Invisibility cloaks have been around in various forms since 2006, when the first cloak based on optical metamaterials
was demonstrated. The design of cloaking devices has come a long way in the past seven years, as illustrated by a simple, yet highly effective, radar cloak developed by Duke University Professor Yaroslav Urzhumov, that can be made using a hobby-level 3D printer.
We expect the world to be predictable. Water flows downhill, fire burns and lenses bend light in a particular way. That worldview took a jolt as Isaac Ehrenberg, an MIT graduate student in mechanical engineering, developed a three-dimensional, lightweight metamaterial lens that focuses radio waves with extreme precision. That may not seem too disturbing, but the lens is concave and works in exactly the opposite manner of how such a lens should.
While “cloaking” technology may have once been limited exclusively to the realm of science fiction, regular Gizmag readers will know that it is now finding its way into real life – just within the past few years, scientists have demonstrated various experimental cloaking systems that prevent small objects from being seen
, and in one case, from being heard
. Such invisibility systems involve the use of metamaterials
, which are man-made materials that exhibit optical qualities not found in nature. These are able to effectively bend light around an object, instead of allowing it to strike the object directly. Now, mathematicians from the University of Manchester are proposing technology based on the same principles, that would allow buildings to become “invisible” to earthquakes.
We’ve previously seen – or should that be “not seen” – invisibility
cloaks in the laboratory that are able to render two-dimensional objects
invisible to microwaves. Such feats relies on the use of metamaterials
– man-made materials that exhibit optical properties not found in nature and have the ability to guide light around an object. Now researchers at the University of Texas at Austin (UT) claim to have brought invisibility cloaks that operate at visible light frequencies one step closer by cloaking a three-dimensional object standing in free space with the use of plasmonic metamaterials.
We cast a wide net over all types of new and emerging technologies here at Gizmag.com - some save us time, some keep us connected, some help us stay healthy and some are just plain fun, but at the core of what we cover are those discoveries and innovations which have the potential to impact the fortunes of the human race as a whole and make a difference to the future of our planet. So with the calender having rolled over into another year, it's an ideal time to take a look back at some of the most significant and far-reaching breakthroughs that we saw during 2011.
North Carolina’s Duke University has been grabbing some headlines over the past few years, due to research carried out there involving the use of metamaterials for creating functioning invisibility cloaks
. Just this month, Duke researchers announced that they had developed another such material that could be used to manipulate the frequency and direction of light at will, for use in optical switching
. Now, Duke’s Prof. Yaroslav Urzhumov has proposed that metamaterials could also be used to drastically reduce the drag on ships’ hulls, “by tricking the surrounding water into staying still.”
Duke University is on a roll, showing off yet another potentially game-changing property of the exotic man-made substances known as metamaterials. This time the property could have deep consequences for the transmission of information via light. Maybe the most important potential use of all.
We may not yet have the liquid metal depicted in the Terminator
movies, but scientists have now developed something that’s vaguely along the same lines. German materials scientist Dr. Jörg Weißmüller and Chinese research scientist Hai-Jun Jin have created a metallic material that can change back and forth between being strong but brittle and soft but malleable, via electrical signals.
The weird properties of artificially engineered metamaterials
are at the core of research into invisibility cloaking, but engineers from Duke University in North Carolina suggest that these materials could also provide a boost to another of technology's quests - wireless power transmission. In this latest hard-to-get-your-head-around metamaterial scenario, it's not the cloaked object that "disappears" - it's the space between
the charger and the chargee.
Efforts to create a working "invisibility cloak
" have generally involved the use of artificial materials with a negative refractive index known as metamaterials
. Another promising technique
involves the use of a natural crystal called calcite that boasts an optical property known as birefringence, or double-refraction. While both methods have proven successful in rendering very small objects invisible in specific wavelengths of light by bending and channeling light around them, both techniques require the "cloak" to be orders of magnitude larger than the object being concealed. Researchers are now reporting progress in overcoming this size limitation using a technology known as a "carpet cloak."