Mention the phrase "real-life invisibility cloak" and you're sure to get a few raised eyebrows. However, science's best efforts so far have merely hinted at what might be possible.
For instance, there's the development of metamaterials that can deflect light waves around an object, making it invisible within the microwave spectrum. It's too bad that human vision operates on a different part of the spectrum. Then there are techniques that hide things within near-infrared light, which may be useful in combat situations -- but in not in broad daylight. You can already start to see how it may be a while before researchers come up with a cloaking technology that renders an object -- in the truest sense of the word -- invisible.
Now a group of scientists at the University of Texas have taken the concept a step further by demonstrating a cloaking device that uses a familiar optical illusion known as the mirage effect. Instead of bending light around an object to make it invisible, their approach utilizes sheets of carbon nanotubes to conduct heat, which causes light rays to bend away from the hidden object.
The technology is based on the same principle that produces a similar phenomenon in the desert. Normally, our eyes make out objects by the way light bounces off them. But in this circumstance, the light never bounces but bends while passing from cooler air to the cooked high-temperature air that sits right above the sand. So instead of seeing what lies ahead, what we get is a mirage of the blue sky superimposed on the ground.
Through electrical stimulation, the transparent sheet of carbon nanotubes has the ability to transfer all its heat to surrounding areas, causing a steep temperature gradient. Just like a mirage, this steep temperature gradient causes the light rays to bend away from the object concealed behind the device, making it appear invisible.
"It is remarkable to see this cloaking device demonstrated in real life and on a workable scale," said a spokesperson for the Institute of Physics. The array of applications that could arise from this device, besides cloaking, is a testament to the excellent work of the authors."
Obviously this method of making objects "invisible" comes with it's own set of challenges. Like for instance, who would wear a scorching hot cloak? And under water no less. Well, perhaps the Navy can figure out a safe way to implement the technology for its stealth operations.
Either way, the effect is pretty cool to watch.
(via CBS News)
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