  A deSitter brane-world bounding regions of anti-deSitter space has a
macroscopic entropy given by one-quarter the area of the observer horizon. A
proposed variant of the AdS/CFT correspondence gives a dual description of this
cosmology as conformal field theory coupled to gravity in deSitter space. In
the case of two-dimensional deSitter space this provides a microscopic
derivation of the entropy, including the one-quarter, as quantum entanglement
of the conformal field theory across the horizon.
