"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.
