THE PATH OF EVOLUTION 



Clausius states : " The mean length of the free path 

 of the particles of a gas increases in proportion as the 

 square of the diameter of the particle diminishes. 

 By assuming the particles to be small enough, the 

 mean length of its path may be increased to any ex- 

 tent. A-priori, one size of particles is as probable 

 as another. The minute size and high velocity 

 would render it possible that no disturbance would 

 be caused amongst the molecules of ordinary matter. 

 This high velocity is necessary to accord with the 

 known facts of gravity. Sir William Thomson has 

 pointed out that the distance through which gravity 

 is affected (i. e., that one body should act upon or at- 

 tract another) is dependent upon the mean length of 

 the path of the particles. By assuming the distance 

 of the fixed stars (not a star and its planets) to be a 

 multiple of the mean path, it would result that the 

 stars would not gravitate towards each other, thus 

 satisfying the condition for the stability of the 

 universe." The assumption that all the bodies of the 

 Universe are gravitating towards each other is evi- 

 dently inconsistent with the stability of the stellar 

 bodies, each of which probably has a planetary system 

 of its own. This does not mean that the gravitic 

 ether has not the same modus operandi at all dis- 

 tances, but that the individual particles would col- 

 lide with others at the end of their free paths at all 

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