214 THE NEW QUANTUM THEORY 



closely, a more extended storm leaves it very vague. If 

 we try to interpret an extended wave-group in classical 

 language we say that it is a particle which is not at any 

 definite point of space, but is loosely associated with a 

 wide region. 



Perhaps you may think that an extended stormy area 

 ought to represent diffused matter in contrast to a con- 

 centrated particle. That is not Schrodinger's theory. 

 The spreading is not a spreading of density; it is an 

 indeterminacy of position, or a wider distribution of the 

 probability that the particle lies within particular limits 

 of position. Thus if we come across Schrodinger waves 

 uniformly filling a vessel, the interpretation is not that 

 the vessel is filled with matter of uniform density, but 

 that it contains one particle which is equally likely to be 

 anywhere. 



The first great success of this theory was in repre- 

 senting the emission of light from a hydrogen atom — 

 a problem far outside the scope of classical theory. The 

 hydrogen atom consists of a proton and electron which 

 must be translated into their counterparts in the sub- 

 aether. We are not interested in what the proton is 

 doing, so we do not trouble about its representation by 

 waves; what we want from it is its field of force, that is 

 to say, the spurious v which it provides in the equation 

 of wave-propagation for the electron. The waves 

 travelling in accordance with this equation constitute 

 Schrodinger's equivalent for the electron; and any solu- 

 tion of the equation will correspond to some possible 

 state of the hydrogen atom. Now it turns out that 

 (paying attention to the obvious physical limitation that 

 the waves must not anywhere be of infinite amplitude) 

 solutions of this wave-equation only exist for waves with 

 particular frequencies. Thus in a hydrogen atom the 



