  The work distribution of an expanding extreme relativistic gas is shown to be
a gamma distribution with a different shape parameter as compared with its
non-relativistic counterpart. This implies that the shape of the transverse
energy distribution in relativistic heavy ion collisions depends on the
particle contents during the evolution of the hot and dense matter. Therefore,
transverse energy fluctuations provide additional insights into the Quark-Gluon
Plasma produced in these collisions.
