  The area of a future holographic screen increases monotonically. Associating
this area with entropy results in a generalized second law for Cosmology
(GSLC). Unlike black hole horizons, screens relevant to Cosmology have no
thermodynamical interpretation. We suggest relating the entropy of the screens
to spacetime degrees of freedom surface density derived from a (seemingly)
phase space. This construction enables us to identify the entropy of any
holographic screen as the entropy detected by accelerating observers due to
their acceleration. Using Unruh's temperature and the equivalence principle,
this gives the holographic screens' temperature and yields a thermodynamical
interpretation of the GSLC.
