Rudolf Clausius
Rudolf Julius Emanuel Clausius (January 2, 1822 – August 24, 1888), was a German physicist and mathematician and is considered one of the central founders of the science of thermodynamics.[1] By his restatement of Sadi Carnot's principle known as the Carnot cycle, he put the theory of heat on a truer and sounder basis. His most important paper, on the mechanical theory of heat, published in 1850, first stated the basic ideas of the second law of thermodynamics. In 1865 he introduced the concept of entropy.[2]
Life
Clausius was born in Köslin in the Province of Pomerania. He started his education at the school of his father. After a few years, he went to the Gymnasium in Stettin. Clausius graduated from the University of Berlin in 1844 where he studied Mathematics and Physics with, among others, Heinrich Magnus, Johann Dirichlet and Jakob Steiner. He also studied History with Leopold von Ranke. In 1847, he got his doctorate from the University of Halle on optical effects in the earth's atmosphere.
Clausius' PhD thesis on the refraction of light proposed that the blue sky observed during the day, and various shades of red at sunrise and sunset (among other phenomena) are due to reflection and refraction of light. Later, Lord Rayleigh would show that it was in fact due to the scattering of light, but regardless, Clausius used a far more mathematical approach than his predecessors.
He then became professor of physics at the Royal Artillery and Engineering School in Berlin and Privatdozent at the Berlin university.
His most famous paper, "Über die bewegende Kraft der Wärme" ("On the Moving Force of Heat and the Laws of Heat which may be Deduced Therefrom")[3] was published in 1850, and dealt with the mechanical theory of heat. In this paper, he showed that there was a contradiction between Carnot's principle and the concept of conservation of energy. Clausius restated the two laws of thermodynamics to overcome this contradiction (the third law was developed by Walther Nernst, during the years 1906–1912). This paper caused his scientific career to take off.
In 1855 he became professor at the ETH Zürich, the Swiss Federal Institute of Technology in Zürich. In 1856, Clausius changed the conditions upon which he had earlier demonstrated the second law. Instead of relying on an argument denying the possibility of perpetual motion, he used a different axiom:
Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.
In 1857, Clausius contributed to the field of kinetic theory after refining August Krönig's very simple gas-kinetic model to include translational, rotational and vibrational molecular motions. In 1858 he introduced the concept of 'Mean free path' of a particle. He also introduced statistical arguments into his calculations, something that had not been done by his predecessors. Clausius took into account the likelihood that molecules in a gas would be moving at many different speeds at different moments. Earlier formulae derived by James Prescott Joule in 1848, for example, were based on a simplified average velocity of the molecules.
Clausius's work was improved upon by James Clerk Maxwell, who by 1860 had estimated the actual distance of the mean free path based on experiments on the rate of diffusion and viscocity of gases. Maxwell also vastly improved and applied the statistical arguments first introduced by Clausius. Maxwell's calculation was used five years later by Josef Loschmidt to calculate the size of an air molecule.
In 1864, Clausius published a version of his collected papers up to that point. A year later, Clausius introduced the word entropy into the lexicon of physicists, it being a quanity which increases in non-reversible processes and which accounts for the limitation placed upon the ability of a given amount of heat to be transformed into work.
In 1867, he moved to Würzburg and two years later, in 1869 to Bonn.
In 1870 Clausius organized an ambulance corps in the Franco-Prussian War. He was wounded in battle, leaving him with a lasting disability. He was awarded the Iron Cross for his services. A year later, he formulated a demonstration of the dynamical principles behind the second law of thermodynamics in a paper entitled On the reduction of the second law of thermodynamics to general mechanical principles. This had been done in 1866 by Ludwig Boltzmann, who commented rather condescendingly on Clausius's belated results:
"I think I have established my priority. At the end I wish to express my pleasure because an authority like Dr. Clausius contributes to the dissemination of the ideas contained in my papers on the mechanical theory of heat." <<<Bricmont, J. 2001. Chance in physics: foundations and perspectives. Berlin: Springer. 30. ISBN 3540420568.>>>
But the route Clausius used to arrive at his conclusions was somewhat different, and in Clausius's mind, superior, to that of Boltzmann. Clausius used a concept called disgregation as a starting point, and not entropy, as Boltzmann had done. He thus believed that he had achieved greater generality in his results.
Clausius's wife, Adelheid Rimpham, died in childbirth in 1875, leaving him to raise their six children. He continued to teach, but had less time for research thereafter. Clausius died in Bonn.
Work
It is important to note that Clausius chose the word "entropy" because the meaning, from Greek, en+tropein, is "content transformative" or "transformation content." In German, introduction of the term "vervanderlungsinhalt" as a descriptive of the entropy concept is also attributed to Clausius.
Clausius deduced the Clausius-Clapeyron relation from thermodynamics. This relation, which is a way of characterizing the phase transition between two states of matter such as solid and liquid, had originally been developed in 1834 by Émile Clapeyron.
Entropy
In his "Abhandlungen über die mechanische Wärmetheorie, Zweite Abteilung," published in 1867, Clausius first gave a mathematical version of the concept of entropy, and gave it its name. He used the now abandoned unit 'Clausius' (symbol: Cl) for entropy.
- 1 Cl = 1 cal/°C = 4.1868 joules per kelvin (J/K)
Tributes
- He was elected a Fellow of the Royal Society of London in 1868 and received its Copley Medal in 1879.
- He received the Huygens Medal in 1870.
- He received the Poncelet Prize in 1883.
- He received an honorary doctorate from the University of Würzburg in 1882.
- The Clausius crater on the Moon was named in his honor.
Quotes
The following are two famous quotes made by Clausius in 1865:
| “ | The energy of the universe is constant. | ” |
| “ | The entropy of the universe tends to a maximum. | ” |
See also
Notes
- ↑ Cardwell, D.S.L. (1971). From Watt to Clausius: The Rise of Thermodynamics in the Early Industrial Age. London: Heinemann. ISBN 0-435-54150-1.
- ↑ Clausius, R. (1865). The Mechanical Theory of Heat – with its Applications to the Steam Engine and to Physical Properties of Bodies. London: John van Voorst, 1 Paternoster Row. MDCCCLXVII.
- ↑ Ann. Phys. (1850), 79, 368–397, 500–524; translated into English in: Phil. Mag. (1851), 2, 1–21, 102–119
ReferencesISBN links support NWE through referral fees
<<We need at least 3 reliable references here, properly formatted.>>
- Leff, Harvey S., and Andrew F. Rex. 2003. Maxwell's demon 2 entropy, classical and quantum information, computing. Bristol: Institute of Physics. 58-70. ISBN 0585492379.
- Bricmont, J. 2001. Chance in physics: foundations and perspectives. Berlin: Springer. ISBN 3540420568.
External links
- Revival of Kinetic Theory by Clausius
- Clausius biography in The MacTutor History of Mathematics archive
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