I explain that background freedom in quantum gravity automatically leads to a
dissociation of the quantum state into states having a classical 3d-space. That
is, interference is not completely well-defined for states with different
3d-space geometries, even if their linear combination is.
The dissociation into 3d-space geometries still allows for interference at
small scales, but precludes it at macro scales. It grants the possibility of
classical-looking macroscopic objects, including measuring devices. Counting
the 3d-space geometries automatically gives the Born rule.
But the wavefunction collapse turns out to be even more ad-hoc. Fortunately,
the dissociation entails a kind of absolute decoherence, making the
wavefunction collapse unnecessary. This naturally leads to a new version of the
many-worlds interpretation, while solving its major problems:
1) the classical-3d-space states form an absolute preferred basis,
2) at any time, the resulting micro-branches look like classical worlds, with
objects in the 3d-space,
3) the 3d-space geometries converge at the Big-Bang, favoring macro-branching
towards the future,
4) macro-branches stop interfering, even though micro-branches can interfere,
5) the wavefunctional becomes real by absorbing the complex phases in the
global U(1) gauge,
6) the ontology is a state vector uniquely dissociable into many gauged
3d-space states, each of them counting as a world by having local beables (the
3d-space geometry and the classical fields),
7) the density of the classical-3d-space states automatically obeys the Born
rule.
