Hi. I'm a sophomore undergrad studying chemistry at Rice University. I recently took quantum mechanics... and I now realize I should have gone into physics rather than chemistry. Ok. Whatever. Bosons are particles with integer spins (helium-4 atoms). Fermions are particles with half-odd integer spins (electrons). I can't think of a non-(God-made-it-so) reason for why every fermion in a given system must have a unique set of quantum numbers (Pauli's Exclusion Principle). This rule simply doesn't apply to bosons. While this phenomena in nature is the very reason we observe such diverse chemistry among the chemical elements, could it be that the exclusion principle is simply an axiom of nature? If not, I'm really, really dying for a good expanation.