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Home > Dictionary of Science Quotations > Scientist Names Index C > Rudolf Clausius Quotes

 Rudolf Clausius (2 Jan 1822 - 24 Aug 1888) German mathematical physicist.

Science Quotes by Rudolf Clausius (5 quotes)

Die Energie der Welt ist constant. Die Entropie der Welt strebt einem Maximum zu.
The energy of the world is constant. The entropy of the world tends towards a maximum.
— Rudolf Clausius
The “world” here refers to the universe as a whole. This is the way Clausius gave a summary of the first and second laws of thermodynamics. German from Clausius, conclusion of 'Ueber verschiedene für die Anwendung bequeme Formen der Hauptgleichungen der mechanischen Wärmetheorie' in Poggendorff’s Annals of Physics (1865)‚ 125, 400. Also quoted at the conclusion of 'Theorie der Wärme', in G. Quincke and B. Schwalbe (eds.), Die Fortschritte der Physik im Jahre 1866 (1869), 22, 254. As translated in P.K. Nag, Engineering Thermodynamics (5th ed., 2013), 25.
Science quotes on:  |  Constant (148)  |  Energy (373)  |  Entropy (46)  |  Tend (124)  |  World (1850)

Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.
— Rudolf Clausius
'On a Modified Form of the Second Fundamental Theorem in the Mechanical Theory of Heat', Philosophical Magazine, 1856, 12, 86.
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In all cases where work is produced by heat, a quantity of heat proportional to the work done is expended; and inversely, by the expenditure of a like quantity of work, the same amount of heat may be produced.
— Rudolf Clausius
'On the Moving Force of Heat, and the Laws regarding the Nature of Heat itself which are deducible therefrom', Philosophical Magazine, 1851, 2, 4.
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The fundamental laws of the universe which correspond to the two fundamental theorems of the mechanical theory of heat.
1. The energy of the universe is constant.
2. The entropy of the universe tends to a maximum.
— Rudolf Clausius
The Mechanical Theory of Heat (1867), 365.
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We might call it the transformational content of the body … But as I hold it better to borrow terms for important magnitudes from the ancient languages, so that they may be adopted unchanged in all modern languages, I propose to call [it] the entropy of the body, from the Greek word “trope” for “transformation” I have intentionally formed the word “entropy” to be as similar as possible to the word “energy”; for the two magnitudes to be denoted by these words are so nearly allied in their physical meanings, that a certain similarity in designation appears to be desirable.
— Rudolf Clausius
In 'The Bulldog: A Profile of Ludwig Boltzmann', The American Scholar (1 Jan 1999), 99.
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Quotes by others about Rudolf Clausius (4)

So many of the properties of matter, especially when in the gaseous form, can be deduced from the hypothesis that their minute parts are in rapid motion, the velocity increasing with the temperature, that the precise nature of this motion becomes a subject of rational curiosity. Daniel Bernoulli, Herapath, Joule, Kronig, Clausius, &c., have shewn that the relations between pressure, temperature and density in a perfect gas can be explained by supposing the particles move with uniform velocity in straight lines, striking against the sides of the containing vessel and thus producing pressure. (1860)
In W.D. Niven (ed.) 'Illustrations of the Dynamical Theory of Gases,' The Scientific Papers of James Clerk Maxwell, Vol 1, 377. Quoted in John David Anderson, Jr., Hypersonic and High Temperature Gas Dynamics (2000), 468.
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It is very desirable to have a word to express the Availability for work of the heat in a given magazine; a term for that possession, the waste of which is called Dissipation. Unfortunately the excellent word Entropy, which Clausius has introduced in this connexion, is applied by him to the negative of the idea we most naturally wish to express. It would only confuse the student if we were to endeavour to invent another term for our purpose. But the necessity for some such term will be obvious from the beautiful examples which follow. And we take the liberty of using the term Entropy in this altered sense ... The entropy of the universe tends continually to zero.
Sketch of Thermodynamics (1868), 100-2.
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In despair, I offer your readers their choice of the following definitions of entropy. My authorities are such books and journals as I have by me at the moment.
(a) Entropy is that portion of the intrinsic energy of a system which cannot be converted into work by even a perfect heat engine.—Clausius.
(b) Entropy is that portion of the intrinsic energy which can be converted into work by a perfect engine.—Maxwell, following Tait.
(c) Entropy is that portion of the intrinsic energy which is not converted into work by our imperfect engines.—Swinburne.
(d) Entropy (in a volume of gas) is that which remains constant when heat neither enters nor leaves the gas.—W. Robinson.
(e) Entropy may be called the ‘thermal weight’, temperature being called the ‘thermal height.’—Ibid.
(f) Entropy is one of the factors of heat, temperature being the other.—Engineering.
I set up these bald statement as so many Aunt Sallys, for any one to shy at.
[Lamenting a list of confused interpretations of the meaning of entropy, being hotly debated in journals at the time.]
In The Electrician (9 Jan 1903).
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I venture to assert that the feelings one has when the beautiful symbolism of the infinitesimal calculus first gets a meaning, or when the delicate analysis of Fourier has been mastered, or while one follows Clerk Maxwell or Thomson into the strange world of electricity, now growing so rapidly in form and being, or can almost feel with Stokes the pulsations of light that gives nature to our eyes, or track with Clausius the courses of molecules we can measure, even if we know with certainty that we can never see them I venture to assert that these feelings are altogether comparable to those aroused in us by an exquisite poem or a lofty thought.
In paper (May 1891) read before Bath Branch of the Teachers’ Guild, published in The Practical Teacher (July 1891), reprinted as 'Geometry', in Frederic Spencer, Chapters on the Aims and Practice of Teaching (1897), 194.
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• 2 Jan - short biography, births, deaths and events on date of Clausius's birth.

In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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