In the TV series "Star trek IV: the Voyage home" crew "enterprise" captures battle cruiser Klingon. Unlike ships Star fleet Federation, ships Klingon Empire equipped secret "masking device"that can make them invisible for the eyes and radar. This device allows Klingon ships go unnoticed in the tail ships Federation and with impunity to deliver a first strike. Due to the masking device Klingon Empire has before Federation of planets strategic advantage.

Perhaps there really such a device? Invisibility has become one of the usual wonders of science fiction and fantasy works - from "the invisible Man" to the magic of the invisible mantle of Harry Potter or a ring from "the Lord of the rings". However, for at least a hundred years of physics unanimously denied the possibility of creating invisibility cloaks and unambiguously stated that it is impossible: cloaks de violate the laws of optics and not consistent with any of the known properties of matter.

But today, an impossible can be possible. Achievements in the area of metamaterials" make substantially revise textbooks optics. Created in the laboratory working samples of these materials are of interest to the media, producers and military; all wondering how to make the invisible visible.
Invisibility in history

Invisibility is probably one of the oldest concepts of ancient mythology. Since the beginning of time man, alone in a frightening silence of the night, felt the presence of invisible beings and feared them. All around him in the darkness lurked spirits of the dead - the souls of those who had gone before him. Greek hero Perseus, armed with a helmet of invisibility, managed to kill the evil Gorgon Medusa. The generals of all time dreamed about masking device that would be invisible to the enemy. Using the invisibility could easily penetrate behind the enemy lines and to catch him unawares. Criminals could use the invisibility to make a daring robbery.

In the theory of ethics and morality Plato invisibility played a major role.[2] In his philosophical work "State" Platon told us a myth about the ring Giga. In this myth poor but honest shepherd Gig from Lydia penetrates into the secret cave and finds there a tomb; the corpse on his finger he sees the Golden ring. Next Gig finds that the ring has magical powers and can make it invisible. Poor shepherd literally gets drunk with power, which gave him the ring. Once you get into the Royal Palace, the Gig with rings seduces her, then with it kills the king and become the next king of Lydia.

Morality, which Plato out of this story, is that no man can resist the temptation to take someone else and kill with impunity. People are weak, and the moral and social phenomenon, which is necessary to enforce and support from outside. In public, people can observe the norms of morality, in order to look decent and honest and to maintain its reputation, but should give him the opportunity to become invisible, and he will not be able to resist and will certainly make use of their new powers. (Some believe that this is the parable of morality inspired Jr Tolkien on the creation of the trilogy "the Lord of the rings; ring that makes its owner invisible, at the same time is the source of evil.)

In science fiction invisibility is one of the common drivers of the plot. In the comic book series of the 1930s, "Flash Gordon" Flash becomes invisible to hide from the execution team villain of Ming the Merciless. In novels and films about Harry Potter, the main character, throwing magic cloak, may go undetected wander Hogwarts.com the castle.

H.G. wells classic novel "the invisible Man" embodied in the specific form around the same ideas. In this novel a medical student accidentally opens up the possibility of the fourth dimension and becomes invisible. Unfortunately, he uses the fantastic opportunities for personal purposes, makes a whole series of minor crimes and eventually dies in a desperate attempt to escape from the police.
Maxwell's equations and the mystery of light

Physicists have any clear idea of the laws of optics relatively recently as a result of works by Scotsman James Clerk Maxwell, one of the giants of the physics of the nineteenth century, In a sense, Maxwell was the complete opposite of the Faraday. If Faraday had a great flair of the experimenter, but had no formal education, his contemporary Maxwell was master of higher mathematics. He with distinction was held a course in mathematical physics at Cambridge, where two centuries before it worked Isaac Newton.

Newton invented the differential calculus - it describes the language of differential equations, as objects continuously undergo infinitesimal changes in time and space. The motion of ocean waves, liquids, gases, and a cannon ball - all this can be described in the language of differential equations. Maxwell began to work, before a clear objective: to Express the revolutionary discoveries of Faraday and its physical field with accurate differential equations.

Maxwell began with the approval of Faraday that electric fields can become magnetic and Vice versa. He took drawn Faraday paintings of physical fields and recorded them on the exact language of differential equations. The result is one of the most important in modern science systems of equations. It is a system of eight differential equations pretty creepy kind. Every physicist and engineer in the world had to sweat over them, mastering at the Institute of electromagnetism.

Next Maxwell asked a crucial question: if the magnetic field can turn into electricity and Vice versa, what happens if they are constantly moving in the endless chain of transformations? Maxwell discovered that this electromagnetic field will generate a wave, like the ocean. He calculated the speed of movement of the waves and, to his amazement, he discovered that it equals the speed of light! In 1864, having discovered this, he prophetically wrote: "This rate is so close to the speed of light, that we, apparently, have every reason to conclude that light itself... is an electromagnetic disturbance".

This discovery was probably one of the greatest in the history of mankind - was finally disclosed the mystery of the world! Maxwell suddenly realized that everything - and the glow of summer sunrise, and the fierce rays of the setting sun, and the dazzling colours of the rainbow and the stars in the night sky - can be described by means of waves, which he carelessly, painted on a piece of paper. Today we understand that the entire electromagnetic spectrum signals, radar, microwave radiation and television waves, infrared, visible and ultraviolet light, x-rays and gamma rays is not that other, as MaxValue water; and they, in turn, represent vibration furadeeva physical fields.

Speaking about the importance of Maxwell's equations, Einstein wrote that "the most profound and fruitful that have experienced physics since Newton".

(Tragically, but Maxwell, one of the greatest physicists of the nineteenth century, died rather young, at age 48, cancer of the stomach is probably the same disease that killed his mother at the same age. Had he lived longer, and perhaps he would have been able to find that the received equations allow distortion of space-time, and this would have led directly to the theory of relativity. The idea that live Maxwell longer, and the theory of relativity could appear during the Civil war in America, shaking to the core.)

Maksvella theory of light and the atomic theory of the substance composition give optics and invisibility simple explanation. In a solid atoms tightly Packed, while in liquid or gas the distance between molecules much more. Most solids opaque, as the rays of light cannot pass through a tight formation of atoms, which plays the role of a brick wall. Many liquids and gases, on the contrary, transparent, because the light is easier to pass between rare atoms, the distance between which is greater than the wavelength of visible light. For example, water, alcohol, ammonia, acetone, hydrogen peroxide, gas and other liquid transparent as transparent and gases, such as oxygen, hydrogen, nitrogen, carbon dioxide, methane and t, p.

This rule there are some important exceptions. Many crystals both solid and transparent. But the atoms in a crystal are located at the nodes of the right of the spatial grid and form regular rows with the same intervals between them. As a result, in the crystal lattice are always many ways in which a beam of light can pass through it. Therefore, although the atoms in the crystal Packed not less tight than in any other solid body, the light still able to pass through.

Under certain circumstances, even a solid object with randomly spaced atoms can become transparent. This effect for some materials can be achieved if heat an object to a high temperature, and then sharply to cool. For example, glass - solid, with due random arrangement of atoms many of the properties of the liquid. Some candy too, can thus be made transparent.

Obviously, the property invisibility occur on the atomic urAries, according to Maxwell's equations, and hence it is extremely difficult, if not impossible, to play with conventional methods. To make Harry Potter invisible, it will translate into a liquid state, boil and turn into steam, to crystallise, heating and cooling - agree, any of these actions would be very difficult for even a magician.

The military, not being able to build stealth aircrafts, tried to do more than simple thing: created "the stele", which makes the aircraft invisible to radar. Technology "the stele", based on Maxwell's equations, is doing a series of tricks. Jet fighter "the stele" it is easy to see with the naked eye, but on the screen enemy radar image size approximately corresponds to a large bird. (In fact, the technology of "the stele" is a combination of a few different tricks. If possible, the materials of construction of the fighter change to transparent for radar: instead of steel uses a variety of plastics and resins; change the angles of the fuselage; changing the design of the engine nozzle, etc. as a result of all of these tricks may make the radar beam enemy, got into the plane, disperse in all directions and not to return to the receiving device. But even with this technology fighter becomes invisible; just his body rejects and scatters the radar beam as much as is technically possible.)
Metamaterials and invisibility

Perhaps the most promising in terms of invisibility of the recent achievements is the exotic new material known as "metamaterial"; it is not excluded that some day he will make objects actually invisible. Funny, but once the existence of metamaterials also considered impossible, because they violate the laws of optics. But in 2006, researchers from Duke University in Durham, North Carolina) and Imperial College in London successfully refuted this was a common view and using metamaterials made the object invisible to microwave radiation. Obstacles on this way until enough, but for the first time in the history of humanity has a method, allowing to make an ordinary objects invisible. (Funded these studies DARPA - Agency perspective research projects of the Ministry of defense of the USA.)

Nathan Myhrvold, former chief technologist of company Microsoft, States that the revolutionary possibilities of metamaterials "completely change our approach to optics and almost all aspects of electronics... Some of metamaterials are capable of such feats that several decades ago would have seemed a miracle"

What are the metamaterials? This is a substance that has a non-existent in nature optical properties. When creating metamaterials in substance introduced tiny implants that cause electromagnetic waves to choose non-standard ways. At Duke University scientists introduced in copper tape is laid flat concentric circles (all this reminds design burner hot plates), a lot of tiny electric circuits. The result was a complex structure of ceramics, Teflon, composite fibres and metal components. Tiny implants present in copper, allow deny microwave radiation and send it to the specified path. Imagine how the river flows around the boulder. The water is quickly wrapped around the stone, so downstream his presence is not affected and to identify its impossible. Similarly, metamaterials able to continuously change the route of microwaves so that they flowed in, say, a cylinder and thus did everything inside that cylinder invisible to radio waves. If metamaterial can also eliminate all reflections and shadows, the object will be completely invisible for this form of radiation.

Scientists have successfully demonstrated this principle by means of a device consisting of ten rings of glass fiber with copper elements. Copper ring inside was almost invisible to microwave radiation; it merely cast a faint shadow.

The unusual properties of metamaterials based on their ability to control option is known as "the refractive index". Refraction is the property of the light to change the direction of propagation while passing through the translucent material. If you dip your hand into the water or simply look through glasses lens, you can see that water and glass deny and distort the course of ordinary light rays.

The reason for the deviation of a light beam in the glass or water is that when you log in dense transparent material light slows down. The speed of light in a perfect vacuum is constant, but in glass or water light "makes his way through the crowd of trillions of atoms and therefore slows down. (The ratio of the speed of light in a vacuum to the speed of light in a medium is called a refractive index. Because the light in any environment slows down, the refractive index is always greater than one.) For example, the refractive index for vacuum is 1.00; for air -1,0003; for glass-1,5; for diamonds and 2.4. Typically, the thicker the environment, the more it rejects the beam of light and greater, respectively, the refractive index.

Very clear demonstration effects associated with refraction, can serve as mirages. If you are driving down the highway on a hot day, will look straight ahead, on the horizon, seats road will seem shimmering and create the illusion of sparkling water. In the desert you can sometimes see on the horizon the outlines of distant cities and mountains. This is because the heated above the road surface or sand desert air has a lower density and correspondingly lower refractive index than the surrounding normal, cooler air; therefore, the light from distant objects can experience refraction in the heated layer of air and go after that in the eyes; when you have the illusion that you actually see the deleted objects.

As a rule, the refractive index is a constant value. A narrow beam of light penetrating into the glass, changes direction, and then continues to move in a straight line. But let's assume for a moment that we are able to control the refractive index, so that at each point of the glass he could always change specified by the way, the Light, moving in this new material, could arbitrarily change direction; the path of the beam in this environment was writhing like a snake.

If you could control the refractive index in the metamaterial so that the light around an object, the object that will be invisible. To get this effect the refractive index in the metamaterial should be negative, but in any textbook optics says that this is impossible,

(For the first time metamaterials have been theoretically predicted in the work of Soviet physicist Victor Veselago in 1967 It Veselago showed that the material shall be of such unusual optical properties as a negative index of refraction and backward Doppler effect. Metamaterials seem so strange and even ridiculous that the first time their practical implementation was considered impossible. However, in recent years metamaterials were actually received in the laboratory, which led physicists to do the rewriting of textbooks on optics.)

Researchers, who are meta-materials, constantly bothers journalists with the question: when the market will finally invisibility cloaks? The answer can be stated very simply: not soon.

David Smith from Duke University says: "reporters calling and begging at least calling time. After how many months or perhaps years it will happen. They pressure, pressure and pressure, and you eventually do not stand up and say that years, maybe fifteen. And here is a headline, right? Fifteen years before the mantle of Harry Potter. That's why he now refuses to call any time.

Fans of Harry Potter or Star trek, most likely, will have to wait. Although this cloak of invisibility already does not contradict the known laws of nature - and this at the moment agrees most physicists, scientists still have to overcome many difficult technical obstacles before this technology can be extended to work with visible light, and not only with microwave radiation.

In General, the size of the internal structures embedded in the metamaterial, must be less than the wavelength of the radiation. For example, microwaves can have a wavelength of about 3 cm, so if we want a metamaterial contorted way microwaves, we must incorporate implants size less than 3 see But to make the object invisible to the green light with a wavelength of 500 nm), metamaterial should have embedded patterns of length only about 50 nm. But the nanometers is already atomic scale, to work with such dimensions are required nanotechnology. (A nanometer is one billionth of a meter. One nanometer can fit about five atoms.) Perhaps this is the key problem that we face in creating this cloak of darkness. To arbitrarily distort, like a snake, the path of the light beam, we would have to modify individual atoms inside the metamaterial.
Metamaterials for visible light

So, the race has started.

Immediately after the announcement of the receipt of the laboratory first metamaterials in this area began feverish activity. Every few months we hear about the revolutionary guesses and amazing breakthroughs. The goal is clear: to create with the help of nanotechnologies metamaterials that can distort not only a microwave, but the visible light. Already proposed several approaches, and they all seem to be quite promising.

One suggestion is to use a ready methods, i.e. to borrow for production of metamaterials waste technology of microelectronic industry. For example, in the basis of miniaturization of computers is the technology of "photolithography"; she also serves as the engine of the computer revolution. This technology allows engineers to place on a silicon substrate, the size of a thumb nail hundreds of millions of tiny transistors.

The computer power doubles every 18 months (this pattern is called Moore's law). This is due to the fact that scientists using ultraviolet radiation "etched" on silicon chips more and more tiny components. This technology is very similar to the process by which put the stencil pattern on colorful t-shirt. (Engineers, computer scientists begin with a thin substrate, on top of which overlap subtlest layers of different materials. Then the substrate is covered with a plastic mask, working as a template. The mask is applied in advance complex picture wires, transistors and computer components, form the basis of the concept. The workpiece is irradiated hard ultraviolet radiation, i.e. subjected to ultraviolet light, a very small wavelength; this radiation would tolerate figure matrix on the light-sensitive substrate. Then preparation process special gases and acids, and complex matrix etched on the substrate in those places, where she was exposed to ultraviolet radiation. The resulting plate with hundreds of millions of tiny indentations, which form the contours of transistors.) Currently the smallest components that can be created using the process described earlier, have a size of about 30 nm (or approximately 150 atoms).

A notable milestone on the way to invisibility was the recent experiment group of scientists from Germany and the U.S. Department of energy, in which the process of etching silicon substrate was able to use for the manufacture of the first meta-material, capable to work in the visible range of light. In early 2007, scientists announced that they have created a metamaterial affects red light. "Impossible" was implemented in a surprisingly short time.

Physicist Kostas of Soukoulis out of Ames Laboratory and Iowa state University together with Stefan Linden, Martin Wegener and Gunnar Dollinger from the University of Karlsruhe in Germany has managed to create a metamaterial with a refractive index of-0.6 to red light with a wavelength of 780 nm. (Prior to this world record wavelength radiation that was "wrapped" using metamaterial, was 1400 nm; it is not already visible, and infrared light.)

For a start, the scientists took a piece of glass and put a thin layer of silver, then a layer of magnesium fluoride, then a layer of silver; therefore, was received by "sandwich" with fluoride thickness of 100 nm. After that, scientists using the standard technology of etching has done in this "sandwich" many tiny square holes (a width of only 100 nm, much less than the wavelength of red light); the result is a lattice structure resembling a fishing net. They then pass through the material obtained beam of red light and measured the refractive index, which amounted to minus 0.6.

The authors anticipate that invented the technology will be widely used. Metamaterials "may someday lead to the creation of a kind of flat superlinzu working in the visible spectrum, " said Dr. of Soukoulis. - This lens will allow you to get a higher resolution than traditional technology and details are significantly inferior in size to the wavelength of light". Obviously, one of the first applications "superlens" will be taking pictures of microscopic objects with unprecedented clarity; we can talk about taking photos inside the living human cells or diagnosis of diseases of the fetus in the womb. Ideally, it will be possible to photograph the components of the DNA molecule directly, without the use rough methods of x-ray crystallography.

While scientists were able to demonstrate a negative index of refraction only for red light. But the method should be developed, and the next step should be the creation of the metamaterial, which could circle with a red light around an object, making it invisible to the red light.

Further development can be expected also in the field of photonic crystals". The goal of technology photonic crystals to create a chip that would have used for information processing light, not electricity. It is supposed to use nanotechnologies for etching on the substrate tiny components - so that with each component has changed the refractive index. Transistors, employing light, have many advantages over email. For example, in photonic crystals much less heat loss. (In complex silicon chips stands out so much heat that would be enough to fry eggs. To such chips refused, they must continuously cooled, and it is very expensive.)

There is nothing surprising in the fact that the technology of obtaining of photonic crystals should ideally be suitable for meta-materials, because both technologies involve the manipulation of the index of refraction of light at the nanoscale.
Invisibility through plasmonics

Not wanting to keep up with rivals, another group of physicists announced in mid-2007, about creating a metamaterial that can turn visible light, on the basis of absolutely other technology, called "plasmonics". Physics Henri LASEK, Jennifer Dionne and Harry Atwater from the California Institute of technology announced the creation of the metamaterial with a negative index of refraction for more complex blue-green region of the visible spectrum.

The purpose of plasmonics - so "compress" the light so that you can manipulate objects at the nanoscale, especially on the surface of metals. The cause of the electrical conductivity of metals lies in the fact that electrons in the atoms of metals are poorly connected with the kernel and can freely move along the surface of a metal grid. Electricity, running through the wires in your home, is a smooth flow of these weakly bound electrons on metal surface. But under certain conditions, when a beam of light encounters a metal surface, electrons can Severinovich in unison with the light. While on the surface of the metal arise wavelike motion of electrons (these waves are called plasmons) in the quantum fluctuations of the electromagnetic field on the metal. More importantly, these plasmons can "squeeze" - they will have the same frequency as the original light beam (and, hence, will carry the same information), but much shorter wavelength. In principle, then these short wave, you can squeeze in nanorobotic. As photonic crystals, the ultimate goal of plasmonics - creation of computer chips, is no electricity, and light.

A group of Caltech built its metamaterial of two layers of silver and nitrogen-silicon insulating layer (thickness of 50 nm) between them. This layer acts as a "waveguide", capable of directing plasmon waves in the right direction. Through a slit cut in the metamaterial, the device enters the laser beam; it passes through the waveguide, and then exits through the other slit. If we analyze the corners that are bent laser beam passing through a metamaterial, it is possible to establish that the material has a negative index of refraction for light with the wavelength.
The future of metamaterials

Promoting the study of metamaterials in the future will accelerate the simple reason that it is already interest in the creation of transistors that work on light beam instead of electricity, is very large. Therefore, we can assume that research in the field of invisibility will be able to get on the ride", i.e. to use the results of ongoing research on the creation of replacement of silicon chip using photonic crystals, plasmonics. Today in the development of technology that would replace silicon chips, invested hundreds of millions of dollars, and along the way will win and research in the field of metamaterials.

Currently, new important discoveries in this area are made every few months, so it is not surprising that some physicists expect in the laboratory first samples of real invisibility shield within a few decades. So, the scientists are sure that will be able in the next few years to create metamaterials, capable to make a project completely invisible, at least in two dimensions, for visible light any particular frequency. To achieve this, it will be necessary to implement in the metamaterial tiny nanoimplants not regular rows, and a complex figure, so that the light is gently rounded the hidden object.

Next, scientists will have to invent and create metamaterials with the ability to bend light in three dimensions, not only on flat two-dimensional surfaces. Photolithography is a proven technology for obtaining a flat silicon circuits; the creation of the three-dimensional metamaterials will require at least a complex composition of several flat schemes.

After that the scientists will have to solve the problem of creation of metamaterials, bending the light not of the same frequency, as short - or, say, frequency band. This is perhaps the most difficult task because everything developed so far tiny implants reject the light of only one precisely specified frequency. Perhaps, the scientists should multilayer metamaterials, where each layer will act on one particular frequency. It is not clear what will be the solution to this problem.

But the invisibility shield, even as finally established in the laboratory, may be not so, as we want, ratherthis, it will be heavy and clumsy device. Cloak Harry Potter was made of thin soft tissue and did anyone wrapped in him invisible. But that such an effect was possible, the refractive index within the tissues should be constantly changing in complex ways in accordance with the fluctuations of the fabric and the movements of the person. This is impractical. Most likely, raincoat-invisible being, at least initially, will be a solid cylinder of metamaterial. In this case, the refractive index of the cylinder can be made permanent. (In more advanced models can appear flexible metamaterials, able to bend and hold the light within yourself on the right track. Then the one who will be inside the "cloak", will get some freedom of movement.)

The invisibility shield there is one drawback, which already repeatedly pointed to the one who is inside, will not be able to look out of the window, not thus becoming visible. Imagine Harry Potter, which was visible only to the eyes; they seem to be floating on air at that altitude. Any openings for the eyes in a cloak of invisibility would be clearly visible from the outside. If you do Harry Potter completely invisible, then he will sit under his cloak and blindly in the dark. (One possible solution to this problem can be two small piece of glass in front of the eyes. These slides will work as "the decomposers beam"; they were tshipinare would be sent into the eyes of a small part of the light falling on them. While most of the light that falls on his cloak, go around, making him inside invisible, but some, very little, his part will be separated and got in my eyes.)

Undoubtedly, the obstacles to invisibility very serious, but scientists and engineers are optimistic and believe that the invisibility shield of some kind can be created within the next few decades.
Invisibility and nanotechnology

As I mentioned, the key to invisibility may be the development of nanotechnologies, i.e. the ability to manipulate the structures of the atomic (about one-billionth of a meter in diameter) sizes.

By the time of the origin of nanotechnology called famous lecture with an ironic name "At the bottom is full of places, which was read by Nobel laureate Richard Feynman before the American physical society in 1959 In this lecture he talked about how that might look the smallest machine in accordance with known laws of physics. Feynman understood that the size of cars will become less and less until you approach the size of an atom, and then to create new machines can be used atoms themselves. He concluded that the simplest atomic machine like a block, lever or the wheel does not contradict the laws of physics, but to manufacture them will be extremely difficult.

Many years nanotechnology vegetated in oblivion, simply because the technology of the time was not allowed to manipulate individual atoms. But in 1981 he was a break - physicists Gerd Binnig and Heinrich Rohrer of the IBM laboratory in Zurich invented the scanning tunneling microscope, which later earned them the Nobel prize in physics.

Scientists have suddenly been able to get amazing images of individual atoms, combined in a structure is exactly the kind which usually depict in books on chemistry; once critics of nuclear theory regarded it as impossible. Now you can get great pictures of atoms arranged in rows in the correct structure of the crystal or metal. Chemical formula by which scientists have tried to reflect the complex structure of the molecule, now could be seen with the naked eye. Moreover, the scanning tunneling microscope gave the ability to manipulate individual atoms. Pioneers posted from individual atoms letters IBM, than has made in the scientific world the present sensation. Scientists have ceased to be blind in a world of individual atoms; they had the opportunity to see the atoms and work with them.

The principle of operation of the scanning tunneling microscope is deceptively simple. Like gramophone scans the disk needle, this microscope slowly conducts sharp probe over the analyzed substance. (The tip of the probe is so sharp that ends in a single atom.) The probe carries a weak electric charge; from his end through the studied material to conducting surface underneath electric current flows, With the passage of the probe over every single atom current changes slightly; current changes are carefully registered. The UPS and downs of current passing the needle on atom very precisely and in detail reflect its shape. Having processed and presented in a graphic form data on fluctuations of a current for a large number of passes that you can get a beautiful picture of individual atoms forming spatial lattice.

(Scanning tunneling microscope can exist thanks to one strange law of quantum physics. Usually electrons do not have enough energy to get from the tip of the probe to the substrate through a layer of a substance. But there is - according to the uncertainty principle is a small probability that the electron tunneling", i.e. penetrate through the barrier, although this is contrary to the Newtonian theory. Therefore, the current through the material, so sensitive to subtle quantum effects in it. Later I will focus on the consequences of the quantum theory in more detail.)

In addition, the probe microscope sensitive enough to move individual atoms and make the simplest of them is for "cars". Currently this technology is so good that you can see a group of atoms on the computer screen and simply by moving the cursor to move individual atoms arbitrarily. You can manipulate dozens of atoms is as easy as building blocks of LEGO. You can not just put the atoms letters, but also to create toys, such as, for example, scores, where the tiles are collected from individual atoms. To do this, the atoms are laid on the surface, is equipped with vertical grooves. In the grooves insert spherical fullerenes ("soccer balls", composed of individual carbon atoms). These carbon balls and serve knuckles atomic accounts, moving up and down in their slots.

You can also cut nuclear device using electronic beams. For example, scientists from Cornell University carved from crystalline silicon smallest in the world the guitar, the amount of which is 20 times less than the thickness of a human hair. The guitar has six strings thick hundred atoms of each that you can manipulate using atomic force microscope. (The guitar is really going to play music, but the frequency that it produces, are far beyond earshot of the human ear.)

Currently, almost all the "machines" are just toys. More complex machines with gears and bearings has yet to create. But many engineers believe that the real nuclear cars already on the way. (In nature such machines exist. Single-celled organisms are able to swim freely in the water due to the motion of tiny hairs. But if to consider carefully the connection between the hair and the cell, it is clear that nuclear machine allows hairs to freely move in all directions. So one of the ways of development of nanotechnologies is copying nature, which has mastered production of nuclear machines billions of years ago.)
Holograms and invisibility

Another way to make a person partly invisible is to photograph the view behind him and then to project this image directly on people's clothing or on a screen in front of him. If you look in the front, it would appear that the person became transparent and light somehow passes through his body.

This process, known as "optical masking", she began, in particular, Naoki Kawakami from the Laboratory Tati the University of Tokyo. He says: "This technology could be used to help pilots to see the landing strip through the floor of the cabin or drivers to look as it should be around when Parking the car." "Cloak" Kawakami covered with tiny reflective beads, working like a movie screen. What happens behind, shot on a camcorder. Then this image comes in video projector, which, in turn, projecting it on the cloak in front. The impression that light penetrates right through a man.

Prototypes cloaks with optical masking already created in the laboratory. If you look exactly the front man in such a cloak, it seems that it disappears, because you see only an image of what happens behind. But if you and together with you and your eyes, slightly shifted, and the image on the cloak will remain the same, it becomes clear that this is just a deception. In the system more realistic optical masking will need to create the illusion of three-dimensional images. This will require a hologram.

A hologram is a three - dimensional image created by lasers (remember the three-dimensional image of Princess Leia in Star wars). You can make a man invisible, if to take a picture of the background behind it using a special holographic camera and then recreate it on a special holographic display in front of him. The observer will see a holographic screen with the image of all that is actually ahead, with the exception of the person. Will look as if people simply disappeared. In its place will prove to be accurate three-dimensional image of the background. Even before you move in, you will not be able to understand what you forgery.

The creation of such three-dimensional images is possible due to the "coherence" of laser light, i.e. the fact that electromagnetic oscillations occur in it strictly in unison. To to build a hologram, coherent laser beam is split into two parts. One half is directed to the film, the other - on the same film, but after reflection from the object. When the interference of the two halves of the beam on the film there is the interference pattern, which contains all the information about the original three-dimensional beam. Film after manifestations does not look too promising - it is visible only cobweb strange lines and curls. But if you skip through this film laser beam, in the air, as if by magic, there is a precise three-dimensional copy of the object.

However holographic invisibility confronts researchers very serious problems. One of them is the creation of holographic camera that can do at least 30 images per second. Another one is storage and processing of this information. Finally, you will need to project the image on the screen so that it looks realistic.
Invisibility through the fourth dimension

We should mention one more, much more clever way to become invisible, stated Herbert wells in the novel "the invisible Man". This method involves the use of opportunities of the fourth dimension. (Later in this book I will tell you more about the possible existence of higher dimensions.) Do you see people leave our three-dimensional universe and soar above it in the fourth dimension, watching from the sidelines? Like a three-dimensional butterfly, flitting over the two-dimensional sheet of paper, such a person would be invisible to any inhabitant of the universe at the bottom. The only problem is that the existence of higher dimensions is still not proven. Moreover, the hypothetical journey in one of such measurements would require much more energy than you have at our disposal at the moment, given the current level of technology. If to speak about real ways to achieve invisibility, this method obviously far beyond our present knowledge and capabilities.

Given the huge achievements already on the way to invisibility, I think we can classify it as the inability of the I class. The invisibility of some kind could become commonplace in the next few decades, at least to the end of the century.