  We present experiments on several distinct effective temperatures in a
granular system at a sequence of increasing packing densities and at a sequence
of decreasing driving rates. This includes single-grain measurements based on
the mechanical energies of both the grains and an embedded oscillator, as well
as a collective measurement based on the Einstein relation between diffusivity
and mobility, which all probe different time scales. Remarkably, all effective
temperatures agree. Furthermore, mobility data along the two trajectories
collapse when plotted vs effective temperature and exhibit an Arrhenius form
with the same energy barrier as the microscopic relaxation time.
