  Recently the neglected issue of the causal structure in the flat spacetime
approach to Einstein's theory of gravity has been substantially resolved.
Consistency requires that the flat metric's null cone be respected by the null
cone of the effective curved metric. While consistency is not automatic,
thoughtful use of the naive gauge freedom resolves the problem. After briefly
recapitulating how consistent causality is achieved, we consider the flat
Robertson-Walker Big Bang model. The Big Bang singularity in the spatially flat
Robertson-Walker cosmological model is banished to past infinity in Minkowski
spacetime. A modified notion of singularity is proposed to fit the special
relativistic approach, so that the Big Bang becomes nonsingular.
