Gizmodo: invisibility cloak

Scientists Thwart the Invisibility Cloak (Again)

Chris Jacob — Sat, 05 Dec 2009 20:00:00 EST

Invisibility cloaks don't even exist (unless you're Liu Bolin), yet scientists keep trying to ruin the fun. C'mon, guys. Wouldn't it be more enjoyable to figure out the awesome uses for one instead of trying to get us all caught?

This latest bummer involves two parts. The first is pretty simple. An invisibility cloak would only deflect specific wavelengths, either part or all of visible light. So if you were to blast it with, say, wavelengths in the IR or ultraviolet spectrum, then sensors could easily see through the cloak.

The second is a way to measure the radiation of electrons as they pass through the cloak. Identifying abnormal radiation patterns would get you caught and ruin your spy career.

Again, too, the researchers point out that you could easily detect a by "throwing a stone at it," or, for a much more humiliating "Gotcha!," tar and feathers.

There's still some small sliver of hope, at least. The researchers admit that this is all theoretical, so here's to hoping no one ever figures it out. Either way, both science and common sense keep trying to kill the dream. [ScienceNews.org via Slashdot

Universal Mirror: Imagine the Exact Opposite of an Invisibility Cloak

Dan Nosowitz — Sat, 18 Jul 2009 13:45:00 EDT

No, the opposite of an invisibility cloak isn't a normal jacket, smartass. This universal mirror uses metamaterials to bounce light back at the same angle from which it came, so no matter where you stand, you can see yourself perfectly.

Normal mirrors reflect light back at a 90-degree angle, but this universal mirror reflects light, including microwaves and lasers, back in the exact same direction from which it originated. It uses metamaterials, structures smaller than the light's wavelength, to force said light to bounce back at this specific angle. Because metamaterials are so difficult to create, this universal mirror is only 1x10 centimeters in size, and can only reflect light with longer wavelengths (like microwaves).

Invisibility cloaks use these same metamaterials to guide light around an object instead of sending it back out, and while the opposite may not seem as cool, it may have just as many uses. It could be used for radar location, deflection laser weaponry and as a general-purpose shield. The tech is still a few years off, but it's very futuristic and interesting stuff. [MSNBC]

The Anti-Invisibility Cloak Discovered, NOOOOOOOOOOO!

Mark Wilson — Wed, 03 Sep 2008 11:30:00 EDT

Why God, why? Just as Man was on the cusp of a real-life invisibility cloak—otherwise known as the gateway to the secrets of international government and the girl's locker room—some stupid-head Chinese scientists have already learned to thwart it. The theoretical "anti-cloak" would be a piece of material with identical optical bending properties to the original cloak. When the anti-cloak comes into contact with the invisibility cloak, it would bend light in such a way that the cloak becomes partially visible again.

But wait...apparently the anti-cloak can actually work to make the invisibility EVEN BETTER. OK, we're listening...

The flaw with the current (presumably scalable) methods of creating invisibility cloaks is that when the light bends around the user, that means the user is in complete darkness with no way to see the world outside.

Needless to say, this isn't what we had in mind at all.

With the anti-cloak, a tiny bit of the invisibility cloak could allow light in for a peep hole. And positioned correctly, such holes could usher in an entirely new era of espionage and/or lingerie. [ScienceDaily]

Japanese Men Perfect the Cloak of Invisibility Much to Japanese Women's Dismay

Jason Chen — Fri, 18 Apr 2008 17:00:00 EDT

Japan's been tooling around with versions of invisibility cloaks for years now, but they seem to have finally perfected it. Theoretically. By using "left-handed metamaterials" to make electromagnetic control devices, researchers can generate lenses that either reflect no light or have a perfect focal point—the end result of which lets you create a perfect invisibility cloak to skulk around Tokyo with. If you're really interested in the physics of the situation, you can head over to Nikkeibp, but we're pretty sure the illustration above will explain the matter just fine. [Nikkeibp]

Invisibility Cloak Is Here (For Really Tiny, 2D People)

Mark Wilson — Wed, 03 Oct 2007 10:21:50 EDT

US scientists have finally done it: they've created a cloak to hide an object in the visual light spectrum. The catch? This cloak is just 10 micrometres in diameter and only works in 2D space. But were still excited about the "locker room potential."

The device works by redirecting light rays around the object and setting them back on path out the opposite end. So as far as one can tell, the light moves in a perfectly straight path instead of reflecting off the object as it normally would (or so our third grade science teacher would oversimplify the concept). And it's built from surprising materials: gold and plastic, arranged in concentric rings, granting them the ability to ripple/dominate light.

While the technology is not anticipated to work in three dimensions, the more depressing notion is that true invisibility is not at all possible, since even this solution would create a window glare effect. But fret not, readers, as other technologies are on the horizon. Their name? Nanocameras. [newscientist]