94 TWO NEW WORLDS 



this increase were maintained down to the seven- 

 teenth magnitude, the light of all stars combined 

 should be seven times as great as moonlight, whereas, 

 in reality, it is only one-twentieth." 



All these arguments are, of course, purely optical. 

 They fall to the ground as soon as we admit the 

 possibility of further stellar universes consisting of 

 dark stars. Our own stellar system contains vast 

 numbers of such bodies, and there is no reason 

 why a stellar system should not be free from light 

 of that particular wave-length which impresses our 

 eyes or our photographic plates. For aught we 

 know, the luminosity of our stellar system may bo 

 a very temporary affair. Lord Kelvin estimates 

 the life of our sun as 50 to 100 million years 

 a period which, on the supra-world scale, would 

 amount to about a ten-millionth of a second. 



There is, of course another possibility. If the 

 world was ere* ted 100,000 years ago, then no light 

 from bodies nore than 100,000 light-years away 

 from us conic 7 possibly have reached us up to the 

 present ; but light from stars further and further 

 away would be continually arriving at the earth's 

 surface, and thus our vision into space, confined at 

 present by the Milky Way, would be expanding 

 at the rate of 186,000 miles per second. That 

 possibility would become a probability if at any 

 time a great cluster of stars were to become 

 visible, and remain visible, without showing any 



