According to the third law of thermodynamics, one could argue that a vacuum has zero entropy, since it has only one ground state and a temperature at absolute zero. However, assuming the accelerated expansion of the universe to result in a 'heat death', i.e. a state of absolute thermal equilibrium with maximum entropy (following from the second law of TD), how is this state different from that of a vacuum? If the universe expands infinitely, energy density will near zero, resulting in absolute zero temperature and the universe basically having one ground state. Could one not argue that, since the thermal equilibrium of a vacuum is (near-)perfect and since there is little 'usable' information, its entropy is actually at a maximum level? In short: which thermodynamical definition of a vacuum or vacuum-like state (such as the infinitely expanding universe) is correct?