. All materials with a negative index of refraction are for microwave frequencies. See Superlens —This unsigned comment was added by 67.189.113.62 (talkcontribs) on 03:04, 20 March 2006.

If it had a negative index of refraction for microwares, then it by defintion has a negative index of refrarction. I just does not have one for visible light, only microwave light. And don't make me explain how microwaves are light again.--Scorpion451 02:46, 25 June 2007 (UTC)

## Theoretical Models, 2nd and 3rd Paragraphs

It says that a 'C' ring with is axis in the propogation direction (I assume this means the ring is flat to oncoming radiation) would produce negative permeability. In fact, this only creates negative permitivitty. Negative permeability is created when propagation is in the plane of the ring and the B field then acts perpendicular to the loop. This is not possible if the axis of the ring is alined with the propogation vector of the light. See "Stefan Linden et. al., Magnetic Response of Metamaterials at 100 Terahertz, www.sciencemag.org, Vol 306, 19th Nov 2004, pg 1351-1353" for diagrams of permeability and permitivity with different orientations in respect to the incoming light.

Although it does say that "an induced current is created and the generated field is perpendicular to the magnetic field of the light. The magnetic resonance results in a negative permeability; the index is negative as well.", this is not magnetic resonsnace; the B field would have to be in the same direction of the normal of the loop (or have a component thereof) to create a current and then the induced field could not possibly be perpendicular to the driving field (just think Lenz's Law). If I'm missing something pleae feel free to enlighten me. —The preceding unsigned comment was added by 137.132.3.12 (talkcontribs) on 07:48, 31 August 2006.

It's like a solenoid, the magnetic force is at a right angle to the current, but the looped shape distorts the field causing it to flow in the same direction as the current. The structure of the metamaterial sets up a similar situation, only it reverses the right hand rule, making it the left hand rule, and effectively making the induced field at a right angle to the driving field. Yes it's wierd, that's what makes metamaterials facinating. --Scorpion451 02:50, 25 June 2007 (UTC)

## Pop Sci

According to the article "Unveiling the first invisibility shield" in Popular Science, light travels faster through a metamaterial than a vacuum. Was this a mistake? — Daniel 04:31, 21 September 2006 (UTC)

The article should clarify between two different measures of velocity: group velocity (energy velocity), and phase velocity (speed of translation of the wave pattern). Physicists agree the energy velocity (i.e. speed of information transmission) never exceeds the constant speed of light in "vacuum," designated c. Ryan Westafer (talk) 13:53, 24 September 2009 (UTC)

## Size ambiguity

The phrase in the first line of the 2nd paragraph that reads "at least as small" is strange wording. Does that mean "at most as small"? In other words, as small or smaller? Please clarify. Unclepea 05:44, 20 October 2006 (UTC)

It means "as small as or smaller". "at most as small" would mean "as small as or larger". English doesn't make sense even if it is your first language.--Scorpion451 02:58, 25 June 2007 (UTC)

## Example of Negative refraction index

Is the example at the end of the Nri paragraph correct?

"consider the following: a person submerged in a swimming pool filled with a hypothetical liquid with negative N would appear to float above the pool instead of appearing to be beneath the surface."

If the positive refraction index would make the submerged body look closer than it is, then the negative will make them appear "underneath" or even behind the view point. I think you have the idea of the Plane and the Normal the wrong way around in this example. Otherwise it's been explained very well.

Daniel --80.195.237.107 22:18, 30 October 2006 (UTC)

I see that my example of the person in the swimming pool has been removed. It was from a Scientific American article, so I'm pretty sure it was right.Rotiro 11:02, 14 March 2007 (UTC)

The negative refractive index would indeed make the swimmer appear above the water, much like a concave mirror does, although by a different mechanism.--Scorpion451 22:20, 26 June 2007 (UTC)

I'm still having trouble with the diagram showing negative refraction. My understanding, backed up by http://physicsworld.com/cws/article/news/2692 is that a positively refracting material bends light away from the normal, and a negatively refracting material bends light towards the normal. This diagram shows both materials bending the beam towards the normal, only that the negative material bends it so far that it goes past the normal. Either this is wrong, or the Wikipedia entry on "refraction" is wrong. ---posted by NobbyNobbs

## NRIs -1 < N < 0?

Can somebody explain how Snell's Law holds for NRIs between minus one and zero?

If we take N1 to be 1 and Theta1 to be 45 degrees, then use a negative N2, say -0.2, then solving Sin(Theta2) = Sin(45) / (-0.2) = -3.53~ has no solutions for N2.

I ask because a metamaterial was recently produced with refractive index -0.6 for visible (780nm, red) light, and I'm still trying to figure out what it would 'look' like. The swimming pool discussions don't make much sense to me because, how on earth can something appear to be 'below me' when I'm standing on concrete. Wouldnt I just see concrete? 222.154.97.61 09:59, 19 December 2006 (UTC)

As for what it would look like, lay a mirror on the ground and look into it. The beams of light reflected from the mirror cover up the beams of light reflected from the concrete. It's hard to explain the way the equations apply to the wierd properties of metamaterials, because they violate fundamental assumptions of the equations. It's one of those cases of the equations say the data is wrong, but the universe says that the data is right. I'm leaning toward the universe. --Scorpion451 03:07, 25 June 2007 (UTC)

I looked closer, and now I see what your problem was. If you try it, you will see that you have the same issue for any number 1>0>-1. The refractive index .2 will give the same error as -.2 It's not the negative, it's the decimal. The following is directly from the snells law page:

When light moves from a dense to a less dense medium, such as from water to air, Snell's law cannot be used to calculate the refracted angle when the resolved sine value is higher than 1. At this point, light is reflected in the incident medium, known as internal reflection.

There is a point of refraction, except its much less than 45 degrees. The angle to the normal at which you not recieve a reflection but a refraction is approximatly 11.5 degrees.
so:
${\displaystyle \sin ^{-1}{({\frac {{n_{1}}*{\sin {\theta _{1}}}}{n_{2}}})}=\theta _{2}}$
${\displaystyle \sin ^{-1}{({\frac {1*sin11.5}{-0.2}})}=-89.4}$ degrees
--Scorpion451 22:08, 26 June 2007 (UTC)

## Breakthrough?

http://www.newscientisttech.com/article/dn10816.html 195.210.210.217 12:39, 19 December 2006 (UTC)

## Possible Factual Error

In the subsection "Negative refractive index", there's a list of some cool properties of metamaterials with negative n. The last point in the list is: "Higher frequencies have longer, not shorter, wavelengths in such a material ". I've added a citation needed flag to this, as I haven't encountered it in the literature on this topic, and I have the feeling it might be incorrect. (It runs contrary to the definition of frequency, which is phase velocity/wavelength.)

Can anyone find the proper reference for this fact? (Otherwise, I think it should be deleted as a precaution...) GameGod 02:26, 2 January 2007 (UTC)

I was just wondering about that before you changed it. What would be the relationship between wavelentgh and frequency in that case, lambda = nw/c ?

18.95.7.45 20:58, 7 January 2007 (UTC) Matthieu

I'm not certain but I belive that the above fact is correct, even though it violates the C=F/W rule. I think this is due to the negative refraction index causing the particle to slow down. To put it this way, if C(phase speed)=1(just for simplicity), then in the metamaterial if it moved at half the speed it would be 1/2=F/W. If frequency is unchanged, then wavelength must double. Does this make sense? I can put it a little more clearly, I think.--Scorpion451 03:04, 25 June 2007 (UTC)

I looked more into this. You are correct that the wavelength expands when frequency decreases and vice versa. The material, however, is not metamaterial. The expanded wavelength at slower speed is seen in materials with extremely high N, such as [[Bose Einstein condensates]. See the Slow Light article.--Scorpion451 02:18, 8 July 2007 (UTC)

## Dubious Science? ("infinite inertia"?)

In the opening paragraph this sentence exists: "Such unusual properties could be a negative refractive index or infinite inertia (which are not found in naturally occurring materials)."

I've gotta say, "infinite inertia" sounds like dubious science to me - generally there's not much in science that is "infinite" and if some object possessed /infinite/ inertia then either its mass or velocity was infinite, both impossible AIUI.

There's no further mention of inertia in the article, nor here on the discussion and google didn't produce anything significant regarding this phrase ... so is this "infinite inertia" just buzzwordiness ... or outright nonsense or vandalism or ...???

--wikifreeman 21:44, 17 October 2007 (UTC)

Also the statement that the doppler effect would be reversed is just hogwash. The doppler effect is a physical interaction between a signal moving through space and a receiver of that signal. A signal can only be expanded if the receiver is moving away from it, and can only be contracted if the reciever is moving towards it. The doppler effect is not effected any properties of the signal generator. Once a signal is moving through space, the doppler effect can only possibly work that way. Why is this article linked in "see also" from a real scientific article like "einstein-rosen-podolsky_bridge ? —Preceding unsigned comment added by 24.2.124.58 (talk) 14:05, 28 September 2008 (UTC)

Agree about the BS Doppler claim as it violates special & general relativity, and conservation of energy. I tried asking for "proof" of this claim, but some idiot admin person yelled at me for "vandalizing the site." I like WIki, but if the admin censors trump scientific integrity, then this site is nothing more than a blog for some IT wannabe. — Preceding unsigned comment added by 72.66.109.243 (talk) 02:55, 28 January 2012 (UTC)

I think I can help with some explanation here, as metamaterials are not fringe or pseudo science but hard science on the cutting edge of our understanding of chemistry, quantum physics, and engineering. The doppler effect is difficult to understand in terms of metamaterials as it requires one to think in ways which we are not used to. The viewer is stationary, yes, but the photons of light or phonons of sound are moving, and moving though a medium with unique refractive properties. This means that the wave itself will be curved in bizare ways. One of the effects of this is that the apparent wavelength of the photon or phonon will appear to lower as it approaches, and rise as it recedes from, a viewer. The infinite inertia refers to the fact that a metamaterial can, in precise circumstances, temporarily halt light by trapping it in the lattice of electromagentic fields within the material or within the particles themselves as a quantum spin state charge. Another way to phrase this would be infintite internal inertia. Such effects have been thoroughly demonstrated, and you can see the article slow light for more information. You are correct in saying that very little in science is infinite, but the catch in a metamaterial is that it is not 'infinite' infinite inertia. The infinite inertia is an induced effect that lasts only as long as the proper conditions remain, whether that be an external current applied to the metamaterial, a temperature to which the material is raised or lowered, or internal quantum state which can be thrown off balance. At the point that these conditions end, the light trapped within the metamaterial is freed from its electromagnetic 'cage' and re-emmited. I hope that I have cleared up some of the misunderstandings about the properties of these materials.--Scorpion451 rant 17:42, 20 August 2010 (UTC)

Scorpion451, your Doppler counter-argument doesn't make any sense because the basic premise of the relativistic Doppler effect & gravitational red/blue shift resides with time dilation, which has nothing to do with materials (positive or negative index of refractions). However, I will be happy to eat my own words if you can cite peer reviewed/credible journal articles that prove me wrong. Until then, that bullet should be deleted from the article because it's unsupported. — Preceding unsigned comment added by 72.66.109.243 (talk) 03:06, 28 January 2012 (UTC)

## TeraHerz metamaterial devices

I am no expert in this field, but there does not appear to be any mention of the developments at Los Alamos National Laboratory by Hou-Tong Chen, Richard Averitt, Willie Padilla and others, which resulted in the fabrication of a controllable device. I would have thought this is very significant for the future use of metamaterials. http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/9935

parellic —Preceding unsigned comment added by Parellic (talkcontribs) 17:52, 2 March 2008 (UTC)

## Ameteur question

I'm just an internet-educated dropout trying to make himself feel less stupid. If this is a stupid question, just delete it and I'll go away.

The page states that "A metamaterial (or meta material) is a material which gains its properties from its structure rather than directly from its composition." How are metamaterials different from allotropes? For example, graphite and diamond are both academically pure carbon, yet are literally as different as black and white. Diamond is one of the hardest materials in nature, but graphite rubs off on a sheet of paper. Graphite conducts electricity, diamond doesn’t. Could you say that metamaterials are allotropes that do not normally exist in nature? Or compounds with structures that do not normally exist in nature?

there's a definition in the article, i guess they have to be man-made (unlike diamonds) and a combination of more than 1 naturally occuring substance (diamonds are just C), and they have to produce an "optimized combination" of 2+ responses to excitation -- seems a ludicrously specific definition that gets us down to just the negative N materials CarlosRodriguez (talk) 05:56, 11 August 2008 (UTC)
If we create such materials, and if we are included in nature, then certainly the materials "exist in nature." Why should we suspect a phenomenon (which we only recently recognize and create) does not occur naturally elsewhere in a way we might not expect? Waiving the arbitrary "man-made" requirement, we see that metamaterials are just like allotropes so far as the common properties of a material may be drastically altered by rearranging the constituent materials at much smaller scale. Perhaps with carbon allotropes, one is rearranging vacuum and carbon, rather than metal structures and dielectrics. I think the "internet-educated dropout" poses a good question about the dividing lines among material classes. Cheers! --Ryan Westafer (talk) 20:00, 24 September 2009 (UTC)
I think that its a case of "all dogs are mammals, but not all mammals are dogs". All metamaterials are alliotropes of some combination of elements, but not all alliotropes display the bizarre properties of metamaterials. Good question, however, keep up the good work!--Scorpion451 rant 18:21, 21 July 2010 (UTC)

## ?Vandalism

I'm new to this, but under External Links | Research groups (in order of importance), the number one spot is occupied by a site which appears to have nothing to do with Metamaterials. Maybe someone can correct this?72.90.243.147 (talk) 16:08, 5 April 2008 (UTC)

Yes, I agree. This appears to be vandalism. I have been going over the history of this page. There are a lot of changes by more than one anonymous IP address and so it is a little difficult to determine what is valid and what is not. From reading the "Oscar" dude's website, I do not believe he has anything to do with metamaterials. I am going to send him an email asking if he does. I am not sure if this "Oscar" guy is the source of the changes or not. He may not be aware of these edits at all. Anyway which way, the research groups should be listed alphabetically.The-tenth-zdog (talk) 06:38, 6 April 2008 (UTC)

## Article quality

This entire article is hard for someone not already familiar with its concepts to understand. Although it has the virtue of having good spelling and of being grammatical, it could benefit from a complete rewrite due to its confusing and overly terse content and style. The final paragraph is particularly infelicitous. It and many others could also benefit from the addition of line drawings or other diagrams.

An example of an article of similar speciality and difficulty that is nevertheless easier for a nonspecialist to understand, due to its clear writing and its use of diagrams, is Block cipher modes of operation.

While it is certainly useful for an encyclopedia article to be accessible only by specialists in its field, it is even more useful if each article were understandable by a much wider audience. Then, besides being informative, the encyclopedia might also be tutorial, which greatly enhances its usefulness to society. David (talk) 14:13, 16 August 2008 (UTC)

## Merge from Cloaking device

I have merged the section Metamaterial research from the article Cloaking device into the section Development and applications. I also split the section "Development and applications" into subsections to present the ideas in a more organized fashion. Please centralize discussion regarding this merge on this talk page, and feel free to change anything I merged. — OranL (talk) 04:06, 21 August 2008 (UTC)

## Metamaterials

You're doing great job expanding that article. Just a bit of advice: (i) please check for duplicate references and replace them using <ref name=xxx> and then <ref name=xxx/> tags; (ii) please format references using {{cite journal}}, {{cite book}} , etc., templates; (iii) please avoid personal phrases ("Author X observed ..." in favor of "... was observed in"). Best wishes. Materialscientist (talk) 01:45, 1 June 2009 (UTC)

I have fixed ref. 18 in metamaterials as <ref>{{cite news| publisher = Office of News & Communications Duke University | title = First Demonstration of a Working Invisibility Cloak | url = http://www.dukenews.duke.edu/2006/10/cloakdemo.html|accessdate = 2009-05-05}}</ref> (well, accessdate is older than today, but this is Ok). Indeed, the topic seems out of fiction, but that is the beauty of modern Science and of wikipedia, which can describe thing which are not in the books yet. That said, information on WP must be reliable. Media tends to grossly exaggerate the facts. Please try to get to the real reports (e.g., in my last edit, I put there the original link to the Science paper). On the other hands, media reports are a useful support, as they provide free-access details, like videos, etc. You can always ask me further details when needed. Materialscientist (talk) 04:26, 1 June 2009 (UTC)

## Citation Tag

I fixed the requested citation tag for Reference number 8. I also added the illustration (or whatever you call it). Ti-30X (talk) 14:09, 7 June 2009 (UTC)

## Negative index metamaterials

Editors of this article may be interested in the new article Negative index metamaterials and the discussion on its talk page. Note that the article really focuses on stealth applications, and there is a discussion in progress on whether to retitle the article, or to broaden its focus to cover negative index materials more broadly. There is some overlap with this article; some shuffling of material between the two articles may be beneficial.--Srleffler (talk) 19:18, 8 August 2009 (UTC)

## Merge from Metamaterial

The negative index metamaterial essay-like article has recently appeared has enormous overlap with this article, in a way that makes it completely synonymous with this one. This is the Wikipedia, an encyclopedia, which is where synonymous material is collected into one article.

The invisibility/cloaking discussion is covered in both places, as is the discussion of negative refractive index, and the lead of negative index metamaterial suggest that it covers all uses of negative index metamaterials; but almost the whole of this article covers that.

Unless a clear distinction can be made between these two articles or a clear subarticle relationship can be established then these two articles need to be merged.- (User) Wolfkeeper (Talk) 14:43, 16 August 2009 (UTC)

Understand but Strongly oppose and suggest focusing on writing and improving the articles rather than talking about that and moving articles forth and back. That metamaterials is in a poor state is an issue which is again to be fixed by editing that article rather than putting other material in its place. Today we move negative index metamaterials (NIM) article into metamaterials (only because it is better developed) and tomorrow say "whoops the article is too large, we should split it up". The way I see is to develop metamaterials in the general way, mentioning NIM, but also covering other directions. This topic has intrinsic tendency to grow, and the small current size is no argument to me. That metamaterials article needs cleanup I agree entirely, just couldn't find time for that. Materialscientist (talk) 22:35, 16 August 2009 (UTC)

If you focus on writing and improving articles so that they don't overlap in the first place then we won't have to pick up the pieces afterwards. It's not like you didn't know these articles existed. This is not a publishing company for your magazine articles. Encyclopedias do not have multiple article on the same topic. They're supposed to say everything once, somewhere, not multiple places in the hope that nobody will notice and will make it FA by mistake or something.- (User) Wolfkeeper (Talk) 04:35, 19 August 2009 (UTC)
Absolutely, but unfortunately that is not how WP operates right now - if you look around you'd notice that overlap is a norm, I think because many editors feel more comfortable working alone. (I have had, by chance two FAs and a few GAs on one overlapping topic - nobody complained ;-) I'm not saying this should be, but believe it is better to let them write, and correct the writing, rather than have nothing written at all - WP is in desperate need of constructive contributors. This especially refers to active projects. Stale, abandoned articles is another story. Regards. Materialscientist (talk) 04:54, 19 August 2009 (UTC)
Well, it's not going to fly this time. Please restrict yourself to not overlapping if it in any way possible; or if they are considered synonymous, merging. You can have strict subsets if they can't be merged.- (User) Wolfkeeper (Talk) 05:48, 19 August 2009 (UTC)
• Strongly oppose The scope of articles on metamaterials vs. the subset of metamaterial content related to negative refractive indices is just too different. The refractive index issue would be lost in the broader article, whilst it's sufficiently important that it deserves its own coverage. Andy Dingley (talk) 17:01, 19 August 2009 (UTC)
Actually, they used to be on different topics, but recent edits have made them on the same thing- electromagnetic metamaterials. I queried the claim that metamaterials are inherently electromagnetic, and 3 'references' to this were produced. Unfortunately I checked all three, and they all qualify the kind of metamaterial it is by prefixing it with optical, electromagnetic and so forth, they do not define the concept of a metamaterial as being electromagnetic, and other sources I have read describe non electromagnetic materials. The way this article and the other article is being edited is causing me increasingly great concern.- (User) Wolfkeeper (Talk) 20:01, 19 August 2009 (UTC)
I do not expect to check references and find that they do not support the claims made, nor do I expect to find non reliable sources like commercial materials made to sell stuff that is doubtless vetted by nobody.- (User) Wolfkeeper (Talk) 20:01, 19 August 2009 (UTC)

There is now a new section entitled "The six spokes of expanded metamaterial research." Please do not remove, move, or delete this section. One or two other editors and I will be editing the section, and hopefully use it as a base to expand the Metamaterial article. This gives a lot of basic information to start with. Thank you for your cooperation. Ti-30X (talk) 18:21, 17 August 2009 (UTC)

Where is the phrase 'spoke' used in relation to these organizations in the references? I had a look, but I found nothing. Is this term your WP:OR???- (User) Wolfkeeper (Talk) 04:38, 19 August 2009 (UTC)
It is a metaphor and organizing principle. But, thanks for asking. I will have to give this some thought, however. I never considered it OR. It is just a tool for clarity at the moment. Anyway, I will confer with other editors and see if this violates OR. Ti-30X (talk) 11:09, 19 August 2009 (UTC)

## Continuing

I am thinking that the paragraphs in the introduction, beginning with "With a negative refractive index researchers have been able to create a device..." probably need to be thrown out. ( I am the previous author of these paragrpahs, too.) Just from my peliminary work on the other section and reading some new information, I can see that this is too narrow a definition. Metamaterials now have broader applications, if they didn't before. Come to think of it, it may be tough to pack all the new available information into one article. Also, I think this statement will have to be removed sooner rather than later: "Electromagnetics researchers often use the term metamaterials more narrowly, for materials which exhibit negative refraction". Again, this is too narrow a focus with the current information available. So if no one objects I will be removing these from the article, soon, to make room for a better introduction. Thanks. As usual this is open to discussion. Ti-30X (talk) 19:46, 17 August 2009 (UTC)

The definition I have provided is a much more accurate definition, than the previous one. Whenever metamaterials are defined, they are defined in reference to the following: artificial (synthetic) materials not found in nature. I don't want to offend anyone but metamaterials are not defined as being different from other synthetic materials. In the scientific journals that I have read, any reference or definition to metamaterials is that they are artificial fabrications not found in nature. Except for the word synthetic I wrote most of this first paragraph also. Well, things change. I kept the rest and we can edit what I have, with what is there already. Thanks Ti-30X (talk) 20:18, 17 August 2009 (UTC)

## References

Regarding the recent reference warring, per WP:RS in the context of science articles, I'd strongly suggest sticking to textbooks and peer-reviewed journal articles where possible. These definitely exist, and I'm pretty sure most of the parties involved have access to relevant online journal databases through your respective universities.

That, and the "electromagnetic vs. non-" dispute seems a bit like a mountain/molehill scenario to me. Why not just hedge and say that the term is usually used to refer to materials with strange electromagnetic properties? There's certainly a mountain of literature to support the claim that this is a very widespread use of the term. --Christopher Thomas (talk) 01:13, 20 August 2009 (UTC)

Hello, Christopher. I was about to quote the disputed sentence along with the sources that I used. As far as RS, the sources that I have used, two of them are texbook level if not in fact textbooks themselves. These are books with mathematical theory, construction techniques, and whatever else. These books are obviously written by researchers working in the field. These are not popular science books. These are also acceptable according to WP guidlines. These are reliable and verifiable sources. Another matter is, I don't have time to go searching through journals. I did for the other article, and that is a matter of choice, as well a matter of time that I was willing to use. These are probably academic books, and are just as good as any number of journal articles. Reliable sources are supposed to conform to WP verifiable sources, and guidelines. Acctepable sources are in fact spelled out. These more than qualify. There is no WP:what some editor likes and there is no WP:what some editor doesn't like.
Here is the link followed by a quotation: Wikipedia:Verifiability#Reliable sources :
"Articles should be based upon reliable, third-party published sources with a reputation for fact-checking and accuracy.[4] Reliable sources are needed to substantiate material within articles, and citations directing the reader to those sources are needed to give credit to authors and publishers, in order to avoid plagiarism and copyright violations. Sources should directly support the information as it is presented in an article and should be appropriate to the claims made: exceptional claims require high-quality sources.
In general, the most reliable sources are peer-reviewed journals and books published in university presses; university-level textbooks; magazines, journals, and books published by respected publishing houses; and mainstream newspapers. Electronic media may also be used. As a rule of thumb, the greater the degree of scrutiny involved in checking facts, analyzing legal issues, and scrutinizing the evidence and arguments of a particular work, the more reliable the source is."
Here are the sources that I used in that sentence.
{{#invoke:citation/CS1|citation

|CitationClass=book }}

{{#invoke:citation/CS1|citation

|CitationClass=book }}

Template:Cite web
I feel that if Wolfkeeper wants journal articles for citations, then he needs to search through journal articles himself and not try to push his preferences and predilicitons on to someone else. I do not have to do someone else's work. Ti-30X (talk) 11:10, 20 August 2009 (UTC)
This is non-issue to me. Lead is a summary, which might and usually is rewritten later. Bulk content is the 1st priority. These refs are fine, just mention the page number when citing, but again, ± one phrase does not shape the article. Actually, books (secondary sources) are preferred over journal articles (primary sources). Materialscientist (talk) 11:33, 20 August 2009 (UTC)
This is entirely the opposite of my position and my experience; the lead guides the shape of the article and helps place the article in context in the wikipedia. To put it melodramatically, given the status of the wikipedia you are essentially actively attempting to redefine the entire topic of metamaterials for the entire world to be only about electromagnetic metamaterials. The actual definition of metamaterial isn't that, and the references I checked all qualified it like 'electromagnetic metamaterial' or 'optical ... metamaterial'. You can probably find one or two sloppy ones that don't do that, but on the whole, misrepresenting sources is pretty serious in my book.- (User) Wolfkeeper (Talk) 13:46, 20 August 2009 (UTC)
Leads and titles are really, really, really important. I've seen it in the past what happens when somebody goes out of their way to create a deliberately narrow definition of something and then applies a broad title to it... stupidly bad things happen to the structure of the wikipedia. You create a lacuna; there is literally no place to put the more general topic at all, even if it's notable; if you create it with a different name, the name is often so awkward the new stub article often gets deleted again in the AFD; mostly because of its title. Or, if you rename the existing article to be more precise, other editors will often move it back again.- (User) Wolfkeeper (Talk) 13:46, 20 August 2009 (UTC)
For the record, the only way to solve these kinds of problems is with persistence; if I really am right- if the net sum of the sources actually agree with my point, then I never, ever give up, even if it takes months. I also find that it helps to point this out.- (User) Wolfkeeper (Talk) 13:46, 20 August 2009 (UTC)
These references are acceptable. They qualify as Wikipedia Reliable Sources. In addition, no single editor can unilaterally decide what is acceptable RS and what is not acceptable. The paragraphs that I quoted above clearly tell us what is acceptable. So, according to the above, the college level books are number two and number three behind journals. I will admit, that it can be argued, that perhaps I should not use David Smith's web site for the lead. Truthfully, I didn't see that before. I am surprised I see it now. And considering the lead is so important to one editor - I will not use David Smith's web page definition of metamterials, and instead replace it with another book of the same level and professionalism as the other two. Therefore, I will have three books of high caliber and high professionalism. Or simply not use David Smith's web page definition, and use only these two books for the source. Are either of these acceptable, to the editor? BTW the way good job with "Groups engaged in metamaterial research". I appreciate it. And it gets rid of any question of WP:OR, at the same time. Ti-30X (talk) 21:59, 20 August 2009 (UTC)
In addition, the page numbers are already part of the reference. These are part of the cite source template. If you go through the sources listed above, you will see page numbers.Ti-30X (talk) 22:17, 20 August 2009 (UTC)
Furthermore, a consensus is developing here. Christopher has already written that these types of books are acceptable RS. Materialscientist has written these references are acceptable RS. And I have written these are acceptable RS. Ti-30X (talk) 22:20, 20 August 2009 (UTC)
The question is not whether they are reliable sources. The question is whether they actually define that metamaterials are invariably electromagnetic. I checked the sources, and they do not.- (User) Wolfkeeper (Talk) 22:33, 20 August 2009 (UTC)

Let me list some terms that are used when discussing characterisitics of metamaterials. Permittivity, permeability, dispersion, frequency, electromagnetic waves, how EM waves are affected by the material, magnetic field, electric field, microwave, wavelength, EM spectrum, phase velocity, etc., etc.... Furthermore, I am only "required" to back up my statements. I am not required to back up your definitions. In addition, you are free to add any content you feel expresses your view. If you want to add, metamaterials are intrisically related to mustard and relish, you can do so. All you have to do is have citations and sources and no one can say it is bologna. Ti-30X (talk) 22:56, 20 August 2009 (UTC)
The references you've been citing specifically refer to "optical metamaterials" and "electromagnetic metamaterials". They're addressing these sub-classes, rather than talking about all types of metamaterial. That is the point that Wolfkeeper has been trying to make to you. Wolfkeeper, your point might be better-received if you can cite references for the term "metamaterial" being used in a context other than EM metamatarials, though. Demonstrable presence or absence of references that do that should settle the debate with minimal fuss. --Christopher Thomas (talk) 23:18, 20 August 2009 (UTC)
Although I don't totally agree - you are expressing my point. I can back up my statements with my references. He is free to do the same. So, in accord with guidelines I can restore the statement, and he is free to expand the definition, with sources. I am not going to do the work for him. So far all I have seen is a propensity to point fingers, refusal to do the work to back up an expanded defintiion, and expect someone else is going to do the work to prove his view. I am sorry, I not going to do that. Ti-30X (talk) 23:39, 20 August 2009 (UTC)
This is a ridiculous argument. Optics has an underlying, fundamental relationship with electromagnetism. Metamaterials has an underlying fundamental relationship with EM. The base of all this is Electromagnetism. So, we are back to square one and this is a totally specious argument. I just proved that writing "metamaterials having an intrisic relationship with electromagnetism" is correct. Optical phenomenon is subtended to the effects of EM on metamaterials. This is not a real argument in my humble opinion. Ti-30X (talk) 00:03, 21 August 2009 (UTC)
Metamaterials are composite materials with properties that do not occur in bulk materials - no more, no less. electromagnetic metamaterials are the subset of these that are engineered to have unusual electromagnetic properties. optical metamaterials are those that have unusual electromagnetic properties at visible and near-visible wavelengths (much harder to do; most work at microwave frequencies, aside from thin-film superlenses). I don't dispute that the term "metamaterial" usually refers to electromagnetic metamaterials. I do dispute that it always refers to them, especially since all of the references you've been quoting take pains to make it clear that they're only talking about the EM kind. Making it clear would not be needed if that was the only use for the term. Your assertion that this is the only use of the term is not backed up (i.e. stated outright) by any of the references cited to date (that I've taken a look at), which is why your statements to that effect (and claims that you've backed it up) have met with poor reactions. Do you understand what I'm getting at, here? You don't have to show that people talk about EM metamaterials. You have to show that nobody talks about non-EM metamaterials, or you have to cite a reference that says outright that this is the only way the term "metamaterial" is used. --Christopher Thomas (talk) 00:15, 21 August 2009 (UTC)
Christopher, thank you for what you have written here. This helps very much to clarify what Wolfkeeper was trying to say, and perhaps it has been me that has been narrow minded. I am really glad to have such talent present such as you and Wolfkeeper. So, let me take a short break here. But, first, I propose that Wolfkeeper write the lead that reflects what we have come to understand here. And I will be glad to try to find sources to back it up. Hopefully he will be willing to do this. Hopefully, my sources will be of help. I am sure that I can learn a lot this way. Thank you all for having this conversation with me. Ti-30X (talk) 00:45, 21 August 2009 (UTC)
If Wolfkeeper wants to use only Scientific journals for the lead, I am willing to search for the scientific journal articles. Ti-30X (talk) 01:07, 21 August 2009 (UTC)
As I wrote, WP encourage using books and reviews rather than original journal articles. Again, this is not an issue. Materialscientist (talk) 01:25, 21 August 2009 (UTC)
And I apologize for being curt. I respect the large amount of effort that you and the other editors working on this have been putting in, and I realize that I may be coming across as an armchair participant due to not devoting as much time to this article.
With regards to references, my understanding is that it's a balancing act between finding references that are authoritative, and references that anyone can access to check. The problem with journal articles is that they're usually not freely available to access (online, at least). The problem with books and popular articles is that unless they're textbooks, they're usually at least one or two steps removed from the technical works. I'd be happy to see both cited, personally, but I defer to all of your judgement in the matter (you're the ones who have put in the work doing the literature search).
Sorry again for not having the time to help out at greater length, and please let me know if there's anything that I can contribute. --Christopher Thomas (talk) 05:26, 21 August 2009 (UTC)
Christopher, no problem and thanks.Ti-30X (talk) 14:24, 21 August 2009 (UTC)
Ironically, or by Wolfkeeper's perceptive understanding, the first two sentences, (the lead paragraph) appear to already express an accurate sense or definition of metamaterials. Interesting. Well, the work for the lead, so far, appears to have been accomplished when I wasn't looking ha! ha! Ti-30X (talk) 12:14, 21 August 2009 (UTC)

## Sections development

Chirality and bi-isotropic media: This section is currently being developed. Thanks Ti-30X (talk) 14:24, 21 August 2009 (UTC)

Acoustic metamaterials is currently being development Ti-30X (talk) 18:40, 24 August 2009 (UTC)

Based on the amount of material we seem to be able to access about metamaterials, we may want to dispense with the section entitled "Groups engaged in metamaterial research". Anybody agree with this? Ti-30X (talk) 22:20, 24 August 2009 (UTC)

I know the section on Split ring cylinders has been sitting there for awhile. I was going through other material before I got to it. This section is still not finished. Ti-30X (talk) 05:34, 31 August 2009 (UTC)

There are two separate section regarding negative index, Negative Refractive Index and Double Negative Metamaterials. One or the other should not exist since they're redundant and both refer the user to the negative index metamaterials page anyhow. 20:03, 15 March 2010 (UTC) —Preceding unsigned comment added by 152.3.196.93 (talk)

Sorry, but I disagree with your assessment. Negative index of refraction is an effect or a phenomenon. In fact, one could say a single phenomenon. Whereas, double negative metamaterials (NIMs, etc.) are metamaterials which can produce negative index of refraction, along with a number of other effects. In addition, as a type of (revolutionary) material they can be discussed from different points of view such as a periodic or lattice structure, effective permittivity and permeability, subwavelength, type of electromagnetic metamaterial, optical or microwave wavelength, exhibit properties not found in nature, and so on and so on... I suppose a connundrum is that both link to "Negative index metamaterials". However, that article appears to be relevant to them both. Steve Quinn (formerly Ti-30X) (talk) 04:35, 28 March 2010 (UTC)

## Acoustic metamaterials

I won't be doing anymore with acoustic metamaterials. I prefer research on other metamaterial types (probably EM). There may more that can be done with acoustic metamaterials if someone else wants to work on that area. Sorry. As much as I try the interest is just not there. Ti-30X (talk) 21:05, 8 September 2009 (UTC)

## Terahertz gap

I have been coming across this term a lot - the “THz gap”. No, it's not about capacitance. It appears to be partly about infrastructure that is not available to deliver Thz radiation which will advance our technologies or capablities in society. This includes a compact source that is proportional to the desired application.

"Many materials inherently do not respond to THz radiation and thus the tools necessary to construct devices operating within this range - sources, lenses, switches, modulators, detectors largely do not exist. Considerable efforts are underway to fill this “THz gap” in view of the wellknown potential applications using THz radiation." That is from one short article that I read regarding Thz-metamaterials. Objectives for Thz-metamaterials are

Terahertz switches
Terahertz modulators
Terahertz lenses
Terahertz detectors
High bit-rate communication

The above would be what I consider to be some of the infrastructure needed. Below, are some of the applications after the delivery systems are developed:

Imaging and screening
Detection of chemical and biological warfare agents
Characterization of explosives
Secure communications
Biomedical devices

An intersting device that was mentioned briefly twice and in one journal article is the Quantum Cascade Laser as a Terahertz Local Oscillator . It said, "Although QCLs have been available at near infrared wavelengths for more than 10 years, the first THz QCL (at 4.4 THz) was only produced 2 years ago." This is being developed as a compact source to deliver Thz radiation. One article said these devices are the size of a baseball, which is pretty small. I am trying to find the article again, but that one said something about a source like this with previous laser technology would have to be huge - like the size of a house or something like that.

I am seeing that the research with metamterials is really important right now. I'll leave you all with another quote - "The design flexibility associated with metamaterials provides a promising approach — from a device perspective — towards filling this gap." These quotes are from the labratories (like Los Alamos). Ti-30X (talk) 05:07, 14 September 2009 (UTC)

Brain-dump follows:
The difficulty with producing this type of radiation is that for the most part, there aren't any quantum state transitions in atoms or molecules that have energies corresponding to THz radiation. Quantized rotation of molecules gives you microwave-frequency transitions (used in masers), quantized vibration of molecules gives you infrared transitions (used in CO2 lasers and so forth), and quantized electron excitation levels giving conventional visible-light, UV, and near-IR lasers. Types of system that I'm aware of that generate THz radiation include variants of masers and IR-lasers that edge into the upper and lower edges of the t-wave band, various vacuum tube resonators that approach the lower edge of the band (used to be called millimetre and submillimetre radiation), and systems that exploit microstructure effects (the niftiest one I'd heard of being an array of miniature dipole antennas tuned to T-wave frequencies, excited into oscillation by an ultrashort pulse of infrared light). This is not an exhaustive list of generation methods; it's just the ones I happened to hear of.
Regarding quantum cascade lasers, these work by having a large stack of quantum wells in a strong electric field. The Fermi level within each well in the stack is different (due to the field), so electrons jumping from one well to another emit at a controllable wavelength. Lasing occurs when jumps are induced by photons already present in the system. Lasing at well-controlled wavelengths occurs because in addition to having wells with different Fermi levels, the structure of the stack quantizes the allowed levels to discrete values. In principle, you can get any wavelength you want out of a system like this (up to some maximum that's in the IR or visible range). In practice, it looks like there are practical problems at the low end of the range that have only recently been overcome. Regarding size, the system would have to be many dozens of wavelengths long, but that's at worst benchtop sized, not room sized. I don't know how big the 1998 one that claimed THz generation was (the quantum cascade laser article doesn't give a citation for it).
Regarding optics and materials, this is indeed a problem. You can use mirrors with metal surfaces, but lenses and refracting waveguides are much harder to make (they require specific refractive index properties that are hard to come by at THz frequencies). Metamaterials do indeed provide an interesting potential solution to this problem. Even without them, though, you could build an external-cavity laser using metal mirrors, and scribe a diffraction grating into one of the mirrors to divert a fraction of the beam for output coupling.
Regarding use of THz radiation for communication (or other applications requiring rapid modulation and demodulation), the main problem is that losses are pretty ugly in THz-frequency electronic circuits, making modulation and rectifier-based detectors very difficult to build. In principle we could use a wave-division multiplexing scheme, with diffraction gratings to separate out channels, but equipiment that does this would be benchtop-scale rather than chip-scale. Long story short, visible and near-IR light is vastly easier to work with and can carry more information as well. This type of manipulation of T-waves would mostly be useful for a higher-frequency equivalent of mm-wave phased-array radar, from what I can tell at first glance. Useful, but with fundamentally different requirements than communication systems.
Brain dump ends. I should probably head to bed in the near future. --Christopher Thomas (talk) 06:04, 14 September 2009 (UTC)
Here is an overview (just one, can't say how good it is) on THz emitters. In my past lab, THz were generated by a maser (if you refill a gas, you get another frequency range, slightly tunable by an in-resonator grating), but this is a bulky and capricious setup. Another technique is to send ultrashort (femtosecond) laser pulses into, e.g., water, generating a spectral continuum in a wide range, but this is again, a complex laboratory setup. Various electronic sources, such as high-frequency diodes (IMPATT, etc) and transistors are much friendlier and smaller, and their frequency can be multiplied. Materialscientist (talk) 07:12, 14 September 2009 (UTC)
Christopher - that was a very informative brain dump. An article in Spacefight Now (dated Aug 15, 2009) about the pre-launch of Space Shuttle Discovery used terahertz imaging - "The ramp in question on Discovery's tank was subjected to non-destructive terahertz inspections before the shuttle was moved to the launch pad and no significant voids were seen." And, "At a shuttle program review last week, some engineers recommended hauling Discovery back to the Vehicle Assembly Building for terahertz inspections of the other ramps.." Back in 2005 the terahertz imagers were undergoing certification test for NASA to be used for this purpose. These were pretty much field ready but they had to be certified.
Also, somewhat related to this is the big news of Terahertz imagers that are being tested at airports, to scan people for to guns, bombs, wads of cash, drugs, etc. etc. which they might be carrying on their person. So, terahertz imagers are available, now. Ti-30X (talk) 17:11, 14 September 2009 (UTC)
I'm aware of these applications, though I don't know exactly how the sources and sensors uesd were built. T-waves work well for this for exactly the same reason they're hard to work with: they pass through most materials (except metals) with relatively little interaction. You end up being able to do the equivalent of x-ray imaging and x-ray tomography with non-ionizing radiation instead of ionizing radiation. I'd bet dollars to donuts the sensor part of the scanners is very bulky, though (far-IR ones would be the most compact, but even then would probably need a liquid helium cryostat to reduce noise). --Christopher Thomas (talk) 17:37, 14 September 2009 (UTC)
I was wondering the same things - how are the sources and sensors built, and how bulky are the different parts. I will bet the NASA imager is pretty big. I have seen pictures of the airport Thz imagers - OK here is a video about terahertz imaging at airports http://www.youtube.com/watch?v=_lz819-77zY. You can see that the imager is about 8 feet tall (more or less). And, interestingly I came across one company, Microtech Instruments, inc., which "...designs, manufactures and distributes Terahertz (THz) components and systems." They have available the following, comercially available products: THz Spectrometers, THz Generators, Thz Detectors, THz Lenses & Windows, and THz Polarizers. There a couple other companies but they don't seem to have the product line that Microtech has: T-Ray Science, and TOPTICA Photonics. So, I guess, I can make a tentative conclusion that this field is still in need of development, based on what I have come across so far. But don't quote me on that. Ti-30X (talk) 18:28, 14 September 2009 (UTC)
Materialscientist - I think that book has a good overview of terahertz sources. I really get a sense of the range that is available. I get the idea that researchers are pursing the terahertz spectrum with determination. Opinion - we are truly living in a scientific age, and science will give us our best future. Ti-30X (talk) 02:38, 15 September 2009 (UTC)
Mind you, most those sources were developed long time ago. The only important recent advances are improvement and commercialization of electronic sources (high-freq. diodes and transistors).

## Terahertz Metamaterials

If no one objects I would like to do a whole article on THZ metamaterials. There appears to be enough material. In this way we could comfortably expand or expound on other categories. I will begin on a sub page using most of what is in this article on THz MM's to start with. And if there are then no objections I can move it out to Wikipedia. By the way, this will be straight science. It will be simply THz Metamaterials. I will see if I can add material to the Split-ring resonator article without taking away from the effectiveness of this article. Ti-30X (talk) 15:07, 16 September 2009 (UTC)

Here is the link to the sub page article (on my sub page): (link no longer needed) Ti-30X (talk) 03:54, 17 September 2009 (UTC)
In case some are not aware, I moved this article out into Wikipedia. Here is the link: Terahertz metamaterials. I am removing the link to my sub page.Ti-30X (talk) 02:47, 24 September 2009 (UTC)

## Groups engaged in metamaterial research

I want to move this here for reference purposes. I will keep the first paragraph in the article because I think it is worth having the information in the article. I think it is noteable enough.Ti-30X (talk) 15:15, 16 September 2009 (UTC)

The number of groups studying metamaterials is continuously increasing. For example, Duke University has initiated a Novel Electromagnetic Materials Program (NEMP) and became a leading metamaterials research center. The center is a part of an international team, which also includes California Institute of Technology, Harvard University, UCLA, Max Planck Institute of Germany, and the FOM Institute of the Netherlands.[1] In addition, there are currently six groups connected to this hub, which are conducting intense metamaterial research:[1]

• Metamaterial Radome Designs is comprised of SensorMetrix and Naval Systems Air Command (Navair), which are applying metamaterial concepts to improve the performance of radome designs. In addition, Navair is the funding organization of the group.[1]
• Metal Structures for Plasmonics and Nanophotonics is an international group that aims at studying both the fundamental propagation properties of surface plasmons, as well as developing new miniaturized nano-optical devices and components based on plasmonic structures. Funding, and also participating in research, is the Air Force Office of Scientific Research (AFOSR).[1][2]
• GHz Electromagnetic Wave Science and Devices for Battlefield Communications[1], along with the Duke's hub - NEMP, California and Colorado Universities collaborate on this project. Its aim is developing tunable devices and components capable of high-frequency operation (30-100 GHz). Funding and conducting research is also the U.S. Army Research Office.[1]
• Development of Novel Electromagnetic Metamaterials for Aerospace Applications and funded by DARPA. In this group, Duke's hub - NEMP is partnered with Boeing, ISU, and UCSD. This group supports Boeing's program on electromagnetic metamaterials, part of the larger DARPA metamaterials program that started in 2001. Selected accomplishments from this program include:[1]
• Development of techniques for retrieving electromagnetic material parameters from scattering parameter data.
• Fabrication of a free-space negative index metamaterial sample.
• Measurement of negative index of a free-space sample.
• Demonstration of a negative index metamaterial lens
• Demonstration of a negative index GRIN metamaterial lens.[1]
• A group designated as Metamaterial Lenses for High-Gain Antenna Applications.[1] funded by the Director of Central Intelligence. The head of Duke's hub - NEMP, David R. Smith and colleague David Shuring, partner with the National Geospatial-Intelligence Agency. This group has come together to "perform a detailed theoretical and experimental study of the properties of negative index lenses, which we have shown to possess a dramatically reduced geometrical aberration profile than is possible with positive index lenses. The coupling of a radiating element with a lens can form the basis of a high-gain antenna, which will be demonstrated and optimized in this program." [1]
• Scalable and Reconfigurable Electromagnetic Metamaterials and Devices. In this ONR/DARPA sponsored group NEMP has combined with MURI - the Multiple University Research Initiative.[1] This group includes UCLA, UCSD, UCB, MIT, Duke University, and Imperial College London (group of Sir John Pendry).[1] The "Multiple University Research Initiative on Metamaterials was one of the first metamaterial programs, launched in 2001. Many key metamaterial and negative refraction developments have emerged from this program, including negative refraction in photonic crystals, the concept of 'negative space' or compensation with negative index media, and the transmission line equivalent circuit of a negative index material. Novel metamaterial fabrication methods have been developed, some of which apply to high frequency (terahertz and higher) structures. Work on plasmonic lithography has also been initiated as part of this MURI program. The following key results were achieved:
• Demonstration of enhanced diffraction in a negative index metamaterial wedge
• Investigation of anisotropic negative refracting materials, termed "indefinite" materials
• Demonstration of partial focusing in an anisotropic negative refracting metamaterial
• Demonstration of artificial magnetism at terahertz frequencies
• Demonstration of a gradient index metamaterial using split-ring resonators[1]

## Journal article refrences

I have found two references in the reference section that are incorrect, so far. These are references that I added for citations. They were correct when I entered them with the templates. Somehow they have been changed where they both have the wrong authors, and a PMID number that goes to an article entitled "Association of cytokine gene polymorphisms and liver fibrosis in chronic hepatitis B". The DOI numbers are correct (were correct?). I simply deleted and re-entered one reference with the correct information (see revision history).

Actually, it is a better reference than the first one. However, I would like this situation corrected. There is no reason to add a PMID number, especially if it is inaccurate, and especially if we end up with the wrong authors. Who knows what else was incorrect. Please don't add PMID numbers if the reference doesn't already have one. Any reference that didn't have one in the first place, is because the DOI led directly to the cite of the journal that published the article. I do supply a link to the PDF when I can. In any case a PMID number is not needed and changing the authors names is not in any way helpful. If someone is in doubt about a reference then address it here on this talk page, or on my talk page. Please, do not blantantly change information in the references. Of course, now, this just occured to me that this could be a case of vandalism. Ti-30X (talk) 23:46, 22 September 2009 (UTC)

I am guessing this was just a good faith error. So, if adding a PMID number makes life easier for the reader or other interested party, then why not - go ahead. It is a good place to find journal articles. Stuff happens, and I am certainly not perfect. I apologize if I came across a little upset. This really isn't a big deal, because I doubt it was intentional. Ti-30X (talk) 22:14, 23 September 2009 (UTC)

Every reference url-linking system has its problems. DOI and PMID are considered most reliable, as they are supposed to be accurate, stable and lead you to the article abstract, instead of annoying with "buy online" options. They are also much shorter than urls. I don't know how the mix-up occurred, but it might be due to citation bot, which I did run several times on metamaterial pages. If there is a problem with pmid or doi number, the bot might pick wrong article for reference from the external database. This is very rare, but it does happen (I have encountered several broken doi during last half a year). Annoying - definitely. We can avoid using citation bots (if they are indeed a problem here), though they are useful, and are generally recommended on WP. Materialscientist (talk) 03:27, 1 October 2009 (UTC)
Posted a complaint at citation bot talk and got reply that the bug is fixed. Let me know if you notice further errors. Materialscientist (talk) 06:57, 6 October 2009 (UTC)

## Metamaterial antennas

If no one objects, I think we could do a whole article on Metamaterial antennas. Of course we would have a summation in this article and a link to the "main" article. I have just barely scratched the surface with the material that is available in this area. The same is true for Terhertz metamaterials. There are also other categories that we haven't looked at yet. Also, I would like to add more to seismic metamaterials.

In any case, this has been really good. We have included many types of metamaterials, and created a much better article. Kudos, to Wolfkeeper for writing a great introduction which provides a focus (for me) for this article. There is so much material out there on metamaterials - it is amazing. Ti-30X (talk) 03:07, 24 September 2009 (UTC)

Here is the link to the new (split off) article Metamaterial antennasTi-30X (talk) 04:41, 24 September 2009 (UTC)

## Acoustic MM's

I am thinking that it is best to go ahead and create a split for Acoustic metamaterials. This will give us more room in this article to expand into other areas, and this will give us more space to expand Acoustic metamaterials. Hopefully, no one objects. Here is the new article: Acoustic metamaterials Ti-30X (talk) 04:01, 26 September 2009 (UTC)

## Avionic metamaterials

There isn't much on metamaterials related to Avionics or Aerospace that I am able to find. So I am going to remove this as a section header. I will change it to "Tuneable metamaterials". And these are different because with previous NIMs discussed - in order to m get a negative refractive index (to operate at a different frequency) the periodicity and size of the elements would have to be changed. These type of "Tuneable metamaterials" appear to be tuneable in hand, so to speak. Ti-30X (talk) 02:31, 1 October 2009 (UTC)

## EBG

I am exapanding this section at the moment. I will be fleshing out the other sections that I have introduced these past few days. Apparently EBG's are photonic crystals (PC) and are also referred to as (PBG). I didn't realize this, and only noticed a similarity previously. I am thinking I will keep the opening line in this section say EBGs are PCs (and PBGs) and then just go ahead and use the nomenclature PC, interchangable with PBG thereafter. I also have research available on PCs that I can use for this section. Ti-30X (talk) 10:20, 7 October 2009 (UTC)

On the other hand there may be some good reasons to refer to these "band gap" structures as EBGs at certain times. Ti-30X (talk) 10:33, 7 October 2009 (UTC)

## Negative refraction in the blue-green spectral range

I added a relevant image to this section. I felt that I had to make it 335 px in size so the words in the image are readable. It helps explain what the image is, besides the caption beneath the image. It seems to look OK. Ti-30X (talk) 14:34, 8 October 2009 (UTC)

## Tunable metamaterials

Because the Metamaterial article was going over 105 kilobytes, and becasue many subsections still need to be expanded I split Tunable metamaterials into a new article. There is still plenty of information and articles available on this topic. So, this will work out fine. Ti-30X (talk) 15:15, 9 October 2009 (UTC)

## History of discovery

I would like to add some information about the history of discovery, but was curtly reverted with comments that appear unrelated to the content of my edit: no names in the lead? or some such. Then move it, don't delete it. But, yes, it needed a reference, and I shouldn't expect everyone to know the key players by name, even if they are editing this article. I would like to insert a history of discovery section, dealing with the theoretical, first experimental result, different wavelengths.

Maybe editors could discuss problems, or bring problems to the talk page, after reversions. The article needs the history of the theoretical and then experimental discovery of metamaterials to be complete. --69.225.5.4 (talk) 00:29, 11 October 2009 (UTC)

I (and user:Ti-30X) might be too quick on reverting your edit, but it did seem suspicious and you'd better come here before starting a revert chain. The issues are: (i) red links do not look good in the lead. (ii) Smith is neither first nor last author of that Science paper, which is unusual for a major contributor or group leader (this can be checked by looking in the article - Science usually tells who did what in an article, but I have very limited internet access these 3 days). In any case, it is a strong statement to pick up a middle author and say he's done it all. Besides, I personally fight adding new "prominent" names (not proclaimed by at least several secondary sources) as much as I can, and there are good reasons for that. Materialscientist (talk) 05:43, 11 October 2009 (UTC)
The red link can be fixed, either of you can post my AfC. I usually ask an editor I know, rather than waiting for AfC. When a red-link is a serious omission on wikipedia it should be fixed rather than used as an excuse to revert.
He's not the last author because he was a grad student, so it wasn't his lab. Don't know why he's not the first author, and I don't even know who the first guy is. Still, he's the one generally given credit for the microwave frequency first discovery of a NIR material.
I didn't "pick up the middle author and say he'd done it all." I can see reverting my first unsourced addition, although it worries me. I added it back with a source who said it-not OR. Not a primary source, either, a secondary source. Smith's not "proclaimed" anything, least of all by me, but it's written up all over the place in textbooks, journals, popular sciences magazines, and in newspapers he was recently all over the place in the news as a potential Nobel Laureate, which made me think of writing about NIR materials.
He's not a "new" prominent name-he's a world-class leading research in metamaterials and negative refractive indexes.
I'm not sure what's going on here, but it does not seem to be about the article? Or I've slid into another dimension. I assumed that a number of people were working on the article, the goal was to increase its usability and quality, and that that would include a history section, including the major players, and I know about Smith's work, I was surprised there wasn't an article about him, the article on metamaterials needs a history section, I started with Smith, and now... Well, my editing appears to have angered some people.
Anyway, I leave your article to you. It appears you don't like Smith, for some maybe personal reason (I don't know, and I don't get it), but probably won't like Schultz, either. --69.225.5.4 (talk) 07:26, 11 October 2009 (UTC)
Please stay calm and impersonal, we are here to improve wikipedia. Period. The rest is irrelevant. Adding name of a person, who is already listed in the references is by no means a major article improvement, but it may be Ok if supported by proper references. Please put your proposed addition here (talk page), with references. It shouldn't take much effort to see whether or not it is ready for the main article. Regards. Materialscientist (talk) 07:47, 11 October 2009 (UTC)
Thank you for making it about my emotional state, but you're off target-one of the best reasons to not make it personal in cyberspace:it's hard to be accurate, unless you're psychic. It seems personal, to me: I add a sentence, with references, and I get dynamic reasons that don't apply as to why it is reverted. Maybe the two of you can settle on a string of reasons why Smith doesn't belong in the lead section, or in the article, why the sentence doesn't belong, why a history section doesn't belong, but both of you staying away from OR (it's not, got it out of textbooks, journals, newspapers), he's red-linked (he should NOT be, and that's not a rule, so), and he's the middle author (so?). I just wrote an entire chapter of a book, and I'm the third author. There's usually a reason.
I already put my proposal in the article and here, and I included a worthy reference selected just for an encyclopedia article. So, you want me to copy and paste myself? I am getting the impression that something else is going on here. He's a leading scientist in the field, he's mentioned in the article, his institution is mentioned in the article, yet, there's a fight about talking about him in the article. Why?
This is one of the problems with wikipedia. One should never write about something in their area, because others with only partial knowledge will fight to make sure you don't. I think my going away is best in this case. The article at least is much better than it was for the work people have done, although it's off on a few points, and needs an accurate time-line. Best of luck. --69.225.5.4 (talk) 10:36, 11 October 2009 (UTC)

## Metamaterial fundamentals and theory

I have been wanting to a write a section like this, but it seems it will be a repeat of content that is already in the article in different places, including the other metamaterial articles. There are two sources that I intend to use for this. The general idea is to give a comprehensive overview of the progression toward the visible spectrum - which I don't think has been achieved. I say this because, I was reading something that seemed to say the visible blue-green capability was not repeatable (by other labs?). I will have to look into this and remove that section, if this is true. However, apparently one of the paramteters - desired permeability value(s) - has been achieved at blue-green frequencies, but negative refraction did not occur during this same experiment (demonstration).

I guess I can work on this section for awhile. If this seems redundant to you other editors please speak up, or go ahead make some edits in the section. One of the sources is referenced by citation 15 (this article is no longer referenced in Metamatrial. The sources are linked below) - and it is a good read by the way. I have to find the other article and I will note that here. Reference 16 is merely a web site, but it has a cited source and appears to be sponsored by the University of Sheffield, in England. Ti-30X (talk) 18:26, 11 October 2009 (UTC)

Here is link to the first source: Optical negative-index metamaterials Ti-30X (talk) 19:15, 11 October 2009 (UTC)

Here is the link for the second source: Perspectives on EM metamaterials

At this point I am pretty sure this section is already contained in the material produced for these articles. Personally, I can't see having this section in the article. It might be worth having as a seperate article. The second linked source, above, seems to have an interesting perspective. This was probably my inspiration for this idea in the first place. I think I will move this content to one of my sub pages while we confer. I guess my question is, should we develop an aritcle with a comprehensive overview? The overarching theme would be the strategies employed to construct different types of metamaterials that have been developed to get us closer to the visible spectrum.Ti-30X (talk) 20:41, 11 October 2009 (UTC)
Here is the link to the sub page which now has the removed content of this section. Metamaterial fundamentals and theory
Ti-30X (talk) 20:58, 11 October 2009 (UTC)
I made a note that the article cited by #15 is no longer refereneced in "Metamaterial" and I removed the link. Ti-30X (talk) 22:20, 11 October 2009 (UTC)
In other words, #15 (and #16) references something else. Ti-30X (talk) 14:16, 12 October 2009 (UTC)

## Magnetic response claim is not supported by reference

The statement "A recurrent issue with either naturally occurring, or conventional materials, is the lack of magnetic response." does not seem to be supported by its reference, which states that there is a magnetic resonance in an array of single nonmagnetic metallic split rings. It seems to me that a resonance is certainly a "response". In fact, the reference indicates that it is precisely this magnetic response that can create a negative index of refraction. David spector (talk) 18:11, 14 October 2009 (UTC)

The statement is false. Feel free to delete in the future. Maybe this sentence was read incorrectly, "however, a large magnetic response, in general, and a negative permeability at optical frequencies, in particular, do not occur in natural materials." --69.225.5.183 (talk) 19:30, 14 October 2009 (UTC)

## NEMP

Google search results for "Novel Electromagnetic Materials Program" are zero, outside of wikipedia, so let's not perpetuate it to wiki mirrors. Why no hits? Because it's not the name of the program you are talking about. You can't just make up an acronym and assign it-well, you can and did, but that's OR and not part of wikipedia.

Don't return the statement about the program with the acronym you assigned it. And get its name correct. If the program is renamed in the future, feel free to use this. But, until then, use the real name, not a name and acronym of your choosing.

Notice the reference I used is referred to in the same way I and everyone refers to the paper, "Smith, Schultz et al."[3] Mine wasn't original research. OK, ask me to add a reference, but when I do, don't delete because you aren't familiar with the field.

This is a small complaint in light of the factual inaccuracy in the theoretical and technical aspects of this article, but, it's my bone. --69.225.5.183 (talk) 19:23, 14 October 2009 (UTC)

First of all please change the tenor or tone of your feedback. It sounds like you are giving orders.
Coming from the sort of Wikipedia editor you appear to be, that's rich. Wikipedia is the home of so many I'm-called-Editor-and-I've-got-Power 'editors' that it always raises a smile amongst readers to see them get into an emotional strop, oblivious to the irony of what they are doing. And, yes, by the way... this observation does contribute to Wikipedia by raising the profile of rogue 'editors' motivated by ego and short in knowledge, understanding and intelligence.
Second I found the program with a google search. It is the seventh entry using this search phrase without quotations - Novel Electromagnetic Materials Program. Here is the link: Novel Electromagnetic Materials Program. Below the David R Smith main entry there is a jump link right to the exact page that I have a reference and a link for. I will be restoring this material. I had it referenced and linked. My link in the refernce proves that it exists and there is a plethora of research going on there. If you click on the link in the reference it will take you right to the page. I don't believe a Google search page qualifies as WP:RS, by the way, and does not prove the worth of this entry either way. The reference itself shows it to qualify for WP:RS and that it is not WP:OR Have a good day now. Ti-30X (talk) 06:05, 15 October 2009 (UTC)
You're kidding me, aren't you? Nowhere on that page you link to, does it call it the "Novel Electromagnetic Materials Program" because that is NOT what it is called. Go, ahead, and prove me wrong by coping and pasting exactly that phrase from that web page. It's not there. Find the acronym on the page. You're making it up!
You're making stuff up and inserting it into a wikipedia article and then fighting to keep it. Sounds like vandalism to me. What tone is appropriate for use with a vandal?
Just copy and paste that group name from the page. Search the DUKE webpage with google. The reason the name isn't anywhere with google is because YOU made it up! You made it up! You attached the word "program" to the end of the name of Smiths' research group, assigned it your very own made up acronym, then posted it to this article!
[4]
Smith's research group is called "Novel Electromagnetic Materials," and you keep adding program to that, because you're not reading Smith's page, you're just glancing at it, and, now, you've titled his research group NEMP, your very own acronym. No one will find that at Duke, unless and until Smith changes his group name to fit your reading.
Your article is very badly and inaccurately written, also, by the way. You should spend some time getting help on the basic physics, instead of making up acronyms and fighting to get your OR onto wikipedia. I've asked other editors at WP:physics to help out with the basic physics, but I can't see anyone coming here with something like this going on, having to fight you to keep out made up acronyms. Making the basic physics accurate would improve this article greatly, before you even move to the problems with the metamaterial information. Also, you might read WP:OWN.
Until you can copy and paste the phrase you made up, exactly as you made it up, showing the acronym you made up, it stays out of this article. This is wikipedia, not whateverpedia. --69.225.5.183 (talk) 06:51, 15 October 2009 (UTC)
You seem to enjoy finding misprints :-) Very useful for wikipedia. Thank you. I would change "program" to "group" in the article, as stated here and go do something more productive. Materialscientist (talk) 07:05, 15 October 2009 (UTC)
Then what, assign the acronym NEMG? The research group is just called Novel Electromagnetic Materials. That's all.
Useful, imo, would be to rewrite this article and make it reflect current physics, so readers don't come here and learn that magnetism isn't a naturally occurring phenomenon.[5] As a paleontologist (not a physicist) you can bet I was surprised to learn that. It's not productive in the least to leave an article in the condition this is in, and it's not productive to allow made-up acronyms to perpetuate in cyber-space. I've looked at some of your substantive article edits across wikipedia, Materialscientist. You're either not reading Ti-30's edits, or I don't know what. Probably the latter. --69.225.5.183 (talk) 07:14, 15 October 2009 (UTC)

I think the name changed to Novel Electromagnetic Media. http://people.ee.duke.edu/~drsmith/index.html YMMV. Rich Farmbrough, 04:31, 16 October 2009 (UTC).

Rich - this is the page that is being refered to: Novel Electromagnetic Materials. However, the page that you linked to is another good one. Ti-30X (talk) 10:37, 16 October 2009 (UTC)

## Photonic metamaterials

The size of the "Metamaterial" article has nearly reached 104 kilobytes. Therefore I split the content of "Photonic metatmaterials" off to a new article entitled Photonic metamaterials.

In addition, I think it would be a good idea to somehow shrink the peliminary information in Seismic metamterials. I mean the general concepts such as S waves, P waves, Elasticity, etc., etc. Since this article could use the space, and since there are already good articles about these concepts, whittling this down, imho, is appropriate. Also, of course, I want to add more content about Seismic metamaterials.

I am wondering if it would be a good idea to move most of the material in the SRR section over to the SRR article. I would rather keep it in Metamaterial, but we could probably use the space.

I came across some research into a type of metamaterial that the army is working on, and I think this would certainly make a fine addition to the "Metamaterial" article. Ti-30X (talk) 22:16, 15 October 2009 (UTC)

## Restoration

I restored the blurb about Novel Electromagnetic Materials without the "P". However, program is used in the section entitled "Current Programs and Overviews." There is also Programs, Collaborators, Funding, and "Research group" are all used on the top part of this page. Each section contains exciting work that is ongoing in metamaterials, in many organizations.

I never wrote "magnetism isn't a naturally occurring phenomenon" anywhere in this article. That would be ridiculous. This particular paragraph has been misunderstood. It is about "magnetic response". It is not about magnetism. I wrote "A recurrent issue with either naturally occurring, or conventional materials, is the lack of magnetic response. Such materials are particularly rare at Terahertz or optical frequencies.[3] However metamaterials are helping to fill this gap." I never wrote magnetism isn't a natural occuring phenomenon. A different meaning has been mistakenly read into this section. This happens all the time with people everywhere about anything. In any case, I can supply peer reviewed journal articles that reiterate what I wrote. It would not be in this article if I could not back it up. Ti-30X (talk) 23:57, 15 October 2009 (UTC)

## "Lack of" does not equal "lack of large"

Not only is that not "basically what you wrote" it shows the problem with this article. You own the article and you won't allow others to correct your glaring errors.

Just because someone's page says the word "program" on it, does not mean that's part of the name of the research group, and doesn't make it the official acronym just because you made up an acronym.

Not even in quantum mechanics does none mean small.[6] You have dozens of problems of these types throughout the article. You're reading books and partially copying from them into this article without any understanding of what they say. Overall the information you've put in this article is factually inaccurate and internally inconsistent.

It took me a week to get you to stop fighting over your renaming of Smith's research group. Nothing, like the fact that wikipedia requires reliable secondary sources and none exists, could get you to see the reason the made up name you applied to the group isn't on the page or in any google searches or anywhere but on your page and copied from your article is that it isn't the name of the group.

Now we've learned from you that "magnetic response" has nothing to do with magnetism.[7] It is about "magnetic response". It is not about magnetism. See above.

There's no way anyone could spend two weeks for every physics error in this article while the article is being copied throughout cyberspace, and people are probably reading it, and its factual inaccuracy is not a concern to anyone, least of all its owner.

The article should be pared down to a stub, rewritten out of article space, and reposted when it has accurate physics.

Yes, no article is better than giving irresponsible made-up, and partially copied random pieces of information to the readers. Wikipedia has a responsibility for accuracy now that it dominates the search engine returns.

This is unbelievable. But, eventually the Essjays are all found out. He was at least embarrassed about it in the end.

When someone fights you for days to keep in a made-up acronym, and then returns that "lack of" is the same as "lack of large," and that "magnetic response" has nothing to do with magnetism, and is writing a wikipedia article that's being copied throughout cyberspace, it's time to stop AingGF and beyond time to start being concerned for the reader.

--69.225.5.183 (talk) —Preceding undated comment added 15:53, 17 October 2009 (UTC).

## Seismic metamaterials

Surprisingly, I haven't acutally found much more information than I have written for Seismic metamaterials. I could use the main peer reviewed article "Achieving control of in-plane elastic waves" and elaborate some of the articles that are numbered as references for the science involved. However, much more than this is really not available. I suspect it is because this is really new science. The last word that I have so far is this type of metamaterial is in the development stage. So, I can add more as more material becomes available. In the meantime this section is probably best merged with "Acoustic metamaterials", with a small summary left behind. Again, we can use the space. Thanks Ti-30X (talk) 01:49, 19 October 2009 (UTC)

I decided to go ahead, and create a new article for Seismic metamaterials. These type of metamaterials are distinct from Acoustic metamaterials, even though similar materials and physics concepts are employed. Ti-30X (talk) 17:16, 20 October 2009 (UTC)

## Perfect lens

I recently split content from Metamaterial lens to the new article: Perfect lens. This will pretty much cover Metamaterial lenses up to the present, including microscopy. Steve Quinn (formerly Ti-30X) (talk) 15:55, 1 November 2009 (UTC)

## Incident wave

I couldn't find anything in wikipedia physics articles that acutally describe what an incident wave is. So here is a section with a brief, and simple description. Please feel free to add to it, or tighten it up if need be. Steve Quinn (formerly Ti-30X) (talk) 01:28, 4 November 2009 (UTC)

This section is completely inappropriate and not very helpful. Terms such as "incident wave" should be explained under a page on optics, electromagnetics or wave theory. It is definitely not specific to metamaterials and the definition given here is not very clear. I suggest that it should be deleted ShiftyDave (talk) 01:10, 23 December 2009 (UTC)

## Nonlinear metamaterials and Controllable magnetic response...

I moved these two sections to the SRR article. It was the most available place at the moment. More than likely Nonlinear metamaterials will become an article, and the articles concerning controllable permeability might be moved to other articles. This merge allows "Metamaterial" to be a regular article once again. Other, future, metamaterial content can be linked to this article. Steve Quinn (formerly Ti-30X) (talk) 04:58, 5 December 2009 (UTC)

Nonlinear metamaterials are not necessarily based on split ring resonators, so moving the material there is not necessarily appropriate. I have added a brief intro to the topic to the main article. I agree with your suggestion to create a separate article on nonlinear metamaterials. ShiftyDave (talk) 01:10, 23 December 2009 (UTC)
I agree that nonlinear metamaterials do not neccessarily belong in in the SRR article. I moved it there so this main "Metamaterial" article could move on and just be its own article. In fact, it is almost time to remove the under construction template for this article. In addition, there are nonlinear metamaterials that consist of SRRs so it is an OK to place to keep them there temporarily. Thanks very much for your input and efforts so far. Steve Quinn (formerly Ti-30X) (talk) 02:44, 23 December 2009 (UTC)

I removed the section "Applications in paranormal research" as probable spam, and as suggested by - User:2over0. An appropriate suggestion imho. Steve Quinn (formerly Ti-30X) (talk) 04:58, 5 December 2009 (UTC)

## Consensus

I appreciate good faith efforts. And the topic of the section where material was removed and then replaced by a blurb on Chiral metamaterials was apparently misunderstood. This section is not about only Chiral metamaterials. As a solution, I replaced the material, which is accurate, and created a section for Chiral metamaterials. In the future, please consult with the other editors involved with this article before removing material so we may achieve some kind of consensus. If this had been discussed first, the topic of the section would have been understood.

Having said, that please feel free to write an article on Chiral metamaterials. This is on my to do list, but, personally I don't know when I will write an article on Chiral metamaterials. Thanks again for the input, and knowledgable editors are always welcome.Steve Quinn (formerly Ti-30X) (talk) 02:53, 23 December 2009 (UTC)

The section on handedness is currently highly misleading. It talks about the difference between left and right handed circularly-polarized waves. This is only relevant to chiral metamaterials. Therefore almost all of this section should be under the chiral metamaterials heading.
There were a couple of paragraphs on the concept of left-versus right handed in terms of the set of vectors given by E, H and k, which is the alternate meaning of the term. This material is related to negative index, however it is already covered in the negative index section, so I deleted it to avoid duplication. There are a couple of notes emphasizing the difference between the two terms which can clearly confuse the reader - as it seems to have confused you. This is quite understandable, so I am not trying to have a go at you.
At any rate, the changes I had made meant that the article was factually correct and did not confuse the two meanings of handedness. By undoing them you have made the article misleading, so please restore them. ShiftyDave (talk) 06:50, 23 December 2009 (UTC)
This section is meant to give the reader a sense of the concept of handedness, because left-handed (negative index) materials are so very important in metamaterials. I admit that my reading has been mostly "direction of propagation". Until you brought up this issue I hadn't looked at wave polarization, specifically, unless it was incidental to my research - not since I wrote most of this section awhile ago.
I did a brief review of one of the sources in this section and it appears that these are two seperate definitions for handednes, inadvertantly meshed together. This is my first thought at the moment. Since this hasn't been more pronounced in my other research I wasn't aware of it. It looks like I may have confused the two, as you say. In any case, for now, I did some minor editing to reflect that left handedness can be defined in terms of either wave propagation or wave polarization - as with chiral media.
I will do further research on this matter. I think the section needs to be renamed as well. I will also look at Chiral metamaterials (or Chiral media) to obtain more accurate definitions. This section may be need to be re-written. I will look at the section on Negative refractive index, but I don't think it covers handedness the way this section can for the general reader. Thanks for your input. Steve Quinn (formerly Ti-30X) (talk) 16:05, 23 December 2009 (UTC)
It seems evident from your comments that you are still trying to learn this area yourself. Surely you should be willing to accept corrections from people with expertise in this area when the material is in error or misleading in some fashion. The two definitions of the issue of handedness should be in the relevant places under chiral metamaterials (for the definition based on circular polarization), and under negative index media, for the definition based on the k vector. If you check out the definitions in Veselago's paper, and any book on chirality you will see that the definitions are quite distinct. Also it should be noted that much of the material relevant to chiral metamaterials is not specific to metamaterials, and should probably be under a separate page on electromagnetic propagation in chiral media (perhaps as a section of Chirality (physics)). The concept of handedness related to negative refraction was in fact introduced in Veselago's paper, because until you consider a negative index, then there can't be any left-handed media (in this sense of the word), so there is no point in making the distinction. ShiftyDave (talk) 03:03, 24 December 2009 (UTC)
Based on what you just wrote, I have no familiarity with Chiral metamaterials and it will take awhile to get up to speed. Yes, of course I am willing to accept corrections from people with expertise in this area. I am glad to have you aboard, and I am of course willing to work with you. Please, just don't expect all the changes to occur in one day. From what I read today the concept of handedness is much more related to Chiral metamaterials than Negative index metamaterials. The term "left handed material" for Negative index materials seems to be almost a mis-nomer, except for the occurance of negative index.
I am beginning to see that the two definitions are distinct. Your statement "...much of the material relevant to chiral metamaterials is not specific to metamaterials..." is baffling but very interesting. On that note I just started reading this article - there is a link to the PDf provided:
My point is that there are many chiral media out there in nature, not just metamaterials, so this is a topic which warrants its own page. Indeed you have mentioned examples from nature such as DNA etc. Although there are other pages on chirality they are not relevant to electromagnetism so I have created another page under chirality (electromagnetism).Currently this is just a raw copy of your text, but at some stage I will fix it up to add more relevant material. Also, please note that the fact that all natural media are positive index (hence right-handed in this sense), and the fact that most natural molecules have right-handed chiral symmetry, are not related and are based on different definitions. ShiftyDave (talk) 13:01, 24 December 2009 (UTC)
{{#invoke:Citation/CS1|citation

|CitationClass=journal }}

I realize that it was Veselago who coined the term Left handed substance or left handed media. We are in an electromagentically right handed world, so when negative index of refraction was first demonstrated it was, and still is revolutionary.
At around the same time you were leaving your message on this talk page I noted that after what I have read to day I could see where you get the idea that this section is mostly related to Chiral metamterials, with a couple of notes regarding negative index. However, it appears to me to be a round about way to lead up to a description of Chiral metamaterials. This would be good as a history of concept section after the introduction in a seperate "Chiral metamaterials" article. I would prefer a more direct description to start out with, and one that could be placed the Chiral metamaterial section at this time. I would rather not take up space in this article about handedness in general, if it is only regading Chiral metamaterials. On the other hand, (no pun intended), this section might be useful to the general reader in some way. What do you think? And do you have a more direct description available? Steve Quinn (formerly Ti-30X) (talk) 04:06, 24 December 2009 (UTC)
Ok I edited the section back to what you wrote, entitled "Chiral artificial materials". It seems to make more sense. Also I have to agree that material related to Negative index metamaterials would be duplication, so I moved it out of there and into "Negative refractive index" for further editing later. Thanks for your input. Steve Quinn (formerly Ti-30X) (talk) 04:44, 24 December 2009 (UTC)
Thankyou. You will see that I have re-organized the material to combine the chiral metamaterials and chiral artificial media sections, as there is no reason to make a distinction. In addition, I have added some clarifying text, and linked it to the paragraph on bi-anisotropic media, as bi-anisotropy and chirality are very closely related (both involve magneto-electric coupling). So all the material is now under the correct headings and should no longer cause confusion to the reader. However there is probably still some work to do on readability, plus I think the concepts of bi-anisotropy and chirality really need to be explained with equations showing the relationships between D, B, E and H. ShiftyDave (talk) 13:01, 24 December 2009 (UTC)
You did an excellent job with this material. Your expertise is appreciated (and needed). Steve Quinn (formerly Ti-30X) (talk) 00:34, 25 December 2009 (UTC)

I am proposing to clean up negative index metamaterials, and move much of the negative index material to there. This includes the double and single negative stuff, which is a fairly in-depth distinction that is only relevant to negative index. However some negative index stuff should definitely still be left on this page, as it is one of the major areas of metamaterials work. ShiftyDave (talk) 01:29, 25 December 2009 (UTC)

This page is now starting to look much better. However, the section titled "Incident Wave" seems very bizarre and unnecessary. Firstly, this term is used widely in microwaves/optics etc and is not specific to metamaterials. Secondly, this section is just duplicating material from Electromagnetic Spectrum. So I am proposing to delete it and add a link somewhere in the introductory paragraphs to Electromagnetic Spectrum. ShiftyDave (talk) 23:55, 28 December 2009 (UTC)

I don't have a problem with your removing it and adding a link. I noticed the other day that it seems to interrupt the continuity of the article, anyway. Also, I don't have a problem if you want to steamline material related to NIMs in this article and merge most of it over to the Negative index metamaterial article. Steve Quinn (formerly Ti-30X) (talk) 02:54, 29 December 2009 (UTC)
If you think the concepts of bi-anisotropy and chirality really need to be explained with equations showing the relationships between D, B, E and H then feel free to add these. Steve Quinn (formerly Ti-30X) (talk) 03:11, 29 December 2009 (UTC)

## References to continuum mechanics

I noticed that the continuum mechanics (CM) navbox (Template:Continuum mechanics) was used on this article; but when I read the section it was used in, the connection / relationship to CM seemed pretty tenuous (I am a casual reader of this article only - maybe it would be obvious to experts). The section ([8]) was the summary for Acoustic metamaterials. Normally, the navbox is used in a fairly prominent position in an article to set the broader context for the topic. It is unusual for it to be placed so far down in a relatively minor section within the broader article, and without explanation.

I think it is important both to make sure the navbox is well used and that the broader context for the article within CM is set.

Fluid mechanics might be a good example of how the navbox is typically used. (Note there is a section which specifically defines its relationship to CM, which is particularly helpful in that instance).

The navbox is also used in the acoustic metamaterials article, but again it isn't very prominent ([9]) and the connection is only made in a vague way in another section ([10]).

I was however kindly informed by user Steve Quinn that there is a definite relevance of continuum mechanics topics to (acoustic) metamaterials, and so to me as a new reader it seems important to set that context more explicitly. I also think consistency with other articles is sensible, where it makes sense.

So I had a few suggestions:

• Expand the summary section for acoustic metamaterials in this article to briefly mention the context and connection to continuum mechanics
• If metamaterials overall has a strong affiliation to continuum mechanics:
• move the navbox up to make it more prominent;
• add a summary of how metamaterials relates to CM, perhaps in the lead
• Metamaterials could even be added to the navbox if appropriate
• Otherwise, remove the navbox from metamaterials.

The same points should be considered for acoustic metamaterials.

Thoughts?

Thanks!

David Hollman (Talk) 08:53, 24 August 2010 (UTC)

• Once again, thank you for your interest in metamaterials. Very broadly, and in this context, metamaterials can be classified into two types. One is Electromagnetic metamaterials, which has the electromagnetism navbox in that section. The other type --- Acoustic metamaterials and Seismic metamaterials --- relate to other properties, such as elasticity (Hooke's law), deformation, bulk modulus, surface tension, etc. etc. Some of these properties turn out be analogous to electromagnetic properties in metamaterials, but they are not the same thing. In a sense it is apples and oranges within the domain of metamaterials.
I don't think it would be appropriate to add metamaterials to either navbox, as these are based on the properties discussed in both navboxes. It would probably be the same as adding any particular technology, which is developed from application of these properties to the navboxes. For example, radio antennas come to mind. These are an electromagnetic technology, but really don't belong in the electromagnetism navbox. Perhaps the same could be said for television, an electromagnetic technology. ---- Steve Quinn (talk) 18:00, 24 August 2010 (UTC)
Steve, thanks for your detailed and considerate reply! Metamaterials are a new topic to me, and I appreciate your input. I see no problems whatsoever with your approach to the navbox, and thanks for making the edits to these pages. I also agree with your comments on placement within the navbox (the antenna analogy does seem a good one; the navbox is not about applications). I think this has improved the context of the topics wrt CM. Best, David Hollman (Talk) 19:23, 24 August 2010 (UTC)

## Critiques

Strong critiques have been made in the literature on the subject of metamaterials. To this day, some of these critiques have not been answered, and a reader of this page might benefit from knowing that not everyone accepts the current views on metamaterials, and in particular on negative index.

Relevant resources include:

1- Vadim A. Markel, "Correct definition of the Poynting vector in electrically and magnetically polarizable medium reveals that negative refraction is impossible," Opt. Express 16, 19152-19168 (2008)

2- Benedikt A. Munk, "Metamaterials: Critique and Alternatives." —Preceding unsigned comment added by Baptiste.auguie (talkcontribs) 16:55, 30 October 2010 (UTC)

## Metamaterials on Fabrics

Just to let those of you who edit this article, that a team at St. Andrews University in Scotland have developed Metamaterials on to fabrics. Before ths they were only found on flat hard surfaces. link here [[11]]. Krásné nápady (talk) 10:53, 4 November 2010 (UTC)

## spacecraft antennas

http://www.lockheedmartin.com/news/press_releases/2011/0215_ss_Metamaterials.html “We are extremely excited about the outcome of this collaboration, which represents a game change in the field of metamaterials,” said Werner. “In particular, we have succeeded in designing metamaterials that considerably improve conventional horn antennas by more than an octave bandwidth with negligible loss, and advanced the state-of-the-art in the process.”

Which type of metamaterial is this? Hcobb (talk) 13:48, 16 February 2011 (UTC)
This is a metamaterial antenna. FYI, this article is written in a highly promotional tone. There are already pratical real world metamterial antennas that are commercially produced for wireless systems. So, it might be best to try to glean the facts and eschew the hype pertaining to this article. Hopefully this is helpful. ---- Steve Quinn (talk) 15:35, 16 February 2011 (UTC)
Also, it appears that only prototype has been built, so it is still in the lab. I surmise that a promotional article like this needs to be written to justify the investment. I think the bottom line is - this is more research, and probably only an incremental advancement. I hope this helps also. Thanks for your interest in the metamaterials articles. ---- Steve Quinn (talk) 15:44, 16 February 2011 (UTC)
Here is another article [12]. This tone is more sedate, and the facts are somewhat clearer. Keep in mind, that when the press carries stories of these novel devices the achievement tends to be inflated to be more than it is. ---- Steve Quinn (talk) 16:07, 16 February 2011 (UTC)

## Copyedit/reorg

Taking a run at this. Feedback welcomed. Comments:

• The inclusion of photonic crystals is confusing. They don't appear to fit the definition of a metamaterial and their WP page doesn't call them one. Conversely, LHM are mentioned but not discussed in the classes section.
• DPS aren't metamaterials, either, according to the engineered, sub-wavelength definition. Do we need a broader definition or should the piece note that they are included for contrast only.
• Shortened section headings (again). These headings need not exactly match the titles of articles that they summarize. They are for the convenience of readers of this article, for whom seeing the word metamaterial over and over is nothing but visual noise.

Cheers! Lfstevens (talk) 04:58, 2 January 2014 (UTC)

## Unintelligible techno-speak: Article needs more parallel non-technical language for the lay reader

Wikipedia is an online encyclopedia for the general public. That is why Wikipedia policy requires that, wherever possible, non-technical language be used in parallel with technical language in its articles (translating and clarifying as much as possible for the lay reader).

This is also good practice for scientists who need, for many reasons, to know how to communicate about their field to non-scientists.

It is also good manners not to communicate in a cryptic, self-absorbed way to people who are not scientists.

2602:306:BDA0:97A0:466D:57FF:FE90:AC45 (talk) 16:07, 25 February 2014 (UTC)

1. Template:Cite web
2. Air Force Office of Scientific Research (AFOSR)
3. Cite error: Invalid <ref> tag; no text was provided for refs named at-100-Thz