CHAPTER IV 



SUPRA-STARS AND LIVING GALAXIES 



WE have now to proceed in making our final choice 

 between the various solutions presented by the 

 problem of the Infinite Universe. We shall 

 assume : 



1. That the material universe is infinite in three- 

 dimensional space, and eternal both in the past 

 and the future. 



2. That the law of gravitation holds good through- 

 out infinite time and space. 



3. That the luminiferous ether has the same 

 properties throughout space. 



These assumptions have already been shown to 

 be well founded. Gravitation and the propagation 

 of light are the same for all parts of the stellar 

 system hitherto explored, and even in spectro- 

 scopic binaries we have enough material to show 

 that their orbits are conic sections. We know 

 that the only laws of central force under which a 

 body will have such an orbit for all initial conditions 

 are: (1) Newton's law of gravitation, and (2) the 

 law according to which the force is directly pro- 



