  We review how reparametrization of space and time, namely the procedure where
both are made to depend on yet another parameter, can be used to formulate
quantum physics in a way that is naturally conducive to relativity. This leads
us to a second quantised formulation of quantum dynamics in which different
points of spacetime represent different modes. We speculate on the fact that
our formulation can be used to model dynamics in spacetime the same way that
one models propagation of an electron through a crystal lattice in solid state
physics. We comment on the implications of this for the notion of mode
entanglement as well as for the fully relativistic Page-Wootters formulation of
the wavefunction of the Universe.
