  A currently active radio galaxy sits at the center of almost every strong
cooling core. What effect does it have on the cooling core? Could its effect be
strong enough to offset the radiative cooling which should be occuring in these
cores? In order to answer these questions we need to know how much energy the
radio jet carries to the cooling core; but we have no way to measure the jet
power directly. We therefore need to understand how the radio source evolves
with time, and how it radiates, in order to use the data to determine the jet
power. When some simple models are compared to the data, we learn that
cluster-center radio galaxies probably are energetically important -- but not
necessarily dominant -- in cooling cores.
