A Finite Universe 15 



after a journey counted in thousands of years" (The 

 Vault of Heaven, 2d ed., 1923, p. 147). 



According to Einstein and others the universe is 

 finite though boundless, and the astronomer De 

 Sitter has estimated its circumference at about 100 

 million light-years — about ten times the possible dis- 

 tance from the earth to the farthest spiral nebula 

 visible in the telescope. De Sitter estimates the mass 

 of the universe at about a quintillion quadrillions 

 (10 54 ) of grams, and the number of electrons at a 

 quintillion octillions (10 78 ) (see Arthur Haas, The 

 New Physics, 1923). 



We cannot think of such vastnesses without feeling 

 that we are citizens of no mean city, but perhaps we 

 should be more impressed by the order and the uni- 

 formity of the heavens. Even the comets have their 

 courses, and though there have been cataclysms in 

 the course of ages a new order rises out of the old. 

 Clerk Maxwell's declaration is familiar : "Though in 

 the course of ages catastrophes have occurred and 

 may yet occur in the heavens, though ancient sys- 

 tems may be dissolved and new systems evolved out 

 of their ruins, the molecules [or atoms, we should 

 say] out of which these systems are built — the foun- 

 dation-stones of the material universe — remain un- 

 broken and unworn. They are this day as they 

 were created — perfect in number and measure and 

 weight." The discovery of radio-activity necessitates 

 some change in the wording, but not in the idea. The 

 world is one and orderly. 



