Pauli's exclusion principle

The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. This principle is significant, because it explains why matter occupies space exclusively for itself and does not allow other material objects to pass through it, while at the same time allowing light and radiation to pass. It states that no two identical fermions may occupy the same quantum state simultaneously. A more rigorous statement of this principle is that, for two identical fermions, the total wave function is anti-symmetric. For electrons in a single atom, it states that no two electrons can have the same four quantum numbers, that is, if n, l, and ml are the same, ms must be different such that the electrons have opposite spins.
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A fundamental principle of A fundamental principle of quantum theory which states that no two fermions in a single system can exist in the same quantum state. The principle describes the physical processes which lead to the structure of atoms. It is also essential in describing the conditions under which degenerate matter exists. Hence it explains how white dwarfs and neutron stars support themselves against the downward pull of gravity.