Pauli’s Exclusion Principle PEP of stdQM states that more than one electron of the same spin cannot occupy the same region in space, while at most two electrons of different spin can. PEP appears as an ad hoc principle without physical rationale, as acknowledged by Pauli in his Nobel Lecture 1946:
- Already in my original paper I stressed the circumstance that I was unable to give a logical reason for the exclusion principle or to deduce it from moregeneral assumptions. I had always the feeling and I still have it today, that this is a deficiency.
In realQM all electrons occupy different regions as a natural effect of mutual repellation and there is no need of any additional ad hoc PEP.
The two-valuedness of the PEP of stdQM in the form of spin up/down of overlapping electrons, is in realQM in basic form replaced by the two-valuedness of the Helium atom with its two electrons occupying different half-spaces (giving rise to the factor 2 in the number of electrons in a fully filled electron shell .