‘Cloaking device’ idea proposed

According to this article on the BBC
website, cloaking devices that are used to render
spacecraft invisible in Star Trek might just work in reality, two
mathematicians have claimed.

They have outlined their concept in a research paper published in one
of the UK Royal Society’s scientific journals.
Nicolae Nicorovici and Graeme Milton propose that placing certain
objects close to a material called a superlens could make them appear
to vanish.
It would rely on an effect known as “anomalous localised resonance”.
However, the authors have so far only done the maths to verify that the
concept could work. Building such a device would undoubtedly pose a
significant challenge.

Starting small

Cloaking devices are a form of stealth technology much favoured by Star
Trek baddies such as the Romulans and Klingons.
The complex mathematical phenomenon outlined by Milton and Nicorovici
closes the gap a little between science fiction and fact.
The phenomenon is analogous to a tuning fork (which rings with a single
sound frequency) being placed next to a wine glass. The wine glass will
start to ring with the same frequency; it resonates.
The cloaking effect would exploit a resonance with light waves rather
than sound waves.
The concept is at such a primitive stage that the scientists talk only
at the moment of being able to cloak particles of dust – not
In this example, an illuminated speck of dust would scatter light at
frequencies that induce a strong, finely tuned resonance in a cloaking
material placed very close by.
The resonance effectively cancels out the light bouncing off the speck
of dust, rendering the dust particle invisible.
One way to construct a cloaking device is to use a superlens, made of
recently discovered materials that force light to behave in unusual

Vanishing point

Professor Sir John Pendry, of Imperial College London, who helped
pioneer superlenses, said: “If the speck of dust is close enough it
induces a very aggressive response in the cloaking material which
essentially acts back on the speck of dust and forces it to stop
“Even though light is hitting the speck of dust, scattering of the
light is prevented by the cloak which is in close proximity,” he told
the BBC News website.
The authors of the paper argue that the cloak needn’t just work with a
speck of dust, but could also apply to larger objects.
But they admit the cloaking effect works only at certain frequencies of
light, so that some objects placed near the cloak might only partially
“I believe their claims about the speck of dust and a certain class of
objects. In the paper, they do give an instance about a particular
shape of material they can’t cloak. So they can’t cloak everything,”
said Professor Pendry.
“Nevertheless, it’s a very neat idea to get this aggressive response
from the material to stop tiny things emitting light.”
The Imperial College physicist agreed this particular concept had
potential military uses: “Providing the specks of dust are within the
cloaked area, the effect will happen. A cloak that only fits one
particular set of circumstances is very restrictive – you can’t
redesign the furniture without redesigning the cloak.”
Details are published in Proceedings of the Royal Society A:
Mathematical, Physical and Engineering Sciences.

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