THERMODYNAMICAL EQUILIBRIUM 77 



complete in itself. It results from a different '(and 

 rather more practical) conception of the aim of our 

 traffic with the secrets of Nature. 



The question whether the second law of thermo- 

 dynamics and other statistical laws are mathematical 

 deductions from the primary laws, presenting their 

 results in a conveniently usable form, is difficult to 

 answer; but I think it is generally considered that there 

 is an unbridgeable hiatus. At the bottom of all the 

 questions settled by secondary law there is an elusive 

 conception of u a priori probability of states of the 

 world" which involves an essentially different attitude to 

 knowledge from that presupposed in the construction of 

 the scheme of primary law. 



Thermo dynamical Equilibrium. Progress of time intro- 

 duces more and more of the random element into the 

 constitution of the world. There is less of chance about 

 the physical universe to-day than there will be to-mor- 

 row. It is curious that in this very matter-of-fact 

 branch of physics, developed primarily because of its 

 importance for engineers, we can scarcely avoid express- 

 ing ourselves in teleological language. We admit that 

 the world contains both chance and design, or at any 

 rate chance and the antithesis of chance. This antithe- 

 sis is emphasised by our method of measurement of 

 entropy; we assign to the organisation or non-chance 

 element a measure which is,* so to speak, proportional 

 to the strength of our disbelief in a chance origin for it. 

 "A fortuitous concourse of atoms" — that bugbear of 

 the theologian — has a very harmless place in orthodox 

 physics. The physicist is acquainted with it as a much- 

 prized rarity. Its properties are very distinctive, and 

 unlike those of the physical world in general. The 



