Metamaterials research has generally focused on media with strange or unique electromagnetic properties, like the ability to bend light or sound in an unnatural way, but materials scientists at Northwestern University are experimenting with an entirely new kind of material with unique mechanical properties. A team there has designed materials with “negative compressibility” that in theory will compress when they are pulled and expand when they are compressed.
Metamaterials hold the elusive promise of the true invisibility cloak, one that bends light right around objects to make them invisible to viewers. But most metamaterials with any kind of potential can only be fabricated in very small sizes, and even the ones that work well--and there are a few--generally don’t work in the visible spectrum.
The search for the perfect invisibility cloak lumbers onward, but that lumbering is starting to pick up speed. We’re hearing more and more these days about metamaterials, the possibilities of time cloaking, and other such future-stuff.
Today in crazy tricks of physics, a few researchers over at the University of Southampton in the U.K. have theorized that metamaterials ought to be able to generate a wholly new kind of force--something akin to the adhesive force created by gecko toes--that can be turned on and off optically with the throwing of a switch. That force ought to be strong enough to overcome the force of Earth’s gravity, opening the door to a range of potential applications--if and when the actual force is found.
By Becky Ferreira
Posted 01.13.2012 at 2:12 pm 44 Comments
The science of stealth has long been a matter of fading into already obscure environments—the night sky, say, or the deep sea. But engineers are now developing materials that could hide anything in plain sight. Instead of bending light inward, like water and glass do, these optical metamaterials bend it outward, guiding photons around an object like river water around a stone.
Metamaterials as a class get a lot of press for their ability to exhibit a negative refraction index, the characteristic that lets them bend light around a space or object (the much ballyhooed “invisibility cloak”). But designer metamaterials have potential reaching far beyond just visible light.
A new acoustic invisibility cloak made of a plastic metamaterial makes objects invisible to sound waves, researchers say. It could be used to shield ships from sonar, or build better soundproof walls for concert halls and other spaces. We’ve seen this idea before, but now Duke University researchers have actually built it.
Metamaterials could make it possible to transmit wireless power while avoiding the complications associated with microwaves or lasers, engineers at Duke University say.
The material would be situated between a power source and a device to be charged, and it would serve as a sort of a bridge so that there appeared to be no space between the transmitter and the recipient.
Metamaterials can be used to create desktop black holes and simulate multiverses; now a physicist is using them to prove time travel can’t happen.
In a new paper, University of Maryland professor and metamaterial theorist Igor Smolyaninov says mapping light distribution in a metamaterial can serve as a model for the flow of time. The model shows that the forward direction of time is unrelenting; you cannot curve back on time and go back to where you started. You just have to build a desktop Big Bang to prove it.
Forget invisibility cloaks. Researchers at Imperial College London have demonstrated – on paper, anyhow – a metamaterial “space-time cloak” that can conceal entire events from view, making a viewer see one thing while something entirely different takes place behind the cloak. Paging DARPA.
To think Marco Polo didn’t even know what he had. Silk and gold, considered luxury items for as long as mankind has enjoyed shiny things, might now lead the way forward in the growing field of metamaterials. Turning flashy into inconspicuous, scientists from Tufts and Boston University have created an invisibility cloak from silk coated with gold.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.