The space time DoF surface density as a phase-space of accelerating   reference frames
  Padmanabhan found a definition for the surface density of space time degrees of freedom. We prove that this density can be constructed from a phase space which is derived with respect to a special space like vector field. This vector field is the direction of an accelerating vector field. After projecting this phase space along a velocity vector field, we show that Padmanabhan's surface density is actually the projected phase space during one period of the Euclidean time which is expected for a canonical ensemble. This suggests that Padmanabhan's density should be regarded as a spatial phase space which is driven by acceleration. 
Merav Hadad
gr-qc