204 THE MECHANISM OF LIFE 



finitesimal period of time, and the " normal " condition of 

 maximum entropy is again attained. 



The visible universe — that is, our galactic system of radiating 

 stars — has, we have reasons for believing, definite boundaries. 

 If we could travel out from our sun in any direction for about 

 30,000 light years* (that is, 30,000x365x24x60x60 seconds X 

 186,000 miles) it is possible that we should reach those boun- 

 daries. But beyond this we can still imagine ourselves travelling 

 on indefinitely far.f In this outer space there would, however, 

 be no radiating cosmic bodies, though we might suppose that 

 there are dark, cold suns and satellites, and cold, cosmic dust. 

 Then, after incredibly further voyaging, we might encounter 

 other galactic universes. This means that our picture of the 

 entire universe is one in which the normal condition is physical 

 I death — the complete cessation of all happening — entropy having 

 attained its maximum. But here and there in the whole uni- 

 verse, and occupying regions that are of infinitesimal extent, 

 there are individual universes, of which our galactic system is 

 one. The normal condition of the entire scheme of things is 

 that to which we see all physical changes tending, the complete 

 dissipation of energy. But now and then, and for periods of 

 time that are infinitesimal in duration, infinitesimally small 

 'regions of the entire universe blaze up, so to speak, the second 

 law becoming reversed and entropy becoming decreased. After 

 this has occurred, the individual universe then much more 

 slowly sinks back again to the normal condition — that in which 

 entropy tends slowly towards its maximum and to which physical 

 death is the limit. The universe, then, in which we are living 

 is an incredibly small fraction of all that exists, and its genesis 

 as an individual, physically active universe was an occurrence 

 essentially similar to that of our gas model. Some time in the 

 past the second law became reversed, and available energy was 

 restored. Then this became slowly dissipated, so that the phase 

 in which we are living is the more probable one — that which 

 tends always towards complete degradation of energy. 



In this way we avoid the physical impasse to which we are 

 brought when we assume the universal validity of the first and 

 second laws of thermo-dynamics. Our whole universe becomes a 



* A light-year is about six billions of miles. 



t Not on the theory of relativity. We cannot go beyond the boundary 

 of the universe, for outside the latter there is no space. See Appendix 11. 



