Chinese researchers have successfully built an electromagnetic absorption device for microwave frequencies. The device, which consists of 60 thin and dense cylindrical rings made of metamaterials is able to absorb microwave radiation, thus it is similar to what in astrophysics is called a "black hole" (which absorbs matter and radiation)
The study, which was published in the New Journal of Physics, shows how the scientists took advantage of the unique properties of metamaterials, which are a group of artificial and ordered materials that can distort light and other waves.
Qiang Chang together with Thi Jun Cui from Nanjing University in China designed the adsorption device known as the "multi-directional electromagnetic absorber", using an electrical board that contained 60 strips of copper circuits close to each other. Embedded in each layer are changing patterns, which create resonant or non-resonant electromagnetic waves.
The device can capture and absorb electromagnetic waves that come from all directions by tuning the radiation inward and turning its energy into heat, 99% of which is absorbed by the device. In this way it behaves like an "electromagnetic black body" or an "electromagnetic black hole".
Currently the device only works on microwaves. The next step for the researchers is to develop a black hole device for visible light waves.
The latest results of the research can be applied in applications in the field of microwaves. The article states "there is an overall agreement between the theoreticians and the experimentalists regarding the superior capabilities of metamaterials as candidates for the construction of multidirectional radiation absorption devices".
"Since the core can convert electromagnetic energies into thermal energy, we expect the device to have applications in the field of thermal emission and absorption of electromagnetic waves."
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Everyone will have a black hole device to create electricity. This way the problem of the electric company will be solved once and for all.
When there will be a real black hole with Hawking radiation then all the political bullshit surrounding energy sources will be obsolete.
Lies!
The Chinese don't know how to make a radio that will work properly, so a black hole?
Here is a sample article published just two months ago:
http://www.nature.com/nmat/journal/v9/n5/abs/nmat2747.html
And the explanation in human language....:
http://www.amolf.nl/news/detailpage/back_to/news/article/optical-metamaterial-with-negative-refractive-index-for-visible-light//chash/7df92703a2/
Again the idea is not to use the chemical properties of the material, which are very significant in material design. but instead create entirely new material properties. This is done by creating structures in the material that respond to incoming radiation actively instead of passively. Formed from a vibrating field that changes the way light propagates inside the material. In optics, a negative refractive index means that the light entering a denser medium is bent in the opposite direction to the positive one - the direction we are used to. There is no such thing in nature and it is created only by engineering the material. But there is a problem common to all these engineered materials: the properties are frequency dependent. This means that a single metamaterial that is prepared to operate at microwave frequencies will not block visible light or radio frequencies.
Ehud and whoever asked,
It is easy to create metamaterials that reverse microwave waves, because it is just a matter of arranging the components, such as the conductive wires and the tiny rings and the other components inside the engineered array on a tiny size scale, that is, on the centimeter scale.
But the question is, will such structures work for visible light? Because then they must be shrunk to the nanometer level. Then the electrical properties of the conducting metals no longer match the wavelength of visible light. And then what happens is that instead of the careful planning that was good at the centimeter level for wavelengths in the microwave range, now that we have reduced it to the nanometer level, it may not work at the wavelengths of visible light.
So some say that it may or may not be possible to build metamaterials with a negative refractive index for visible light. We may never be able to produce metamaterials with an effective negative refractive index for visible light. Others are still looking for arrays of structures in the nano field, such as nanowires, nanoparticles and all kinds of nanostructures that are combined with different materials so that they work as perfect metamaterials with a negative refractive index for visible light. And every time a new study emerges that announces: we have found a metamaterial that hides visible light. Here is the new invisibility cloak. Then science newspapers announce the discovery and a picture of Harry Potter appears...
Metamaterials generally have a property that depends on the structure of their components and not on the properties of the materials they are made of. And so it is thought that they can make light do all kinds of things that are impossible with natural materials, such as bending it backward and giving it a backward Doppler effect.
Father, I thank you for your learned answer
Now I can sleep peacefully without you disturbing my rest
I guess the reasoning behind the decision to change the logo is that the Earth is a more sympathetic thing than an asteroid;
On the other hand, the earth is not so sympathetic anymore and in the next round I suggest changing the logo to a kitten or a goat
Yael, thank you
I still don't understand what gives metamaterials their special optical properties, i.e. how do you produce a material with a negative refractive index? Why is it a problem to produce a metamaterial with a negative refractive index in the visible range?
And what is the dimension of the black holes created in the laboratory. Astronomical black holes "live" in four-dimensional space What about the black hole created by the Chinese scientists? From the picture, I would expect that it would behave like a black hole in one spatial dimension (radial), but this is just speculation.
Sonne, the scientist's logo was a rocket until about a year and a half or two years ago.
This is all well and good, but there are things that are more disturbing...
Is it true that when you enter a page in the browser, it gets its own icon (such a small one), so the scientist's icon is a missile, right? It looks like a missile to me but I'm not sure
On the main page the logo of the scientist is the earth at all I'm all confused =(
Thank you for your learned opinion
Given that metamaterials are not superconductors, it seems that their temperature should
rise following their irradiation at the microwave frequencies.
So they most likely emit infrared radiation following the rise in temperature.
It's not really a black hole.
I looked at the original article
http://iopscience.iop.org/1367-2630/12/6/063006/pdf/1367-2630_12_6_063006.pdf
Apparently no energy is invested in it, but in any case it's not a problem to turn waves into heat energy, that's what happens in solar cells. Metamaterials may have added value in this area, but I don't think that's the point.
The stated ultimate goal of the researchers is to create an optical device that will absorb spiral waves at certain frequencies.
It will finally be possible to disprove or confirm Hawking radiation
Perhaps there is a possible use here in the future in the field of energy as media that picks up frequencies in a certain field and turns them into usable energy? Is it required to put energy into this black hole for it to absorb electromagnetic waves?
sympathetic,
Metamaterials are artificial materials engineered to provide properties which may not be readily available in nature. These materials usually gain their properties from structure rather than composition, using the inclusion of small inhomogeneities to enact effective macroscopic behavior.[1][2][3]
From Wikipedia
http://en.wikipedia.org/wiki/Metamaterial
What is important here is the arrangement of the material particles more than their chemical composition - this gives them certain properties that are impossible or very difficult to find in natural materials.
jelly
Your comments are very interesting and raise many questions for me.
I didn't understand why exactly in the visible field metamaterials have a problem? That is, why exactly in the visible field do metamaterials not absorb? There is nothing mystical about the visible field as a whole, it is a specific region of the electromagnetic spectrum.
I assume that the negative refractive index causes the light to fade within the material but I would love to hear more about
The meaning of materials with a negative refractive index. What apart from the refractive index distinguishes them from ordinary material?
You mentioned that metamaterials are engineered using nanotechnology, why is nanotechnology needed for this? Why is it not possible to find substances with this property in nature or simply synthesize them chemically?
By the way, you talked about a mathematical transformation between the metric in general relations and the space of optics. What dimension is it about? In general terms the matrix is a 4 x 4 matrix (like the jeep) what is the dimension of the optical black hole? It doesn't seem to me that there are enough degrees of freedom to produce an analogy for a 4-dimensional matrix.
Regarding metamaterials for stealth purposes, for those who are interested:http://www.popsci.com/technology/article/2010-06/metamaterials-are-new-black-and-perhaps-new-stealth (Recently published in Popular Science).
There is an interesting piece of news in the field of electromagnetism (a breakthrough in the field of small magnetic resonance scanners) (not really related to the above article, I just wanted to spread the word): http://www.popsci.com/science/article/2010-06/breakthrough-could-shrink-nmr-magnets-room-size-palm-size
What is a "Sony Black Hole"? Are there Shiite black holes??
The invention is not a step on the way to "invisible" abilities
In fact, substances that absorb radiation in the visible range have been known to science for a long time. These substances are usually referred to by the not-so-scientific name "anything that is black in color"
Indeed, painting a body black will make it difficult to distinguish it by optical means in a dark environment (it is difficult to see it at night), but from here to "invisible" there is a long way to go.
(:
sympathetic,
I wanted to consult you on a certain subject, if you could please
write to edlmagnets@yahoo.com
Sorry for disturbing the other readers.
Thanks
Maybe if they manage to build one that absorbs ionizing radiation it will be possible to properly shield manned space travel
Xiang Zhang - known for his research in metamaterials - from the Berkeley Lab in California also built a model for an Earth black hole: http://www.notes.co.il/gali/58706.asp.
It is worth remembering that this is a model. This is an optical-mechanical analogy. Zhang took a metamaterial that operates in the infrared range: Gallium Indium Arsenide Phosphide GaInAsP and he used the well-known property of metamaterials that distort light waves.
Mathematically, this is expressed with the help of transformation optics: transformation optics.
The researchers began to think about electromagnetic space-time in analogy to the optical space - this is the transformation optics for materials with a negative refractive index. That is, coordinate transformation, on the light paths in curved lines in a grid of transformed coordinates and all this for the electromagnetism in metamaterials engineering.
In any case, in the case of metamaterials, it is about engineering at the nano level of the material. It should be like that here too. True Jeff Steinhauer built a Sony black hole and continued a tradition of research in the field of Sony black holes. At the time I published an article about it on Ynet:
http://www.ynet.co.il/articles/0,7340,L-3734068,00.html
There is a problem of switching to visible light waves in general in metamaterials. There were studies that announced: we have succeeded in creating metamaterials that hide in the visible light range. But there is always some problem. It seems that the Harry Potter-style maidens' cloak or the invisible Danny Dean will have to stay in adventure books. Or alternatively a black hole... will not be discovered on Earth.
This is not the first "black hole" to be created, even here in Israel an acoustic "black hole" is created in a lab at the Technion (Jeff Steinhauer's lab). Yes, this is the first black hole created that absorbs electromagnetic radiation.
R.H.
There is some truth in your words, but it is necessary to understand the wider context. The science of astronomy and astrophysics deals with observations and the researchers have almost no possibility to perform experiments. For example, there is an amazing prediction about black holes that has not yet been observed, the halo is Hawking radiation (some claim that Hawking will win the Nobel when it is discovered). It is in this context that the attempt to create researchable models of astronomical bodies in the laboratory must be understood.
Eliyahu
It will take a long time for this experiment as described to yield technological achievements. In the context of a stealth plane it is more natural to think about the invisibility cloak experiment reported here in the science of making objects transparent. A black hole is very easy to identify, no light comes from it!
In my humble opinion, this is just a populist title. What is the connection between what they developed and a black hole? A black hole is a body with a large mass, as a result of which the escape velocity is greater than the speed of light, so nothing can escape from it. Is therefore everything absorbed a black hole? Is activated carbon a black hole? Is a sponge a black hole?
As it sounds, I assume that it will be possible to create "invisible" abilities from this, after all evidence is based on the reflection of the photons that hit the surface, but what happens when photons do not return?... Interesting?! indeed…
As it sounds, I assume that it will be possible to create "invisible" abilities from this, after all ray is based on the reflection of the photons that hit the surface, but what happens when photons do not return?... Interesting?! indeed…
Or maybe it is possible to build a stealth plane from it in the future?
They basically built a super air conditioner