EVOLUTION IN GENERAL 271 



thesis of natural selection it was generally held that there was one 

 process of universal evolution and that stellar, planetary, geological 

 and organic evolutionary processes were all phases in one general 

 process. We can now easily see that this view is unsound and 

 that the process of organic evolution exhibits a tendency which 

 is the opposite to that of stellar, planetary and geological evolution. 



89. ON THE TENDENCY IN COSMIC EVOLUTION 



On the older views the stars and planets were regarded as very 

 hot bodies that were cooling, or had cooled down to the tempera- 

 ture of cosrpic space. This is true, but it is not the whole truth. 

 The consequence of the views was this : there were concentrations 

 of energy in the universe and these were the stars. If we w^ere 

 to '* sample " the universe by taking blocks of space of, say, one 

 billion of miles in volume there would be a certain, rather small 

 probability that any such block taken at random would contain 

 a concentration of energy — that is, a cooling, but hot star. On 

 the other hand, so far apart from each other are the stars that the 

 probability that our sampled volume would not contain a star 

 would be much greater. 



As the stars cool their energy is radiated away as heat (low- 

 frequency radiation) and this energy travels in all directions 

 throughout interstellar space. The more the hot stars cool down 

 the less energy they " contain," but the more energy is " con- 

 tained " in the interstellar space. Finally (when each star gives 

 off just as much energy, as heat, as it receives from the heat given 

 off by all other stars), all universal stellar and interstellar space 

 will be at the same temperature. Therefore, while cooling is 

 going on, energy becomes more and more uniformly distributed 

 and the probability that random sampling of cosmic space w^ould 

 give equal energy-contents would become maximal. 



The recent cosmogony does not affect this conclusion. First 

 it was shown that hot stars, like our sun, and cold bodies, like 

 the earth, emit energy that comes from the radio-active disintegra- 

 tions of atoms like those of uranium. But however protracted 

 such a source of energy must be, it must ultimately fail and these 

 emissions of high-frequency radiation ultimately degenerate into 

 low- frequency radiation, or heat. And the latter tends to become 

 uniformly diffused throughout interstellar space, as before. 



