July 23, 1920] 



SCIENCE 



73 



luminous backgrounds. Is it too mucli to 

 suppose that these nebulae consist of atoms re- 

 cently formed in the laboratory of space and 

 beginning to assemble for their careers in the 

 world of matter? This would seem to be the 

 simplest guess, and it is worth considering. 



The physicists are inclined to believe that 

 the property of mass is due to the electric 

 charges of the electrons. If now a negative 

 electron should collide and unite with a posi- 

 tive electron the electric charges would disap- 

 pear, and so also would the property of mass. 

 If the speed of this collision were equal to the 

 velocity of light, which seems probable enough 

 from the known speeds of the electrons then 

 the energy set free is calculable. It is found 

 that one gram of matter passing through such 

 an experience would liberate five billion calor- 

 ies of heat. The unit resulting from this 

 collision would not possess the property of 

 mass, but it would be an organization of some 

 kind. If we suppose that the radiant energy 

 of the stars as it flows through space should 

 succeed in splitting this unit again into two 

 electrons the property of mass would be re- 

 stored, but a corresponding amount of radiant 

 energy would have disappeared. 



So far as I know the physicists have not 

 announced a law that for every positive elec- 

 tron there exists a corresponding negative 

 electron, but the electrical neutrality of mat- 

 ter seems to imply that it is true. If the two 

 kinds of electrons exist as the result of the 

 splitting of a single unit it is easy to see why 

 it should be true, but quite a considerable 

 puzzle otherwise. 



It seems almost axiomatic that no organized 

 physical system can endure a condition of un- 

 limited violence without breaking down; and 

 since the atom is such a system it seems in- 

 evitable that under suitable conditions it will 

 collapse, and its energy of organization will 

 be set free. The extreme conditions as to 

 temperature and pressure which exist in the 

 interior of a star seem to make this an ideal 

 place for an atom to break down and give up 

 its energy and its property of mass, if such an 

 event is to occur anywhere. Such a process 

 seems almost necessary if we are to account 



for the energies of the stars over the extended 

 periods of time which the dimensions and 

 forms of the galaxies seem to imply. On such 

 a basis the sun possesses in its present mass a 

 siifficient store of energy to last, at its present 

 rate of radiation, five thousand millions of 

 years. Such a period of time is short from an 

 astronomical point of view, but as the sun 

 travels through space at a speed of about 

 twelve miles per second it must pick up atoms, 

 and molecules, and an occasional solid frag- 

 ment, and in this way add to its mass. Oc- 

 casionally it will pass throug'h nebulous re- 

 gions and add to its mass with relative ra- 

 pidity. We can suppose that on the whole the 

 sun, and the other stars also, gather in as 

 much energy as they radiate, and the em- 

 barrassment arising from their relatively 

 sliort periods of luminosity and their reckless 

 expenditure of energy disappears. 



To an audience of astronomers much could 

 be said in favor of accounting for the sun's 

 heat in this manner, but such evidence would 

 be of but little interest to those who are not 

 astronomers. The main point of interest to 

 them would be that under this hypothesis the 

 geologists and biologists are freed from the 

 restraints as to time, for the astronomers 

 could furnish them with all of the time which 

 they wished. There would be no fixed upper 

 limit to the life of the sun, and the stars in 

 general could continue to illuminate their paths 

 through space for indefinite ages still to come. 

 The haunting fear of a general stellar death is 

 gone and the forbidding picture of the galaxy 

 as a dismal, dreary graveyard of dead stars 

 fades away from our sight; and in its stead 

 we see an indefinite continuation of our pres- 

 ent active, living universe with its never-ceas- 

 ing ebb and flow of energy. Those wonderful 

 organizations which we call the physical units 

 will continue to be built up when the condi- 

 tions are favorable, pass their allotted time in 

 such activities as are suitable to their nature, 

 and finally yielding up the energy by which 

 they were organized, be resolved again into the 

 elements from which they came. The individ- 

 ual perishes, but the race lives on. 



The astronomer with his telescope, the biol- 



