It would be difficult to understand the behavior of electrons
without the Fermi Dirac statistics. Why in a metal, electrons can
move freely to conduct the electric current and why their
contribution in the same metal to the specific heat is negligible,
as if their number become for an unknown reason, considerably
reduced. We have here a problem of "statistical order" that can be
explained only by using the Fermi Dirac statistics (the classical
statical mechanics was unable to explain this phenomenon).