I got an email from New Scientist this morning, announcing that a "working invisibility cloak" had been "created at last." "At last?" I thought to myself. "What, like we've all been sitting around wondering what's taking so long?" Never mind that this is one of those science fiction type of concepts that most of us think must be heavy on the fiction, despite all the technological breakthroughs of recent years. I just don't really think I'm comfortable with the idea of invisibility being an option. I have not been pining for the day when enemy planes can fly over New York undetected. I also am not anxious for terrorist bombers to be able to walk with impunity through a crowded mall, looking for a properly substantial number of people to target. I have not even been impatiently checking the latest scientific journals for signs of progress in the fine art of "cloaking," frustrated that I can't yet slip into a room and hear what's being said about me when no one thinks I'm around. I don't want to know. Some genies are better left in the bottle.
Fortunately, upon reading the fine print in the article Justin Mullins wrote for New Scientist, I discovered that the technology is not quite as far along as the headline made it sound. Air Force commanders will not be telling their helmsmen to "raise shields and engage the cloaking device" anytime soon. (Although the shields are coming along, from what I've read, and are a much better idea than the cloak, if you ask me.) The progress that has been made, at Duke University, is in the "microwave region of the electromagnetic spectrum," which means that scientists can now bend light around an object at a very specific frequency, and make it "disappear"--albeit a frequency which people can't see, and only in two dimensions.
It's still a remarkable scientific breakthrough, and the first step in what David Smith, a member of the Duke team, said he hopes will lead to "a 3D structure that could hide an object completely from view." When he says "structure," he means it. The success they've had to this point rests in a set of rings that encircle an object completely--the object in question for the tests at Duke being a copper ring, that mostly disappeared. There was still some distortion to indicate the ring was there, but mostly invisible is still mostly invisible. I'm betting if you didn't know to look for it, you probably would miss it, if you could see it in the first place, that is, which since we're talking microwaves, you can't, but...(moving on.)
Multiple steps led up to this amazing, if somewhat undesirable, accomplishment. The set-up involved creating new materials:
In recent years, materials scientists have made rapid progress in making so-called "metamaterials", which can have exotic electromagnetic properties unseen in nature. These are made up of repeating structures of simple electronic components such as capacitors and inductors.
In 2001, Smith built a metamaterial with a negative refractive index, which bends microwaves in a way impossible for ordinary lenses. Now he has gone one step further.
The one step further is the aforementioned rings, which "distort an electromagnetic field as it passes through." According to Smith, they "steer microwaves around the central region of the device," the region where they stashed the copper ring. Needless to say, the way they can tell it worked must involve fancy machines that can detect electromagnetic waves in this range, since we're not talking about something that's visible to the human eye. Making these materials in such a way that the results could be seen (or not seen, as it happens), creates some challenges. Mullins clarifies, "The problem with visible light is that it has a much smaller wavelength, meaning an optical metamaterial would have to be built on the nanoscale, which is beyond the limits of current nanotechnology." (Probably not for long. We know how nanotech is advancing by leaps and bounds.) There also would still be limitations as to frequency--Smith says even nanomaterials would still only work on one frequency. They'll have to work on that if they want to make Federation vessels disappear, or make spies' jobs really, really easy.
I have no doubt the problems can be overcome, maybe not in the immediate future, but probably sooner than I will be ready for such technology to make its way into ubiquity. Am I the only one who finds such an "advance" to have dubious merit? Maybe I'm just in a tech funk. Saturday I wrote with disapproval about the latest form of scientifically invented self-flagellation. (Some of you will remember the post about the mirror/camera combo. It's a different kind of "guilt mirror.") I don't think that's it, though. I really just think it's that some things bring up that old truism that just because we can build something doesn't mean we should. All of the applications I can think of for this new scientific direction are either nefarious, or pointless. Can anybody help me out here? Anyone else have an idea of how to use this in a good and fruitful way, especially one that can't be abused by the bad guys?
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