Tag Archives: metamaterials

The emperor’s new threads

New Scientist has a brief report on a team working toward making metamaterial threads that would be functionally invisible:

… fabricating metamaterials using components small enough to manipulate the sub-micrometre wavelengths of visible light is no mean feat. To avoid that problem, Tuniz’s colleagues Boris Kuhlmey, Simon Fleming and Maryanne Large have suggested an elegant way to shrink a larger metamaterial-like structure down to a size capable of controlling visible light: assemble standard glass rods and metal tubes into a cylinder, heat the assembly until it softens, and draw it into a long thin fibre. The process preserves the shapes of internal structures, but shrinks them down to the nanoscale needed to control visible light, and the resultant metamaterial is in the form of a thread that is thin enough to be flexible, like an optical fibre. So far, Tuniz and colleagues have produced 10-micrometre-thick threads.

Now, the researchers have used a computer model to design an invisible version of their thread. To achieve that, the thread must be just 1 micrometre thick – the metamaterial absorbs some light and so would appear dark if it was any thicker. Their calculations suggest that the thread would be invisible if seen from the side – rather than end on – in polarised light.

No promises of invisibility cloaks yet, sadly. But you never know…

A material world

layersA rather touching story of one man’s creation of a vast materials library of weird and wonderful substances, Mark Miodownik talks about the Kings College Materials Library:

There are turbine jet-engine blades grown from a single crystal and designed to function in the most inhospitable places on the planet. There’s a swatch of the world’s blackest black, 25 times blacker than conventional black paint. There’s a lead bell that refuses to ring, a piece of bone with a saw through it, and the largest blob of Silly Putty you’re ever likely to see.

The philosophy behind the project is charming as well, an attempt to bridge the gap between the two cultures of science and art:

“It’s a way into science for arts people,” Miodownik says. “And for the scientists it’s a lesson in aesthetics and the sensual nature of what they’re doing. It’s a place for people to go to who have an idea floating around the back of their head that hasn’t bubbled to the surface yet.”

[image from doug88888 on flickr][from the FT]

Behold – the magic cloak of illusion! Er… it was here a minute ago…

vanishing actA big part of the fun of this blogging gig (for me at least) is watching stories resurface and reiterate themselves over time. Point in case: metamaterials and ‘invisibility cloaks’, which cropped up a few times last year, and which raise their head again with news from Hong Kong University that researchers have discovered a theoretical method for not only making things appear invisible, but also for making one thing appear to be another thing entirely. Confused? Well, this might help:

The trick is to create a material in which the permittivity and permeability are complementary to the values in a nearby region of space containing the mouse we want to hide. “Complementary” means that the material cancels out the effect that the mouse has on a plane lightwave passing through. So a plane wave would be bent by the mouse but then bent back into a plane as it passes through the complementary material, making the mouse disappear.

The second step is to then distort this plane wave in the way that an elephant would. This means creating transformational material that distorts a plane lightwave in the same way as an elephant. So anybody looking at this mouse would instead see an elephant.

An invisibility cloak is just a special case of this, when the mouse is simply replaced by the illusion of free space, say Chan and co.

Simply? Well, they sound pretty sure of themselves, but I’ll maintain my skepticism until I see it actually working… or don’t see it, rather. [via SlashDot; image by crystalchu]