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How to make things Invisible

Scientists and researchers have made lots of important discoveries in the field of metamaterials, they have found ways to bend light so the it passed around an object as if it weren't even there. So now the hunt has been on to find a Metamaterial that will do this for the visible frequency range, so that visible light will pass around an object making it appear as if it weren't even there.

A metamaterial is a material which gains its properties from its structure rather than directly from its composition. Kind of like the way you can see through a screen becuase of the holes in it. If you get up close to the screen you can see that it is made of something but from far away you can see right through it.

The main reason researchers have investigated metamaterials is the possibility to create a structure with a negative refractive index, since this property is not found in any naturally occurring material. Almost all materials encountered in optics, such as glass or water, have positive values for both permittivity e and permeability µ. However, many metals (such as silver and gold) have negative e at visible wavelengths. A material having either (but not both) e or µ negative is opaque to electromagnetic radiation. This is due to the interaction of the surface plasmons.

In order for its structure to affect electromagnetic waves, a metamaterial must have structural features smaller than the wavelength of the electromagnetic radiation it interacts with. For instance, if a metamaterial is to behave as a homogeneous material accurately described by an effective refractive index, the feature sizes must be much smaller than the wavelength.

For visible light, which has wavelengths of less than one micrometre typically (560 nanometers for sunlight), the structures are generally half or less than half this size; i.e., less than 280 nanometres.

For microwave radiation, the structures need only be on the order of one decimetre. Microwave frequency metamaterials are almost always artificial, constructed as arrays of current-conducting elements (such as loops of wire) which have suitable inductive and capacitive characteristics.