On Being Invisible
Who among us hasn’t harbored the fantasy of being invisible? It offers so many juicy possibilities, both licit and illicit.
But—there’s always a but—no respectable scientist would tell you anything other than it’s impossible. Unless you’re Harry Potter, of course.
Until recently, that is. In 2006 researchers from Duke University announced the creation of metamaterials that can bend light around an object and reconstitute it on the other side. Voila, the object becomes invisible (Science 312 [June 23, 2006], 1780–1782).
Trouble is, it works only in a narrow slice of the microwave region of the spectrum where human beings can cook but have no visual acuity. No use being invisible where you can’t see.
Science always moves along, though, and now the Duke research group, joined by collaborators at Southeast University, Nanjing, China, have expanded the spectrum of invisibility in a new publication (Science 323 [January 16, 2009], 366–369). The metamaterial cloak is a complex structure with thousands of individual glass-fiber subunits arranged on a copper-clad circuit board. The exact arrangement is determined through an intricate mathematical algorithm. The device covers a broader wavelength distribution than the original and also redirects a higher fraction of the incident light (i.e., the object underneath is more invisible).
Alas, the coverage is still confined to the microwave region of the spectrum, but according to the authors, it “should scale well toward optical wavelengths.”
Better put your cape on eBay, Harry Potter!