  The metric determines the casual structure of spacetime, but in quantum
gravity it is also a dynamical field which must be quantized using this causal
structure; this is the famous problem of time. A radical resolution of this
paradox is proposed: remove the concept of space-like separation entirely. This
can be done by describing all fields in terms on p-jets, living on the
observer's trajectory; all points on the trajectory have time-like separations.
Such a description is necessary to construct well-defined representations the
N-dimensional generalization of the Virasoro algebra Vir(N); this is the
natural quantum extension of vect(N), which is the correct symmetry algebra of
general relativity in N dimensions. The limit p -> oo, necessary for a field
theory interpretation, only exists if N = 4 and there are three fermions for
every two bosons, a relation that is satisfied in the standard model coupled to
gravity.
