CHAPTER I 



The Birth of Our World 



ALL that we know of the extent of the universe has been 

 revealed to us by the light of the stars. At a speed of 

 186,000 miles a second the light of the nearest of these stars 

 takes about two years to reach us. We do not know how far 

 removed the furthest of them is ; we cannot even affirm that 

 their distance is inversely proportional to their brilliance, nor 

 can we say how many figures would be necessary to express 

 this distance in miles. Whatever the nature of light may be 

 we are at all events certain that it cannot reach us from those 

 stars unless it is borne by that " unknown something " which 

 fills space. It was once believed that this unknown medium was 

 the substance of light itself. To-day, however, there are strong 

 reasons for assuming that this medium exists in its own right. 

 It has been named the ether, and has been pictured as composed 

 of particles so small that in comparison with them an atom is 

 enormous. These particles are capable of oscillating around a 

 fixed point from which they can deviate only very slightly, 

 and these regular oscillations, propagated in the ether 

 as ripples are propagated in water when a stone is dropped 

 into it, constitute light. The light of the sun and of the various 

 stars maintain vibrations in the ether, which cross each other 

 in every direction without mingling, but they are not alone in 

 traversing it, for the ether is the scene of tremendous agitations. 

 Through its medium the stars attract each other and the sun- 

 spots influence our magnetic needles, and there is even a 

 question whether it is not actually the substratum of matter. 

 Contrary to a belief that seemed at one time to be final, the 

 study of radium has demonstrated that matter is neither 

 eternal nor immutable. Atoms of radium destroy themselves 

 spontaneously and give rise to helium and hydrogen. This 

 destruction liberates a sufficient quantity of energy to act 

 at a distance, through the ether, upon other atoms. 



