The power to render objects and even people invisible to the visible spectrum of light is something that many scientists have been working to develop for years. And now a cloak made of silk can actually render subjects invisible to certain areas to the spectrum of light. Unfortunately, the light it cloaks is outside of the human visibility spectrum. Scientists are hoping, however, to use this technology to extend the properties of the cloak to the visible spectrum.
It sounds almost like a joke, a cloak that renders the wearer invisible to light humans cannot see. The obvious question that follows is, “Then how do they know it works?” Boston and Tufts Universities have developed the cloak as a possible precursor to more advanced and intricate models that would exclude smaller wavelengths than the current broad wavelengths between radio and infrared.
How does invisibility work? The silk material is interwoven with gold spirals each acting to reflect the light around, bending the light actually through the object. The end result is light which rather than reflects is conducted through the material and comes out at the same location it would have normally, essentially bypassing the object cloaked altogether. But it isn’t so easy to make these objects. The SRRs (Split Ring Resonators) actually have to be crowded onto a very small area, packing 10,000 miniature resonators into an area as tiny as a space no larger than half a mailing stamp.
So what needs to happen before the invisibility cloak is ready for the market? At the moment, since invisibility cloaks can only absorb a small portion of the electromagnetic spectrum, the material is virtually useless except for experimentation purposes. But when the material is made to work inside the visible light spectrum it will eventually be able to absorb more and more of the light spectrum. First it will likely be able only to absorb light from a much lower frequency, but it may eventually be able to shield all light from the spectrum so that subjects are shielded not only from visible light, but possibly from infrared as well.
Such applications would be incredibly useful obviously for the military, but could also be used in other fields such as observing natural habitats, personal security, and even electronics and media. Unfortunately, there are also plenty of applications that other sources would find such as burglary and espionage. Hopefully this device, when developed, will prove to be more useful to humanity and less of a burden.
But even with an invisibility cloak, there is still an obvious object in the area. Last year when the invisibility cloak was proposed by scientists, we covered the potential defenses against someone with an invisibility cloak including potentially using smoke screens, water, and even lasers that may be able to overwhelm the material making the object partially visible in damaged areas. And as this new world where invisibility is a reality the development of ideas to provide a defense against invisibility seem all the more important.