# pauli exclusion principle Formulated by Wolfgang Pauli in 1925, Pauli exclusion principle states that "no two fermions can have the same quantum state simultaneously. In the spectra of every element #The Pauli Exclusion Principle arises from the antisymmetric nature of the wavefunction for fermions. When two identical fermions are swapped, the total wavefunction must change sign. This requirement leads to the conclusion that the wavefunction must be zero if two fermions are in the same state, implying that they cannot occupy the same quantum state. #Mathematically , this can be expressed as: ψ ( r 1 , r 2 ) = − ψ ( r 2 , r 1 ) where ψ \psi is the wavefunction, and r 1 and r 2 \mathbf{r}_2 are the coordinates of the two fermions. If r 1 = r 2 \mathbf{r}_1 = \mathbf{r}_2 ,then ψ = 0, enforcing the exclusion principle.