Invisibility cloak one step closer, scientists say

[SinoIndusFriendship]

Invisibility cloak one step closer, scientists say


By Maggie Fox, Reuters
January 16, 2009

A ray of light travels through a prism. The age-old fantasy of making yourself invisible has taken a step toward reality, with scientists saying they have created three-dimensional materials that can bend visible light.

Scientists have created two new types of materials that can bend light the wrong way, creating the first step toward an invisibility cloaking device.

One approach uses a type of fishnet of metal layers to reverse the direction of light, while another uses tiny silver wires, both at the nanoscale level.

Both are so-called metamaterials -- artificially engineered structures that have properties not seen in nature, such as negative refractive index.

The two teams were working separately under the direction of Xiang Zhang of the Nanoscale Science and Engineering Center at the University of California, Berkeley with U.S. government funding. One team reported its findings in the journal Science and the other in the journal Nature.

Each new material works to reverse light in limited wavelengths, so no one will be using them to hide buildings from satellites, said Jason Valentine, who worked on one of the projects.

"We are not actually cloaking anything," Valentine said in a telephone interview. "I don't think we have to worry about invisible people walking around any time soon. To be honest, we are just at the beginning of doing anything like that."

Valentine's team made a material that affects light near the visible spectrum, in a region used in fiber optics.

"In naturally occurring material, the index of refraction, a measure of how light bends in a medium, is positive," he said.

"When you see a fish in the water, the fish will appear to be in front of the position it really is. Or if you put a stick in the water, the stick seems to bend away from you."

These are illusions caused by the light bending when it moves between water and air.

NEGATIVE REFRACTION

The negative refraction achieved by the teams at Berkeley would be different.

"Instead of the fish appearing to be slightly ahead of where it is in the water, it would actually appear to be above the water's surface," Valentine said. "It's kind of weird."

For a metamaterial to produce negative refraction, it must have a structural array smaller than the wavelength of the electromagnetic radiation being used. This was done using microwaves in 2006 by David Smith of Duke University in North Carolina and John Pendry of Imperial College London.

Visible light is harder. Some groups managed it with very thin layers, virtually only one atom thick, but these materials were not practical to work with and absorbed a great deal of the light directed at it.

"What we have done is taken that material and made it much thicker," Valentine said.

His team, whose work is reported in Nature, used stacked silver and metal dielectric layers stacked on top of each other and then punched through with holes. "We call it a fishnet," Valentine said.

The other team, reporting in Science, used an oxide template and grew silver nanowires inside porous aluminum oxide at tiny distances apart, smaller than the wavelength of visible light. This material refracts visible light.

Immediate applications might be superior optical devices, Valentine said -- perhaps a microscope that could see a living virus.

"However, cloaking may be something that this material could be used for in the future," he said. "You'd have to wrap whatever you wanted to cloak in the material. It would just send light around. By sending light around the object that is to be cloaked, you don't see it."

© Copyright (c) Canwest News Service

 

[SinoIndusFriendship]

Keep in mind the large number of bright Asian, in particular Chinese minds in USA and Europe. Any attempts to racially target any particular ethnic, religious or racial group will be met with consequences. Already a "witch-hunt" is on Arabs/Muslims, now imagine what would happen if a "witch-hunt" was applied to prosecute Chinese and Asians. Not only would you get a exodus of reverse-brain-drain, but also a backlash of epic proportions.

Think before you act. Accept the reality that all us humans are EQUAL. Respect us and respect our human rights. Now, tell me what is so "WRONG" about other races improving themselves??? Why do you fear the betterment of humanity???

Humane intelligent people are happy when others prosper. It is only small-minded evil selfish people who cannot stand others being happy and prosperous.

There is no reason why we should view the rise of a MULTI-POLAR world where all people's achievements and accomplishments are seen without prejudice.

 

[S-2]

"Already a "witch-hunt" is on Arabs/Muslims, now imagine what would happen if a "witch-hunt" was applied to prosecute Chinese and Asians."

So how are matters going again with your uighar muslims?

This diatribe of yours is irrelevant to the article at hand. Save your self-serving, irrelevant rants for those that need it most-like yourselves.

Thanks.

 

[Creder]

I dont get this forum mayn :S...how do you go from bending the light around the objects to witch-hunts in just three posts

 

[Vassnti]

I dont get this forum mayn :S...how do you go from bending the light around the objects to witch-hunts in just three posts

I was wondering the same thing and the way its listed on my screen in two posts one an interesting scientific artice then straight after a OMG im being persecuted rant that seemed totaly unrelated.

 

[Creder]

A team from Fudan University in Shanghai believes that silver-plated nanoparticles suspended in water could be the trick to draping yourself in invisibility

In the absence of a magnetic field, such nanoparticles would simply float around in the water, but if a field were introduced, the particles would self-assemble into chains whose lengths depend on the strength of the field, and which can also attract one another to form thicker columns.

The chains and columns would lie along the direction of the magnetic field. If they were oriented vertically in a pool of water, light striking the surface would refract negatively – bent in way that no natural material can manage.

This property could be exploited for invisibility devices, directing light around an object so that it appears as if nothing is there, or be put to use in lenses that could capture finer details than any optical microscope.

 

[Creder]

In the study, which is to appear in the Oct. 12 issue of Physical Review Letters, Allan Greenleaf, professor of mathematics at the University of Rochester, and his coauthors lay out a variation on the theme of cloaking. Their results open the possibility of building a sort of invisible tunnel between two points in space.

"Imagine wrapping Harry Potter's invisibility cloak around a tube," says Greenleaf. "If the material is designed according to our specifications, you could pass an object into one end, watch it disappear as it traveled the length of the tunnel, and then see it reappear out the other end."

Current technology can create objects invisible only to microwave radiation, but the mathematical theory allows for the wormhole effect for electromagnetic waves of all frequencies. With this in mind, Greenleaf and his coauthors propose several possible applications. Endoscopic surgeries where the surgeon is guided by MRI imaging are problematical because the intense magnetic fields generated by the MRI scanner affect the surgeon's tools, and the tools can distort the MRI images. Greenleaf says, however, that passing the tools through an EM wormhole could effectively hide them from the fields, allowing only their tips to be "visible" at work.

To create cloaking technology, Greenleaf and his collaborators use theoretical mathematics to design a device to guide the electromagnetic waves in a useful way. Researchers could then use these blueprints to create layers of specially engineered, light-bending, composite materials called metamaterials.

Last year, David R. Smith, professor of electrical and computer engineering at Duke's Pratt School, and his coauthors engineered an invisibility device as a disk, which allowed microwaves to pass around it. Greenleaf and his coauthors have now employed more elaborate geometry to specify exactly what properties are demanded of a wormhole's metamaterial in order to create the "invisible tunnel" effect. They also calculated what additional optical effects would occur if the inside of the wormhole was coated with a variety of hypothetical metamaterials.

Assuming that your vision was limited to the few frequencies at which the wormhole operates, looking in one end, you'd see a distorted view out the other end, according the simulations by Greenleaf and his coauthors. Depending on the length of the tube and how often the light bounced around inside, you might see just a fisheye view out the other end, or you might see an Escher-like jumble.

Greenleaf and his coauthors speculated on one use of the electromagnetic wormhole that sounds like something out of science fiction. If the metamaterials making up the tube were able to bend all wavelengths of visible light, they could be used to make a 3D television display. Imagine thousands of thin wormholes sticking up out of a box like a tuft of long grass in a vase. The wormholes themselves would be invisible, but their ends could transmit light carried up from below. It would be as if thousands of pixels were simply floating in the air.

But that idea, Greenleaf concedes, is a very long way off. Even though the mathematics now says that it's possible, it's up to engineers to apply these results to create a working prototype.

Greenleaf's coauthors are Matti Lassas, professor of mathematics at the Helsinki University of Technology; Yaroslav Kurylev, professor of mathematics at the University College, London; and Gunther Uhlmann, Walker Family Endowed Professor of Mathematics at the University of Washington.

Source: University of Rochester

 

[rubyjackass]

Keep in mind the large number of bright Asian, in particular Chinese minds in USA and Europe. Any attempts to racially target any particular ethnic, religious or racial group will be met with consequences. Already a "witch-hunt" is on Arabs/Muslims, now imagine what would happen if a "witch-hunt" was applied to prosecute Chinese and Asians. Not only would you get a exodus of reverse-brain-drain, but also a backlash of epic proportions.

Think before you act. Accept the reality that all us humans are EQUAL. Respect us and respect our human rights. Now, tell me what is so "WRONG" about other races improving themselves??? Why do you fear the betterment of humanity???

Humane intelligent people are happy when others prosper. It is only small-minded evil selfish people who cannot stand others being happy and prosperous.

There is no reason why we should view the rise of a MULTI-POLAR world where all people's achievements and accomplishments are seen without prejudice.

Wow!! what the hell was that?! what is wrong with you mann? that post was not necessary at all. You are being a racist here. The professor working on this project might as well be an American citizen. You look at some name and hang on to it with your racist ****?

 

[SinoIndusFriendship]

"Already a "witch-hunt" is on Arabs/Muslims, now imagine what would happen if a "witch-hunt" was applied to prosecute Chinese and Asians."

So how are matters going again with your uighar muslims?

This diatribe of yours is irrelevant to the article at hand. Save your self-serving, irrelevant rants for those that need it most-like yourselves.

Thanks.

Is that what you are doing in Palestine, Iraq, Iran, Afghan and now Pakistan?! You are intentionally persecuting Arabs and Muslims. You repeatedly expressed you enjoyment at it in numerous postings in the past, yet you dare play "innocent"?

How many more innocent human beings are you going to slaughter, sergeant? This thread was to show that WE ALL are important such that it is WRONG for one particular group to suppress others.

Like it or not, the future there will be a power-sharing. There's nothing you can do to stop it. Why don't you stop your phoney "war on terror"???

Later!

Oh, and say hi to Rebiya Kadeer. I'm glad she can be of service to you, and that she performed an excellent job setting up that TERROR attack.

 

[Iggy]

SIF whats the relation of your rants wiith the invisibility cloak?? are you suggesting the cloak will be a good help for Asians and Muslims ? ..

 

[Gazzi]

I think we should work with the Indians instead, I somehwat like there method of research

-----------------


Indian scientists are turning to an ancient Hindu text in their search for the secrets of effective stealth warfare.


(We) do not for a moment think that the idea is crazy

Professor SV Bhavasar

They believe the book, the Arthashastra, written more than 2,300 years ago, will give Indian troops the edge on their enemies.

India's Defence Minister George Fernandes has approved funding for the project, and told parliament recently that experiments had begun.

The research is being carried out by experts from the Defence Research and Development Organisation and scientists from the University of Pune and National Institute of Virology in western India.

The book includes the recipe for a single meal that will keep a soldier fighting for a month, methods of inducing madness in the enemy as well as advice on chemical and biological warfare.

Powders and remedies

The book was written by military strategist Kautilya, also known as Chanakya and Vishnugupta, a prime minister in the court of India's first emperor Chandragupta Maurya, in the fourth century BC.

Mural of Emperor Chandragupta Maurya
The author was an adviser to India's first emperor

"All of us are excited about the possibilities and do not for a moment think that the idea is crazy," said Professor SV Bhavasar, a space scientist who has spent many years researching the Arthashastra.

"Decoding ancient texts is not an easy task but we are very hopeful of success," he added.

According to a Pune University report, the book says that soldiers fed with a single meal of special herbs, milk and clarified butter can stay without food for an entire month.

Shoes made of camel skin smeared with a serum made from the flesh of owls and vultures can help soldiers walk hundreds of miles during a war without feeling tired.

A powder made from fireflies and the eyes of wild boar can endow soldiers with night vision.

Chemical warfare

Kautilya wrote in the Arthashastra that a ruler could use any means to attain his goal, and Book XIV touches on aspects of chemical and biological warfare.

Indian soldier
Scientists say the text can help in modern warfare

The book says that smoke from burning a powder made from the skin and excreta of certain reptiles, animals and birds can cause madness and blindness in the enemy.

The book also provides the formula to create a lethal smoke by burning certain species of snakes, insects and plant seeds in makeshift laboratories.

"Our focus at present is on how humans can control hunger for longer durations and walk for longer period without experiencing fatigue,

Project leader Dr VS Ghole, head of the environmental engineering department of Pune university, said the team was now focusing on the methods of controlling hunger and increasing stamina.

"Once we have made some headway we will go into researching Kautilya's notes on night vision and other fields," he said.

Professor SV Bhavasar said the team also had plans to research other ancient Hindu texts.

These include manuscripts which "claim to provide secrets of manufacturing planes which can not be destroyed by any external force, could be motionless in the sky and even invisible to enemy planes."

------------

BBC News | SOUTH ASIA | India defence looks to ancient text

 

[PlanetWarrior]

I like the invisible cloak idea. Could save me the trouble of explaining to my wife why I came home late on a Saturday night after a night out with my buddies. "Honey I used the invisible cloak last night and was home by 10pm"

 

[S-2]

"How many more innocent human beings are you going to slaughter, sergeant?"

That's CAPTAIN, you civilian puke. A simple search of my personal data would tell you I'm a former artillery OFFICER.

Can't you get anything correct-even your insults?

You've diminished your posting competence in my eyes sufficient to qualify for "ignore" status.

Idiocy-tested. Idiocy-approved. Later...

Thanks.

 

[Canaan]

stick to the subject people.
Now the military is the first place to use such a product.
How would it be encountered? I know of Thermal, infrared and acoustic detection. Any other ways?

 

[Gazzi]

I have already answered, see above post #11