Emergence in holographic scenarios for gravity

Abstract

'Holographic' relations between theories have become an important themein quantum gravity research. These relations entail that a theorywithout gravity is equivalent to a gravitational theory with an extraspatial dimension. The idea of holography was first proposed in 1993 byGerard 't Hooft on the basis of his studies of evaporating black holes.Soon afterwards the holographic 'AdS/CFT' duality was introduced, whichsince has been intensively studied in the string theory community andbeyond. Recently, Erik Verlinde has proposed that even Newton's law ofgravitation can be related holographically to the 'thermodynamics ofinformation' on screens. We discuss these scenarios, with specialattention to the status of the holographic relation in them and to thequestion of whether they make gravity and spacetime emergent. Weconclude that only Verlinde's scheme straightforwardly instantiatesemergence. However, assuming a non-standard interpretation of AdS/CFTmay create room for the emergence of spacetime and gravity there aswell.