Thursday, May 25, 2006

Harry, Somebody Is Studying Your Cloak

I wonder what else is being studied? More kids would do science if they knew this what was in the future. Not the military aspects of course.
Here’s how to make an invisibility cloak - Science - "'The cloak would act like you've opened up a hole in space,' Duke University's David Smith, one of Pendry's co-authors, explained in a news release. 'All light or other electromagnetic waves are swept around the area, guided by the metamaterial to emerge on the other side as if they had passed through an empty volume of space.'

Pendry told that the cloak wouldn't reflect any light, and wouldn't cast a shadow either. 'It would be like Peter Pan had lost his shadow,' he said, referring to the fictional character who had to have his shadow stitched back on.

Dreams come true, with a few catches
Theoretically at least, the metamaterial could work like the helmet of invisibility celebrated in Greek myth, or the cloaking device that hid Romulan and Klingon vessels in the 'Star Trek' series, or the invisibility cloak that came in so handy for Harry Potter in J.K. Rowlings' novels.

'Fiction has predicted the course of science for some time. ... Maybe these Harry Potter novels were ahead of their time,' Pendry said, half-jokingly.

Of course, there are some scientific catches that the tale-tellers never had to worry about:

* For a total invisibility effect, the waves passing closest to the cloaked object would have to be bent in such a way that they would appear to exceed relativity's light speed limit. Fortunately, there's a loophole in Albert Einstein's rules of the road that allows smooth pulses of light to undergo just such a phase shift.
* The invisibility effect would work only for a specific range of wavelengths. 'There is a price to be paid if you want a thin cloak, in that it operates only over a narrow range of frequencies,' Pendry said.
* The cloak could be made to cover a volume of any shape, but 'you can't flap your cloak,' Pendry said. Moving the material around would spoil the effect.
* The tiny structures embedded in the metamaterial would have to be smaller than the wavelength of the electromagnetic rays you wanted to bend. That's a tall order for optical invisibility, because the structures would have to be on the scale of nanometers, or billionths of a meter. It's far easier to create radar invisibility, Pendry said: 'You're talking millimeters' — that is, thousandths of a meter."
Just a matter of time. I can see uses for it in the home. This is the kind of stuff that still gives me hope. Star Trek isn't that far away. Probably still not in my lifetime. I just hope we don't detour into the Terminator or create Cylons or some such unexpected consequence.

Of course, there was that Khan guy...

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