Skip to main content

Metamaterials

After another news story about a “Harry Potter invisibility cloak”, we take a look at the science behind metamaterials.
A metamaterial cloak bends light around an object
Science
Invisibility has long been employed in works of science fiction and fantasy, from “cloaking devices” on spaceships in the various Star Trek series to Harry Potter’s magic cloak. But physicists are beginning to think they can actually make devices with just these properties.
To achieve the feat of “cloaking” an object, they have developed what are known as “metamaterials”, some of which can bend electromagnetic radiation, such as light, around an object, giving the appearance that it isn’t there at all.
The first examples only worked with long-wavelength radiation such as microwaves.
One small device that made small objects invisible to near-infrared radiation and worked in three dimensions was unveiled by physicists from the UK and Germany earlier this year.
Its creators claimed there was nothing stopping them from scaling their invention up to hide larger objects from visible light – although others had pointed out a flaw in their design.
Now, researchers at Boston University and Tufts University claim that they have come up with an invisibility cloak that works within the terahertz band – the radiation between infrared and radio wavelengths – but could be modified to work with visible light. Intriguingly, it is made out of silk.
Metamaterials
Such invisibility cloaks rely on metamaterials, which are a class of material engineered to produce properties that don’t occur naturally.
Light is electromagnetic radiation, made up of perpendicular vibrations of electric and magnetic fields. Natural materials usually only affect the electric component – this is what is behind the optics that we’re all familiar with such as ordinary refraction.
But metamaterials can affect the magnetic component too, expanding the range of interactions that are possible.
The metamaterials used in attempts to make invisibility cloaks are made up of a lattice with the spacing between elements less than the wavelength of the light we wish to ‘bend’.
The silk-based cloak recently announced uses “split-ring resonators” – concentric pairs of rings with splits at opposite ends. 10,000 gold resonators were initially attached to a one-centimetre-square piece of silk.
As silk is not rejected by the human body, it is thought that they could be used to coat internal organs so that surgeons can easily see what lies behind them.
A metamaterial array – split-ring resonators mounted on fiberglass circuit board. Testing on an array like this showed negative refraction of microwave radiation








Superlens
Another use for metamaterials, potentially with greater scientific applications, is in building a superlens.
Ordinary lenses are restricted by their “diffraction limit”. As David R Smith of the University of California, San Diego explained in Physics World, this means that “the best resolution that is possible corresponds to about half of the incident wavelength of the light that is used to produce the image”.
In 2000, Sir John Pendry of Imperial College London suggested that a metamaterial with a negative refractive index might get around problems such as wave decay and allow imaging of objects only nanometers in size.
Among the first practical applications would likely be using metamaterial lenses to view live viruses and maybe even bits of DNA. In 2005, a thin slab of silver was used to image objects just 60nm across – just over one hundredth the size of a red blood cell.

Comments

Popular posts from this blog

Hidden Wiki

Welcome to The Hidden WikiNew hidden wiki url 2015 http://zqktlwi4fecvo6ri.onion Add it to bookmarks and spread it!!!
Editor's picks Bored? Pick a random page from the article index and replace one of these slots with it.
The Matrix - Very nice to read. How to Exit the Matrix - Learn how to Protect yourself and your rights, online and off. Verifying PGP signatures - A short and simple how-to guide. In Praise Of Hawala - Anonymous informal value transfer system. Volunteer Here are five different things that you can help us out with.
Plunder other hidden service lists for links and place them here! File the SnapBBSIndex links wherever they go. Set external links to HTTPS where available, good certificate, and same content. Care to start recording onionland's history? Check out Onionland's Museum Perform Dead Services Duties. Introduction PointsAhmia.fi - Clearnet search engine for Tor Hidden Services (allows you to add new sites to its database). DuckDuckGo - A Hidden S…

Explainer: The nico-teen brain

Explainer: The nico-teen brain The adolescent brain is especially vulnerable to the addictive effects of nicotine BY  TERESA SHIPLEY FELDHAUSEN 7:00AM, AUGUST 19, 2015 Nicotine (black triangle towards center left) tricks the nerve cell (neuron) into sending a message to release more dopamine (yellow dots). Those molecules enter the space (synapse) between one nerve cell and the next. When they get picked up by neighboring cells, this gives users a feel-good high. It also creates the risk of addiction and other health problems.  EMail Print Twitter Facebook Reddit Google+ NATIONAL INSTITUTE ON DRUG ABUSE, ADAPTED BY J. HIRSHFELD Nicotine is the addictive chemical in tobacco smoke and e-cigarette vapors. And doctors say the teenage brain is no place for it to end up. Nicotine can reach the brain within seven seconds of puffing on a cigar, hookah, cigarette or electronic cigarette.
The area of the brain responsible for emotions and controlling our wild impulses is known as the prefrontal c…

fix idm integration on chrome

Chrome Browser IntegrationI do not see IDM extension in Chrome extensions list. How can I install it? 
How to configure IDM extension for Chrome?Please note that all IDM extensions that can be found in Google Store are fake and should not be used. You need to install IDM extension manually from IDM installation folder. Read in step 2 how to do it.

1. Please update IDM to the latest version by using "IDM Help->Check for updates..." menu item

2. I don't see "IDM Integration module" extension in the list of extensions in Chrome. How can I install it?

Press on Chrome menu (arrow 1 on the image), select "Settings" menu item (arrow 2 on the image) and then select "Extensions" tab (arrow 3 on the image). After this open IDM installation folder ("C:\Program Files (x86)\Internet Download Manager" by default, arrow 4 on the image) and drag and drop "IDMGCExt.crx" (arrow 5 on the image) file into "Extensions" page opened in…