CONFLICT WITH WAVE-THEORY 185 



smaller pieces without limit there is no end to the 

 process of shuffling. The indivisible units in the shuf- 

 fling of energy are the quanta. By radiation absorp- 

 tion and scattering energy is shuffled among the different 

 receptacles in matter and aether, but only a whole 

 quantum passes at each step. It was in fact this definite- 

 ness of thermodynamical equilibrium which first put 

 Prof. Max Planck on the track of the quantum; and the 

 magnitude of h was first calculated by analysis of the 

 observed composition of the radiation in the final state 

 of randomness. Progress of the theory in its adolescent 

 stage was largely due to Einstein so far as concerns the 

 general principles and to Bohr as regards its connection 

 with atomic structure. 



The paradoxical nature of the quantum is that 

 although it is indivisible it does not hang together. We 

 examined first a case in which a quantity of energy was 

 obviously cohering together, viz. an electron, but we did 

 not find h; then we turned our attention to a case in which 

 the energy was obviously dissolving away through space, 

 viz. light-waves, and immediately h appeared. The 

 atom of action seems to have no coherence in space; 

 it has a unity which overleaps space. How can such a 

 unity be made to appear in our picture of a world 

 extended through space and time? 



Conflict with the Wave-Theory of Light. The pursuit of 

 the quantum leads to many surprises; but probably none 

 is more outrageous to our preconceptions than the 

 regathering of light and other radiant energy into 

 A-units, when all the classical pictures show it to be 

 dispersing more and more. Consider the light-waves 

 which are the result of a single emission by a single atom 

 on the star Sirius. These bear away a certain amount of 



