CONFLICT WITH WAVE-THEORY 189 



on, there comes a time when one begins to perceive that 

 the evasions are far-fetched. If we have any instinct 

 that can recognise a fundamental law of Nature when 

 it sees one, that instinct tells us that the interaction of 

 radiation and matter in single quanta is something lying 

 at the root of world-structure and not a casual detail in 

 the mechanism of the atom. Accordingly we turn to the 

 "sweepstake" theory, which sees in this phenomenon a 

 starting-point for a radical revision of the classical con- 

 ceptions. 



Suppose that the light-waves are of such intensity that, 

 according to the usual reckoning of their energy, one- 

 millionth of a quantum is brought within range of each 

 atom. The unexpected phenomenon is that instead of 

 each atom absorbing one-millionth of a quantum, one 

 atom out of every million absorbs a whole quantum. 

 That whole quanta are absorbed is shown by the photo- 

 electric experiments already described, since each of the 

 issuing electrons has managed to secure the energy of a 

 whole quantum. 



It would seem that what the light-waves were really 

 bearing within reach of each atom was not a millionth 

 of a quantum but a millionth chance of securing a whole 

 quantum. The wave-theory of light pictures and 

 describes something evenly distributed over the whole 

 wave-front which has usually been identified with energy. 

 Owing to well-established phenomena such as interfer- 

 ence and diffraction it seems impossible to deny this uni- 

 formity, but we must give it another interpretation; it 

 is a uniform chance of energy. Following the rather 

 old-fashioned definition of energy as "capacity for doing 

 work" the waves carry over their whole front a uniform 

 chance of doing work. It is the propagation of a chance 

 which the wave-theory studies. 



