Researchers Say That True Invisibility Cloaks Will Always Remain in the Realm of Fantasy

Even within the world of Harry Potter, Harry’s perfect invisibility cloak is a thing of legend. In our world, achieving some level of invisibility via cloaking devices is possible — but it’ll never measure up to the level of a Deathly Hallow, thanks to the pesky laws of physics. Researchers at the Ludwig Maximilian University of Munich and the University of Otago have been studying various cloaking techniques, and they believe that a cloak like Harry’s is still just a fantasy.

That doesn’t mean that some forms of cloaking aren’t still achievable, of course. Current cloaking technologies deal with diverting light around the “invisible” object so that it will be hidden from view. These developments are imperfect, however. Jad Halimeh, one of the researchers, put it this way:

In principle, what this paper shows is that invisibility cloaking is not possible for all observers. Real invisibility cloaks will have to stay in the realm of fiction. Your cloak, if it is to be pragmatically broadband, will pretty much look like that of Predator, giving away what it hides via distortions when you move relative to it.

The problem arises when the cloaked person starts to move, say researchers. If both the cloaked person and the viewer remain stationary, then the cloak-wearer will remain invisible. But if either person starts to move, light waves get “dragged” in the process, causing a visual blur effect. Robert T. Thompson, Halimeh’s co-researcher, explains:

Although our results may be disappointing for would-be wizards, understanding the limitations of cloaking devices is actually important in real life. New technologies are beginning to emerge from cloaking research, and we’re looking for effects that could either compromise the functionality of these technologies, or which could be exploited for some new practical purpose in the future.

Still sounds like the current cloaks would be strong enough to allow a couple of kids to sneak into a school library’s restricted section, right?

(via Gizmodo, image via Harry Potter Wiki)

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