  An attempt is made to de-mystify the apparent "paradox" between microscopic
time revsersibility and macroscopic time irreversibility. It is our common
experience that a hot cup of coffee cools down to room temperature and it never
automatically becomes hot (unless we put that in a microwave for heating or on
stove etc) and there are numerous examples. This "one sidedness" of physical
processes (like cooling of hot cup) is in apparent contradiction with the time
reversibility of the dynamical equations of motion (classical or quantum). The
process of automatic heating of a cold cup etc is perfectly possible from the
dynamical equations perspective. Ludwig Boltzmann explained this "one
sidedness" of physical processes starting from dynamical equations (his
H-theorem). A criticism was raised by Boltzmann's contemporaries. The origin of
this criticism lies in the very philosophy of "mechanism" that was very
prevalent in the 19th century. Everyone wanted to understand physical phenomena
through Newtonian mechanics (even J. C. Maxwell devised a mechanical mechanism
using gears to explain the electromagnetic field!). The central issue was how
can one obtain this "one sidedness" (time irreversiblility) if the underlying
dynamical laws are time reversible. Number of articles exist in literature on
the issue. But those are mathematically oriented and a simple presentation from
practical point of view is seriously lacking. This article is an attempt to
de-mystify this "paradox" from simple and practical point of view.
