Rudolf Clausius

One of the main founders of thermodynamics

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synonym Clausius (Clausius) Generally refers to Rudolf Clausius

German mathematician Rudolf Julius Emanuel Clausius (January 2, 1822-August 24, 1888), German physicist and mathematician, thermodynamics One of the main founders of. Born in Prussia poland Koshalin ）, died bonn 。^{[1 ]} He restated Sadi Carnot The law of Carnot cycle ）And push the thermal theory to a more real and sound foundation.

Chinese name: Rudolf Julius Emmanuel Clausius
Foreign name: Rudolf Julius Emanuel Clausius
Alias: Rudolf Clausius
Nationality: Germany

date of birth: January 2, 1822
Date of death: August 24, 1888
University one is graduated from: University of Berlin
Key achievements: point out The second law of thermodynamics Basic concepts of
one's native heath: Koslin, Pomerania, Germany (now Poland Kosalin)

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Rudolf Julius Emanuel Clausius, a German physicist and mathematician, thermodynamics One of the main founders of. He restated Nicolas Cano's law (also known as Carnot cycle ）And push the thermal theory to a more real and sound foundation. His most important paper was published in 1850, which is about the mechanical theory of heat, in which he clearly pointed out for the first time The second law of thermodynamics Basic concepts of. He also introduced the concept of entropy in 1865.

Academic attainments

His most important paper was published in 1850, which is about the mechanical theory of heat, in which he clearly pointed out for the first time The second law of thermodynamics Basic concepts of. He also introduced the concept of entropy in 1865.

Main experience

On January 2, 1822, he was born in a family of intellectuals in Keslin, Prussia (today's Polankoshalin). Joined in 1840 University of Berlin 。 Majored in mathematics and physics at Harley University in 1847 Doctor of Philosophy 。 Since 1850, he has served first and then Berlin Artillery Engineering College Zurich University of Technology 、 Universitaet Wuerzburg 、 University of Bonn Professor of Physics. He was once French Academy of Sciences 、 Royal Society and Petersburg Academy of Sciences Elected as academician or member. He is famous for his paper "On the power of heat and the laws of heat itself derived from it". Professor of Zurich University of Technology in 1855 and 1867 German Empire Professor of the University of Vilzburg, Professor of the University of Bonn since 1869. In 1865 and 1868, he was elected as an academician of the French Academy of Sciences and president of the Royal Society of England respectively.

Life

Clausius was born Pomeranian Voivodeship In Kerslin, he began to receive education in his father's school. A few years later, he went Shicheqing He studied in the Liberal Arts and Science Middle School in the city. In 1844, he went from University of Berlin After graduation, he studied mathematics and physics in the university. Among his classmates were Heinrich Magnus, John Peter Dilikley and Jacob Steiner (Jakob Steiner), also studied history with Rank. In 1847, he completed Earth's atmosphere He obtained a doctorate degree in optical research from Harley University and later became a German Royal Artillery Technical College He is a professor of physics at the University of Berlin and an unpaid lecturer at the University of Berlin. From 1855 to 1867 Zurich Federal Institute of Technology He served as a professor, and then moved to Vilzburg. Two years later, he moved to 1869 bonn 。

In 1870, Clausius Franco-Prussian War China has organized a rescue team, which was injured and permanently disabled in the war, so it was awarded Iron Cross 。

His wife Adelheid Rimpham in 1875 dystocia He died, leaving him alone to raise six children. However, he continued to teach, but there was less time for research since then. Clausius died in Bonn.

Research

Clausius Light refraction In his doctoral thesis, he proposed that the blue sky we see in the daytime and the red sky we see at sunrise and sunset (as well as some other phenomena) are all caused by the refraction and reflection of light. in the future, rayleigh The Lord suggested that this was actually caused by the scattering of light, but anyway, Claudius research method Than before Related research It's much more mathematical.

His most famous paper,Ü ber die bwegende Kraft der Wä rme, was published in 1850, involving the mechanical theory of heat. In this paper, he proposed Cano's law and Conservation of energy The concept of is inconsistent, and Clausius restates two Thermodynamic law To overcome this contradiction (the third law was published by Walter Nernst between 1906 and 1912). This paper made his scientific career take off.

Clausius improved in 1857 Auguste Crowe August Krö nig is a very simple gas motion model, which introduces the translational, rotational and vibrational motion of molecules Theory of molecular motion The field has made contributions. In the same study, he also introduced the concept of the average free path of a particle.

Clausius deduced Clausius from thermodynamics- Clapeyron equation This relationship is a way to describe the phase transition between two states, such as solid and liquid, which was first published by Emile Clabron in 1834.

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Thermodynamic study

Clausius is mainly engaged in Molecular physics , thermodynamics steam engine Theory Theoretical mechanics , mathematics, especially in thermodynamics theory Kinetic theory of gas He has made outstanding achievements in many aspects. He is the first accurate expression in history Thermodynamic law Scientists. In 1850, William John Ma － Zuorn Rankine (1820 ～ 1872) and William John Ma － Zuorn Rankine independently expressed heat and machinery Work General relationship of—— First law of thermodynamics And put forward the ideal Thermodynamic cycle (Rankin Clausius cycle). In 1850, Clausius published a paper on the power of heat and the laws of heat itself. He is right from the point of view that heat is movement heat engine Of working process New research has been carried out. The paper first established from Joule Thermal equivalent Set out to Thermodynamic process Compliant conservation of energy It comes down to the first law of thermodynamics, which points out that part of the heat is consumed in the process of the heat engine doing work, and the other part of the heat is transferred from the hot body to the cold body. There is a relationship between these two parts of heat and the work generated:. Where dQ is the heat transferred to the object, dW is the work done, and U is a new function introduced by Clausius into thermodynamics for the first time, which is a function of volume and temperature. Later Kelvin called U the energy of the object, that is Thermodynamic system Internal energy of. In the second part of the paper Carnot theorem Based on the research of energy conversion and transmission direction The second law of thermodynamics The most famous expression of（ clausius statement ）Heat cannot be spontaneously transferred from a cooler object to a hotter object. Therefore, Clausius is one of the two main founders of the second law of thermodynamics (the other is Kelvin).

Encyclopedia x ignorance: graphical second law of thermodynamics

On the basis of the discovery of the second law of thermodynamics, people expect to find a physical quantity To establish a universal criterion Spontaneous process Direction of progress. Clausius first found such a physical quantity. In 1854, he published the paper Another Form of the Second Law of the Thermal Theory of Mechanics, and gave the reversible Cyclic process The mathematical expression form of the second law of thermodynamics is:, and a new state parameter later named entropy is introduced. In 1865, he published a paper titled "The Main Equations of the Thermal Theory of Mechanics in an Easy to Use Form", and formally named this new state parameter entropy. The above integral is extended to a more general cyclic process, and it is obtained that The second law of thermodynamics Mathematical expression of: ≤ 0 Equal sign Corresponds to Reversible process ， Unequal sign Corresponds to Irreversible process 。 This is the famous Clausius inequality 。 Using the new function of entropy, Clausius proved that: Isolated system The total entropy of the system will never decrease, or the spontaneous process of nature is in the direction of increasing entropy. This is“ Principle of entropy increase ”It is the second law of thermodynamics expressed by the concept of entropy. Later, Clausius inappropriately extended the second law of thermodynamics to the whole universe and proposed the so-called“ Heat silence theory ”。

Study on kinetic theory of gas

stay Kinetic theory of gas On the other hand, Clausius made outstanding contributions. Clausius, Maxwell Boltzmann It is called the three main founders of the kinetic theory of gases. Because of their series of work, the kinetic theory of gas finally becomes quantitative system theory 。 In 1857, Clausius published his paper "On the Forms of Thermal Motion", which developed the basic idea of the kinetic theory of gases in a very clear way. He assumed that the molecules in the gas moved randomly in all directions at the same speed, and the collision of gas molecules with the wall produced the pressure of the gas ideal gas Pressure formula, and it is deduced that Boyle Mallott's law and Guy Lussac's law , showing the achievement of gas kinetic theory. It is also the first time to explicitly put forward the concept of statistics in physics statistical mechanics The development of has played a pioneering role.

In 1858, he published "On Average free path of gas molecule 》In this paper, starting from the analysis of the mutual collisions between gas molecules, the important concepts of the number of collisions occurring in unit time and the average free path of gas molecules are introduced, which solve the problem of calculating gas according to theory Molecular motion Very fast and Gas diffusion Of propagation velocity The slow contradiction has opened up the way to study the gas transport process.

Thermodynamic theory

Thermodynamic Founder Clausius studied extensively throughout his life, but his most famous achievement is to put forward The second law of thermodynamics And became one of the founders of thermodynamic theory. With the development of human science in the 19th century, steam engines have been widely used. How to further improve heat engine The efficiency of Theoretical physics Key research topics. In 1824, Cano made peace in the theory of heat and mass Perpetual motion machine It is impossible to prove the later famous Carnot theorem , which not only infers that Heat engine efficiency It also includes some contents of the second law of thermodynamics. Since then, after long-term research by many scientists, by the middle of the 19th century, Energy conversion and conservation law Established, this extremely important universal law in physics soon became a research hotspot and other various Sports form A solid foundation for mutual transformation.

Since his youth, Clausius has decided to conduct theoretical research on heat. He believes that once there is a breakthrough in theory heat engine The problem of efficiency can be easily solved. With a clear goal, Clausius studied very hard. He knew that only by laying a solid foundation in mathematics and physics at the student stage can he make achievements in the future research. Therefore, Clausius spent nearly 10 years studying hard in school. Where there is a will, there is a way. In 1850, Clausius published his first paper on the theory of heat - "On the power of heat and the law of heat itself". In his paper, he first established Thermal equivalent On the basis of, it is the first time to clearly put forward First law of thermodynamics : In all cases where heat generates work, there must be heat that is proportional to the generated work consumed; On the contrary, if the same amount of work is consumed, the same amount of heat will be generated. According to this basic law, Clausius ideal gas As an example, the further discussion negates the basic premise of the theory of heat and mass, that is, the conservation of heat in the universe, and the heat in the matter is Kinetic theory of gas molecules Contribution of

As the founder of the theory of thermodynamics, Clausius has achieved more than that in his life. He has made remarkable research achievements in many aspects, especially in the theory of gas molecular motion habituation He and Maxwell Boltzmann Collectively referred to as Theory of molecular motion The founder of.

Gas molecule theory

As early as the 18th century, scientists found that gas is composed of a large number of particles in fierce motion, and the pressure of gas comes from the collision of particles on the wall. In the 1850s, Clausius and others established the theory of thermodynamics, and used the theory of heat movement as the basis Molecular motion Research, which greatly promoted the development of molecular motion theory. In 1857, Clausius published a groundbreaking paper, "On the kind of motion we call heat", which was rich in content and expounded many issues related to molecular motion. From the point of view that gas is a collection of moving molecules, Clausius believes that it is neither possible nor meaningful to investigate the motion of a single molecule, and the macro properties of the system are not determined by the motion of one or some molecules, but by the motion of a large number of molecules average value 。 Therefore, he proposed Statistical average This is the premise of establishing the theory of molecular motion. Based on this premise, Clausius established ideal gas Molecular motion And emphasize Molecular kinetic energy Not only their Rectilinear motion It is also the movement of the rotation and oscillation of atoms in molecules, thus correctly determining the difference between the actual gas and the ideal gas. On this basis, Clausius calculated the number of molecules on the wall of the impactor and the corresponding momentum change of molecules, and through a series of complex calculations and demonstrations, he finally concluded that Molecular collision The pressure formula applied to the vessel wall reveals that Gas law The micro essence of. Not only that, Clausius also focused on the solid and liquid state of gas. He concluded that: three Aggregate state The molecules in are all moving, but the way of movement is different.

In his 1857 paper, Clausius calculated for the first time the rate of oxygen, nitrogen and hydrogen at freezing point. However, the conclusion that the movement speed of gas molecules is as high as hundreds of meters per second is far beyond people's expectation, because in real life, the process of gas diffusion (such as the diffusion of smoke) is quite slow, so people have expressed great doubts about Clausius' research results. How to explain the theoretical calculation Molecular motion Velocity, versus gas Diffusion phenomenon What about the contradiction between the displayed speed and the two? Clausius fell into a new perplexity. He realized that the model he used to regard molecules as mathematical geometric points was not accurate enough and must be corrected. He started from the analysis of the collision between gas molecules Scope of action As his main concept, he introduced the number of collisions and the Free path Two concepts, and the formula of the first sub mean free path is obtained. Through these new research methods, Clausius believes that although the speed of single molecule movement is very fast, due to the collision between molecules, the trajectory of molecular movement is very tortuous. As far as the whole molecular assembly is concerned, its journey is much longer, far less than Molecular motion The result of velocity display is Gas diffusion Reason for slowness. Clausius pioneered the solution of gas Diffusion velocity The contradiction of less than the molecular motion speed finally dispels people's doubts, making them Theory of molecular motion He was full of confidence and opened up the way to study the phenomenon of gas movement.

Entropy theory

In his paper "Abhandlungen ü ber die mechanische Wä rmetheorie, Zimbabwe Abteilung" published in 1867, Clausius provided a mathematical version of the concept of entropy for the first time and named it. He used the entropy unit "Clausius" (symbol: Cl ）。

1 Cl = 1 cal/°C = 4.1868 J/K

Other contributions

Clausius also contributed a lot in other aspects. He theoretically demonstrated Joule Lenz's law. From thermodynamics in 1851 Theoretical demonstration Has Clapeyron equation , so this equation is also called Claperon - Clausius equation. In 1853, he developed Thermoelectric phenomenon The thermodynamic theory of. In 1857, he put forward the theory of electrolysis. In 1870, he created one of the important theorems in statistical physics—— Potential force theorem 。 In 1879, he proposed Dielectric polarization The theory of dielectric Of Dielectric constant rather than Polarizability The relationship between them - Clausius Mosoti formula.

His main works include Thermal Theory of Mechanics, Potential Function and Potential, Second Proposal of Thermal Theory, etc.

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Academic honor

In 1868, he was elected Royal Society Member, awarded in 1879 Copley Medal 。 He won the Huygens Prize in 1870. Won in 1883 Poncelet Award. Won in 1882 Universitaet Wuerzburg Award Honorary doctorate 。 Moon Clausius on Crater Named after him.