  We investigate the dependence of the longitudinal emitter dimension of
identical bosons, produced in the hadronic Z$^0$ decays, on their transverse
mass obtained from 2-dimensional Bose-Einstein correlations (BEC) analyses. We
show that this dependence is well described by the expression
$r_{||}=c\sqrt{\hbar\Delta t}/\sqrt{m_T}$, deduced from the uncertainty
relations, setting $\Delta t$ to be a constant of the order of $10^{-24}$ sec.
This equation is essentially identical to the one previously applied to the
1-dimensional BEC results for the emitter radius dependence on the boson mass
itself. It is further shown that a very similar behaviour exists also for the
dependence of the interatomic separation in Bose condensates on their atomic
masses when they are at the same very low temperature.
