Pauli Exclusion Principle: Why You Don't Implode . ... Credit Copyright: Andrew Truscott Randall Hulet ( Rice U. ) Explanation: Why doesn't matter just bunch up? ... Earlier this decade, the Pauli Exclusion Principle was demonstrated graphically in the above picture of clouds of two isotopes of lithium -- the left cloud composed of bosons while the right cloud is composed of fermions . ... The reason why the Pauli Exclusion Principle is true and the physical limits of the principle are still unknown. ...