  The conventional approach to study glasses either requires considering the
rapid drop in the excess entropy {\Delta}S_ex or the free volume V_f. As the
two quantities are not directly related to each other, the viscosity in the two
approaches do not diverge at the same temperature, which casts doubt on the
physical significance of the divergence and of the ideal glass transition (IG).
By invoking a recently developed nonequilibrium thermodynamics, we identify the
instantaneous temperature, pressure, entropy, etc. and discover the way they
relax. We show that by replacing {\Delta}S_ex by a properly defined communal
entropy S^comm (not to be confused with the configurational entropy) and V_f
vanish simultaneously at IG, where the glass is jammed with no free volume and
communal entropy. By exploiting the fact that there are no thermodynamic
singularities in the entropy of the supercooled liquid at IG, we show that
various currently existing phenomenologies become unified.

Statistical Mechanics