ENERGY 



2902 



ENFANTIN 



ENERGY: THE DISSIPATION OF POWER 



Sir Oliver J. Lodge, F.R.S., Author of Man and the Universe 



This article, following those on Energy and Conservation of Energy, 



deals with the waste of power, i. e. the loss due to its dissipation 



throughout the universe, in machinery, and in other ways. Consult 



also Heat ; Physics ; Thermodynamics 



Lord Kelvin first noticed and 

 formulated in 1852 "a universal 

 tendency in nature to the dissipa- 

 tion of mechanical energy." The 

 idea is associated with that of 

 different forms or grades of energy, 

 some higher in the scale than 

 others, from the point of view of 

 utility or availability. 



Energy is protean in form, and 

 in the physical universe activity is 

 always accompanied by transfor- 

 mation of energy ; as soon as all 

 transformation ceases, activity 

 ceases, and torpor sets in. Now 

 some forms of energy are readily 

 controllable, and are transformable 

 into others at will. A rotating 

 flywheel and a raised weight are 

 types of easily transformable 

 energy ; either can be made to 

 drive machinery, and so do anything 

 required. In such cases very little 

 energy need be wasted by taking 

 the form of heat, though friction 

 cannot altogether be avoided. An 

 electric current is another useful 

 and tractable form of energy. But 

 some forms are comparatively in- 

 tractable, such as sound and light 

 and random eddies ; the only result 

 that can be shown for such forms, 

 when they have ceased to be, is a 

 modicum of heat. 



Energy and Heat 



In every activity contrived by 

 man some portion of energy is 

 always liable to run down into the 

 form of heat. The analogy of 

 water running down hill may be 

 adduced. When taken from a high- 

 level source, water can be em- 

 ployed to drive water-wheels or 

 turbines, but as it descends its 

 working power becomes less, and 

 ultimately, when it reaches the 

 level of the sea, though the quan- 

 tity of water remains the same, its 

 availability for power is lost. 



So when energy has reached 

 the form of heat, not much can be 

 done with it mechanically, unless 

 indeed the body possessing it is at 

 a high temperature. Heat at high 

 temperature can be utilised by 

 engineers, through steam engines, 

 internal-combustion engines, and 

 other devices. To work any form 

 of heat-engine there must be a 

 difference of temperature ; one 

 body, acting as source, must be 

 hotter than another, acting as sink ; 

 just as in the utilisation of water 

 one reservoir must be at a higher 

 level than another. If all were at 

 dead level, or all at the same tern- 

 perature, nothing could be done. 



But everyone knows that reser- 

 voirs tend to leak, and hot bodies 

 tend to cool, without doing any 

 work at all ; in other words, speak- 

 ing thermally, useful inequalities of 

 temperature tend to become ob- 

 literated by the ordinary processes 

 of radiation and conduction. Hence 

 heat is considered the lowest form 

 of energy. The proportion of heat 

 that can be utilised by a perfect 

 engine, working between given 

 limits of temperature, depends 

 directly on the difference of tem- 

 perature and inversely on how far 

 the higher of the two temperatures 

 is above absolute zero. 



Laws of Thermodynamics 



This, in mathematical language, 

 is called the second law of thermo- 

 dynamics, a law which we owe 

 originally to the genius of Sadi 

 Carnot (1796-1832). This law in- 

 volves in a precise and mathemati- 

 cal manner much that has been 

 popularly expressed above about 

 the dissipation of energy. The con- 

 servation of energy, similarly ex- 

 pressed, is called the first law of 

 thermodynamics; a law which, 

 though simple to state, was by no 

 means obvious, and had to be 

 proved, notably by Joule's experi- 

 ments between 1840 and 1860. 

 The second law, on the other hand, 

 was established by reasoning, and 

 historically preceded the first law. 



It may be perceived that in a 

 popular statement of the second 

 law of thermodynamics, or the law 

 of metrical dissipation of energy, 

 such terms as " utility " or " avail- 

 ability " are naturally employed ; 

 this tends to show that the law is 

 associated with our present means 

 of utilising the energy of heat. 

 And even when expressed precisely, 

 the terms heat and temperature 

 are essentially employed. Now 

 when we consider what heat and 

 temperature really are, and think 

 of them in terms of the motion of 

 molecules, we perceive that if only 

 the molecules themselves could be 

 harnessed we could extract their 

 energy from them and utilise it, 

 just as we utilise the energy of a 

 driven flywheel. If we possessed 

 such power, the idea of different 

 grades of energy would be super- 

 fluous or misleading. But since no 

 means of dealing individually with 

 molecules has as yet been dis- 

 covered, heat is, to us, a low form 

 of energy ; and the tendency of all 

 other forms of energy sooner or 

 later to degenerate into heat, and 



for heat to become of uniform tem- 

 perature, is what is meant by the 

 universal tendency in nature to 

 dissipation of mechanical energy. 



It is unwise, however, to base 

 on this law any confident eschato- 

 logical prediction about the uni- 

 verse, because it is always con- 

 ceivable that a mode of utilising 

 molecular energy may be dis- 

 covered, less indirect and statisti- 

 cal than any so far known. People 

 have, in fact, speculated whether 

 some low forms of life may not be 

 already selectively extracting the 

 energy of quick-moving molecules. 

 But for practical purposes, at 

 present, the law of dissipation of 

 energy, as well as the law of con- 

 servation, holds sway. 



If there is any appearance of 

 contradiction between these two 

 laws it is only superficial, and can 

 be avoided by precision of state- 

 ment and careful definition of 

 terms, especially by careful defini- 

 tion of the term energy. The irreg- 

 ular motion of a set of molecules, 

 called heat, is as much energy as 

 their regular motion, called wind ; 

 but one is easy to utilise, while the 

 other is not. Hence, when wind 

 or water currents run down into 

 generally diffused heat, their en- 

 ergy is not destroyed nor diminished 

 in quantity, but for all useful pur- 

 poses is dissipated ; the case is 

 similar when milk is spilt upon the 

 ground. 



The Problem before Humanity 



We live in a stream of continu- 

 ously dissipating energy, emitted 

 by an exceptionally hot body, the 

 sun. Plants are able to utilise and 

 store some of this, and thus tem- 

 porarily rescue it from dissipation. 

 Dissipation of the energy so stored 

 in wood or coal ultimately occurs 

 in our homes, furnaces, and factor- 

 ies. Without solar energy every- 

 thing on earth would be stagnant. 

 The chief problem which faces 

 humanity is to see that the uses 

 to which we put all this beneficent 

 energy are good. 



Enfantin, BARTH^LEMY PROSPER 

 (1796-1864). French Socialist. 

 Born in Paris, Feb. 8, 1796, he was 

 educated at the Ecole Polytech- 

 nique. In 1825 he met Saint- 

 Simon and adopted his teaching, 

 which he and Bazard disseminated 

 during the next five years. In 1832 

 he was sentenced to a year's im- 

 prisonment for his public advocacy 

 of free love. After a journey to 

 Egypt he was appointed post- 

 master of Lyons, and in 1845 be- 

 came a director of the Paris-Lyons 

 Ely. He died at Paris, Aug. 31, 

 1864. Enfantin's principal works 

 are Doctrine Saint - Simonienne, 

 with Amand Bazard, 1830; Econo- 

 mic Politique, 1831. 



