These microwave images show how an object looks in normal view (top row) and oblique view (bottom row) when it's uncloaked, and when it's cloaked by a metascreen. A free-space view of the scene is included as well.

If you liked last year's bulky invisibility cloaks, you'll love this year's fashionable ultra-thin invisibility wrap — which is just a tenth of a millimeter thick but can still make the objects inside undetectable to microwave scans.

"This is the first time an ultra-thin cloak has been realized, much thinner than the wavelength," Andrea Alu, a materials-science researcher at the University of Texas at Austin, told NBC News in an email. "The approach is unique."

Invisibility cloaks have been the stuff of science-fiction stories ranging from the "Star Trek" TV series to the Harry Potter sorcery saga, but they're also becoming the stuff of science fact. The first real-life invisibility cloak was created in 2006, and they've gotten a lot better since then.

Alu and his colleagues describe what they call a "3-D stand-alone mantle cloak" this week in the New Journal of Physics. The research builds on past work with bulkier kinds of cloaking devices. The first invisibility cloaks guided light waves around hidden objects. Last year, Alu's group showed how a shell of plasmonic materials could cancel out the scattering of light waves by an object, rendering it invisible. This week's research paper features a new kind of wave-canceling cloak that's much thinner than the shell.

The University of Texas researchers took a 18-centimeter-long cylindrical ceramic rod and wrapped it in what they call a "metascreen," a layer of flexible plastic film overlaid with a fishnet pattern of copper tape. In the visible spectrum, the wrapped-up object looked like a tube of kitchen plastic wrap. But when the researchers beamed microwaves at the object, their microwave imagers couldn't pick up the object's signature.

"The wave can pass through the object, if it is penetrable," Alu explained.

Alu et al. via New Journal of Physics

This image shows the experimental set-up for far-field microwave observations. The cylinder at the center of the scene is a ceramic rod wrapped in an invisibility cloak that's just a tenth of a millimeter thick.

Alu et al. via New Journal of Physics

A near-field experiment demonstrated that the rod wrapped in a copper-and-plastic metascreen was invisible to microwaves, even when the rod was inclined at an angle.

The researchers reported that invisibility effect was present over a moderately broad bandwidth, with optimal performance at a wavelength of 3.6 gigahertz. The same technique could be used to produce invisibility in different wavelengths.

"In terms of applications, radar camouflaging is one," Alu said. He said the technique could defeat advanced countermeasures for stealth radar detection, such as looking for the radar "shadow" of a stealth-concealed object. Alu and a colleague also have proposed a method for terahertz-wave invisibility, which could theoretically make objects invisible to airport security scanners.

Alu said the potential applications aren't limited to stealth and spycraft. "The main civil applications we have suggested for this technology are in the area of non-invasive sensing, biomedical and optical nanodevices for computing, and energy harvesting," he said.

Harry Potter might not want to give his old cloak of invisibility cloak to Goodwill just yet, though. The metascreen constructed by Alu and his colleagues will work only for microwaves, and not for the visible-light wavelengths that our eyes can see.

"In principle, this technique could also be used to cloak light," Alu said in a news release. "In fact, metascreens are easier to realize at visible frequencies than bulk metamaterials, and this concept could put us closer to a practical realization. However, the size of the objects that can be efficiently cloaked with this method scales with the wavelength of operation, so when applied to optical frequencies, we may be able to efficiently stop the scattering of micrometer-sized objects."

That means Harry will still have to keep the bulky old cloak in his closet — unless he can use the "Decresplitudo" spell to shrink himself to a millionth of a meter in size. And if he can do that, who needs a cloak?

More about invisibility:

• Invisibility gets a reality check
• Invisibility cloak for quakes? It's possible
• Invisibility could lead to super-Internet

In addition to Alu, the authors of "Demonstration of an Ultralow Profile Cloak for Scattering Suppression of a Finite-Length Rod in Free Space" include J.C. Soric, P.Y. Chen, A. Kerkhoff, D. Rainwater and K. Melin.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

All swords are not created equal, particularly when it comes to "Game of Thrones," the HBO series based on George R.R. Martin's character-rich sword-and-sorcery saga. When the series opens its second season on Sunday, some of the swords you'll see are made of cheap resin, others are metal blades just meant to look good — and a few of them have been custom-crafted using a technique reminiscent of the story's fictional, magic-laden Valyrian steel.

For Martin, swords are serious business.

"The one thing I can say is that he is very, very knowledgeable about history, including weaponry," said Chris Beasley, the proprietor of Valyrian Steel, the Michigan-based company that produces licensed replicas of "Game of Thrones" swords. "When designing the swords, and he is highly involved in the design process of our book replicas, he doesn't want something to look cool. He is more concerned with realism — who made it, why, and how?"

For example, let's talk about Valyrian steel. In the "Game of Thrones" TV series and Martin's "Song of Ice and Fire" book series, the Valyrian blades were created ages earlier by a vanished civilization, using a blend of alloys forged with magic spells. There's actually a real-life analog, minus the magic, known as Damascus steel. Damascus swords are famous for their resilience and the intricate, flowing patterns that are imprinted on the blades, but the secret of their forging has been lost for centuries.

A few years ago, researchers found that at the microscopic level, Damascus steel contains carbon nanotubes — structures that seem like 21st-century technological magic dropped into the 17th century. The super-strong nanostructures are mixed in with softer metal in the sword. That solves the classic dilemma of sword-making: how to make a blade that is hard enough to do damage, yet supple enough not to break.

HBO

Young King Joffrey (Jack Gleeson) sits on an Iron Throne made from the swords of enemies.

Modern-day Valyrian steel
Today, swordsmiths use a process known as "pattern welding" that produces results similar to the lost art of Damascus steel. Multiple layers of steel, with different amounts of carbon and other elements, are forge-welded together to create a blade that combines strength and suppleness. When all the layers of metal are flattened and folded together, over and over, it's like having two blades — or, more accurately, 200 blades — in one.

Some of the best-known Valyrian blades seen in the "Game of Thrones" TV series, such as the swords nicknamed Ice and Longclaw, were made using the pattern-welding technique.

"Ice was the main weapon to get right," Tommy Dunne, the weaponmaster for the series, said in a Westeros.org interview. "From the concept to the construction, it was about three weeks to make, as the blade was hand-forged by pattern welding, and the blade was drawn using machine hammers. But as with any good weapons, there's some other secrets that will remain secret!"

Beasley's business also sells some swords made with pattern-welded steel. "Those could technically be used, but we never recommend it," he told me. "Our swords are limited-edition collectibles, and no sword is impervious to damage. If used, they will get nicks, and chips, and scratches."

Beasley recalls that Valyrian Steel's Longclaw replica originally sold for $600, but after the swords were sold out, one customer reported receiving an offer of $3,000 to $4,000 for his sword. "I wouldn't recommend that anyone risk damage to something so valuable," Beasley told me.

Needle at work
If real fake Valyrian steel is too expensive for your taste, you can shell out $170 for Needle, the kid-sized sword that pre-teen Arya Stark learns to uses with deadly effect in "Game of Thrones." Beasley said Martin had a hand in designing the replica.

"Reading the books, I and many others thought, 'OK, this is a small rapier,'" Beasley recalled. "George very quickly put that notion to rest. He said that Mikken, the Winterfell smith who made it, would never have seen a rapier in his life, so how could he make one? That is why the book version of needle is more or less a small, slim longsword, and not a rapier."

Martin was so pleased with the result that he had one of Valyrian Steel's Needles sent to the actress who plays Arya so she could practice with it. And she's not the only one.

"One customer did tell us that they use Needle in their offhand to increase strength and coordination," Beasley told me. "They keep it in their office, and when on the phone or otherwise occupied they just jab and thrust with their left hand." (Remind me not to burst into that office unexpectedly.)

New twists in an old trade
Some of the secrets from the golden age of swordsmithing may have been lost over the past few centuries, but technology is adding new twists to the trade. There's been a lot of research into the use of alloying elements such as carbon, manganese, chromium, nickel, titanium and molybdenum. Materials scientists also are developing metallic materials infused with carbon nanotubes, just like in the good old days of Damascus steel.

"In more modern times, steel can be precisely made, and the overall material creation process can be more scientific so that you can get precisely the steel with the hardness and flexibility you desire," Beasley said. "So materials science has probably made modern swords stronger than older ones, but construction methods have not changed — though, obviously, power tools and other equipment have replaced arm power."

Ah, power tools — I'll bet the swordsmiths of King's Landing would have shelled out hundreds of silver stags for a good belt grinder. Are you in a mood to geek out over the science and technology of "Game of Thrones"? Feel free to indulge yourself in the comment section.

Update for 6 p.m. ET March 30: Veteran sword designer Kit Rae, who has created replicas for a variety of swords made famous by Hollywood, agrees with the parallel between the Valyrian steel of George R.R. Martin and the Damascus steel of real-life swordsmithing. "George Martin's universe is a parallel to what I would guess is the 12th to 14th century in our history," Rae told me. "Around the 10th century, that's when we were really starting to get into properly quenched and hardened steel."

There is a difference between the fictional and the factual universe, however. In "Game of Thrones," it's no longer possible to make brand-new swords with Valyrian steel. In the real world, there's a wide spectrum of swords and knives being made with the "Damascus steel" label — ranging in price from less than $200 to much more than $1,000.

"There are people who will argue that we don't have the technology to make something that compares with what the master swordmakers in Japan or Europe did. That's a bunch of bull," Rae said. "We're actually much farther along than that. But in that regard, you get what you pay for." 

More angles on 'Game of Thrones':

• Teens rule in bloody 'Game of Thrones'
• 'Game of Thrones' headed to PS3, Xbox 360
• George R.R. Martin previews his next book
• All about 'Game of Thrones' on The Clicker
• Medieval knights may have had PTSD

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

Dan Little / HRL Laboratories

A new type of nickel-phosphorus lattice is so light it can sit atop a ball of dandelion fluff without disturbing it.

Researchers have created a new kind of metal that rates as the world's lightest material — and just might show up in future batteries and shock absorbers.

The nickel-phosphorus "microlattice," which is described in this week's issue of the journal Science, is the stuff that gee-whiz is made of: It actually consists of 99.99 percent air. The other 0.01 percent is made up of interconnected hollow tubes with a wall thickness of 100 nanometers. That's 1,000 times thinner than a human hair.

To get technical about it, the density of the material is 0.9 milligrams per cubic centimeter. In comparison, the lightest sample of aerogel, the stuff that's been called "solid smoke," has a density of 1.1 mg/cc.

The microlattice is made through a process that's completely different from the "cooking" technique that gives rise to aerogel. The researchers start by setting up a matrix of polymer lattices, and then deposit thin films of nickel-phosphorus. When the polymer is etched away, tiny metal tubes are left behind in the shape of the lattice.

Aerogel is foamy stuff that makes a great insulator but chips off easily. In contrast, the highly ordered structure of the microlattice makes it strong and resilient.

"Modern buildings, exemplified by the Eiffel Tower or the Golden Gate Bridge, are incredibly light and weight-efficient by virtue of their architecture," William Carter, manager of the architected materials group at California-based HRL Laboratories, explained today in a news release. "We are revolutionizing lightweight materials by bringing this concept to the nano and micro scales."

Lorenzo Valdevit, a materials scientist at the University of California at Irvine, said materials actually get stronger when the scale is reduced to the nanometer level. "Combine this with the possibility of tailoring the architecture of the microlattice, and you have a unique cellular material," he said in a UC-Irvine news release.

The material is strong enough to bounce back after being compressed by 50 percent, yet light enough to sit on top of a fluffy dandelion without disturbing it, as shown in the photo above. The stuff's properties make it ideal for applications that involve soundproofing or shock absorption, and it could also lead to lighter battery electrodes. It's no wonder that the material was developed for the Pentagon's Defense Advanced Research Projects Agency. (And yes, the developers have applied for a patent on the microlattice structure and formation process.)

Update for 10:15 p.m. ET: Valdevit provided a little more perspective on the "lightest material" claim in a follow-up phone call. "You might argue that it's a 'structure' rather than a 'material,'" he acknowledged. But the key factor has to do with how strong and resilient the microlattice is for its weight. That's what will determine how widely it's used.   

More material about materials science:

• Aerogel used in artificial muscles
• 'Frozen diamond smoke' is rich in possibilities
• Aerogel could be used in batteries and robo-surgery
• Lightweight metallic glass is as strong as steel

In addition to Carter and Valdevit, authors of "Ultralight Metallic Microlattices" include Tobias Schaedler, A.J. Jacobsen, A.E. Sorensen, J. Lian and J.R. Greer.

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or following the Cosmic Log Google+ page. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.