Absolute zero temperature
The limiting temperature at which the volume of an ideal gas becomes zero is taken as absolute zero temperature.
Let's find the value of absolute zero on the Celsius scale.
Equating volume V in formula (3.1) to zero and taking into account that
.
Hence the absolute zero temperature is
t= -273 °С. 2
This is the limiting, lowest temperature in nature, that “greatest or last degree of cold”, the existence of which Lomonosov predicted.
The highest temperatures on Earth - hundreds of millions of degrees - were obtained during the explosions of thermonuclear bombs. Even higher temperatures are characteristic of the inner regions of some stars.
2A more accurate value for absolute zero: -273.15°C.
Kelvin scale
The English scientist W. Kelvin introduced absolute scale temperatures. Zero temperature on the Kelvin scale corresponds to absolute zero, and the unit of temperature on this scale is equal to degrees Celsius, so the absolute temperature T is related to temperature on the Celsius scale by the formula
T = t + 273. (3.2)
On fig. 3.2 shows the absolute scale and the Celsius scale for comparison.
The SI unit of absolute temperature is called kelvin(abbreviated as K). Therefore, one degree Celsius equals one degree Kelvin:
Thus, the absolute temperature, according to the definition given by formula (3.2), is a derivative quantity that depends on the Celsius temperature and on the experimentally determined value of a.
Reader: What is the physical meaning of absolute temperature?
We write expression (3.1) in the form
.
Given that the temperature on the Kelvin scale is related to the temperature on the Celsius scale by the ratio T = t + 273, we get
where T 0 = 273 K, or
Since this relation is valid for an arbitrary temperature T, then the Gay-Lussac law can be formulated as follows:
For a given mass of gas at p = const, the relation
Task 3.1. At a temperature T 1 = 300 K gas volume V 1 = 5.0 l. Determine the volume of gas at the same pressure and temperature T= 400 K.
STOP! Decide for yourself: A1, B6, C2.
Task 3.2. With isobaric heating, the volume of air increased by 1%. By what percent did the absolute temperature rise?
= 0,01.
Answer: 1 %.
Remember the resulting formula
STOP! Decide for yourself: A2, A3, B1, B5.
Charles' Law
The French scientist Charles experimentally found that if you heat a gas so that its volume remains constant, then the pressure of the gas will increase. The dependence of pressure on temperature has the form:
R(t) = p 0 (1 + b t), (3.6)
where R(t) is pressure at temperature t°C; R 0 – pressure at 0 °C; b is the temperature coefficient of pressure, which is the same for all gases: 1/K.
Reader: Surprisingly, the temperature coefficient of pressure b is exactly equal to the temperature coefficient of volumetric expansion a!
Let us take a certain mass of gas with a volume V 0 at temperature T 0 and pressure R 0 . For the first time, keeping the pressure of the gas constant, we heat it to a temperature T one . Then the gas will have volume V 1 = V 0 (1 + a t) and pressure R 0 .
The second time, keeping the volume of the gas constant, we heat it to the same temperature T one . Then the gas will have pressure R 1 = R 0 (1 + b t) and volume V 0 .
Since the gas temperature is the same in both cases, the Boyle–Mariotte law is valid:
p 0 V 1 = p 1 V 0 Þ R 0 V 0 (1 + a t) = R 0 (1 + b t)V 0 Þ
Þ 1 + a t = 1+b tÞ a = b.
So there is nothing surprising in the fact that a = b, no!
Let us rewrite Charles's law in the form
.
Given that T = t°С + 273 °С, T 0 \u003d 273 ° С, we get
What is absolute zero (more often - zero)? Does this temperature really exist anywhere in the universe? Can we cool anything down to absolute zero in real life? If you're wondering if it's possible to outrun a wave of cold, let's explore the furthest limits of cold temperature...
What is absolute zero (more often - zero)? Does this temperature really exist anywhere in the universe? Can we cool anything down to absolute zero in real life? If you're wondering if it's possible to outrun a wave of cold, let's explore the furthest limits of cold temperature...
Even if you are not a physicist, you are probably familiar with the concept of temperature. Temperature is a measure of the amount of internal random energy in a material. The word "internal" is very important. Throw a snowball, and although the main movement will be quite fast, the snowball will remain quite cold. On the other hand, if you look at air molecules flying around a room, an ordinary oxygen molecule fries at a speed of thousands of kilometers per hour.
We tend to be silent when it comes to technical details, so just for the experts, we note that the temperature is a little more complicated than we said. The true definition of temperature is how much energy you need to expend for each unit of entropy (disorder, if you want a better word). But let's skip the subtleties and just focus on the fact that random air or water molecules in the ice will move or vibrate slower and slower as the temperature drops.
Absolute zero is -273.15 degrees Celsius, -459.67 Fahrenheit, and just 0 Kelvin. This is the point where thermal motion stops completely.
Does everything stop?
In the classical consideration of the issue, everything stops at absolute zero, but it is at this moment that the terrible muzzle of quantum mechanics peeps out from around the corner. One of the predictions of quantum mechanics that has tainted the blood of no small number of physicists is that you can never measure the exact position or momentum of a particle with perfect certainty. This is known as the Heisenberg uncertainty principle.
If you could cool a sealed room to absolute zero, strange things would happen (more on that in a moment). The air pressure would drop to almost zero, and since air pressure normally opposes gravity, the air would collapse into a very thin layer on the floor.
But even so, if you can measure individual molecules, you'll find something curious: they vibrate and rotate, quite a bit - quantum uncertainty at work. To dot the i's, if you measure the rotation of carbon dioxide molecules at absolute zero, you'll find that oxygen atoms circle carbon at a speed of several kilometers per hour - much faster than you thought.
The conversation comes to a standstill. When we talk about the quantum world, movement loses its meaning. At these scales, everything is defined by uncertainty, so it's not that the particles are stationary, you just can never measure them as if they were stationary.
How low can you fall?
The pursuit of absolute zero essentially meets the same problems as the pursuit of the speed of light. It takes an infinite amount of energy to reach the speed of light, and reaching absolute zero requires an infinite amount of heat to be extracted. Both of these processes are impossible, if anything.
Despite the fact that we have not yet achieved the actual state of absolute zero, we are very close to it (although "very" in this case is a very loose concept; like a children's counting rhyme: two, three, four, four and a half, four on a string, four by a thread, five). The lowest temperature ever recorded on Earth was in Antarctica in 1983, at -89.15 degrees Celsius (184K).
Of course, if you want to cool off like a child, you need to dive into the depths of space. The entire universe is flooded with the remnants of radiation from the Big Bang, in the emptiest regions of space - 2.73 degrees Kelvin, which is slightly colder than the temperature of liquid helium, which we were able to get on Earth a century ago.
But low-temperature physicists are using freeze rays to take technology to a whole new level. It may surprise you that freeze beams take the form of lasers. But how? Lasers must burn.
That's right, but lasers have one feature - one might even say, an ultimatum: all light is emitted at the same frequency. Ordinary neutral atoms do not interact with light at all unless the frequency is finely tuned. If the atom flies towards the light source, the light receives a Doppler shift and goes to a higher frequency. An atom absorbs less photon energy than it could. So if you set the laser lower, fast moving atoms will absorb light, and emitting a photon in a random direction will lose a little energy on average. If you repeat the process, you can cool the gas down to less than one nanoKelvin, a billionth of a degree.
Everything becomes more extreme. The world record for the coldest temperature is less than one tenth of a billion degrees above absolute zero. Devices that achieve this trap atoms in magnetic fields. "Temperature" depends not so much on the atoms themselves, but on the spin of atomic nuclei.
Now, to restore justice, we need to dream a little. When we usually imagine something frozen to one billionth of a degree, you are sure to get a picture of even air molecules freezing in place. One can even imagine a destructive apocalyptic device that freezes the spins of atoms.
Ultimately, if you really want to experience low temperatures, all you have to do is wait. After about 17 billion years, the radiation background in the Universe will cool down to 1K. In 95 billion years, the temperature will be about 0.01K. In 400 billion years, deep space will be as cold as the coldest experiment on Earth, and even colder after that.
If you're wondering why the universe is cooling so quickly, say thanks to our old friends: entropy and dark energy. The universe is in an accelerating mode, entering a period of exponential growth that will continue forever. Things will freeze very quickly.
What's our business?
All this, of course, is wonderful, and breaking records is also nice. But what's the point? Well, there are many good reasons to understand the lowlands of temperature, and not only as a winner.
The good guys at the National Institute of Standards and Technology, for example, would just like to make cool clocks. Time standards are based on things like the frequency of the cesium atom. If the cesium atom moves too much, there is an uncertainty in the measurements, which will eventually cause the clock to malfunction.
But more importantly, especially from a scientific point of view, materials behave insanely at extremely low temperatures. For example, just as a laser is made up of photons that are synchronized with each other - at the same frequency and phase - so the material known as a Bose-Einstein condensate can be created. In it, all atoms are in the same state. Or imagine an amalgam in which each atom loses its individuality and the entire mass reacts as one null super-atom.
At very low temperatures, many materials become superfluid, which means they can be completely viscous, stack in ultrathin layers, and even defy gravity to achieve a minimum of energy. Also at low temperatures, many materials become superconductive, which means they don't have any electrical resistance.
Superconductors are able to respond to external magnetic fields in such a way as to completely cancel them inside the metal. As a result, you can combine the cold temperature and the magnet and get something like levitation.
Why is there an absolute zero but no absolute maximum?
Let's look at the other extreme. If temperature is just a measure of energy, then you can just imagine atoms getting closer and closer to the speed of light. It can't go on indefinitely, can it?
There is a short answer: we don't know. It's entirely possible that there is literally such a thing as an infinite temperature, but if there's an absolute limit, the early universe provides some pretty interesting clues as to what it is. The highest temperature that has ever existed (at least in our universe) probably happened in the so-called "Planck time".
It was a moment 10^-43 seconds long after the Big Bang, when gravity separated from quantum mechanics and physics became exactly what it is now. The temperature at that time was about 10^32 K. That's a septillion times hotter than the inside of our Sun.
Again, we're not at all sure if this is the hottest temperature ever. Because we don't even have a big model of the universe at Planck's time, we're not even sure the universe was boiling to that state. In any case, we are many times closer to absolute zero than to absolute heat.
Absolute temperature zero corresponds to 273.15 degrees Celsius below zero, 459.67 below zero Fahrenheit. For the Kelvin temperature scale, this temperature itself is the zero mark.
The essence of absolute zero temperature
The concept of absolute zero comes from the very essence of temperature. Any body that gives up to the external environment in the course of . In this case, the body temperature decreases, i.e. there is less energy left. Theoretically, this process can continue until the amount of energy reaches such a minimum at which the body can no longer give it away.
A distant harbinger of such an idea can already be found in M.V. Lomonosov. The great Russian scientist explained heat by "rotary" motion. Therefore, the limiting degree of cooling is a complete stop of such movement.
According to modern concepts, the absolute zero temperature is at which molecules have the lowest possible energy level. With less energy, i.e. at a lower temperature, no physical body can exist.
Theory and practice
Absolute zero temperature is a theoretical concept, it is impossible to achieve it in practice, in principle, even in the conditions of scientific laboratories with the most sophisticated equipment. But scientists manage to cool the matter to very low temperatures, which are close to absolute zero.
At such temperatures, substances acquire amazing properties that they cannot have under ordinary circumstances. Mercury, which is called "living silver" because of its near-liquid state, at this temperature becomes solid - to the point that it can hammer nails. Some metals become brittle, like glass. The rubber becomes just as hard. If a rubber object is hit with a hammer at a temperature close to absolute zero, it will break like glass.
Such a change in properties is also associated with the nature of heat. The higher the temperature of the physical body, the more intense and chaotic the molecules move. As the temperature decreases, the movement becomes less intense, and the structure becomes more ordered. So the gas becomes a liquid, and the liquid becomes a solid. The limiting level of order is the crystal structure. At ultra-low temperatures, it is acquired even by substances that in the normal state remain amorphous, for example, rubber.
Interesting phenomena occur with metals. The atoms of the crystal lattice vibrate with a smaller amplitude, the scattering of electrons decreases, therefore, the electrical resistance decreases. The metal acquires superconductivity, the practical application of which seems very tempting, although difficult to achieve.
Sources:
- Livanova A. Low temperatures, absolute zero and quantum mechanics
Body- this is one of the basic concepts in physics, which means the form of existence of matter or substance. This is a material object, which is characterized by volume and mass, sometimes also by other parameters. The physical body is clearly separated from other bodies by a boundary. There are several special types of physical bodies; their enumeration should not be understood as a classification.
In mechanics, a physical body is most often understood as a material point. This is a kind of abstraction, the main property of which is the fact that the real dimensions of the body for solving a specific problem can be neglected. In other words, a material point is a very specific body that has dimensions, shape and other similar characteristics, but they are not important in order to solve the existing problem. For example, if you need to count an object on a certain section of the path, you can completely ignore its length when solving the problem. Another type of physical bodies considered by mechanics is an absolutely rigid body. The mechanics of such a body is exactly the same as the mechanics of a material point, but additionally it has other properties. An absolutely rigid body consists of points, but neither the distance between them nor the distribution of mass change under the loads to which the body is subjected. This means that it cannot be deformed. To determine the position of an absolutely rigid body, it is enough to set the coordinate system attached to it, usually Cartesian. In most cases, the center of mass is also the center of the coordinate system. An absolutely rigid body does not exist, but for solving many problems such an abstraction is very convenient, although it is not considered in relativistic mechanics, since during movements whose speed is comparable to the speed of light, this model demonstrates internal contradictions. The opposite of a perfectly rigid body is a deformable body, which can be displaced relative to each other. There are special types of physical bodies in other branches of physics. For example, in thermodynamics, the concept of a completely black body is introduced. This is an ideal model, a physical body that absorbs absolutely all electromagnetic radiation that falls on it. At the same time, it itself may well produce electromagnetic radiation and have any color. An example of an object that is closest in properties to a completely black body is the Sun. If we take substances that are widespread beyond the Earth, then we can recall soot, which absorbs 99% of what falls on it, except for infrared, which is much worse at absorbing.
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When the weather report predicts temperatures around zero, you should not go to the skating rink: the ice will melt. The melting temperature of ice is taken as zero degrees Celsius - the most common temperature scale.
We are well aware of the negative degrees of the Celsius scale - degrees<ниже
нуля>, degrees of cold. The lowest temperature on Earth was recorded in Antarctica: -88.3°C. Outside the Earth, even lower temperatures are possible: on the surface of the Moon at lunar midnight it can reach -160°C.
But nowhere can there be arbitrarily low temperatures. Extremely low temperature - absolute zero - on the Celsius scale corresponds to - 273.16 °.
The absolute temperature scale, the Kelvin scale, originates from absolute zero. Ice melts at 273.16° Kelvin, and water boils at 373.16° K. Thus, degree K is equal to degree C. But on the Kelvin scale, all temperatures are positive.
Why is 0°K the limit of cold?
Heat is the chaotic movement of atoms and molecules of matter. When a substance is cooled, thermal energy is taken away from it, and in this case, the random movement of particles weakens. In the end, with strong cooling, thermal<пляска>particles almost completely stops. Atoms and molecules would freeze completely at a temperature that is taken as absolute zero. According to the principles of quantum mechanics, at absolute zero, it is precisely the thermal motion of particles that would stop, but the particles themselves would not freeze, since they cannot be completely at rest. Thus, at absolute zero, the particles must still retain some kind of motion, which is called zero.
However, to cool a substance to a temperature below absolute zero is an idea as meaningless as, say, the intention<идти медленнее, чем стоять на месте>.
Moreover, even reaching exact absolute zero is also almost impossible. You can only get closer to him. Because absolutely all of its thermal energy cannot be taken away from a substance by any means. Some of the thermal energy remains during the deepest cooling.
How do they reach ultra-low temperatures?
Freezing a substance is more difficult than heating it. This can be seen at least from a comparison of the design of the stove and refrigerator.
In most household and industrial refrigerators, heat is removed due to the evaporation of a special liquid - freon, which circulates through metal tubes. The secret is that freon can remain in a liquid state only at a sufficiently low temperature. In the refrigerating chamber, due to the heat of the chamber, it heats up and boils, turning into steam. But the steam is compressed by the compressor, liquefied and enters the evaporator, making up for the loss of evaporating freon. Energy is used to run the compressor.
In deep-cooling devices, the carrier of cold is a supercold liquid - liquid helium. Colorless, light (8 times lighter than water), it boils under atmospheric pressure at 4.2°K, and in vacuum at 0.7°K. An even lower temperature is given by the light isotope of helium: 0.3°K.
It is quite difficult to arrange a permanent helium refrigerator. Research is carried out simply in liquid helium baths. And to liquefy this gas, physicists use different techniques. For example, pre-cooled and compressed helium is expanded by releasing it through a thin hole into a vacuum chamber. At the same time, the temperature still decreases and some part of the gas turns into a liquid. It is more efficient not only to expand the cooled gas, but also to make it do work - to move the piston.
The resulting liquid helium is stored in special thermoses - Dewar vessels. The cost of this coldest liquid (the only one that does not freeze at absolute zero) is quite high. Nevertheless, liquid helium is now being used more and more widely, not only in science, but also in various technical devices.
The lowest temperatures were achieved in a different way. It turns out that the molecules of some salts, such as potassium chromium alum, can rotate along magnetic lines of force. This salt is preliminarily cooled with liquid helium to 1°K and placed in a strong magnetic field. In this case, the molecules rotate along the lines of force, and the released heat is taken away by liquid helium. Then the magnetic field is sharply removed, the molecules again turn in different directions, and the spent
this work leads to further cooling of the salt. Thus, a temperature of 0.001°K was obtained. By a similar method in principle, using other substances, one can obtain an even lower temperature.
The lowest temperature obtained so far on Earth is 0.00001°K.
Substance frozen to ultra-low temperatures in liquid helium baths changes noticeably. Rubber becomes brittle, lead becomes hard as steel and resilient, many alloys increase strength.
Liquid helium itself behaves in a peculiar way. At temperatures below 2.2 °K, it acquires a property unprecedented for ordinary liquids - superfluidity: some of it completely loses viscosity and flows without any friction through the narrowest slots.
This phenomenon, discovered in 1937 by the Soviet physicist Academician P. JI. Kapitsa, was then explained by Academician JI. D. Landau.
It turns out that at ultralow temperatures, the quantum laws of the behavior of matter begin to noticeably affect. As one of these laws requires, energy can be transferred from body to body only in quite definite portions-quanta. There are so few heat quanta in liquid helium that there are not enough of them for all atoms. Part of the liquid, devoid of heat quanta, remains at absolute zero temperature, its atoms do not participate in random thermal motion at all and do not interact with the vessel walls in any way. This part (it was called helium-H) possesses superfluidity. With decreasing temperature, helium-II becomes more and more, and at absolute zero, all helium would turn into helium-H.
Superfluidity has now been studied in great detail and has even found a useful practical application: with its help, it is possible to separate helium isotopes.
Near absolute zero, extremely curious changes occur in the electrical properties of certain materials.
In 1911, the Dutch physicist Kamerling-Onnes made an unexpected discovery: it turned out that at a temperature of 4.12 ° K, electrical resistance completely disappears in mercury. Mercury becomes a superconductor. The electric current induced in the superconducting ring does not decay and can flow almost forever.
Above such a ring, a superconducting ball will float in the air and not fall, as if from a fairy tale.<гроб Магомета>, because its heaviness is compensated by the magnetic repulsion between the ring and the ball. After all, the undamped current in the ring will create a magnetic field, and it, in turn, will induce an electric current in the ball and, along with it, an oppositely directed magnetic field.
In addition to mercury, tin, lead, zinc, and aluminum have superconductivity near absolute zero. This property has been found in 23 elements and over a hundred different alloys and other chemical compounds.
The temperatures at which superconductivity appears (critical temperatures) are in a fairly wide range, from 0.35°K (hafnium) to 18°K (niobium-tin alloy).
The phenomenon of superconductivity, as well as super-
fluidity, studied in detail. The dependences of critical temperatures on the internal structure of materials and the external magnetic field are found. A deep theory of superconductivity was developed (an important contribution was made by the Soviet scientist Academician N. N. Bogolyubov).
The essence of this paradoxical phenomenon is again purely quantum. At ultralow temperatures, electrons in
superconductor form a system of pairwise connected particles that cannot give energy to the crystal lattice, spend energy quanta to heat it. Pairs of electrons move like<танцуя>, between<прутьями решетки>- ions and bypass them without collisions and energy transfer.
Superconductivity is increasingly being used in technology.
For example, superconducting solenoids are coming into practice - superconductor coils immersed in liquid helium. Once induced current and, consequently, the magnetic field can be stored in them for an arbitrarily long time. It can reach a gigantic value - over 100,000 oersted. In the future, powerful industrial superconducting devices will undoubtedly appear - electric motors, electromagnets, etc.
In radio electronics, supersensitive amplifiers and generators of electromagnetic waves begin to play a significant role, which work especially well in baths with liquid helium - there the internal<шумы>equipment. In electronic computing technology, a bright future is promised for low-power superconducting switches - cryotrons (see Art.<Пути электроники>).
It is not difficult to imagine how tempting it would be to advance the operation of such devices to higher, more accessible temperatures. Recently, the hope of creating polymer film superconductors has been opened up. The peculiar nature of electrical conductivity in such materials promises a brilliant opportunity to maintain superconductivity even at room temperatures. Scientists are persistently looking for ways to realize this hope.
And now let's look into the realm of the hottest thing in the world - into the bowels of the stars. Where temperatures reach millions of degrees.
The chaotic thermal motion in stars is so intense that whole atoms cannot exist there: they are destroyed in countless collisions.
Therefore, a substance so strongly heated cannot be either solid, liquid, or gaseous. It is in the state of plasma, i.e., a mixture of electrically charged<осколков>atoms - atomic nuclei and electrons.
Plasma is a kind of state of matter. Since its particles are electrically charged, they sensitively obey electric and magnetic forces. Therefore, the close proximity of two atomic nuclei (they carry a positive charge) is a rare phenomenon. Only at high densities and enormous temperatures are atomic nuclei colliding with each other able to come close. Then thermonuclear reactions take place - the source of energy for stars.
The closest star to us - the Sun consists mainly of hydrogen plasma, which is heated in the bowels of the star up to 10 million degrees. Under such conditions, close encounters of fast hydrogen nuclei - protons, though rare, do happen. Sometimes approaching protons interact: having overcome electrical repulsion, they fall into the power of giant nuclear forces of attraction, rapidly<падают>each other and merge. Here an instantaneous rearrangement occurs: instead of two protons, a deuteron (the nucleus of a heavy isotope of hydrogen), a positron and a neutrino appear. The energy released is 0.46 million electron volts (Mev).
Each individual solar proton can enter into such a reaction on average once in 14 billion years. But there are so many protons in the bowels of the luminary that here and there this unlikely event takes place - and our star burns with its even, dazzling flame.
The synthesis of deuterons is only the first step in solar thermonuclear transformations. The newborn deuteron very soon (on average after 5.7 seconds) combines with one more proton. There is a core of light helium and a gamma quantum of electromagnetic radiation. 5.48 MeV of energy is released.
Finally, on average, once every million years, two nuclei of light helium can converge and fuse. Then an ordinary helium nucleus (alpha particle) is formed and two protons are split off. 12.85 MeV of energy is released.
This three-stage<конвейер>thermonuclear reactions is not the only one. There is another chain of nuclear transformations, faster ones. The atomic nuclei of carbon and nitrogen participate in it (without being consumed). But in both cases, alpha particles are synthesized from hydrogen nuclei. Figuratively speaking, the solar hydrogen plasma<сгорает>, turning into<золу>- helium plasma. And in the process of synthesis of each gram of helium plasma, 175 thousand kWh of energy are released. Great amount!
Every second, the Sun radiates 4,1033 ergs of energy, losing 4,1012 g (4 million tons) of matter in weight. But the total mass of the Sun is 2 1027 tons. This means that in a million years, due to the emission of radiation, the Sun<худеет>only one ten millionth of its mass. These figures eloquently illustrate the effectiveness of thermonuclear reactions and the gigantic calorific value of solar energy.<горючего>- hydrogen.
Thermonuclear fusion seems to be the main source of energy for all stars. At different temperatures and densities of stellar interiors, different types of reactions take place. In particular, solar<зола>- helium nuclei - at 100 million degrees it becomes thermonuclear itself<горючим>. Then even heavier atomic nuclei - carbon and even oxygen - can be synthesized from alpha particles.
According to many scientists, our entire Metagalaxy as a whole is also the fruit of thermonuclear fusion, which took place at a temperature of a billion degrees (see Art.<Вселенная вчера, сегодня и завтра>).
The extraordinary calorie content of thermonuclear<горючего>prompted scientists to seek artificial implementation of nuclear fusion reactions.
<Горючего>There are many isotopes of hydrogen on our planet. For example, superheavy hydrogen tritium can be obtained from lithium metal in nuclear reactors. And heavy hydrogen - deuterium is part of heavy water, which can be extracted from ordinary water.
Heavy hydrogen extracted from two glasses of ordinary water would provide as much energy in a fusion reactor as burning a barrel of premium gasoline now provides.
The difficulty lies in preheating<горючее>to temperatures at which it can ignite with mighty thermonuclear fire.
This problem was first solved in the hydrogen bomb. Hydrogen isotopes there are set on fire by the explosion of an atomic bomb, which is accompanied by heating of the substance to many tens of millions of degrees. In one version of the hydrogen bomb, the thermonuclear fuel is a chemical compound of heavy hydrogen with light lithium - deuteride of light l and t and i. This white powder, similar to table salt,<воспламеняясь>from<спички>, which is the atomic bomb, instantly explodes and creates a temperature of hundreds of millions of degrees.
In order to initiate a peaceful thermonuclear reaction, one must first of all learn how, without the services of an atomic bomb, to heat up small doses of a sufficiently dense plasma of hydrogen isotopes to temperatures of hundreds of millions of degrees. This problem is one of the most difficult in modern applied physics. Scientists from all over the world have been working on it for many years.
We have already said that it is the chaotic motion of particles that creates the heating of bodies, and the average energy of their random motion corresponds to the temperature. To heat up a cold body means to create this disorder in any way.
Imagine that two groups of runners are rapidly rushing towards each other. So they collided, mixed up, a crowd began, confusion. Great mess!
Approximately in the same way, physicists at first tried to obtain a high temperature - by pushing high-pressure gas jets. The gas was heated up to 10 thousand degrees. At one time it was a record: the temperature is higher than on the surface of the Sun.
But with this method, further, rather slow, non-explosive heating of the gas is impossible, since thermal disorder instantly spreads in all directions, warming the walls of the experimental chamber and the environment. The resulting heat quickly leaves the system and it is impossible to isolate it.
If the gas jets are replaced by plasma flows, the problem of thermal insulation remains very difficult, but there is also hope for its solution.
True, plasma cannot be protected from heat loss by vessels made of even the most refractory substance. In contact with solid walls, the hot plasma immediately cools down. On the other hand, one can try to hold and heat up the plasma by creating its accumulation in a vacuum so that it does not touch the walls of the chamber, but hangs in the void, without touching anything. Here one should take advantage of the fact that plasma particles are not neutral, like gas atoms, but electrically charged. Therefore, in motion, they are subject to the action of magnetic forces. The problem arises: to arrange a magnetic field of a special configuration in which the hot plasma would hang like in a bag with invisible walls.
The simplest form of such an electric field is created automatically when strong electric current pulses are passed through the plasma. In this case, magnetic forces are induced around the plasma filament, which tend to compress the filament. The plasma separates from the walls of the discharge tube, and the temperature rises to 2 million degrees near the axis of the filament in a rush of particles.
In our country, such experiments were carried out as early as 1950 under the guidance of Academicians JI. A. Artsimovich and M.A. Leontovich.
Another direction of experiments is the use of a magnetic bottle, proposed in 1952 by the Soviet physicist G. I. Budker, now an academician. The magnetic bottle is placed in a corktron - a cylindrical vacuum chamber equipped with an external winding, which thickens at the ends of the chamber. The current flowing through the winding creates a magnetic field in the chamber. Its lines of force in the middle part are parallel to the generatrices of the cylinder, and at the ends they are compressed and form magnetic plugs. Plasma particles injected into a magnetic bottle curl around the lines of force and are reflected from the corks. As a result, the plasma is kept inside the bottle for some time. If the energy of the plasma particles introduced into the bottle is high enough and there are enough of them, they enter into complex force interactions, their initially ordered motion becomes entangled, becomes disordered - the temperature of hydrogen nuclei rises to tens of millions of degrees.
Additional heating is achieved by electromagnetic<ударами>by plasma, magnetic field compression, etc. Now the plasma of heavy hydrogen nuclei is heated to hundreds of millions of degrees. True, this can be done either for a short time or at a low plasma density.
To excite a self-sustaining reaction, it is necessary to further increase the temperature and density of the plasma. This is difficult to achieve. However, the problem, as scientists are convinced, is undeniably solvable.
G.B. Anfilov
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ABSOLUTE ZERO
ABSOLUTE ZERO, the temperature at which all components of the system have the least amount of energy allowed by the laws of QUANTUM MECHANICS; zero on the Kelvin temperature scale, or -273.15 ° C (-459.67 ° Fahrenheit). At this temperature, the entropy of the system - the amount of energy available for doing useful work - is also zero, although the total amount of energy of the system may be different from zero.
Scientific and technical encyclopedic dictionary.
See what "ABSOLUTE ZERO" is in other dictionaries:
Temperatures are the minimum temperature limit that a physical body can have. Absolute zero is the starting point for an absolute temperature scale, such as the Kelvin scale. On the Celsius scale, absolute zero corresponds to a temperature of −273 ... Wikipedia
ABSOLUTE ZERO TEMPERATURE- the origin of the thermodynamic temperature scale; located at 273.16 K (Kelvin) below (see) water, i.e. equal to 273.16 ° C (Celsius). Absolute zero is the lowest temperature in nature and almost unattainable ... Great Polytechnic Encyclopedia
This is the minimum temperature limit that a physical body can have. Absolute zero is the starting point for an absolute temperature scale, such as the Kelvin scale. On the Celsius scale, absolute zero corresponds to a temperature of −273.15 ° C. ... ... Wikipedia
Absolute zero temperature is the minimum temperature limit that a physical body can have. Absolute zero is the starting point for an absolute temperature scale, such as the Kelvin scale. On the Celsius scale, absolute zero corresponds to ... ... Wikipedia
Razg. Neglect An insignificant, insignificant person. FSRYA, 288; BTS, 24; ZS 1996, 33 ...
zero- absolute zero … Dictionary of Russian Idioms
Zero and zero n., m., use. comp. often Morphology: (no) what? zero and zero, why? zero and zero, (see) what? zero and zero, what? zero and zero, about what? about zero, zero; pl. what? zeros and zeros, (no) what? zeros and zeros, why? zeros and zeros, (I see) ... ... Dictionary of Dmitriev
Absolute zero (zero). Razg. Neglect An insignificant, insignificant person. FSRYA, 288; BTS, 24; ZS 1996, 33 To zero. 1. Jarg. they say Shuttle. iron. About severe intoxication. Yuganov, 471; Vakhitov 2003, 22. 2. Jarg. music Exactly, in full accordance with ... ... Big dictionary of Russian sayings
absolute- absolute absurdity absolute authority absolute impeccability absolute disorder absolute fiction absolute immunity absolute leader absolute minimum absolute monarch absolute morality absolute zero ... ... Dictionary of Russian Idioms
Books
- Absolute Zero, Absolute Pavel. The life of all the creations of the mad scientist of the nes race is very short. But the next experiment has a chance to exist. What lies ahead for him?...
