6 



SCIENCE 



[JSr. S. Vol. LIV. No. 1383 



of matter. With radium and witli uranium 

 we do not see anything but the decay. And 

 yet somewhere, somehow, it is almost certain 

 that these elements must be continually form- 

 ing. They are probably being put together 

 now somewhere in the laboratories of the 

 stars. That is still something of a guess, 

 it is true, and yet the spectra of the nebulae 

 show that they contain only the lighter ele- 

 ments. Can we ever learn to control the 

 process? Why not? Only research can tell. 

 What is it worth to try it? A million dol- 

 lars? A hundred million? A billion? It 

 would be worth that much if it failed, for you 

 could count on more than that amount in 

 by-products. And if it succeeded — a new 

 world for man! But what have we got al- 

 ready through the discovery of radio-activity? 

 An immensely stimulating new conception of 

 the universe and of the way matter is be- 

 having. 



'Next the significance of radium with re- 

 spect to the question of the availability of en- 

 ergy. The amount of heat given ofE from one 

 gram of radium in disintegrating into lead is 

 300,000 times as much as the amount of heat 

 given off in the burning of one gram of coal. 

 There is, then, in the radium a supply of 

 sub-atomic energy, and this raises the ques- 

 tion as to whether such energy exists locked up 

 in other atoms and as to whether there is any 

 possible way we can get at it? Do not be too 

 sanguine about it as far as radium is con- 

 cerned, because if all the radium at present in 

 the world were set to work, although it is 

 300,000 times as potent as coal per gram in 

 giving off energy, it would not suffice to keep 

 the corner popcorn man's outfit going. It 

 does not exist in sufficient quantity. 



But what has its discovery done then in the 

 field of energy? It has opened our eyes to the 

 fact that certain kinds of matter certainly 

 possess these stores of energy and it is almost 

 a foregone conclusion that similar stores are 

 also possessed by the atoms which we have not 

 yet found to be changing — which are not 

 radio-active. The astronomer has for years 

 been completely puzzled to account for enor- 

 mous amounts of energy which the sun and 



stars emit. He has not been able to find its 

 source. It is impossible that the sun is 

 simply a hot body cooling off, because we 

 have evidence that it has lived longer than it 

 could have lived if that were the case. The 

 astronomer has now, however, seized upon 

 the facts of radio-activity and surmises that 

 these sub-atomic energies may be the source 

 of the sun's radiation. If so the supplies are 

 not so limited as we thought. 



Look now at another side of this same prob- 

 lem. I am thinking particularly of the work 

 of Professor Joly and Lord Rayleigh, who 

 have made measurements of the amount of 

 radio-activity of the ordinary surface rocks. 

 Professor Joly has computed that if there are 

 two parts of radio-active material for every 

 million million parts of other matter through- 

 out the whole volume of the earth, and 

 this is considerably less than he has found on 

 the average in the earth's crust, then this 

 earth, instead of cooling off, is actually now 

 heating up ; so that in a hundred million years 

 the temperature of its core will have risen 

 through 1,800 degrees centigrade. That is a 

 temperature which will melt almost all of our 

 ordinary substances. Wliat does it mean? It 

 means that the life history of our planet is 

 perhaps not at all what we have heretofore 

 thought that it was. It means that a planet 

 that seems to be dead, as this our earth seems 

 to be, may, a few eons hence, be a luminous 

 body, and that it may go through periods of 

 expansion when it radiates enormously, and 

 then of contraction when it becomes like our 

 present earth, a body which is a heat insulator 

 and holds in its interior the energy given off 

 by radio-active processes, until another period 

 of luminosity ensues. What I am now point- 

 ing out is the growth in our conception of the 

 world, the growth in the thoughts of men 

 that has come out from these studies. Do 

 not think that this is not of importance. 

 When Galileo discovered the moons of Jupiter 

 he was doing just about as useless a thing 

 from the standpoint of its irmnediate appli- 

 cability to human relations as he could have 

 found to do. And yet what did he actually 

 accomplish? He started off the train of 



