"Shields up!" - this is the first order, which in the endless series "Star Trek" gives a harsh voice Captain Kirk to his crew; obedient to the order, the crew turns on the force fields designed to protect the spacecraft "Enterprise" from enemy fire.
In the Star Trek storyline, force fields are so important that their condition may well determine the outcome of a battle. As soon as the energy of the force field is depleted, and the hull of the Enterprise begins to receive blows, the further, the more crushing; eventually, defeat becomes inevitable.
So what is a protective force field? In science fiction, it's a deceptively simple thing: a thin, invisible yet impenetrable barrier capable of reflecting laser beams and missiles with equal ease. At first glance, the force field seems so simple that the creation - and soon - of battle shields based on it seems inevitable. So you expect that not today or tomorrow some enterprising inventor will announce that he has managed to obtain a protective force field. But the truth is much more complicated.
Like Edison's light bulb, which radically changed modern civilization, the force field can deeply affect all aspects of our life without exception. The military would use the force field to become invulnerable, creating an impenetrable shield from enemy missiles and bullets on its basis. In theory, one could create bridges, great highways and roads at the touch of a button. Entire cities would spring up in the desert as if by magic; everything in them, down to the skyscrapers, would be built exclusively from force fields. Force field domes over cities would allow their inhabitants to arbitrarily control weather events - storm winds, snowstorms, tornadoes. Under the secure canopy of the force field, cities could be built even at the bottom of the oceans. Glass, steel and concrete could be completely abandoned,replacing all building materials with force fields.
But, oddly enough, the force field turns out to be one of those phenomena that are extremely difficult to reproduce in the laboratory. Some physicists even believe that it will not be possible to do this at all without changing its properties.
Michael Faraday
The concept of the physical field originates in the works of the great British scientist of the 19th century. Michael Faraday.
Promotional video:
Faraday's parents belonged to the working class (his father was a blacksmith). He himself in the early 1800s. was an apprentice for the bookbinder and eked out a rather miserable existence. But young Faraday was fascinated by the recent giant breakthrough in science - the discovery of the mysterious properties of two new forces, electricity and magnetism. He eagerly devoured all the information available to him on these matters and attended lectures by Professor Humphrey Davy of the Royal Institute in London.
Professor Davy once seriously injured his eyes during a failed chemical experiment; needed a secretary, and he took Faraday to this position. Gradually, the young man won the trust of scientists at the Royal Institution and was able to conduct his own important experiments, although he often had to endure a dismissive attitude. Over the years, Professor Davy became increasingly jealous of the successes of his talented young assistant, who was initially considered a rising star in experimental circles, and over time eclipsed the glory of Davy himself. It was only after Davy's death in 1829 that Faraday received scientific freedom and made a whole series of startling discoveries. Their result was the creation of electric generators that provided energy to entire cities and changed the course of world civilization.
The key to Faraday's greatest discoveries was force, or physical, fields. If you place iron filings over a magnet and shake it, it turns out that the filings fit into a pattern that resembles a cobweb and takes up all the space around the magnet. The "threads of the web" are the Faraday lines of force. They clearly show how electric and magnetic fields are distributed in space. For example, if you graphically depict the Earth's magnetic field, you will find that the lines originate from somewhere in the North Pole area, and then return and again go into the earth in the South Pole area. Similarly, if you depict the lines of force of the electric field of lightning during a thunderstorm, it turns out that they converge at the tip of the lightning.
Empty space for Faraday was not empty at all; it was filled with lines of force that could make distant objects move.
(Faraday's poor youth prevented him from receiving a formal education, and he had little knowledge of mathematics; as a result, his notebooks were filled not with equations and formulas, but with hand-drawn diagrams of field lines. Ironically, it was his lack of mathematical education that made him develop magnificent diagrams lines of force, which today can be seen in any physics textbook. The physical picture in science is often more important than the mathematical apparatus that is used to describe it.)
Historians have put forward many assumptions about what exactly led Faraday to the discovery of physical fields - one of the most important concepts in the history of all world science. In fact, all modern physics, without exception, is written in the language of Faraday fields. In 1831, Faraday made a key discovery in the field of physical fields that forever changed our civilization. One day, while carrying a magnet - a child’s toy - over the wire frame, he noticed that an electric current was generated in the frame, although the magnet did not touch it. This meant that the invisible field of a magnet could make electrons move at a distance, creating a current.
Faraday's force fields, which until this moment were considered useless pictures, the fruit of an idle fantasy, turned out to be a real material force capable of moving objects and generating energy. Today, we can say for sure that the light source you use to read this page is powered by Faraday's discoveries in electromagnetism. The spinning magnet creates a field that pushes the electrons in the conductor and makes them move, creating an electric current that can then be used to power the light bulb. Generators of electricity are based on this principle, providing energy to cities around the world. For example, a stream of water falling from a dam causes a giant magnet in a turbine to spin; the magnet pushes electrons in the wire, forming an electric current; current, in turn,flows through high-voltage wires to our homes.
In other words, Michael Faraday's force fields are the very forces that drive modern civilization, all of its manifestations - from electric locomotives to the latest computing systems, the Internet and pocket computers.
For a century and a half, Faraday's physical fields have inspired further research by physicists. Einstein, for example, was so strongly influenced that he formulated his theory of gravity in the language of physical fields. Faraday's works made a strong impression on me too. Several years ago, I successfully formulated string theory in terms of Faraday physical fields, thus laying the foundation for string field theory. In physics, to say about someone that he thinks with lines of force is to give that person a serious compliment.
Four fundamental interactions
One of the greatest achievements of physics over the past two millennia has been the identification and definition of the four types of interactions that rule the universe. All of them can be described in the language of the fields to which we owe Faraday. Unfortunately, however, none of the four species has the full properties of the force fields described in most science fiction books. Let's list these types of interaction.
1. Gravity. The silent power that keeps our feet from leaving the support. It does not allow the Earth and the stars to crumble, helps preserve the integrity of the Solar System and the Galaxy. Without gravity, the planet's spinning would kick us off Earth and into space at 1,000 miles an hour. The problem is that the properties of gravity are exactly the opposite of the properties of fantastic force fields. Gravity is the force of attraction, not repulsion; it is extremely weak - relatively, of course; it works at enormous, astronomical distances. In other words, it is almost the exact opposite of the flat, thin, impenetrable barrier that can be found in almost any science fiction novel or film. For example, a feather to the floor is attracted by the whole planet - the Earth,but we can easily overcome the gravity of the Earth and lift the feather with one finger. The impact of one of our fingers can overcome the gravity of an entire planet, which weighs more than six trillion kilograms.
2. Electromagnetism (EM). The power that illuminates our cities. Lasers, radio, television, modern electronics, computers, the Internet, electricity, magnetism are all consequences of the manifestation of electromagnetic interaction. It is perhaps the most useful force that humanity has managed to harness throughout its history. Unlike gravity, it can work both for attraction and repulsion. However, it is not suitable for the role of a force field for several reasons. First, it can be easily neutralized. For example, plastic or any other non-conductive material can easily penetrate a powerful electric or magnetic field. A piece of plastic thrown into a magnetic field will freely fly right through it. Secondly, electromagnetism acts at large distances, it is not easy to concentrate it in a plane. The laws of EM interaction are described by the equations of James Clerk Maxwell, and it seems that force fields are not a solution to these equations.
3 and 4. Strong and weak nuclear interactions. Weak interaction is the force of radioactive decay, the one that heats up the radioactive core of the Earth. This power is behind volcanic eruptions, earthquakes and continental plate drift. Strong interaction does not allow the nuclei of atoms to crumble; it provides energy to the sun and stars and is responsible for lighting the universe. The problem is that nuclear interaction only works at very small distances, mostly within the atomic nucleus. It is so strongly associated with the properties of the core itself that it is extremely difficult to control it. Currently, we know of only two ways to influence this interaction: we can break a subatomic particle into pieces in an accelerator or detonate an atomic bomb.
Although science fiction protective fields do not obey the known laws of physics, there are loopholes that are likely to make force field creation possible in the future. First, there is perhaps a fifth type of fundamental interaction that no one has yet been able to see in the laboratory. It may turn out, for example, that this interaction only works at distances of a few inches to a foot - and not at astronomical distances. (True, the first attempts to detect the fifth type of interaction yielded negative results.)
Second, we may be able to get the plasma to mimic some of the properties of the force field. Plasma is the "fourth state of matter". The first three, familiar to us, states of matter are solid, liquid and gaseous; nevertheless, the most common form of matter in the universe is plasma: a gas made up of ionized atoms. The atoms in the plasma are not connected with each other and are devoid of electrons, and therefore have an electric charge. They can be easily controlled using electric and magnetic fields.
The visible matter of the universe exists for the most part in the form of various kinds of plasma; the sun, stars and interstellar gas are formed from it. In ordinary life, we almost never encounter plasma, because on Earth this phenomenon is rare; nevertheless, the plasma can be seen. All you need to do is look at lightning, the sun, or a plasma TV screen.
Plasma windows
As noted above, if the gas is heated to a sufficiently high temperature and thus plasma is obtained, then using magnetic and electric fields it will be possible to hold and shape it. For example, plasma can be shaped like a sheet or window glass. Moreover, such a "plasma window" can be used as a partition between vacuum and ordinary air. In principle, in this way it would be possible to keep the air inside the spacecraft, preventing it from escaping into space; plasma in this case forms a convenient transparent shell, the boundary between open space and the ship.
In Star Trek, the force field is used, in part, to isolate the compartment where the small space shuttle is located and from where it starts from outer space. And it's not just a clever trick to save money on decorations; such a transparent invisible film can be created.
The plasma window was invented in 1995 by physicist Eddie Gershkovich at Brookhaven National Laboratory (Long Island, New York). This device was developed in the process of solving another problem - the problem of welding metals using an electron beam. The welder's acetylene torch melts the metal with a stream of hot gas, and then joins the pieces of metal together. It is known that the electron beam is able to weld metals faster, cleaner and cheaper than conventional welding methods. The main problem with the electron welding method is that it must be carried out in a vacuum. This requirement is very inconvenient, since it means building a vacuum chamber - perhaps the size of an entire room.
To solve this problem, Dr. Gershkovich invented the plasma window. This device is only 3 feet high and 1 foot in diameter; it heats the gas to a temperature of 6500 ° C and thus creates a plasma, which immediately falls into the trap of electric and magnetic fields. Plasma particles, like particles of any gas, exert pressure that prevents air from rushing in and filling the vacuum chamber. (When used in a plasma window, argon emits a bluish glow, just like the force field in Star Trek.)
The plasma window will obviously find wide application in the space industry and industry. Even in industry, micromachining and dry etching often requires a vacuum, but it can be very expensive to use in a manufacturing process. But now, with the invention of the plasma window, holding a vacuum at the push of a button will become easy and inexpensive.
But can a plasma window be used as an impenetrable shield? Will it protect against a cannon shot? One can imagine the appearance in the future of plasma windows with much higher energy and temperature, sufficient for the evaporation of objects falling into it. But to create a more realistic force field with characteristics known from science fiction, a multi-layered combination of several technologies will be required. Each layer may not be strong enough on its own to stop a cannonball, but together several layers may be sufficient.
Let's try to imagine the structure of such a force field. The outer layer, such as a supercharged plasma window, heated to a temperature sufficient to vaporize metals. The second layer could be a curtain of high-energy laser beams. Such a curtain of thousands of intersecting laser beams would create a spatial grid that would heat objects passing through it and effectively vaporize them. We'll talk more about lasers in the next chapter.
Further, behind the laser curtain, one can imagine a spatial lattice of "carbon nanotubes" - tiny tubes of individual carbon atoms with walls one atom thick. Thus, tubes are many times stronger than steel. The world's longest carbon nanotube is currently only about 15 mm long, but we can already foresee the day when we will be able to create carbon nanotubes of arbitrary length. Let us assume that a spatial network can be weaved from carbon nanotubes; in this case, we get an extremely durable screen that can reflect most objects. This screen will be invisible, since each individual nanotube is comparable in thickness to an atom, but the spatial network of carbon nanotubes will surpass any other material in strength.
So, we have reason to assume that the combination of a plasma window, a laser curtain and a screen of carbon nanotubes can serve as the basis for creating an almost impenetrable invisible wall.
But even such a multi-layered shield will fail to demonstrate all the properties that science fiction attributes to a force field. So, it will be transparent, which means that it will not be able to stop the laser beam. In a battle with laser cannons, our multi-layer shields will be useless.
In order to stop the laser beam, the shield must, in addition to the above, have a strongly pronounced property of "photochromatic", or variable transparency. Currently, materials with such characteristics are used in the manufacture of sunglasses that can darken when exposed to UV radiation. Variable transparency of the material is achieved through the use of molecules that can exist in at least two states. In one state of the molecules, such a material is transparent. But under the influence of UV radiation, the molecules instantly change to another state and the material loses its transparency.
Perhaps someday we will be able to use nanotechnology to obtain a substance as strong as carbon nanotubes and capable of changing its optical properties under the influence of a laser beam. A shield made of such a substance will be able to stop not only particle flows or cannon shells, but also a laser strike. At present, however, there are no materials with variable transparency that can stop the laser beam.
Magnetic levitation
In science fiction, force fields serve another function in addition to repelling hits from ray weapons, namely, they serve as a support that allows you to overcome the force of gravity. In Back to the Future, Michael Fox rides a hoverboard, or floating board; this thing resembles a familiar skateboard in everything, only it "rides" through the air, above the surface of the earth. The laws of physics, as we know them today, do not allow such an anti-gravity device to be implemented (as we will see in Chapter 10). But you can imagine in the future the creation of other devices - floating boards and floating cars on a magnetic cushion; these machines will allow us to easily lift and hold large objects. In the future, if "room temperature superconductivity" becomes an affordable reality,a person will be able to lift objects into the air using the capabilities of magnetic fields.
If we bring the north pole of a permanent magnet to the north pole of another of the same magnet, the magnets will repel each other. (If we turn one of the magnets over and bring it with its south pole to the north pole of the other, two magnets will be attracted.) The same principle - that the same poles of magnets repel - can be used to lift huge weights from the ground. Technically advanced magnetic suspension trains are already being built in several countries. Such trains do not zip along the tracks, but over them at a minimum distance; ordinary magnets hold them in weight. Trains seem to float in the air and can reach record speeds thanks to zero friction.
The world's first commercial automated transport system on magnetic suspension was launched in 1984 in the British city of Birmingham. It connected the terminal of the international airport and the nearby railway station. Magnetic levitation trains also operate in Germany, Japan, and Korea, although most are not designed for high speeds. The first high-speed commercial magnetic levitation train has begun to run on a running section of a track in Shanghai; this train moves along the highway at speeds up to 431 km / h. A Japanese maglev train in Yamanashi prefecture accelerated to a speed of 581 km / h - that is, it moved much faster than conventional trains on wheels.
But magnetically suspended devices are extremely expensive. One of the ways to increase their efficiency is the use of superconductors, which, when cooled to temperatures close to absolute zero, completely lose their electrical resistance. The phenomenon of superconductivity was discovered in 1911 by Heike Kamerling-Onnes. Its essence was that some substances, when cooled to temperatures below 20 K (20 ° above absolute zero), lose all electrical resistance. As a rule, when the metal is cooled, its electrical resistance gradually decreases. {The fact is that random vibrations of atoms interfere with the directional movement of electrons in a conductor. As the temperature decreases, the range of random fluctuations decreases, and electricity experiences less resistance.) But Kamerlingh Onnes, to his own amazement, foundthat the resistance of some materials at a certain critical temperature drops sharply to zero.
Physicists immediately understood the importance of this result. Significant amounts of electricity are lost in transmission lines over long distances. But if the resistance could be eliminated, electricity could be transferred anywhere for almost nothing. In general, an electric current excited in a closed circuit could circulate in it without energy loss for millions of years. Moreover, from these extraordinary currents it would not be difficult to create magnets of incredible power. And with such magnets, it would be possible to lift huge loads without effort.
Despite the wonderful possibilities of superconductors, their use is very difficult. It is very expensive to keep large magnets in tanks of extremely cold liquids. Keeping liquids cold will require huge cold factories that will raise the cost of superconducting magnets to sky-high heights and make them unprofitable.
But one day physicists may be able to create a substance that retains superconducting properties even when heated to room temperature. Superconductivity at room temperature is the holy grail of solid-state physicists. The production of such substances is likely to be the start of the second industrial revolution. The powerful magnetic fields that can hold cars and trains suspended will become so cheap that even “gliding cars” may be economically viable. It is very possible that with the invention of superconductors that retain their properties at room temperature, the fantastic flying machines that we see in the films "Back to the Future", "Minority Report" and "Star Wars" will become a reality.
In principle, it is quite conceivable that a person will be able to put on a special belt made of superconducting magnets, which will allow him to freely levitate above the ground. With such a belt, one could fly through the air, like Superman. In general, room temperature superconductivity is such a remarkable phenomenon that the invention and use of such superconductors is described in many science fiction novels (such as the series of novels about the Ringworld, created by Larry Niven in 1970).
For decades, physicists have been unsuccessfully looking for substances that would have superconductivity at room temperature. It was a tedious, boring process - looking for it by trial and error, testing one material after another. But in 1986 a new class of substances was discovered, which were called "high-temperature superconductors"; these substances acquired superconductivity at temperatures of the order of 90 ° above absolute zero, or 90 K. This discovery became a real sensation in the world of physics. The airlock seemed to have opened. Month after month, physicists competed with each other to set a new world record for superconductivity. For a while, it even seemed that room temperature superconductivity was about to disappear from the pages of science fiction novels and become a reality. But after several years of rapid development, research in the field of high-temperature superconductors began to slow down.
Currently, the world record for high-temperature superconductors belongs to a substance that is a complex oxide of copper, calcium, barium, thallium and mercury, which becomes superconducting at 138 K (-135 ° C). This relatively high temperature is still very far from room temperature. But this is also an important milestone. Nitrogen becomes liquid at 77 K, and liquid nitrogen costs about the same as regular milk. Therefore, to cool high-temperature superconductors, ordinary liquid nitrogen can be used, it is inexpensive. (Of course, superconductors that remain so at room temperature do not require cooling at all.)
Another thing is unpleasant. Currently, there is no theory that would explain the properties of high-temperature superconductors. Moreover, an enterprising physicist who will be able to explain how they work will receive a Nobel Prize. (In the well-known high-temperature superconductors, atoms are organized into well-defined layers. Many physicists suggest that it is the layering of the ceramic material that allows electrons to move freely within each layer, thus creating superconductivity. But how and why this happens is still a mystery.)
Lack of knowledge is forcing physicists to look for new high-temperature superconductors the old-fashioned way, by trial and error. This means that the notorious room temperature superconductivity can be discovered anytime, tomorrow, in a year, or never at all. Nobody knows when a substance with such properties will be found and whether it will be found at all.
But if superconductors are discovered at room temperature, their discovery is likely to generate a huge wave of new inventions and commercial applications. Magnetic fields a million times stronger than the earth's magnetic field (which is 0.5 gauss) may become commonplace.
One of the properties inherent in all superconductors is called the Meissner effect. If you place a magnet over a superconductor, the magnet will hover in the air, as if supported by some invisible force. [The reason for the Meissner effect is that the magnet has the property of creating its own "mirror image" inside the superconductor, so that the real magnet and its reflection begin to repel each other. Another graphic explanation for this effect is that a superconductor is impenetrable to a magnetic field. It kind of pushes out the magnetic field. Therefore, if you place a magnet over a superconductor, the lines of force of the magnet will be distorted upon contact with the superconductor. These lines of force will push the magnet upward, causing it to levitate.)
If humanity gets the opportunity to use the Meissner effect, then one can imagine the highway of the future with a coating of such special ceramics. Then, with the help of magnets placed on our belt or on the bottom of the car, we can magically hover over the road and rush to our destination without any friction or loss of energy.
The Meissner effect only works with magnetic materials such as metals, but superconducting magnets can also be used to levitate non-magnetic materials known as paramagnets or diamagnets. These substances by themselves are not magnetic; they acquire them only in the presence and under the influence of an external magnetic field. Paramagnets are attracted by an external magnet, diamagnets are repelled.
Water, for example, is a diamagnetic. Since all living things are made of water, they too can levitate in the presence of a powerful magnetic field. In a field with a magnetic induction of about 15 T (30,000 times more powerful than the Earth's magnetic field), scientists have already managed to get small animals such as frogs to levitate. But if superconductivity at room temperature becomes a reality, it will be possible to lift large non-magnetic objects into the air, taking advantage of their diamagnetic properties.
In conclusion, we note that force fields in the form in which science fiction literature usually describes them do not agree with the description of the four fundamental interactions in our Universe. But it can be assumed that a person will be able to imitate many of the properties of these fictitious fields using multilayer shields, including plasma windows, laser curtains, carbon nanotubes and substances with variable transparency. But in reality, such a shield can only be developed in a few decades, or even in a century. And if superconductivity at room temperature is discovered, humanity will have the opportunity to use powerful magnetic fields; perhaps, with their help, it will be possible to lift cars and trains into the air, as we see in science fiction films.
Taking all this into account, I would classify force fields as class I of impossibility, that is, I define them as something impossible for today's technologies, but implemented in a modified form over the next century or so.