The law of conservation of energy states that the amount of energy in any process remains unchanged. But he says nothing about what energy transformations are possible.
Z-energy conservation does not prohibit, processes that are experienced do not occur:
Heating a hotter body with a colder one;
Spontaneous swinging of the pendulum from a state of rest;
Collecting sand into stone, etc.
Processes in nature have a certain direction. They cannot flow spontaneously in the opposite direction. All processes in nature are irreversible(aging and death of organisms).
Irreversible a process can be called such a process, the reverse of which can occur only as one of the links of a more complex process. Spontaneous These are processes that occur without the influence of external bodies, and therefore without changes in these bodies).
Processes of transition of a system from one state to another, which can be carried out in the opposite direction through the same sequence of intermediate equilibrium states, are called reversible. In this case, the system itself and the surrounding bodies completely return to their original state.
The second law of thermodynamics indicates the direction of possible energy transformations and thereby expresses the irreversibility of processes in nature. It was established by direct generalization of experimental facts.
R. Clausius' formulation: it is impossible to transfer heat from a colder system to a hotter one in the absence of simultaneous changes in both systems or surrounding bodies.
W. Kelvin's formulation: it is impossible to carry out such a periodic process, the only result of which would be the production of work due to heat taken from one source.
Impossible thermal perpetual motion machine of the second kind, i.e. an engine that performs mechanical work by cooling any one body.
The explanation of the irreversibility of processes in nature has a statistical (probabilistic) interpretation.
Purely mechanical processes (without taking into account friction) are reversible, i.e. are invariant (do not change) when replacing t→ -t. The equations of motion of each individual molecule are also invariant with respect to time transformation, since contain only distance-dependent forces. This means that the reason for the irreversibility of processes in nature is that macroscopic bodies contain a very large number of particles.
The macroscopic state is characterized by several thermodynamic parameters (pressure, volume, temperature, etc.). The microscopic state is characterized by specifying the coordinates and velocities (moments) of all particles that make up the system. One macroscopic state can be realized by a huge number of microstates.
Let us denote: N is the total number of states of the system, N 1 is the number of microstates that realize a given state, w is the probability of a given state.
The greater N 1, the greater the probability of a given macrostate, i.e. the longer the system will remain in this state. The evolution of the system occurs in the direction from unlikely states to more probable ones. Because Mechanical movement is an ordered movement, and thermal movement is chaotic, then mechanical energy turns into thermal energy. In heat transfer, a state in which one body has a higher temperature (the molecules have a higher average kinetic energy) is less likely than a state in which the temperatures are equal. Therefore, the heat exchange process occurs in the direction of equalizing temperatures.
Entropy - measure of disorder. S - entropy.
where k is Boltzmann's constant. This equation reveals the statistical meaning of the laws of thermodynamics. The amount of entropy in all irreversible processes increases. From this point of view, life is a constant struggle to reduce entropy. Entropy is related to information, because information leads to order (if you know a lot, you will soon grow old).
The law of conservation of energy states that energy in nature does not arise from nothing and does not disappear without a trace, the amount of energy is unchanged, and it only passes from one form to another. Moreover, some processes that do not contradict the law of conservation of energy never occur in nature.
Objects that have a higher temperature cool down and at the same time give up their energy to colder surrounding bodies. But the reverse process never occurs in nature: spontaneous transfer of heat from a cold body to a warmer one, although this does not contradict the law of conservation of energy. For example, a kettle with boiling water was placed on the table. Gradually cooling, the kettle gives up part of its internal energy to the air in the room. As a result, the air heats up. This process will continue only until the temperatures of the kettle and the air in the room are equal. After this, temperature changes will not occur.
Another example. The oscillations of a swing, taken out of equilibrium, die out if it is not rocked. The mechanical energy of the swing decreases due to the negative work done by the air resistance force, and the internal energy of the swing and the environment increases. A decrease in mechanical energy is equal to an increase in internal energy. The law of conservation of energy does not exclude the reverse process: the transition of the internal energy of the air and the swing into the mechanical energy of the swing. Then the amplitude of the swing’s oscillations would increase due to a decrease in the temperature of the environment and the swing itself. But such a process never happens. Internal energy never turns into internal energy. The energy of ordered motion of a body as a whole always turns into the energy of disordered thermal motion of its constituent molecules, but not vice versa.
Under the influence of external forces, a stone may crumble into sand over time, but sand will never “gather” into a stone without external influences.
The transition of energy from a hot body to a cold one, the transformation of mechanical energy into internal energy, the destruction of bodies over time are examples of irreversible processes. Irreversible processes are those that, without external influences, proceed only in one specific direction; in the opposite direction they can proceed only as one of the links in a more complex process. You can again increase the temperature of a cooled kettle and the water in it, but not due to the internal energy of the air, but by transferring energy to it from external bodies, for example, from the burner of an electric stove. You can again increase the amplitude of the swing's oscillations by pushing it with your hands. You can melt sand and, when frozen, it turns into stone. But all these changes may not occur spontaneously, but become possible as a result of an additional process, including the influence of an external force.
Many such examples can be given. They all say that the first law of thermodynamics does not take into account a certain direction of processes in nature. All macroscopic processes in nature proceed only in one specific direction. They cannot flow in the opposite direction by themselves. All processes in nature are irreversible, and the most tragic of them are the aging and death of organisms.
The concept of irreversibility of processes constitutes the content of the second law of thermodynamics, which indicates the direction of energy transformations in nature. This law was established by direct generalization of experimental facts. It has several equivalent formulations, which, despite their external differences, essentially express the same thing. The German scientist Rudolf Clausius in 1850 formulated the second law of thermodynamics as follows: it is impossible to transfer heat from a colder system to a hotter one in the absence of other simultaneous changes in both systems or in surrounding bodies.
Independently of Clasius, in 1851 the British physicist William Thomson (Lord Kelvin) came to the same conclusion: “A circular process is impossible, the only result of which would be the production of work by cooling the heat reservoir.”
From the above formulations it follows that if the process of energy transfer from a cold body to a hot one is carried out, then certain changes occur in the surrounding bodies. In particular, such a process occurs in a refrigeration unit: energy is transferred from the refrigeration chamber to an environment that has a higher temperature, but this process is carried out when work is performed on the working fluid, and at the same time certain changes occur in the environment.
The importance of this law lies primarily in the fact that irreversibility can be extended from the heat transfer process to any processes occurring in nature. If heat in some cases could be spontaneously transferred from cold bodies to hot ones, then this would make it possible to make other processes reversible.
All processes spontaneously proceed in one specific direction. They are irreversible. In any case, heat moves from a hot body to a cold one, and the mechanical energy of macroscopic bodies turns into the internal energy of their molecules.
The direction of processes in nature is determined using the second law of thermodynamics.
How do irreversible processes occur? There are a lot of events happening in the world every day. They can be quite common and permanent, or they can have irreversible consequences. It is these events that will be discussed in the article below.
Concept and definition
Irreversible processes are unchangeable, often regressive processes. They can occur in absolutely any area of human life. But, according to scientists, the most important are similar processes in nature. Unfortunately, there are many such examples. But in this article we will highlight the most basic ones. They tend to represent large-scale environmental problems.
Extinction of animals, destruction of plants
It is quite reasonable to say that the extinction of various animal species is a natural process of evolution.
According to Google, every year the world loses from 1 to 10 species of animals and about 1-2 species of birds. Moreover, the disappearance tends to increase. Because, according to the same statistics, about 600 species are officially in danger of extinction.
Thus, these are completely irreversible processes occurring in the world of animals and plants. The main reasons are the following factors:
- Pollution, emissions and other negative impacts on the environment.
- The use of chemical compounds in agriculture, which makes it impossible for certain species of animals and plants to exist in such areas.
- A constant decrease in the amount of food for animals, associated, for example, with deforestation.
Earth depletion
Every day, every person on the planet uses mineral energy. Be it oil, gas, coal, or other necessary sources of electricity. Here you have a new irreversible process - the depletion of the “treasuries” of our planet. Scientists believe that the main reason for this regression is the constant growth of population.
The number of people increases, and accordingly, consumption and demand also increase. Along with the increase in demand, critics also point out that the constant depletion of mineral basins will lead to inevitable climate change. And this, as we know, will entail even greater problems than we can imagine.
As Thor Heyerdahl said:
Dead ocean - dead Earth.
He was absolutely right in his statement, hinting at one of the examples of irreversible processes - the absolutely dishonest behavior of people in relation not only to the ocean, but also to nature as a whole.
Back in the 20th century, it became known that the World Ocean belongs to everyone. This, in particular, led him to the state in which he is now. The main thing is that it is also an irreversible process - the illiterate use of its resources, as well as the fact that the World Ocean does not tend to withstand the entire load of the atmosphere into which humanity produces daily emissions. But more on that in the next chapter.
Irreversible processes in nature often cover the most global and serious areas of our life. The release of chemicals into the atmosphere is a really important problem. The consequences of such emissions are so dangerous that in 1948, the state of Pennsylvania (USA) was covered in extremely dense fog. At that time, about 14,000 people lived in the city of Donora.
According to historical sources, of these 14 thousand, about 6 thousand people fell ill. The fog was so thick that it was almost impossible to discern the road. They began to actively contact doctors with complaints of nausea, eye pain, and dizziness. After some time, 20 people died.
Dogs, birds, cats also died en masse - those who could not find shelter from the suffocating fog. It is not difficult to guess that the cause of this phenomenon was none other than emissions into the atmosphere. Scientists claim that the situation is due to improper distribution of air temperature in the area as a result of the use of chemicals.
Ozone layer problems
For many centuries, people did not even suspect the existence of such a phenomenon as the ozone layer (until 1873 - that’s when the scientist Schönbein discovered it). However, this did not prevent humanity from having a very detrimental effect on the ozone layer. The reasons for its destruction, to the surprise of many, are quite simple but compelling reasons:
At the moment, the problem of ozone layer destruction is relevant. People are thinking about how to use less freons and are actively searching for their substitutes. There are also many volunteers who agree to help scientists and go into science to save the environment.
Human "contribution" to natural landscapes
There are two categories of people. For some, environmental protection is important, while for others it is the opposite. Unfortunately, destruction prevails. An environment that, thanks to the influence of humanity, is no longer suitable for life is considered to be completely disfigured. And there are a large number of such people nowadays. Basically, changes in natural landscapes are deforestation, as a result of which animals become extinct, plants, birds, etc. disappear.
Renewing the affected area after this is extremely difficult, and, as a rule, almost no one does it. Many organizations involved in nature restoration know what processes are called irreversible. But will their strength be enough to preserve our entire ecology?
How to prevent the inevitable?
It’s not for nothing that global problems are called that - they have no tendency to return. However, great help can be provided to the world so that these processes do not continue to have a detrimental effect on the environment. There are many ways to help nature. They have been known to everyone for a long time, but it is impossible not to talk about them.
- Political way. It implies the creation of laws to protect the environment, to protect it. Many countries already have many such laws. However, humanity needs effective, literally, ones that force us to stop and not destroy our own habitat.
- Organizations. Yes, today there are environmental organizations. But it would also be nice to make sure that everyone has the opportunity to participate in their actions.
- Ecological way. The simplest thing is to plant a forest. Trees, bushes, seedlings and propagation of various plants is a very basic task, but it can have a profound impact on nature.
Holzer biocenosis
An ordinary person, not a botanist or a scientist of the highest category, but just an ordinary farmer created a biocenosis. The essence is to ensure the existence of fish, insects, animals, plants in a certain place, without practically taking part in their development. Thus, the whole of Austria lines up for meat, fruits and other products. He proved by example that if you do not interfere with nature’s development, it will only bring benefits. The so-called harmony with nature is the goal that everyone in this world should strive for.
conclusions
Humanity is accustomed to acting according to the principle: I see the goal - I see no obstacles. Even if this leads to such global problems (if it has not already begun to do so) that humanity itself will disappear. In trying to achieve our goals and ensure our own comfort, we do not notice how everything around us is being destroyed. How many people, after reading this article, will wonder which processes are irreversible?
If we do not overcome the thinking process of modern people, nature will face real danger in just a few years. It is a pity that we live in a world where our own benefit prevails over the state of the world around us.
The harmony of the processes of conservation, destruction and creation is the basis of the existence and evolution of the Universe. Synergetics recognized the Universe as open, but did not find God in it! Before the advent of synergetics, the world was dominated by the second law of thermodynamics. In accordance with this law, the evolution of the Universe was accompanied by an increase in entropy and the equalization of all gradients and potentials. The world was heading toward a state of homogeneous chaos, which was called “heat death.” Synergetics, the science of self-organization and cooperation in natural phenomena, brought humanity out of the despondency of such a prospect. It is synergetic processes that underlie morphogenesis - the emergence of new forms of matter. At the same time, the authors believed that the prerequisites for such processes are exchange with the environment, the random nature of external or internal influences, as well as instability, nonlinearity and irreversibility. A process occurring in a system under the influence of certain factors should be considered reversible (irreversible) if when the influence of these factors ceases, the process stops and the system returns (does not return) to its original state
There are several formulations of the second law of thermodynamics. One of them says that it is impossible to have a heat engine that would do work only due to a heat source, i.e. no refrigerator. The world's oceans could serve for him as a practically inexhaustible source of internal energy (Wilhelm Friedrich Ostwald, 1901). Other formulations of the second law of thermodynamics are equivalent to this one. Clausius' formulation (1850): a process in which heat would spontaneously transfer from less heated bodies to more heated bodies is impossible. There are several formulations of the second law of thermodynamics. One of them says that it is impossible to have a heat engine that would do work only due to a heat source, i.e. no refrigerator. The world's oceans could serve for him as a practically inexhaustible source of internal energy (Wilhelm Friedrich Ostwald, 1901). Other formulations of the second law of thermodynamics are equivalent to this one. Clausius' formulation (1850): a process in which heat would spontaneously transfer from less heated bodies to more heated bodies is impossible.
The reserves of internal energy in the earth's crust and oceans can be considered practically unlimited. But having energy reserves is not enough. It is necessary to be able to use energy to set in motion machine tools in factories and factories, vehicles, tractors and other machines, to rotate the rotors of electric current generators, etc. Humanity needs device engines that can do work. Most of the engines on Earth are heat engines, i.e. devices that convert the internal energy of fuel into mechanical energy.
A heat engine (machine) is a device that performs mechanical work cyclically due to the energy supplied to it during heat transfer. The source of the incoming amount of heat in real engines can be burning organic fuel, a boiler heated by the Sun, a nuclear reactor, geothermal water, etc. A heat engine (machine) is a device that performs mechanical work cyclically due to the energy supplied to it during heat transfer. The source of the incoming amount of heat in real engines can be burning organic fuel, a boiler heated by the Sun, a nuclear reactor, geothermal water, etc.
Currently, two types of engines are most common: a piston internal combustion engine (land and water transport) and a steam or gas turbine (energy). Modern thermal engines include rocket and aircraft engines.
In the theoretical model of a heat engine, three bodies are considered: a heater, a working fluid and a refrigerator. Heater – a thermal reservoir (large body), the temperature of which is constant. In each cycle of engine operation, the working fluid receives a certain amount of heat from the heater, expands and performs mechanical work. The transfer of part of the energy received from the heater to the refrigerator is necessary to return the working fluid to its original state. In the theoretical model of a heat engine, three bodies are considered: a heater, a working fluid and a refrigerator. Heater – a thermal reservoir (large body), the temperature of which is constant. In each cycle of engine operation, the working fluid receives a certain amount of heat from the heater, expands and performs mechanical work. The transfer of part of the energy received from the heater to the refrigerator is necessary to return the working fluid to its original state.
For each cycle, based on the first law of thermodynamics, we can write that the amount of heat Qheat received from the heater, the amount of heat |Qcol| given to the refrigerator, and the work A performed by the working fluid are interconnected by the relation: A = Qheat – |Qcol |. In real technical devices, which are called heat engines, the working fluid is heated by the heat released during the combustion of fuel.
Efficiency of a heat engine If a model of the working fluid in a heat engine is given (for example, an ideal gas), then it is possible to calculate the change in the thermodynamic parameters of the working fluid during expansion and compression. This allows the efficiency of a heat engine to be calculated based on the laws of thermodynamics. The figure shows cycles for which the efficiency can be calculated if the working fluid is an ideal gas and the parameters are specified at the transition points of one thermodynamic process to another.
Environmental consequences of the operation of thermal engines Intensive use of thermal engines in transport and in the energy sector (thermal and nuclear power plants) significantly affects the Earth's biosphere. Although there are scientific disputes about the mechanisms of influence of human activity on the Earth's climate, many scientists note the factors due to which such an influence can occur: 1. The greenhouse effect - an increase in the concentration of carbon dioxide (a product of combustion in heaters of heat engines) in the atmosphere. Carbon dioxide allows visible and ultraviolet radiation from the Sun to pass through, but absorbs infrared radiation from the Earth into space. This leads to an increase in the temperature of the lower layers of the atmosphere, increased hurricane winds and global melting of ice. 2. Direct impact of toxic exhaust gases on wildlife (carcinogens, smog, acid rain from combustion by-products). 3. Destruction of the ozone layer during airplane flights and rocket launches. Ozone in the upper atmosphere protects all life on Earth from excess ultraviolet radiation from the Sun. The intensive use of heat engines in transport and energy (thermal and nuclear power plants) significantly affects the Earth's biosphere. Although there are scientific disputes about the mechanisms of influence of human activity on the Earth's climate, many scientists note the factors due to which such an influence can occur: 1. The greenhouse effect - an increase in the concentration of carbon dioxide (a product of combustion in heaters of heat engines) in the atmosphere. Carbon dioxide allows visible and ultraviolet radiation from the Sun to pass through, but absorbs infrared radiation from the Earth into space. This leads to an increase in the temperature of the lower layers of the atmosphere, increased hurricane winds and global melting of ice. 2. Direct impact of toxic exhaust gases on wildlife (carcinogens, smog, acid rain from combustion by-products). 3. Destruction of the ozone layer during airplane flights and rocket launches. Ozone in the upper atmosphere protects all life on Earth from excess ultraviolet radiation from the Sun.
The law of conservation of energy states that the amount of energy during any transformation remains unchanged. But he says nothing about what energy transformations are possible. Meanwhile, many processes that are completely acceptable from the point of view of the law of conservation of energy never occur in reality.
Examples of irreversible processes. Heated bodies gradually cool down, transferring their energy to colder surrounding bodies. The reverse process of heat transfer from cold
body to hot does not contradict the law of conservation of energy, but such a process has never been observed.
Another example. The oscillations of the pendulum, removed from the equilibrium position, die out (Fig. 49; 1, 2, 3, 4 - successive positions of the pendulum at maximum deviations from the equilibrium position). Due to the work of friction forces, mechanical energy decreases, and the temperature of the pendulum and the surrounding air (and therefore their internal energy) slightly increases. The reverse process is also energetically permissible, when the amplitude of the pendulum’s oscillations increases due to the cooling of the pendulum itself and the environment. But such a process has never been observed. Mechanical energy spontaneously transforms into internal energy, but not vice versa. In this case, the ordered movement of the body as a whole turns into disordered thermal movement of the molecules composing it.
General conclusion about the irreversibility of processes in nature. The transition of heat from a hot body to a cold one and mechanical energy into internal energy are examples of the most typical irreversible processes. The number of such examples can be increased almost unlimitedly. They all say that processes in nature have a certain direction, which is not reflected in any way in the first law of thermodynamics. All macroscopic processes in nature proceed only in one specific direction. They cannot flow spontaneously in the opposite direction. All processes in nature are irreversible, and the most tragic of them are the aging and death of organisms.
A precise formulation of the concept of an irreversible process. To properly understand the essence of irreversibility of processes, it is necessary to make the following clarification. Irreversible is a process whose reverse can occur only as one of the links in a more complex process. So, you can again increase the swing of the pendulum by pushing it with your hand. But this increase does not occur by itself, but becomes possible as a result of a more complex process involving the movement of the hand.
It is possible, in principle, to transfer heat from a cold body to a hot one. But this requires a refrigeration unit that consumes energy.
Cinema is the opposite. A striking illustration of the irreversibility of phenomena in nature is watching a movie in reverse. For example, a jump into water will look like this. The calm water in the pool begins to boil, legs appear, rapidly moving upward, and then
and the whole diver. The surface of the water quickly calms down. Gradually, the diver’s speed decreases, and now he is calmly standing on the tower. What we see on the screen could happen in reality if the processes could be reversed. The “absurdity” of what is happening stems from the fact that we are accustomed to a certain direction of processes and do not doubt the impossibility of their reverse flow. But such a process as lifting a diver onto a tower from the water does not contradict either the law of conservation of energy, or the laws of mechanics, or any laws at all, except for the second law of thermodynamics.
Second law of thermodynamics. The second law of thermodynamics indicates the direction of possible energy transformations and thereby expresses the irreversibility of processes in nature. It was established by direct generalization of experimental facts.
There are several formulations of the second law, which, despite their external differences, essentially express the same thing and are therefore equivalent.
The German scientist R. Clausius formulated this law as follows: it is impossible to transfer heat from a colder system to a hotter one in the absence of other simultaneous changes in both systems or in surrounding bodies.
Here the experimental fact of a certain direction of heat transfer is stated: heat always passes by itself from hot bodies to cold ones. True, in refrigeration units heat transfer occurs from a cold body to a warmer one, but this transfer is associated with “other changes in the surrounding bodies”: cooling is achieved through work.
The importance of this law lies in the fact that from it one can draw a conclusion about the irreversibility of not only the heat transfer process, but also other processes in nature. If heat in some cases could be spontaneously transferred from cold bodies to hot ones, then this would make it possible to make other processes reversible. In particular, it would make it possible to create engines that completely convert internal energy into mechanical energy.
