242 THE NEW KNOWLEDGE. 



it is available, some is non-available: the former is in every 

 phenomenon somewhat diminished but never increased : the 

 non-available energy is constantly increasing: hence the 

 Available Energy of the Universe tends to Zero." Again, 

 Professors Stewart and Tait say: ". . . it is absolutely 

 certain that age after age the possibility of such trans- 

 formations (of energy) is becoming less and less; and, so 

 far as we yet know, the final state of the present Universe 

 must be an aggregation into one mass of all the matter it 

 contains, i. e., the potential energy gone, and a practically 

 useless state of kinetic energy, i. e., uniform temperature 

 throughout that mass." 



Is such a conclusion absolutely certain? It all depends 

 upon the validity of the Second Law of Thermodynamics. 

 This "law" states that "one part of a body of uniform 

 temperature cannot grow hotter at the expense of the heat 

 of the remainder unless work is performed upon it," con- 

 sequently, if the energy of the universe is being continu- 

 ously degraded into heat of equal temperature it will even- 

 tually be a dead universe. That this "law" however has 

 limitations has been recognised since the time of Clerk- 

 Maxwell. The kinetic theory of gases teaches us that in a 

 gas of uniform temperature, while the average velocity of 

 the molecules comprising the gas must be a constant quan- 

 tity the individual velocities of the molecules must vary to 

 a great degree, some of them possessing velocities higher and 

 others lower than the average. 



Clerk-Maxwell imagined a firm partition, full of little 

 doors, to be placed so as to divide the vessel into two, 

 and to each door he placed an intelligent little demon 

 with precise instructions to open the door whenever he 

 saw a quick moving molecule approach in such a way 

 that it could get through from the first compartment 



