  Standard statistical thermodynamic views of temperature fluctuations predict
a magnitude $(\sqrt{<(\Delta T)^2>}/T)\approx\sqrt{(k_B/C)}$ for a system with
heat capacity $C$. The extent to which low temperatures can be well defined is
discussed for those systems which obey the thermodynamic third law in the form
$\lim_{(T\to 0)}C=0$. Physical limits on the notion of very low temperatures
are exhibited for simple systems. Application of these concepts to bound Bose
condensed systems are explored, and the notion of bound Boson superfluidity is
discussed in terms of the thermodynamic moment of inertia.
