Have you watched Star Wars or perhaps, Harry Potter? If so, you should have seen the great invisible cloak. A group of specialist who were currently working at the Duke University in North Carolina in USA, utilises British profesor's theory, and has built a device from fantasies such as Starwars or from fictitious wizards (Harry Potter) by Rowling. Anyway, this has been a fact that these experts have created such a cloak - yes, the invisible cloak.


Caption: an invisible cloak

This cloak could only work as a device to hide object from view, only from a person's eye with a microwave detector. I did not read the entire article (from a 2007 new scientist magazine), but this cloak would very specifically rely on microwave frequency. From my personal opinion after reading the article, this device would only work in 2-dimensionals form. Since 2007, my friends and I have discussed about this cloak. It is an extremely amazing discovery though it was only a relatively small invisibility barrel.


Caption: the theory that lies behind the invisible device

According to the journal, the build of the invisibility cloak required complex materials. For such, they uses copper rings and metamaterials, artifical composites and arranged in concentric circles. This has shown that microwave radiation can be deflected past an object just as water will flow past an obstacle. When a beam (the signal) was aimed at the device, sensors were unable to visibly see the object hidden in the middle because the microwaves were not bounced back. As a result, the human body that lies in the middle of the device will become invisible. However, before scientists could make an object vanish before a person’s eyes, a cloak would have to be devised that simultaneously interacted with all the wavelengths in light. This is also known as their very first invisibility device.

Three years later, in 2009, scientist modified the cloak to provide greater illusion. A physicist at the Hong Kong University of Science and Technology suggests to extend the initial concept of invisibility. Instead of bending light around a central cavity to hide the object lies in the middle of the device (read above), the team has worked out the mathematical rules for bending light in a totally different way. For example, a material could be designed to bend light in the same way as a spoon would. So the light hitting the material would be distorted, making it to look as if the spoon were there. It is also possible to design a complementary material that has an opposite effect, that is to exactly cancelling out the effect that an object has turned on light. So light distorted by a spoon could be passed through a complementary material to eliminate these distortions. This has been revealed in the Physical Review Letters, in vol. 102, page: 253902. Their idea is to develop some surprising technology. For example, creating a 'fake' hole in the middle of the wall so that people could see what lies opposite the wall.


Caption: an invisible hole (or ultimate illusion) formulated by mathematical calculations

Sir John Pendry, a professor at Imperial College, London (UK) was expecting to produce total invisibility for larger objects. So what are they expecting? An invisible home in a busy street? Sometimes, I was wondering if this kind of great invention will significantly benefit us or will flawlessly destruct human being's life?