Description of the Electron Degeneracy Principle

[realPhysics49]

I understand that the electron degeneracy principle states that no two electrons can occupy the same space at once. However, I do not think I clearly understand the physics behind that. I talked to my physics teacher about this and he said it had to do with the electron spin; I thought it was the electric repulsion force between the electrons. Can someone please clarify this?

 

[e.bar.goum]

It's more fundamental that that - the principle states that two (spin half) particles cannot have exactly the same quantum state - so the two electrons may not share exactly the same properties, like position, momentum and spin - something about them must be different. So two electrons in an atomic orbital must have opposite spins, for instance.

The principle comes out of a theory called Quantum Field Theory quite naturally, but we usually just take it as a principle (and it was assumed before QFT).