﻿51G Mr. S. B. McLaren on Emission and Absorption 



I argue finally that the problem of the distribution of 

 energy reduced as it is to the determination of the function 

 / is beyond dynamics in its present state. Equipartition is 

 a necessary inference if we assume Hamilton's equations 

 deduced as they are from the principle of least action, and 

 an essentially positive energy function. If we are willing 

 to resign the law of minimum action, equations of motion 

 differing from Hamilton's will lead to different results. 

 Equipartition can then be avoided. But the problem of 

 radiation is not thus brought nearer a solution. No con- 

 tinuous laws of motion in which energy is conserved can 

 account for that distribution of energy which we find realized 

 in nature. (See, however, conclusion.) Some such revolution 

 of our physical ideas as is foreshadowed in the work of Planck 

 and Einstein is, it would seem, inevitable; at the most it may 

 be hoped that the future will adapt and not destroy the work 

 of the past. In this paper " aether " still retains its classical 

 traditional value, it is the aether of Maxwell's equations. I 

 have determined how it would interact with matter in any 

 continuous motion. It is only by pushing the mechanical 

 theory to its limits that we can discover where these limits lie. 

 But to maintain such types of motion as in reality exist, other 

 forces must be involved than those known to our present 

 dynamics. Only the aether then, only what is not matter is 

 completely mechanical. Nor need this be surprising. The 

 problem of radiation involves the ultimate constitution of 

 matter, and the latest work on Physics makes it even more 

 evident how inadequate mechanical ideas are to unravel that. 

 The spectroscope shows us matter classified in distinct 

 species without continuous change from one species to 

 another. On any purely mechanical theory this is almost 

 impossible to explain. If any one type of motion is possible 

 in a dynamical system there must be others continuous with 

 the first. And the theory of relativity removes even the 

 possibility of rigid bodies. Where all substance is mobile 

 how does each atom or molecule remain within such narrow 

 limits constant to its own type ? The conclusion forces itself 

 that the mechanics which describes the motion of matter 

 in bulk cannot deal with its ultimate parts. 



§2. The Definition of Radiation. 



Electromagnetic theory explains the inertia of matter in 

 terms of its own fundamental concepts of electric and 

 magnetic intensity. Thus regarded the kinetic energy of 

 an electron is energy of the field surrounding it. In any 



