  Field theories that are generally covariant but nongravitational at tree
level typically give rise to an emergent gravitational interaction whose
strength depends on a physical regulator. We consider emergent gravity models
in which scalar fields assume the role of clock and rulers, addressing the
problem of time in quantum gravity. We discuss the possibility of nontrivial
dynamics for clock and ruler fields, and describe some of the consequences of
those dynamics for the emergent gravitational theory.
