Harry Potter’s Invisibility in Jeopardy
Last year I wrote about the prospects for an “invisibility cloak” that works by bending light around an object so it can’t be observed. (See my post of January 29, 2009.) Amazing as it seems, this is not only theoretically possible but has already been realized for a limited range of wavelengths.
New work from MIT imagines a “perfect invisibility cloak” that smoothly glides light of any wavelength around Harry Potter. Alas, these researchers also throw cold water on the theory that hides Harry’s cape. Their results show that shooting fast-moving charged particles at the invisibility cloak renders it visible via emitted radiation, even though light doesn’t detect the object (Physical Review Letters 103 , 243901).
Come to think of it, cold water itself would detect the perfect invisibility cloak too. You might not be able to see it, but you could feel it, and it would repel water. Too bad, Harry, that invisibility doesn’t really make one undetectable.