  We present a short, general and accessible introduction to quantizing gravity
in the Heisenberg picture. We then apply this formalism to the scenario where
two spatially superposed masses interact through the gravitational field. We
discuss some of the consequences for quantum gravity including the spin of the
graviton, the notions of locality and causality, as well as going beyond the
linear regime. We use the Schwinger action principle and the Heisenberg
representation which we believe make the issues involved clearer. We conclude
by commenting on a number of traditionally discussed apparent problems with
quantizing gravity (only to, ultimately, deny their very existence).
