202 THE NEW QUANTUM THEORY 



be amply covered by the wave-theory; and the clearing 

 away of false evidence for a partly corpuscular theory, 

 which influenced Newton, is as much a part of scientific 

 progress as the bringing forward of the (possibly) true 

 evidence, which influences us to-day. To imagine that 

 Newton's great scientific reputation is tossing up and 

 down in these latter-day revolutions is to confuse science 

 with omniscience. 



To return to the wavicle. — If that which we have 

 commonly regarded as a wave partakes also of the 

 nature of a particle, may not that which we have com- 

 monly regarded as a particle partake also of the nature 

 of a wave? It was not until the present century that 

 experiments were tried of a kind suitable to bring out 

 the corpuscular aspect of the nature of light; perhaps 

 experiments may still be possible which will bring out 

 a wave aspect of the nature of an electron. 



So, as a first step, instead of trying to clear up the 

 mystery we try to extend it. Instead of explaining how 

 anything can possess simultaneously the incongruous 

 properties of wave and particle we seek to show experi- 

 mentally that these properties are universally associated. 

 There are no pure waves and no pure particles. 



The characteristic of a wave-theory is the spreading 

 of a ray of light after passing through a narrow aper- 

 ture — a well-known phenomenon called diffraction. The 

 scale of the phenomenon is proportional to the wave- 

 length of the light. De Broglie has shown us how to 

 calculate the lengths of the waves (if any) associated 

 with an electron, i.e. considering it to be no longer a pure 

 particle but a wavicle. It appears that in some circum- 

 stances the scale of the corresponding diffraction effects 

 will not be too small for experimental detection. There 

 are now a number of experimental results quoted as 



