Invisibility

Imagine a home where your living room items, kitchen appliances, or anything that may be an eye sore, were made to be only visible when needed. Think now of your office, and the all in one laser printer and other office equipment only visible when needed. For the minimalist, it sounds like heaven.

OK, so this may be going a bit too far but what has been stuck in the realm of science fiction for decades may actually become reality, as a number of researchers across the world demonstrate invisibility.

If this comes as a surprise, you’ll be even more surprised to hear there are not just one, but a few techniques around. The only catch with the majority of them is that they have only been demonstrated on a 2-Dimensional microscopic scale.

Engineers from the University of Michigan have been playing with the idea of Carbon Nano Tube coatings. Effectively a flat sheet of carbon atoms rolled into a cylindrical shape, this ‘miracle material’ has already demonstrated strength greater than that of Steel and conductivity greater than that of Copper.

But the advantage in this technique is the refractive index, or the speed at which light travels through them. When light travels through air and onto an object, the difference in the refractive index between air and the object causes light to scatter, enabling us to see the object.

But in the case of Carbon Nano Tubes, their refractive index is very similar to air. A coating of these on an object will cause minimal scattering of light therefore rendering the object ‘invisible’. The Michigan team demonstrated this on a microscopic piece of silicon.

The fact that the material can coat the object will enable full 3D invisibility.

Researchers at the University of Texas at Austin have looked into Metamaterials, another class of ‘miracle materials’, but which are man-made.

The use of these materials for invisibility is based on the same concept of light scattering as with Carbon Nano Tubes, but in reverse.

The metamaterial is placed in front of the object. Any light that shines upon the object is scattered, but when the scattered light reaches the metamaterial, it scatters in the opposite direction, effectively cancelling out the light.

The advantage here as well as with the Carbon Nano Tubes, is that this could potentially be used for 3D objects, giving rise to the hope that the day will come, when we will actually be able to put on a cloak that will make us invisible.

The main uses here will of course be military, and there has already been some progress in this field, with the first infra-red invisible tank being developed. NASA has also been using the materials discussed to analyse deep space planets.

But how far do we go with this? Clearly this technology getting into the wrong hands could be disastrous.

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