Tuesday, January 10, 2012

How to pull of an art heist...or how scientists have created a time-masking cloak

In a popular comparison: an art heist takes place in a crowded museum--before your eyes and surveillance cameras. you don't see the thief, not even the actual taking of the painting. The opportunities would be staggering...and scary, but this is exactly what scientists at Cornell U are claiming to have done. Not the actual heist, but creating a time cloak that hid an event for 40 trillionths of a second.

While other invisibility cloaks created move light beams away from an object (like making an armored tank disappear or nanotubes creating a mirage), the Cornell team (backed by the Pentagon) found a way to alter how fast the light moves, changing the dimension in time, not space. By doing this, it makes it appear to the human eye or surveillance cameras (or even laser security beams) that an event isn't happening.
"You kind of create a hole in time where an event takes place," said study co-author Alexander Gaeta, director of Cornell's School of Applied and Engineering Physics. "You just don't know that anything ever happened."
This 'hole in time' is created using fiber optics as light moves inside a fiber thinner than a human hair. The scientists shoot the beam of light out. With other beams, they create a time lens that splits the light into two different speed beams that create the effect of invisibility by being too fast or too slow.

In the diagram a laser beam passes through a "split-time lens" - a specially designed waveguide that bumps up the wavelength for a while then suddenly bumps it down. The signal then passes through a filter that slows down the higher-wavelength part of the signal, creating a gap in which the cloaked event takes place. A second filter works in the opposite way from the first, letting the lower wavelength catch up, and a final split-time lens brings the beam back to the original wavelength, leaving no trace of what happened during the gap. (Image and Caption via Cornell University)
"It is significant because it opens up a whole new realm to ideas involving invisibility," McCall said
Click to watch a time cloaking simulation:

If you had such technology, what would you do with it?

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