ON THE NATURE OF LIFE 197 



may happen in our universe is that there must be available 

 energy, and that this must transform into the inavailable form. 

 In other words, energy must be concentrated somewhere, and 

 when a phenomenon occurs it becomes dissipated, or spread out. 

 Having become dissipated or spread out, nothing more can happen, 

 for this energy has lost its capacity for doing work. The second 

 law of thermo-dynamics states that in all natural changes energy 

 becomes dissipated, or entropy increases. 



The Condition of the Universe. — Next, we must consider this 

 problem. Is the universe finite or infinite in space and duration ? 

 Or we may put the question more clearly. If we were able to 

 travel away from our earth into outer space, like Richter's 

 Dreamer, should we at length enter regions where there were no 

 longer any stars ? Or if we could, like Mr. Wells's Time Traveller, 

 go indefinitely far back into duration, should we come to a time 

 when there were no earth and stars ? It may seem foolish to 

 suggest these questions, but, as a matter of fact, we can, pro- 

 visionally at least, answer the first one. There does seem to be a 

 ^ limit to the number of stars in the sky, and it seems that these 

 form a cluster, or galaxy, which is finite. If the numbers of 

 stars were really infinite, certain consequences would be the 

 result. If there were no absorption of light by dark cosmic 

 bodies the night sky would be an uniform blaze of light, and even 

 if there were absorption of light energy would still be infinite 

 in some form or other. Such is not the case, and so we conclude 

 that the stellar universe which radiates energy is a finite one.* 



Is its past duration also infinite ? We can easily imagine 

 ourselves travelling further and further away from the earth 

 without limit, and passing out at last from the region of stars, 

 or, more generally, of available energy. But we cannot think of 

 a time in the past, however remote, when the universe did not 

 exist, when there was no available energy. For the quantity 

 of available energy in our universe is decreasing, and in the past 

 it must have been greater than it now is. Was there a time, then, 

 when energy came into existence from nothing ? That implies 

 creation, and, since we hold to the law of conservation as a mode 

 of our thought, we cannot, therefore, think of a time when the uni- 

 verse began. We conclude, then, that its past duration is infinite.f 



* The theory of relativity helps us here. The universe that we see 

 is finite, but unbounded. Its fonn of space is four-dimensional and 

 spherical. See Appendix II. 



t See Appendix II. 



