Emergent Models for Gravity: an Overview of Microscopic Models
  We give a critical overview of various attempts to describe gravity as an emergent phenomenon, starting from examples of condensed matter physics, to arrive to more sophisticated pregeometric models. The common line of thought is to view the graviton as a composite particle/collective mode. However, we will describe many different ways in which this idea is realized in practice. 
Lorenzo Sindoni
gr-qc hep-th