J.K. Rowling was on to something after all.
The Harry Potter creator, whose hero has an invisibility cloak (among other heroic things) with which to battle the evil Voldemort, says her creation is a physical thing that can be draped over one or a few people, rendering them invisible to even magical eyes. The invisibility cloak just announced by researchers in the U.S. is a bit more high-tech than that, but the result is the same.
This cloaks bends microwave light around an object. To the human eye, whatever is under that cloak isn’t there. (That’s a description of what reality and perception are, and really, that’s the subject for another day.) Suffice it to say that if I’m standing right in front of you and I don this cloak, it will look like I’ve disappeared in front of your very eyes. Of course, you can just take a swing at me and hit me upside the head, assuming that I haven’t moved out of the way. And you really could see me if you were just using your eyes, since the cloak works now only in the microwave area of the spectrum of light. But you get the idea.
The key is metamaterials, which sport electromagnetic properties not usually found in nature. In other words, scientists had to create them. A group of these scientists at Duke University have done just that.
The cloak is said to be a series of concentric rings, each of which contains componentry that zap an elecromagnetic field as it passes through, battling it away to a different space. The effect is that the light bends, or disappears. Anything that would have been seen is not seen, at least by those who are using microwave-only detectors.
The application to the rest of the spectrum of light is still in the works. Visible light is so much smaller and requires a nanoscale version of the metamaterial. That’s next.