  Experiments performed in the last years demonstrated slow relaxations and
aging in the conductance of a large variety of materials. Here, we present
experimental and theoretical results for conductance relaxation and aging for
the case-study example of porous silicon. The relaxations are experimentally
observed even at room temperature over timescales of hours, and when a strong
electric field is applied for a time $t_w$, the ensuing relaxation depends on
$t_w$. We derive a theoretical curve and show that all experimental data
collapse onto it with a single timescale as a fitting parameter. This timescale
is found to be of the order of thousands of seconds at room temperature. The
generic theory suggested is not fine-tuned to porous silicon, and thus we
believe the results should be universal, and the presented method should be
applicable for many other systems manifesting memory and other glassy effects.
