Super materials from dreams to reality

Three physicists of the Fresnel Institute (Marseille, France) have identified the characteristics of a device capable of turning objects into invisible to the human eye, despite the nature and distance of the light source. No matter how strong the object is, it doesn't matter.

This work is initially purely mathematical, but is an important new step for mankind on the way to find an "invisible existence" state, which we humans still dream long ago.

A British colleague in the research group later proved confident that, with the current level of technology, we can completely apply the above achievements into practice.

When hidden inside a hat, a " metamorphic " plain tube, with the ability to " evade " electromagnetic waves, light, will turn the object into " invisible "

Strange nature

" It's like you open a hole in an empty space !", Expert David R. Smith of Duke's Pratt School explained. Theoretically, an object can become invisible if its physical structure can "bend" the incoming light. Then the light beam will " glide " through the object like a stream of water sliding through the pebbles on the stream, and then, the light will " correct " the path straight back. As a result of this light's bending phenomenon, our eyes will not be able to see the object "in the middle of the day" .

This square is a nanostructure of a " metamaterial " form.Evenly engraved patterns change the direction of the beam of light

But in fact, the problem of science and technology is to solve, how to create a material that can " shape " the flow of light. In nature, there is absolutely no such material. So, humans have to invent a completely " artificial " physical structure, in order to " invisible " what they want. These are the "metamaterial" forms.

The characteristic of this material is that, with a nanostructure that has been "finely cut ", the mass of this mass will " control " the electromagnetic properties of the material itself. According to the explanation of physicist John Pendry, who pioneered this " magic " field, when we change the structure of matter at the microscopic level by " carving " them with The pattern has a uniform geometric dimension, so that the material has a negative refractive index, we will create a new form of material that will deform the incoming radar waves, when its structure.

And also in theory, to get this level of index, the principle is quite simple: just turn the two physical characteristics of matter - permeability and dielectric constant into " sound ". However, in nature, we also find that some forms of matter such as metal also have a dielectric constant that is negative, but ironically, there is absolutely no material structure that can simultaneously possess two properties. The above is negative. It was not until 2001 that two American physicists David Smith and Sheldon Schultz succeeded in creating the first " super-physical " samples from copper metal.This is a great success of advanced nanotechnology.However, difficulties are still many.

The left " NA " is observed from a normal microscope, but when the microscope is attached to a " super-physical " lens, the following image (right) will have a dark resolution. pros

Practical applications

According to Professor Frédéric Zolla, the author of a study on the applications of "metamaterials", the ability to create a device that can completely "fool" the human eye will only return. come true within no sooner than 10 years!A co-author of this study has metaphorically stated: " We need to have more technological leaps to be able to reach the destination. And if we mobilize all means. In the end, perhaps humans will set foot on Mars sooner than they can stealth right on this Earth! ". So, is the human invisibility dream just a fantasy? That, the future will answer. But in the short term, people know how to apply the superior characteristics of " super materials " for dreams . at hand!

An application that physicists are most interested in is making optical lenses with extremely high resolution, without aberration, to help people observe objects at a high level of sophistication. possible.Knowing that, the resolution of a picture is always limited by the wavelength of the light source.

Therefore, for visible light, our eyes can only recognize to the maximum the shapes with the smallest size of several hundred nanometers.But when using lenses made of " super-matter ", with negative refractive index, the wavelengths will resonate with their nanostructures and be amplified. Since then, the reflected image of the eye will be " identified " at the highest resolution, that is, the clearest. In addition, the application of " metamaterials " is also being studied to apply to high-end printing techniques and information storage on laser discs.

Visual illusion.When you dip a pencil into the water basin, we will see that the pen is folded, because the light travels more slowly in the water than the air.But when placed in a material with a negative refractive index, the pen will be completely " broken " in half!

Tuong Nguyen