Wednesday, 17 November 2010

Space-time cloak can edit history

One of the central planks of science-fiction, the invisibility cloak, has taken one step closer to becoming reality, according to extraordinary new research revealed today in the Journal of Optics. And it isn't just matter it can render invisible, but entire tracts of history.

The "space-time cloak" is a device conceived by Martin McCall, an optical physicist at Imperial College London. It generates a pocket in reality in which actions can be concealed. Unlike "standard" invisibility cloaks, which bend light around an object, a space-time cloak would open up a time gap in the light by controlling its speed through optical fibres, and then seal it again to hide all traces of activity within the gap.

"I realised that it may be possible to use metamaterials to bend light rays in both space and time, not just in space," says Martin McCall, in Nature. "This would add a new dimension to the invisibility cloak - literally."

"You could imagine a burglar using a space-time cloak to create an invisible corridor leading to a safe," says McCall. With the cloak turned on, the burglar could run through this corridor, open the safe, steal the contents, shut the safe and escape, while any security camera trained on the safe would just show a continuous image of a locked door at every point in time, explains McCall. "The dastardly event would have been edited from history," he says.

Nature go on to explain that the key feature of the proposed space-time cloak is that its refractive index - the optical property that governs the speed of light within a material - is continually changed, pulling light rays apart in time. When the leading edge of a light wave hits the cloak, the material is manipulated to speed up the light, but when the trailing edge hits, the light is slowed down and delayed. "Between these two parts of the light, there will be a temporal void - a space in which there will be no illuminating light for a brief period of time," explains McCall.

McCall hopes that a fibre-optic cloak creating a space-time void around 30 centimetres long, to hide actions taking place over a few nanoseconds, could be built within the next year.


Wednesday, 10 November 2010

The galaxy is full of fullerenes

Last week, the Astrophysical Journal Letters published an interesting finding from astronomers working with NASA's Spitzer Space Telescope. It appears that fullerenes (aka buckyballs) are far more widespread in our galaxy than what we thought. The discovery has lead some astronomers to speculate that the spherical carbon molecules may have even seeded life of earth.

Astronomers found fullerenes in staggering quantities throughout the Milky Way, in the space between stars and around dying stars. Fullerenes are molecules consisting of 60 linked carbon atoms. They are also known as buckyballs, so named for their resemblance to the architect Buckminster Fuller's geodesic domes.

As NASA report: "The miniature spheres were first discovered in a lab on Earth 25 years ago, but it wasn't until this past July that Spitzer was able to provide the first confirmed proof of their existence in space. At that time, scientists weren't sure if they had been lucky to find a rare supply, or if perhaps the cosmic balls were all around."

"It turns out that buckyballs are much more common and abundant in the universe than initially thought," said astronomer Letizia Stanghellini of the National Optical Astronomy Observatory in Tucson. "Spitzer had recently found them in one specific location, but now we see them in other environments. This has implications for the chemistry of life. It's possible that buckyballs from outer space provided seeds for life on Earth."