THE SCALE OF THE UNIVERSE THE SOLAR 



SYSTEM 



i 



THE story of the triumphs of modern science naturally 

 opens with Astronomy. The picture of the Universe 

 which the astronomer offers to us is imperfect; the lines 

 he traces are often faint and uncertain. There are many 

 problems which have been solved, there are just as many about 

 which there is doubt, and notwithstanding our great increase in 

 knowledge, there remain just as many which are entirely 

 unsolved. 



The problem of the structure and duration of the universe 

 [said the great astronomer Simon Newcomb] is the most 

 far-reaching with which the mind has to deal. Its solution 

 may be regarded as the ultimate object of stellar astronomy, 

 the possibility of reaching which has occupied the minds of 

 thinkers since the beginning of civilisation. Before our time 

 the problem could be considered only from the imaginative 

 or the speculative point of view. Although we can to-day 

 attack it to a limited extent by scientific methods, it must 

 be admitted that we have scarcely taken more than the first 

 step toward the actual solution. . . . What is the dura- 

 tion of the universe in time? Is it fitted to last for ever in its 

 present form, or does it contain within itself the seeds of dis- 

 solution? Must it, in the course of time, in we know not 

 how many millions of ages, be transformed into something 

 very different from what it now is? This question is inti- 

 mately associated with the question whether the stars form 



