"Your father left this in my possession before he died. It is time it was returned to you. Use it well."
- note from Albus Dumbledore to Harry Potter
While many people, both young and old alike, probably imagined a number of things they could do with a cloak of invisibility, they knew that, like Harry Potter himself, it was merely an object of fantasy. At least back in 1997. In 2013, fantasy has nearly met reality.
Back in 2006, researchers were able to develop a laboratory experiment whereby objects were made invisible in the microwave light range (just below the visible spectrum). Scientists were able to bend light waves around the object, removing its shadow and making it appear invisible.
In 2011, scientist Xiang Zhang was able to develop a cloak that bends visible light around objects so that it appears flat and the image projected is that of the objects lying behind the cloaked object. You can think of it as gravitational lensing (where a massive object (galaxy for example) (“Massive Object 1”) lies between our sight lines and that of another bright object (“Bright Object 2”). In these instances, the gravity from the Massive Object 1 bends the light emitting from the Bright Object 2 around its edges so that the image of the Bright Object 2 actually appears as two objects on either side of the Massive Object 1.) except rather than merely projecting the light from the hidden object along side the object doing the hiding, it bends the light enough that light from the hidden object wraps around to the front of the object doing the hiding, resulting in the light waves from behind the object being projected to the viewer. The 2011 experiment, however, dealt with the cloaking of microscopic object (about the size of a human red blood cell).
Recently, Yaroslav Urzhumov, of Duke University has developed a cloak made from a 3-D printer using plastic to make objects invisible in microwave range. This cloak is specially designed with an algorithem used to calculate the location, size and shape of holes in the cloak to deflect light properly to make materials invisible in the microwave range. He has run tests and believes that this process can be transferred to the visible light range in the not-too-distant future. His simulations show that not only will a cloak as thin as one inch in diameter be able to make objects several meters in diameter invisible, but the cloaks will be able to be produced from transparent polymers and glass on (relatively) inexpensive home 3-D printers – which are currently available in several price ranges at or below $3000.
It’s possible that by the end of the decade, we can all be giving our children their very own invisibility cloaks. The only question is what they will do with it and, perhaps more importantly, whether they will use it well.