  The time scale $\Delta t$ parameter, which appears in the Bose-Einstein
Correlations (BEC) treated in term of the Heisenberg uncertainty relations, is
reexamined. Arguments are given for the role of $\Delta t$ as a measure of the
particles' emission time rather than representing the strength property of the
correlated particles. Thus in the analyzes of the $Z^0$ hadronic the $\Delta t$
given value of ~$10^{-24}$ seconds is the particles' emission time prescribed
by the $Z^0$ lifetime. In heavy ion collisions $\Delta t$ measures the emission
time duration of the particles produced from a nucleus of atomic number $A$
which is here shown to be equal to $\Delta t =(m_{\pi}a^2)/(\hbar
c^2})*A^{2/3}$ where a is about 1 fm, that is, proportional to the nucleus
surface area. This dependence agrees rather well with the experimental $\Delta
t$ values deduced from the BEC analyzes of heavy ion collisions.
