In AdS-space the (linearized) Einstein equations can be derived by applying the 1st law of thermodynamics to the entanglement entropy associated with finite boundary regions. The notion of holographic entanglement can be generalized to finite regions in the bulk, but the relevant degrees of freedom are only well understood at scales large compared to the AdS-radius.
To go to smaller scales one needs to introduce additional “confined” degrees of freedom using an analogue of the long string phenomena. This description of space time entanglement generalizes to flat space and even to de Sitter space. In the latter case, one finds that the space-time degrees of freedom are (contrary to AdS) in an excited state characterized by the Gibbons-Hawking entropy and temperature. This observation has important implications for emergent gravity in a cosmological setting.
