  We argue that a conformally invariant extension of general relativity coupled
to the Standard Model is the fundamental theory that needs to be quantized. We
show that it can be treated by loop quantum gravity techniques. Through a gauge
fixing and a modified Higgs mechanism particles acquire mass and one recovers
general relativity coupled to the Standard Model. The theory suggests new views
with respect to the definition of the Hamiltonian constraint in loop quantum
gravity, the semi-classical limit and the issue of finite renormalization in
quantum field theory in quantum space-time. It also gives hints about the
elimination of ambiguities that arise in quantum field theory in quantum
space-time in the calculation of back-reaction.
