We introduce a duality relation between two distinct branes, a cosmological brane with macroscopic matter and a holographic brane with microscopic gauge fields. Using brane-world cosmology with a single brane in a 5-dimensional AdS(5) background, we find an explicit time-dependent holographic correspondence between the bulk metric surrounding the cosmological brane and the N = 4 gauge field theory living on the boundary of the Z(2)-symmetric mirror bulk, identified with the holographic brane. We then relate the cosmic acceleration on the cosmological brane to the conformal anomaly of the gauge theory on the holographic brane. This leads to a dual microscopic interpretation of the number of e-foldings of the cosmological eras on the cosmological brane.