Clarification of susskind lectures

[Getterdog]

In lecture 2,he states that when we prepare an electron and then apply a magnetic field,only 2 things can happen, no photon,or 1 photon. " if a photon is emitted,then its frequency corresponds to the amount of energy that would be radiated if the electron had been prepared in the <north-down> position." Now if the photon can have only 1 energy , how do we now for a single electron what up or down is? I'm confused .

 

[Nugatory]

"Up" is the direction the magnetic field is pointing, "down" is the opposite direction, and the interesting (and somewhat confounding) thing is that the electron never acts as if it's in between the two.

 

[Getterdog]

"Up" is the direction the magnetic field is pointing, "down" is the opposite direction, and the interesting (and somewhat confounding) thing is that the electron never acts as if it's in between the two.

So you would say that when no photon is emitted that corresponds to an up spin?