Wednesday, August 3, 2011

Scientists Create Space-Time Invisibility Cloak

Scientists have created a real life invisibility cloak. This one doesn't just make objects disappear, it hides entire events.

Physicists have discussed the theoretical possiblity of a space-time "event cloak" to theoretically conceal an event in time. A Cornell team made it happen, for 110 nanoseconds anyway.

The necessary equipment: two time-lenses that can compress and decompress light in time and two electro-optic modulators. Using two of these modulators, you can slow down or compress the light travelling through the first lense. The second lense, downrange from the first, can then decompress (accelerate) the incoming photons from the first lense. (Don't have electro-optic modulators? A nice used model can be yours for a mere $1,499.99, plus shipping and handling, via eBay.)

Stopping the photon flow is like stopping the traffic on the highway. As you sit upstream in your idling car, more than half fretting over the delay, you send up a small prayer for anyone involved in the accident, knowing that if you can just get past this it will be free sailing on the highway. The all-powerful physicist crosses the higway through the gap and then accelerates the traffic to catch up with the traffic ahead, closing the gap. To a driver further downstream, the gap isn't there; from their observation point it might as well have never existed. There is no evidence.

That gap is your period of invisibility. Whatever happens under the "event cloak" goes unrecorded. But you'll have to be mighty quick in order pull off that bank heist. The Cornell scientists concede that the best they could achieve is 120 microseconds. That said, science is always advancing, so who knows what the future holds. Meanwhile, the space-time invisibility cloak is great fodder for science fiction. I feel a story coming on....

For a very readable and more detailed account, I recommend National Geographic's article: Space-Time Cloak Possible, Could Make Events Disappear?

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