This weeks BMC post is a bit of an oddball.  We’ve been asked to describe our favorite fermionic system.  I’ll just leave this here:



It's where I keep all my stuff


Any guesses?

Well, my favorite fermionic system is chemistry!  Without the fermionic property of Pauli exclusion, complex chemistry would not work at all.  And, without complex chemistry there would not only be no life, there would be no rocks, no water, nothing more complicated than individual atoms and strange, disorganized molecules.  All chemical bonding relies on the fact that the electrons in an atom cannot all simply fall into the lowest energy state (something that could occur if they obeyed Bose-Einstein statistics).  This shoves electrons into the higher energy levels we all know and love from our chemistry classes.  When the highest energy levels are unfilled, the electrons like to pair up with other electrons from other atoms (kind of like the pairing up in superconducting Cooper Pairs).  This pairing up is what makes carbon form four bonds, oxygen two, etc.  If electrons did not obey Fermi-Dirac statistics, this would simply not work!  Valence electrons, and the pairing of them, exist only because of Pauli exclusion pushing electrons into these higher energy levels.  And without chemistry, none of the wonderful complexity of our everyday world would be possible.

This was a bit of a short post, but I hope I’ve shown you one way in which Fermi-Dirac statistics has importance to your daily life, beyond exotic things like neutron stars and superfluids.  Fermion exclusion is, quite literally, right at your fingertips.