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Harry Potter (Daniel Radcliffe) and the goblin banker Griphook (Warwick Davis) are concealed beneath an invisibility cloak in "Harry Potter and the Deathly Hallows: Part 2."
Harry Potter's invisibility cloak comes in handy for the final installment of the boy wizard's film saga, but real-life invisibility technologies might well be at least as useful — even if they aren't as cool as Harry's cloak.
For the foreseeable future, the benefits provided by the real-life gizmos that have come to be called "invisibility cloaks" or "cloaking devices" really won't have much to do with the kind of tricks you'll see in "Harry Potter and the Deathly Hallows: Part 2." Sorry to disappoint, but you won't be able to throw a high-tech fabric over your head and disappear from the scene when the bad guys come looking for you.
However, it is conceivable that scientists could look at viruses and protein molecules directly, using new breeds of ultra-high-resolution "superlenses." Physicians might have more accurate ultrasound scanners at their disposal. Acoustical cloaks could hide ships or underwater assets from sonar detection. And offshore facilities could be engineered to soften the effects of wave erosion on the shore ... or amplify ocean waves for generating renewable power.
All this magic could come about through the power of metamaterials. These are materials that are specially structured and shaped to bend electromagnetic waves or acoustical waves in weird ways. Real-life invisibility cloaks, for example, are actually devices or layers of material designed to divert light around the object that's concealed.
This month's issue of Physics World delves into the past, present and future of invisibility — and the best part about this particular issue is that you can download it for free as a PDF file.
One of the limiting factors for invisibility cloaks has to do with wavelength. Shorter wavelengths require smaller structures in order to produce the bending effect. That's why bending sound waves is easier than bending electromagnetic waves, and why bending microwaves is easier than bending visible light. Scientists have been able to develop "invisibility carpets" that can render bumps in the carpet undetectable — but the bumps have to be so tiny that you couldn't see them with the naked eye anyway (on the order of a millionth of a meter), and the invisibility effect only works for near-infrared wavelengths.
A different research team came up with a way to hide objects in a region about three-quarters of an inch wide, using calcite crystals, but the invisibility effect is produced only with respect to light of a specific polarization.
"While what has been so far achieved in invisibility science has been a tour de force of physics and engineering, our children will probably still have to wait some time for that real Harry Potter cloak," Stanford University's Wenshan Cai and Purdue's Vladimir Shalaev write in Physics World.
Metamaterials aren't the only way to achieve invisibility, however. There are also active-camouflage techniques, ranging from video projection to a high-tech light-emitting matrix that's inspired by a squid's skin.
The latest scientific buzz focuses on space-time cloaking, which involves using "time lenses" to compress and then decompress light. This would result in an apparent time gap during which an event could go unobserved. Scientists have discussed time cloaking as a theoretical possibility for quite some time (so to speak), but researchers led by Cornell University physicist Moti Fridman say they actually created a "time hole" that lasted 15 trillionths of a second. The Guardian, the Physics arXiv Blog and Science News delve into the details.
For much, much more about metamaterials, event cloaking, active camouflage and other real-life magic spells, check out Physics World's special issue as well as these links:
- Cloaking device edits out space-time events
- Military studies squid camouflage
- Get set for invisible war machines
- Invisibility cloak made of silk and gold
- How to make an invisibility cloak
- Harry Potter's hallowed high-tech
Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. You can also add me to your Google+ circle, and check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.
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Would you really wear an invisible cloak? Nobody would notice it was even worn because it is invisible and I think there is a Irish joke in invisible clothing.
Correct me if I'm wrong, but we "see" by our eyes picking up light being reflected back off the things we are looking at, so if the cloak is bending incoming light rays around it, then anything inside would be in "absolute darkness", as no light would be getting "through" the bending. Even though we couldn't "see" them, we would see the things they were bumping into and knocking over.
Interesting point... if you were wearing a cloak of that type, how could you see what's happening outside of it?
This cloak would also need to be able to produce an image on the inside of the fabric that is a visual representation of what is around it. So the light coming in to it from outside would be bent around it, but also the image would be captured and copied in the process for display on the inside surface. The end result would be an invisible object on the inside of the cloak, and a TV on the inside surface of the cloak representing what is outside of it.
Of course if you just want to hide inanimate objects, there is no need for the object inside getting any light.
Richard, the point I was making was that there would be no way of "visually representing" anything from the outside (short of echo location) because the bending of light would be a passive effect of the meta-material used to create the cloak. There would be no light inside the cloak that didn't originate from inside because all outside light is being bent around the cloak. But it's make-believe anyway, as meta-materials are designed for a very narrow frequency range, and we would end up with a "blue invisible" a "red invisible" and "green invisible" cloak, and there would be no way of mixing any of them together.
I believe we will see RADAR invisibility material long before anything else. Pun intended.
MacGyver I see what you are getting at, since the light from outside cannot get to our eyes inside the cloak the person inside the claok wouldnt be able to see anything outside.
Of course one could put micro pin head video and infared cameras at various points all over the cloaking apparatis to read outside light so the people could see inside the cloaking field.
The cameras could be made so small that they are not noticable unless against a solid white background. Kind of like how when you hear a plane in the sky and look up its is very hard to see them do to the size distance factors....
dude. it's fiction.
those invisable things are so hard to see...
Flipped the switch, and Damn can't find my truck. This sucks.
As usual, once again, Scotty already figured this out when he had to adapt a Klingon cloaking device on the Enterprise
I agree with MacGyver-2750749, this story has a way to go yet! Hardly imagined as a child that we would be talking invisibility cloaks as a real live thing, I though Star Trek was fake!
Some of Star Trek is real. :-}~
Invisibility / Non-visibility IS real, and has been for millennia.