Manifestly Gauge-Invariant General Relativistic Perturbation Theory: II. n FRW Background and

In our companion paper we identified a complete set of manifestly ngauge-invariant observables for general relativity. This was possible by ncoupling the system of gravity and matter to pressureless dust which plays the nrole of a dynamically coupled observer. The evolution of those observables is ngoverned by a physical Hamiltonian and we derived the corresponding equations ..