302 THE FITNESS OF THE ENVIRONMENT 



currences, it is evident that nebulae them- 

 selves are in a general way determined by 

 other antecedent conditions and phenomena, 

 which turn out to be collisions between stars. 

 Thus arises the suspicion that cosmic evolu- 

 tion may be in truth a cyclic process which 

 had no beginning and can have no end. 1 

 An alternative hypothesis regards the pres- 



1 Such a view, until quite recently, was universally rejected 

 because it appeared to conflict with the second law of thermo- 

 dynamics, — that of the degradation of energy. But lately it 

 has been put forth by no less an authority than Arrhenius, 

 who has advanced a theory to explain away the difficulty of 

 the second law. 



"The recognition of the indestructibility of energy 

 seemed to accentuate the difficulties of the cosmogonic prob- 

 lems. The theses of Mayer and of Helmholtz, on the man- 

 ner in which the Sun replenished its losses of heat, have had 

 to be abandoned. My explanation is based upon chemical 

 reactions in the interior of the Sun in accordance with the 

 second law of thermodynamics. The theory of the 'degra- 

 dation' of energy appeared to introduce a still greater diffi- 

 culty. That theory seems to lead to the inevitable conclu- 

 sion that the Universe is tending towards the state which 

 Clausius has designated as 'Warme Tod' (heat death), when 

 all the energy of the Universe will be uniformly distributed 

 through space in the shape of movements of the smallest 

 particles. That would imply an absolutely inconceivable 

 end of the development of the Universe. The way out of this 

 difficulty which I propose comes to this : the energy is * de- 

 graded' in bodies which are in the solar state, and the energy 

 is 'elevated,' raised to a higher level, in bodies which are in 

 the nebular state." — Arrhenius, "Worlds in the Making," 

 translated by Boras. New York and London, 1908, p. xiii. 



