PPT Slide
A particular quantum state, completely described by enough quantum numbers, is called a state function or wave function: ?
When we observe the state, we find out its quantum numbers, “observables”
The state function of two different states ?1 ?2 is equal to the linear sum of the two ?s = ?1 + ?2 and this is attested by many experimental facts, e.g. two electron states like He or the hydrogen molecule.
The interpretation of this given by Borh and others seems very strange. Examples were given by Schrodinger and Einstein (who did not believe it) to show that it must be wrong. Schrodinger gave the example of his cat: ironically, both would be paradoxes have important applications.