The invisibility cloak worn by Harry Potter in the best-selling children’s novels is a fantasy. But in the real world, new work on light bending with nanomaterials makes the invisibility cloak look like child’s play. Consider this: you’re part of a squadron in Iraq charged with stopping roadside bombs. You stake out a location on a busy highway used in the past for IEDs (improvised explosive devices). The terrorists can’t see you as they approach. You spring the trap, and the terrorists can see you, but you are actually 20 feet to the left!
An article in the March 28th edition of Science News called “Cornering the Tetrahertz Gap”, lays outs the scientific foundation on how this “sleight of light” could conceivably happen. Physicists start with man-made composites called “metamaterials” that consist of elements from the Periodic table. Their structure gives them unusual refractive properties. According to a report from Boston College: “Constructed on the micron-scale, metamaterials are composites that use unique metallic contours in order to produce responses to light waves, giving each metamaterial its own unique properties beyond the elements of the actual materials in use.”
Professors at the University of California Berkeley also employ a property called chiralty to literally bend light backwards.
Collaborators at Boston College and Boston University are investigating the potential for a security screening device that would not have the adverse biological effect of x-rays. Invisibility cloaks developed so far can only hide objects that are very small. A computer simulation shows that a can-shaped cloaking device made of many layers of concentric film could work.
Making cloaks that could cover the entire electromagnetic spectrum at the same time is still a major challenge.