The Science of Invisibility

When it comes to illusions, one of the oldest favorites is Invisibility. Be it in ancient texts

of Plato and Homer, or Wells’s 19th originalCentury “The Invisibility Man”, Invisibility has been portrayed as one of the fondest fantasies. While many of these have the character in question possess a specific ‘power’ that grants him the ability to disappear at will, the representation of the Invisibility Cloak in the Harry Potter series imbues the power into an inanimate object, namely a cloak.

With recent advances in the fields of optics and the increased understanding of the working of our eyes, scientists have claimed that it is theoretically possible to create an Invisibility Cloak. The essential principle is intricately linked to how we perceive objects around us, i.e. how we ‘see’. We ‘see’ an object when the electromagnetic wave that is light is reflected from its surfaces and forms an image on the retina in our eyes. Therefore, in order to mask an object, the material must act upon light in such a way that it is not reflected or scattered by the object it cloaks.

According to a study by scientists at Berkeley published in the journal Science in September last year, they had successfully produced a small scale version of the cloak, capable of shielding a very tiny object. Their “ultra thin invisibility skin cloak for visible light” was about 80 nm thick and used nano antennas of different sizes to counteract the distortion. The study said that since prior attempts had been too bulky, there was no ability to scale-up.  However, the current form of the cloak was not yet suited for making people or larger objects invisible.

A study published by scientists in the U.K. earlier this year in July in the journal Scientific Reports demonstrated a so-called “surface wave cloak” which could make curved surfaces appear flat when they come in contact with Electromagnetic waves. Yang Hao, professor of antennas and electromagnetism at Queen Mary University of London led the study to develop the cloak, which has 7 super thin layers [7 – The magically most powerful number. Coincidence? I think not.] each with different electrical properties. Since the cloak mainly prevents interaction of object with Electromagnetic waves, it can also find application in radio and aerospace communications where it can be used to reduce scattering of waves and related transmission losses.

While most attempts at making an Invisibility cloak focus on meta materials and optics, researchers believe the future lies in making a digital cloak. This cloak would measure space as pixels, and collect and emit light in such a way that it would cloak the object from the human eye. However, unlike passive cloaks that shield by virtue of material, such a cloak would require an active power supply, similar to how ‘magic’ was needed for Harry’s cloak.

As we advance further into uncharted fields of science, what was once fantasy will become reality. However, science is but a tool, and it is up to us whether we use it for betterment or further destroy with our own hands what we have created.

– Akhil Shri

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