228 MODEKN VIEWS ON MATTER. 



then pass on from one into another, going- through a series of transi- 

 tional states, and abiding for a long time in those contigurations which 

 are most stable; giving a process of evolution inconceivably slow in 

 its later stages, comparatively rapid in its early ones, and yet not so 

 rapid, even in a substance like radium, but that its life as such may 

 be reckoned by thousands of years. 



If such a transitory existence is ever established for the forms of 

 matter as we know them, it by no means follows that the process goes 

 on in one direction only, or that the total amount of matter in the 

 universe is subject to diminution. There may be regeneration as well 

 as degeneration. 



The total amount of radio-activity in a substance is singularly con- 

 stant. If the radio-active portion is removed, a fresh supply makes 

 its appearance at a measured rate, that rate being expressible by a 

 decreasing geometrical progression, and being precisely equal to the 

 rate at which the power of the removed portion decays. 



Whether the total amount of matter in the universe is constant 

 likewise, as much disappearing at one end by resolution into electrons 

 as is formed at the other end by their aggregating together, is at 

 present ()uite unknown; and, indeed, it is clear that we have now become 

 far immersed in the region of speculation. Nevertheless, it is specula-' 

 tion not of an illegitimate character, for it is ver}^ consistent with all 

 that we know about the rest of the material uni\erse. 



Astronomy tells us that the cosmic scheme, though it looks perma- 

 nent, is subject to constant flux. In the sky we see solar systems and 

 suns in process of formation by aggregation out of nebula?; we see 

 them rise in brillianc}', maintaining a number of planets in health and 

 activity for a time, and then slowly become subject to decay and death. 

 What happens after that is not certainly known. It may be that by col- 

 lision a nebula mav be reconstituted and the process started again; 

 though so long as there is only a force of one sign at work (gravitation 

 onl}') it would seem that ultimately the regenerative process must 

 come to an end. The repellent force exerted by light upon small 

 particles, however, must not be forgotten; it can overcome gravitation 

 when it acts on small enough ])odies; and there are other possibilities. 

 Among the parts of an atom certainly the forces are conspicuously not 

 of one sign. Inside an atom there exist both attractive and repulsive 

 forces. The resolution of an atom into its electron constituents, and 

 the aggregation of these constituents into fresh atoms, are both per- 

 fectly^ thinkable. All we have to do is to ascertain by careful and 

 patient investigation wliat really happens; and my experience has led 

 me to feel sure of this — that whatever hypotheses and speculations we 

 may frame, we can not exceed the reality in genuine wonder; and I 

 believe that the simplicity and beauty of the truth concerning even 

 the material universe, when we know it, will be such as to elicit feel- 

 ino's of reverent awe and adoration. 



