In 1846, Kelvin was elected professor of natural philosophy at the University of Glasgow. Natural philosophy was another name for physics at the time. Kelvin served as a professor for 53 years before retiring in 1899. In 1904 he became Chancellor of the University of Glasgow, a position he held until his death.
Kelvin was born in Belfast, Ireland, on June 26, 1824. He was smart and studious since he was a child. At the age of 10, he entered the preparatory course of Glasgow University. When he was 17 years old, he once determined: “Wherever science leads the way, we will continue to climb.” He graduated from Cambridge University in 1845. During his studies at the university, he won the second place in the Langler Prize and the first place in the Smith Prize. After graduation, he went to Paris to engage in experimental work with the physicist and chemist V. Renault for a year. In 1846, he was appointed professor of natural philosophy (another name for physics at the time) at the University of Glasgow, a position he held for 53 years. For his contribution to the installation of the first Atlantic submarine cable, the British government knighted him in 1866 and was promoted to Lord Kelvin in 1892. This is where the name Kelvin came from. From 1890 to 1895, he served as president of the Royal Society of London. In 1877, he was elected as an academician of the French Academy of Sciences. In 1904, he served as Chancellor of the University of Glasgow until his death in Netherhall, Scotland, on December 17, 1907.
Kelvin has a wide range of research and has made contributions in thermal, electromagnetic, fluid mechanics, optics, geophysics, mathematics, engineering applications, etc. He published more than 600 papers in his lifetime and obtained 70 invention patents. He enjoyed a high reputation in the scientific community at that time and was highly praised by scientists and scientific groups in the UK, Europe and the United States. His research is most distinguished in the fields of heat, electromagnetism and their engineering applications.
Kelvin was one of the main founders of thermodynamics and made a series of major contributions in the development of thermodynamics. He created the thermodynamic temperature scale in 1848 based on the theories of Gay-Lussac, Carnot and Clapeyron. He pointed out: "The characteristic of this temperature scale is that it does not depend at all on the physical properties of any special substance." This is the standard temperature scale in modern science. He was one of the two main founders of the second law of thermodynamics (the other was Clausius). In 1851 he proposed the second law of thermodynamics: "It is impossible to absorb heat from a single heat source and convert it completely into useful work without Produce other effects." This is the accepted standard statement of the second law of thermodynamics. And pointed out that if this law does not hold, it must be admitted that there can be a kind of perpetual motion machine, which can obtain unlimited mechanical work by cooling sea water or soil, which is the so-called second kind of perpetual motion machine. He asserted from the second law of thermodynamics that energy dissipation is a universal tendency. In 1852, he collaborated with Joule to further study the internal energy of gases. He improved Joule's gas free expansion experiment and conducted a porous plug experiment on gas expansion. He discovered the Joule-Thomson effect, which is the adiabatic expansion of gas through a porous plug. Temperature change phenomenon. This discovery became one of the main methods to obtain low temperature and was widely used in cryogenic technology. In 1856, he predicted a new thermoelectric effect from theoretical research, that is, when current flows through a conductor with uneven temperature, in addition to generating irreversible Joule heat, the conductor also absorbs or releases a certain amount of heat (called Thomson fever). This phenomenon is later called the Thomson effect.
In electricity, Thomson studied various types of problems with great skill, from electrostatics to transient currents. He revealed the similarities between Fourier's theory of heat conduction and potential theory, discussed Faraday's concepts of the propagation of electrical action, and analyzed oscillating circuits and the resulting alternating currents. His article influenced Maxwell, who asked him for advice, hoping to study the same topic with him, and gave him high praise.
Kelvin has made outstanding achievements in electromagnetic theory and engineering applications. In 1848, he invented the electroimage method, which was an effective method for calculating the electrostatic field problem generated by the charge distribution of a conductor of a certain shape. He conducted in-depth research on the discharge oscillation characteristics of the Leyden jar and published the paper "Oscillating Discharge of the Leyden Jar" in 1853. He calculated the frequency of oscillation and made a pioneering contribution to the theoretical study of electromagnetic oscillation.
He had used mathematical methods to conduct useful discussions on the properties of electromagnetic fields, and tried to unify electric power and magnetism using mathematical formulas. In 1846, he successfully completed the "moving image method of force" on electricity, magnetism and current, which was already the prototype of electromagnetic field theory (if you go one step further, you will delve into the problem of electromagnetic waves). He once wrote in his diary: "If I could make a more special investigation of the electromagnetic and electric current-related states of objects, I would definitely go beyond what I know now, but that is of course a matter for the future. "His greatness was that he was able to introduce all his research results to Maxwell without reservation, and encouraged Maxwell to establish a unified theory of electromagnetic phenomena, which laid the foundation for Maxwell's final completion of the electromagnetic field theory.
He attaches great importance to integrating theory with practice. In 1875, he predicted that cities would use electric lighting, and in 1879, he proposed the possibility of long-distance power transmission. These ideas of his were later realized. In 1881, he modified the electric motor, which greatly improved its practical value. In terms of electrical instruments, his main contribution was the establishment of precise unit standards for electromagnetic quantities and the design of various precision measuring instruments. He invented the mirror galvanometer (which greatly improved the measurement sensitivity), the double-arm bridge, the siphon recorder (which can automatically record telegraph signals), etc., which greatly promoted the development of electrical measuring instruments. According to his suggestion, the British Science Association established an Electrical Standards Committee in 1861, which laid the foundation for the unit standard of modern electrical quantities. In 1855, he studied the signal propagation in cables and solved the problem of long-term electrical quantities. A series of theoretical and technical issues in distance submarine cable communication. After three failures and two years of various research and experiments, Kelvin finally helped install the first Atlantic submarine cable in 1858. This was a job for which Kelvin was quite famous. He is good at combining teaching, scientific research, and industrial application, and pays attention to cultivating students' practical working abilities in teaching. At the University of Glasgow he established the UK's first extracurricular laboratory for students.
Thomson also used physics in completely different areas. He has studied the origin of solar thermal energy and the Earth's thermal balance. His method was reliable and interesting, but it was impossible to reach correct conclusions simply because he did not know that the energy in the sun and the earth came from nuclear energy. He tried to explain the origin of solar heat in terms of meteorites falling on the sun or in terms of gravitational contraction. Around 1854, he estimated the age of the Sun to be less than 5×10^8 years, which is only one-tenth of the value we now know.
From the temperature gradient near the Earth's surface, Thomson tried to deduce the Earth's thermal history and age. His estimate was still too low, at only 4×108 years, while the actual value was about 5×109 years. The geologist based his theory on the evolution of geological phenomena and soon discovered that his estimate was wrong. They could not refute Thomson's mathematics, but they were certain that his assumptions were wrong. Similarly, biologists also found that Thomson's time course was inconsistent with the latest evolutionary concepts. The controversy raged on for many years, with Thomson rightly incapable of understanding the objections of others. Finally, it was not until the discovery of radioactivity and nuclear reactions that the premise of Thomson's hypothesis was proved to be completely wrong.
Fluid mechanics, especially the vortex theory, became one of Thomson's favorite subjects. Inspired by the work of Helmholtz, he discovered some valuable theorems. One of the rewards of his voyage was the invention in 1876 of a special compass for iron ships, which was later adopted by the British Navy and remained in use until it was replaced by the modern gyrocompass. Thomson's business produced many magnetic compasses and water depth sounders, from which he profited greatly.
Based on his practical experience and theoretical knowledge, Thomson felt the urgent need to unify electrical units. The introduction of the metric system made the French Revolution a big step forward, but electrical measurement created entirely new problems. Gauss and Weber laid the theoretical foundation for the system of absolute units, which means they have nothing to do with a specific substance or standard, but only depend on universal physical laws.
How to determine the scale in the absolute unit system, how to choose the appropriate multiple factor so that it can be easily used in industry, and how to persuade the scientific and technological community to accept this unit system, all of these are important and difficult tasks. In 1861 the British Scientific Association appointed a committee to begin the work, of which Thomson was a member. They worked hard for many years, and it was not until an international congress held in Paris in 1881, led by Thomson and Helmholtz, and another congress held in Chicago in 1893, that the idea was officially accepted. A new system of units, using volts, amperes, farads, and ohms as electrical units, which have been in common use ever since. However, the issue of the unit system was not resolved. Later meetings changed the definition of some of the standard quantities, and their actual values ??also changed accordingly, although this change was very small.
Kelvin was humble and diligent throughout his life, strong-willed, unafraid of failure and indomitable. When dealing with difficult issues, he said: "We all feel that difficulties must be faced squarely and cannot be avoided; we should keep them in our hearts and hope to solve them. In any case, every difficulty must have a solution, although we may not find it in our lives. You can find it." His spirit of unremitting struggle for the cause of science throughout his life will always be admired by future generations. At a conference celebrating the 50th anniversary of his professorial career at the University of Glasgow in 1896, he said: "There are two words that best represent my 50 years of scientific research struggle, and that is the word 'failure'." This is enough to illustrate his modest character. . In order to commemorate his achievements in science, the International Congress of Weights and Measures called the thermodynamic temperature scale (i.e. absolute temperature scale) the Kelvin (Kelvin) temperature scale. Thermodynamic temperature is measured in Kelvin, which is one of the seven basic units in the current International System of Units.
Kelvin's life was very successful, and he can be counted as one of the greatest scientists in the world. When he died on December 17, 1907, he was mourned by scientists throughout Britain and the world. His body was buried next to Newton's tomb in Westminster Abbey.