Geodesic distance: A descriptor of geometry and correlator of pregeometric density of spacetime events

Abstract

Classical geometry can be described either in terms of a metric tensor [Formula: see text] or in terms of the geodesic distance [Formula: see text]. Recent work, however, has shown that the geodesic distance is better suited to describe the quantum structure of spacetime. This is because one can incorporate some of the key quantum effects by replacing [Formula: see text] by another function [Formula: see text] such that [Formula: see text] is nonzero. This allows one to introduce a zero-point-length in the spacetime. I show that the geodesic distance can be an emergent construct, arising in the form of a correlator [Formula: see text], of a pregeometric variable [Formula: see text], which can be interpreted as the quantum density of spacetime events. This approach also shows why null surfaces play a special role in the interface of quantum theory and gravity. I describe several technical and conceptual aspects of this construction and discuss some of its implications.