310 SCIENCE PROGRESS 



again, preceded Life in the world's history, just as Vitality itself has preceded con- 

 sciousness and social change. 



Can we further ascertain the general conditions of this evolution, and whether 

 its future course and increased complexity are limited or not ? 



II. The Relation between Development and the Degradation 



of Energy. 



(8) The relation between vital phenomena and the universal transformation of 

 energy has been considered by Dr. Johnstone, 1 who concludes pessimistically that 

 " the universe tends towards a limit which is the cessation of all phenomena — 

 universal physical death " (p. 650). But I think it is possible to show that such a 

 negation of the evolution of Life and Mind is not altogether justified. 



Clerk Maxwell has pointed out that while the dissipation of energy is closely 

 connected with the increase of entropy, it is not identical with it ; and that in 

 calculating dissipated energy we must take account of the final temperature of the 

 system when in thermal and mechanical equilibrium 2 ; so that the apparently 

 wasteful exothermic chemical production of heat must be considered together 

 with (a) the initial and final temperature of the whole system, and (b) the in- 

 creasing stability of the resultant products. 3 



Is it possible, then, from this standpoint to suggest any rationale of the actual 

 distribution of universal heat and matter among bodies varying enormously in 

 volume and temperature, and all in the main losing heat ? 



(9) Obviously the only conceivable alternative— a system with low or zero 

 temperature— would be mechanically quite valueless; and since every physical* 

 process has its optimum range of temperature, any diversified system of change 

 plainly necessitates a very extensive scale of temperatures, each optimal to some 

 definite process, and therefore possibly only through a slow fall from a very high 

 initial temperature. Optimal temperatures, again, fall into (a) those which make 

 possible any given combination— critical temperatures ; and (b) those which 

 permit any such combination, once formed, to persist ; and, as Dr. Johnstone 

 observes, all exothermic changes tend towards increased stability. Thus the 

 protracted temperature fall, necessary in the first place for diversified physical 

 changes, also makes possible (a) the initiation and {b) the persistence of stable 

 combinations—/.^, in short a continuous increase in stable complexity. 5 



But it also brings about other results. For since the sum of the moments of 

 momentum in a system is constant, it must, in face of the continued heat loss, 

 tend to assume a symmetrical instead of any originally irregular form, and this 

 the more rapidly the more heat is lost ; while at the same time the resultant con- 

 traction tends to accelerate rotational velocity, so that {e.g.) the present form and 

 motions of the solar system could only have been brought about through the loss 

 of its initial heat. 



(10) Thus the heat loss, which at first sight appears to be a serious defect, is 



1 Science Progress, ix. p. 646. 



2 Theory of Heat, p. 192. 



3 Johnstone, loc. cit. p. 648. 



* " Physical" is used here in its widest possible meaning. 



5 But this change is wrongly regarded as being from homogeneity to hetero- 

 geneity, for the initial stage must be itself as heterogeneous as the final, since the 

 ultimate elements throughout remain the same ; the point is that the resultant 

 systems become more complex and stable, 



